Version bump

* Move MTaskState to ThreadSchedule

MTaskState does not concern itself with sandbagging, and thus solely contains information related to the finalized schedule, i.e., completion time, thread ID and next MTask on thread.

* Add .dot graph visualization of ThreadSchedule

Follow-up to #2779.

This commit adds the creation of .dot files - used by GraphViz - to visualize how mtasks are statically scheduled across the set of specified threads.
We visualize each thread as a row, with nodes of a row being the mtasks scheduled for the given thread. The width of the mtask nodes are proportional to their cost. MTask dependencies are shown using an edge between the source and sink mtasks.

.clang-format

@@ -0,0 +1,111 @@
+---
+Language:        Cpp
+# BasedOnStyle:  LLVM
+AccessModifierOffset: -4
+AlignAfterOpenBracket: Align
+AlignConsecutiveAssignments: false
+AlignConsecutiveDeclarations: false
+AlignEscapedNewlines: DontAlign
+AlignOperands:   true
+AlignTrailingComments: false
+AllowAllParametersOfDeclarationOnNextLine: true
+AllowShortBlocksOnASingleLine: true
+AllowShortCaseLabelsOnASingleLine: true
+AllowShortFunctionsOnASingleLine: All
+AllowShortIfStatementsOnASingleLine: true
+AllowShortLoopsOnASingleLine: true
+AlwaysBreakAfterDefinitionReturnType: None
+AlwaysBreakAfterReturnType: None
+AlwaysBreakBeforeMultilineStrings: false
+AlwaysBreakTemplateDeclarations: false
+BinPackArguments: true
+BinPackParameters: true
+BraceWrapping:
+  AfterClass:      false
+  AfterControlStatement: false
+  AfterEnum:       false
+  AfterFunction:   false
+  AfterNamespace:  false
+  AfterObjCDeclaration: false
+  AfterStruct:     false
+  AfterUnion:      false
+  AfterExternBlock: false
+  BeforeCatch:     false
+  BeforeElse:      false
+  IndentBraces:    false
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+BreakBeforeBinaryOperators: All
+BreakBeforeBraces: Attach
+BreakBeforeInheritanceComma: false
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: false
+BreakConstructorInitializers: BeforeComma
+BreakAfterJavaFieldAnnotations: false
+BreakStringLiterals: true
+ColumnLimit:     99
+CommentPragmas:  '^ IWYU pragma:'
+CompactNamespaces: false
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+ConstructorInitializerIndentWidth: 4
+ContinuationIndentWidth: 4
+Cpp11BracedListStyle: true
+DerivePointerAlignment: false
+DisableFormat:   false
+ExperimentalAutoDetectBinPacking: false
+FixNamespaceComments: true
+ForEachMacros:
+  - foreach
+  - Q_FOREACH
+  - BOOST_FOREACH
+IncludeBlocks:   Preserve
+IncludeCategories:
+  - Regex:           '^"(llvm|llvm-c|clang|clang-c)/'
+    Priority:        2
+  - Regex:           '^(<|"(gtest|gmock|isl|json)/)'
+    Priority:        3
+  - Regex:           '.*'
+    Priority:        1
+IncludeIsMainRegex: '(Test)?$'
+IndentCaseLabels: false
+IndentPPDirectives: None
+IndentWidth:     4
+IndentWrappedFunctionNames: false
+JavaScriptQuotes: Leave
+JavaScriptWrapImports: true
+KeepEmptyLinesAtTheStartOfBlocks: true
+MacroBlockBegin: ''
+MacroBlockEnd:   ''
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+ObjCBlockIndentWidth: 2
+ObjCSpaceAfterProperty: false
+ObjCSpaceBeforeProtocolList: true
+PenaltyBreakAssignment: 2
+PenaltyBreakBeforeFirstCallParameter: 19
+PenaltyBreakComment: 300
+PenaltyBreakFirstLessLess: 120
+PenaltyBreakString: 1000
+PenaltyExcessCharacter: 1000000
+PenaltyReturnTypeOnItsOwnLine: 60
+PointerAlignment: Left
+ReflowComments:  true
+SortIncludes:    false
+SortUsingDeclarations: true
+SpaceAfterCStyleCast: false
+SpaceAfterTemplateKeyword: true
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeParens: ControlStatements
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 2
+SpacesInAngles:  false
+SpacesInContainerLiterals: true
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+Standard:        Cpp11
+TabWidth:        8
+UseTab:          Never
+...
+

.clang-tidy

@@ -1,8 +1,8 @@
-Checks:          'clang-diagnostic-*,clang-analyzer-*,*,-modernize*,-hicpp*,-android-cloexec-fopen,-cert-dcl50-cpp,-cert-env33-c,-cert-err34-c,-cert-err58-cpp,-clang-analyzer-core.UndefinedBinaryOperatorResult,-clang-analyzer-security*,-cppcoreguidelines-no-malloc,-cppcoreguidelines-owning-memory,-cppcoreguidelines-pro-bounds-array-to-pointer-decay,-cppcoreguidelines-pro-bounds-array-to-pointer-decay,-cppcoreguidelines-pro-bounds-constant-array-index,-cppcoreguidelines-pro-bounds-pointer-arithmetic,-cppcoreguidelines-pro-type-const-cast,-cppcoreguidelines-pro-type-reinterpret-cast,-cppcoreguidelines-pro-type-static-cast-downcast,-cppcoreguidelines-pro-type-union-access,-cppcoreguidelines-pro-type-vararg,-cppcoreguidelines-special-member-functions,-fuchsia-default-arguments,-fuchsia-overloaded-operator,-google-default-arguments,-google-readability-todo,-google-runtime-references,-llvm-header-guard,-llvm-include-order,-misc-string-integer-assignment,-misc-string-literal-with-embedded-nul,-readability-braces-around-statements,-readability-container-size-empty,-readability-delete-null-pointer,-readability-else-after-return,-readability-implicit-bool-conversion,-readability-named-parameter,-readability-static-accessed-through-instance'
+Checks:          '*,-hicpp*,-android-cloexec-fopen,-cert-dcl50-cpp,-cert-env33-c,-cert-err34-c,-cert-err58-cpp,-clang-analyzer-core.UndefinedBinaryOperatorResult,-clang-analyzer-security*,-cppcoreguidelines-avoid-magic-numbers,-cppcoreguidelines-no-malloc,-cppcoreguidelines-owning-memory,-cppcoreguidelines-pro-bounds-array-to-pointer-decay,-cppcoreguidelines-pro-bounds-array-to-pointer-decay,-cppcoreguidelines-pro-bounds-constant-array-index,-cppcoreguidelines-pro-bounds-pointer-arithmetic,-cppcoreguidelines-pro-type-const-cast,-cppcoreguidelines-pro-type-reinterpret-cast,-cppcoreguidelines-pro-type-static-cast-downcast,-cppcoreguidelines-pro-type-union-access,-cppcoreguidelines-pro-type-vararg,-cppcoreguidelines-special-member-functions,-fuchsia-*,-google-default-arguments,-google-readability-todo,-google-runtime-references,-llvm-header-guard,-llvm-include-order,-misc-string-integer-assignment,-misc-string-literal-with-embedded-nul,-modernize-use-auto,-modernize-use-trailing-return-type,-readability-braces-around-statements,-readability-container-size-empty,-readability-delete-null-pointer,-readability-else-after-return,-readability-implicit-bool-conversion,-readability-named-parameter,-readability-static-accessed-through-instance'
 WarningsAsErrors: ''
 HeaderFilterRegex: ''
 FormatStyle:     none
-CheckOptions:    
+CheckOptions:
   - key:             google-readability-braces-around-statements.ShortStatementLines
     value:           '2'
   - key:             google-readability-namespace-comments.SpacesBeforeComments

.codacy.yml

@@ -0,0 +1,6 @@
+---
+exclude_paths:
+  - '.github/**'
+  - 'ci/build_verilator.sh'
+  - 'include/vltstd/**'
+  - 'nodist/fastcov.py'

.gitattributes

@@ -0,0 +1,5 @@
+*.v linguist-language=SystemVerilog
+*.vh linguist-language=SystemVerilog
+*.sv linguist-language=SystemVerilog
+Changes linguist-language=reStructuredText
+nodist linguist-detectable=false

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,16 @@
+---
+name: Bug report
+about: Something isn't working as expected, and it isn't "Unsupported." (Note our contributor agreement at https://github.com/verilator/verilator/blob/master/docs/CONTRIBUTING.rst)
+title: ''
+labels: new
+assignees: ''
+
+---
+
+Thanks for taking the time to report this.
+
+Can you attach an example that shows the issue?  (Must be openly licensed, ideally in test_regress format.)
+
+What 'verilator --version' are you using?  Did you try it with the git master version?
+
+Would you be willing to try to fix Verilator yourself with assistance?

.github/ISSUE_TEMPLATE/feature.md

@@ -0,0 +1,16 @@
+---
+name: Feature Request
+about: Request something should be supported, or a new feature added. (Note our contributor agreement at https://github.com/verilator/verilator/blob/master/docs/CONTRIBUTING.rst)
+title: ''
+labels: new
+assignees: ''
+
+---
+
+Thanks for taking the time to report this.
+
+What would you like added/supported?
+
+Can you attach an example that runs on other simulators?  (Must be openly licensed, ideally in test_regress format.)
+
+May we assist you in trying to fix this yourself?

.github/ISSUE_TEMPLATE/questions.md

@@ -0,0 +1,10 @@
+---
+name: Q and A, or Other
+about: Ask a question, not related to a specific bug or feature request. (Note our contributor agreement at https://github.com/verilator/verilator/blob/master/docs/CONTRIBUTING.rst)
+title: ''
+labels: new
+assignees: ''
+
+---
+
+How may we help - what is your question?

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1 @@
+We appreciate your contributing to Verilator.  If this is your first commit, please add your name to docs/CONTRIBUTORS, and read our contributing guidelines in docs/CONTRIBUTING.rst.

.github/labels.toml

@@ -0,0 +1,199 @@
+["area: assertions"]
+color = "ffffe8"
+name = "area: assertions"
+description = "Issue involves assertions"
+
+["area: configure/compiling"]
+color = "ffffe8"
+name = "area: configure/compiling"
+description = "Issue involves configuring or compilating Verilator itself"
+
+["area: coverage"]
+color = "ffffe8"
+name = "area: coverage"
+description = "Issue involves coverage generation"
+
+["area: data-types"]
+color = "ffffe8"
+name = "area: data-types"
+description = "Issue involves data-types"
+
+["area: documentation"]
+color = "ffffe8"
+name = "area: documentation"
+description = "Issue involves documentation"
+
+["area: elaboration"]
+color = "ffffe8"
+name = "area: elaboration"
+description = "Issue involves elaboration phase"
+
+["area: invoking/options"]
+color = "ffffe8"
+name = "area: invoking/options"
+description = "Issue involves options passed to Verilator"
+
+["area: lint"]
+color = "ffffe8"
+name = "area: lint"
+description = "Issue involves SystemVerilog lint checking"
+
+["area: parser"]
+color = "ffffe8"
+name = "area: parser"
+description = "Issue involves SystemVerilog parsing"
+
+["area: performance"]
+color = "ffffe8"
+name = "area: performance"
+description = "Issue involves performance issues"
+
+["area: portability"]
+color = "ffffe8"
+name = "area: portability"
+description = "Issue involves operating system/compiler portability"
+
+["area: runtime result"]
+color = "ffffe8"
+name = "area: runtime result"
+description = "Issue involves an incorrect runtine result from Verilated model"
+
+["area: scheduling"]
+color = "ffffe8"
+name = "area: scheduling"
+description = "Issue involves scheduling/ordering of events"
+
+["area: tests"]
+color = "ffffe8"
+name = "area: tests"
+description = "Issue involves the testing system"
+
+["area: usability"]
+color = "ffffe8"
+name = "area: usability"
+description = "Issue involves general usability"
+
+["effort: days"]
+color = "d0c0b0"
+name = "effort: days"
+description = "Expect this issue to require roughly days of invested effort to resolve"
+
+["effort: hours"]
+color = "f5e6d6"
+name = "effort: hours"
+description = "Expect this issue to require roughly hours of invested effort to resolve"
+
+["effort: minutes"]
+color = "f5e6d6"
+name = "effort: minutes"
+description = "Expect this issue to require less than an hour of invested effort to resolve"
+
+["effort: weeks"]
+color = "d0c0b0"
+name = "effort: weeks"
+description = "Expect this issue to require weeks or more of invested effort to resolve"
+
+["good first issue"]
+color = "7057ff"
+name = "good first issue"
+description = "Good for newcomers"
+
+["help wanted"]
+color = "008672"
+name = "help wanted"
+description = "Extra attention is needed"
+
+["new"]
+color = "ff4400"
+name = "new"
+description = "New issue, not yet seen by maintainers"
+
+["resolution: abandoned"]
+color = "cfd3d7"
+name = "resolution: abandoned"
+description = "Closed; not enough information or otherwise never finished"
+
+["resolution: answered"]
+color = "cfd3d7"
+name = "resolution: answered"
+description = "Closed; only applies to questions which were answered"
+
+["resolution: duplicate"]
+color = "cfd3d7"
+name = "resolution: duplicate"
+description = "Closed; issue or pull request already exists"
+
+["resolution: external"]
+color = "cfd3d7"
+name = "resolution: external"
+description = "Closed; passed to another tool's bug tracker"
+
+["resolution: fixed"]
+color = "cfd3d7"
+name = "resolution: fixed"
+description = "Closed; fixed"
+
+["resolution: invalid"]
+color = "cfd3d7"
+name = "resolution: invalid"
+description = "Closed; issue or pull request is no longer relevant"
+
+["resolution: no fix needed"]
+color = "cfd3d7"
+name = "resolution: no fix needed"
+description = "Closed; no fix required (not a bug)"
+
+["resolution: wontfix"]
+color = "cfd3d7"
+name = "resolution: wontfix"
+description = "Closed; work won't continue on an issue or pull request"
+
+["status: asked reporter"]
+color = "ffffff"
+name = "status: asked reporter"
+description = "Bug is waiting for reporter to answer a question"
+
+["status: assigned"]
+color = "a0f0ff"
+name = "status: assigned"
+description = "Issue is assigned to someone to work on"
+
+["status: blocked"]
+color = "00007f"
+name = "status: blocked"
+description = "Issue is waiting for another bug, when other bug is fixed, then goes to 'status: assigned'"
+
+["status: discussion"]
+color = "d876e3"
+name = "status: discussion"
+description = "Issue is waiting for discussions to resolve"
+
+["status: ready"]
+color = "b6c92a"
+name = "status: ready"
+description = "Issue is ready for someone to fix; then goes to 'status: assigned'"
+
+["type: bug"]
+color = "d73a4a"
+name = "type: bug"
+description = "Defect"
+
+["type: feature-IEEE"]
+color = "cfccff"
+name = "type: feature-IEEE"
+description = "Request to add new feature, described in IEEE 1800"
+
+["type: feature-non-IEEE"]
+color = "cfccff"
+name = "type: feature-non-IEEE"
+description = "Request to add new feature, outside IEEE 1800"
+
+["type: maintenance"]
+color = "cfccff"
+name = "type: maintenance"
+description = "Internal maintenance task"
+
+["type: q and a"]
+color = "84ba34"
+name = "type: q and a"
+description = "Question and answer about some feature or user question"

.github/workflows/build.yml

@@ -0,0 +1,148 @@
+# DESCRIPTION: Github actions config
+# This name is key to badges in README.rst, so we use the name build
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+name: build
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+  schedule:
+  - cron: '0 0 * * 0' # weekly
+
+env:
+  CI_OS_NAME: linux
+  CI_COMMIT: ${{ github.sha }}
+  CCACHE_COMPRESS: 1
+  CCACHE_DIR: ${{ github.workspace }}/.ccache
+  CCACHE_LIMIT_MULTIPLE: 0.95
+
+defaults:
+  run:
+    shell: bash
+    working-directory: repo
+
+jobs:
+
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-20.04, ubuntu-18.04, ubuntu-16.04]
+        compiler:
+          - { cc: clang, cxx: clang++ }
+          - { cc: gcc,   cxx: g++     }
+        m32: [0, 1]
+        exclude:
+          # Build pull requests only with ubuntu-20.04 and without m32
+          - os:  ${{ github.event_name == 'pull_request' && 'ubuntu-18.04' || 'do-not-exclude' }}
+          - os:  ${{ github.event_name == 'pull_request' && 'ubuntu-16.04' || 'do-not-exclude' }}
+          - m32: ${{ github.event_name == 'pull_request' && 1              || 'do-not-exclude' }}
+          # Build -m32 only on ubuntu-20.04
+          - {os: ubuntu-18.04, m32: 1}
+          - {os: ubuntu-16.04, m32: 1}
+    runs-on: ${{ matrix.os }}
+    name: Build | ${{ matrix.os }} | ${{ matrix.compiler.cc }} ${{ matrix.m32 && '| -m32' || '' }}
+    env:
+      CI_BUILD_STAGE_NAME: build
+      CI_RUNS_ON: ${{ matrix.os }}
+      CI_M32: ${{ matrix.m32 }}
+      CC: ${{ matrix.compiler.cc }}
+      CXX: ${{ matrix.compiler.cxx }}
+      CACHE_BASE_KEY: build-${{ matrix.os }}-${{ matrix.compiler.cc }}-m32=${{ matrix.m32 }}
+      CCACHE_MAXSIZE: 250M # Per build matrix entry (2000M in total)
+      VERILATOR_ARCHIVE: verilator-${{ github.sha }}-${{ matrix.os }}-${{ matrix.compiler.cc }}${{ matrix.m32 && '-m32' || '' }}.tar.gz
+    steps:
+
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        path: repo
+
+    - name: Cache $CCACHE_DIR
+      uses: actions/cache@v2
+      env:
+        CACHE_KEY: ${{ env.CACHE_BASE_KEY }}-ccache
+      with:
+        path: ${{ env.CCACHE_DIR }}
+        key: ${{ env.CACHE_KEY }}-${{ github.sha }}
+        restore-keys: |
+          ${{ env.CACHE_KEY }}-
+
+    - name: Install packages for build
+      run: ./ci/ci-install.bash
+
+    - name: Build
+      run: ./ci/ci-script.bash
+
+    - name: Tar up repository
+      working-directory: ${{ github.workspace }}
+      run: tar --posix -c -z -f ${{ env.VERILATOR_ARCHIVE }} repo
+
+    - name: Upload tar archive
+      uses: actions/upload-artifact@v2
+      with:
+        path: ${{ github.workspace }}/${{ env.VERILATOR_ARCHIVE }}
+        name: ${{ env.VERILATOR_ARCHIVE }}
+
+
+  test:
+    needs: build
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-20.04, ubuntu-18.04, ubuntu-16.04]
+        compiler:
+          - { cc: clang, cxx: clang++ }
+          - { cc: gcc,   cxx: g++     }
+        m32: [0, 1]
+        suite: [dist-vlt-0, dist-vlt-1, dist-vlt-2, vltmt-0, vltmt-1]
+        exclude:
+          # Build pull requests only with ubuntu-20.04 and without m32
+          - os:  ${{ github.event_name == 'pull_request' && 'ubuntu-18.04' || 'do-not-exclude' }}
+          - os:  ${{ github.event_name == 'pull_request' && 'ubuntu-16.04' || 'do-not-exclude' }}
+          - m32: ${{ github.event_name == 'pull_request' && 1              || 'do-not-exclude' }}
+          # Build -m32 only on ubuntu-20.04
+          - {os: ubuntu-18.04, m32: 1}
+          - {os: ubuntu-16.04, m32: 1}
+    runs-on: ${{ matrix.os }}
+    name: Test | ${{ matrix.os }} | ${{ matrix.compiler.cc }} | ${{ matrix.suite }} ${{ matrix.m32 && '| -m32' || '' }}
+    env:
+      CI_BUILD_STAGE_NAME: test
+      CI_RUNS_ON: ${{ matrix.os }}
+      CI_M32: ${{ matrix.m32 }}
+      CC: ${{ matrix.compiler.cc }}
+      CXX: ${{ matrix.compiler.cxx }}
+      CACHE_BASE_KEY: test-${{ matrix.os }}-${{ matrix.compiler.cc }}-m32=${{ matrix.m32 }}-${ matrix.suite }}
+      CCACHE_MAXSIZE: 64M # Per build matrix entry (2160M in total)
+      VERILATOR_ARCHIVE: verilator-${{ github.sha }}-${{ matrix.os }}-${{ matrix.compiler.cc }}${{ matrix.m32 && '-m32' || '' }}.tar.gz
+    steps:
+
+    - name: Download tar archive
+      uses: actions/download-artifact@v2
+      with:
+        name: ${{ env.VERILATOR_ARCHIVE }}
+        path: ${{ github.workspace }}
+
+    - name: Unpack tar archive
+      working-directory: ${{ github.workspace }}
+      run: tar -x -z -f ${{ env.VERILATOR_ARCHIVE }}
+
+    - name: Cache $CCACHE_DIR
+      uses: actions/cache@v2
+      env:
+        CACHE_KEY: ${{ env.CACHE_BASE_KEY }}-ccache
+      with:
+        path: ${{ env.CCACHE_DIR }}
+        key: ${{ env.CACHE_KEY }}-${{ github.sha }}
+        restore-keys: |
+          ${{ env.CACHE_KEY }}-
+
+    - name: Install test dependencies
+      run: ./ci/ci-install.bash
+
+    - name: Test
+      env:
+        TESTS: ${{ matrix.suite }}
+      run: ./ci/ci-script.bash

.github/workflows/contributor.yml

@@ -0,0 +1,17 @@
+# DESCRIPTION: Github actions config
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+name: Contributor Agreement
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  Test:
+    name: "'docs/CONTRIBUTORS' was signed"
+    runs-on: ubuntu-20.04
+    steps:
+    - uses: actions/checkout@v2
+    - run: test_regress/t/t_dist_contributors.pl

.github/workflows/coverage.yml

@@ -0,0 +1,99 @@
+# DESCRIPTION: Github actions config
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+name: coverage
+
+on:
+  workflow_dispatch:
+  schedule:
+  - cron: '0 0 * * 0' # weekly
+
+env:
+  CI_OS_NAME: linux
+  CI_COMMIT: ${{ github.sha }}
+  CI_M32: 0
+  COVERAGE: 1
+  VERILATOR_ARCHIVE: verilator-coverage-${{ github.sha }}.tar.gz
+
+defaults:
+  run:
+    shell: bash
+    working-directory: repo
+
+jobs:
+
+
+  Build:
+    runs-on: ubuntu-20.04
+    env:
+      CI_BUILD_STAGE_NAME: build
+      CI_RUNS_ON: ubuntu-20.04
+    steps:
+
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        path: repo
+
+    - name: Install packages for build
+      run: ./ci/ci-install.bash
+
+    - name: Build
+      run: ./ci/ci-script.bash
+
+    - name: Tar up repository
+      working-directory: ${{ github.workspace }}
+      run: tar --posix -c -z -f ${{ env.VERILATOR_ARCHIVE }} repo
+
+    - name: Upload tar archive
+      uses: actions/upload-artifact@v2
+      with:
+        path: ${{ github.workspace }}/${{ env.VERILATOR_ARCHIVE }}
+        name: ${{ env.VERILATOR_ARCHIVE }}
+
+
+  Test:
+    needs: Build
+    strategy:
+      fail-fast: false
+      matrix:
+        test:
+        - vlt-
+        - vltmt-
+        num:
+        - 0
+        - 1
+        - 2
+        - 3
+        - 4
+        - 5
+        - 6
+        - 7
+        - 8
+        - 9
+        include:
+        - { test: dist, num: '' }
+    runs-on: ubuntu-20.04
+    name: test-${{ matrix.test }}${{ matrix.num }}
+    env:
+      CI_BUILD_STAGE_NAME: test
+      CI_RUNS_ON: ubuntu-20.04
+    steps:
+
+    - name: Download tar archive
+      uses: actions/download-artifact@v2
+      with:
+        name: ${{ env.VERILATOR_ARCHIVE }}
+        path: ${{ github.workspace }}
+
+    - name: Unpack tar archive
+      working-directory: ${{ github.workspace }}
+      run: tar -x -z -f ${{ env.VERILATOR_ARCHIVE }}
+
+    - name: Install test dependencies
+      run: ./ci/ci-install.bash
+
+    - name: Test
+      env:
+        TESTS: coverage-${{ matrix.test }}${{ matrix.num }}
+      run: ./ci/ci-script.bash

.github/workflows/format.yml

@@ -0,0 +1,44 @@
+# DESCRIPTION: Github actions config
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+name: format
+
+on:
+  push:
+  pull_request_target:
+  workflow_dispatch:
+
+jobs:
+  format:
+    runs-on: ubuntu-20.04
+    name: Ubuntu 20.04 | format
+    env:
+      CI_OS_NAME: linux
+      CI_RUNS_ON: ubuntu-20.04
+      CI_COMMIT: ${{ github.sha }}
+      CI_M32: 0
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+      - name: Install packages for build
+        env:
+          CI_BUILD_STAGE_NAME: build
+        run: |
+          bash ci/ci-install.bash &&
+          sudo apt-get install clang-format-11 yapf3 &&
+          git config --global user.email "[email protected]" &&
+          git config --global user.name "github action"
+      - name: Format code
+        run: |
+          autoconf &&
+          ./configure &&
+          make -j 2 format CLANGFORMAT=clang-format-11 &&
+          git status
+      - name: Push
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            git commit . -m "Apply 'make format'" &&
+            git push origin
+          fi

.gitignore

@@ -1,5 +1,6 @@
 \#*
 .#*
+.nfs*
 *~
 *.tidy
 *.old
@@ -14,9 +15,12 @@
 *.tex
 *.pdf
 /Makefile
+/.ccache
+/artifact/
 README
 TAGS
 autom4te.cache
+compile_commands.json
 config.cache
 config.status
 configure
@@ -30,4 +34,8 @@ verilator.txt
 verilator_bin*
 verilator_coverage_bin*
 verilator.pc
+verilator-config.cmake
+verilator-config-version.cmake
+**/__pycache__/*
+**/_build/*
 **/obj_dir/*

COPYING

@@ -1,674 +0,0 @@
-                    GNU GENERAL PUBLIC LICENSE
-                       Version 3, 29 June 2007
-
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- Everyone is permitted to copy and distribute verbatim copies
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-but the special requirements of the GNU Affero General Public License,
-section 13, concerning interaction through a network will apply to the
-combination as such.
-
-  14. Revised Versions of this License.
-
-  The Free Software Foundation may publish revised and/or new versions of
-the GNU General Public License from time to time.  Such new versions will
-be similar in spirit to the present version, but may differ in detail to
-address new problems or concerns.
-
-  Each version is given a distinguishing version number.  If the
-Program specifies that a certain numbered version of the GNU General
-Public License "or any later version" applies to it, you have the
-option of following the terms and conditions either of that numbered
-version or of any later version published by the Free Software
-Foundation.  If the Program does not specify a version number of the
-GNU General Public License, you may choose any version ever published
-by the Free Software Foundation.
-
-  If the Program specifies that a proxy can decide which future
-versions of the GNU General Public License can be used, that proxy's
-public statement of acceptance of a version permanently authorizes you
-to choose that version for the Program.
-
-  Later license versions may give you additional or different
-permissions.  However, no additional obligations are imposed on any
-author or copyright holder as a result of your choosing to follow a
-later version.
-
-  15. Disclaimer of Warranty.
-
-  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
-APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
-HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
-OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
-THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
-PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
-IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
-ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
-
-  16. Limitation of Liability.
-
-  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
-WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
-THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
-GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
-USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
-DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
-PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
-EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
-SUCH DAMAGES.
-
-  17. Interpretation of Sections 15 and 16.
-
-  If the disclaimer of warranty and limitation of liability provided
-above cannot be given local legal effect according to their terms,
-reviewing courts shall apply local law that most closely approximates
-an absolute waiver of all civil liability in connection with the
-Program, unless a warranty or assumption of liability accompanies a
-copy of the Program in return for a fee.
-
-                     END OF TERMS AND CONDITIONS
-
-            How to Apply These Terms to Your New Programs
-
-  If you develop a new program, and you want it to be of the greatest
-possible use to the public, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these terms.
-
-  To do so, attach the following notices to the program.  It is safest
-to attach them to the start of each source file to most effectively
-state the exclusion of warranty; and each file should have at least
-the "copyright" line and a pointer to where the full notice is found.
-
-    <one line to give the program's name and a brief idea of what it does.>
-    Copyright (C) <year>  <name of author>
-
-    This program is free software: you can redistribute it and/or modify
-    it under the terms of the GNU General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-Also add information on how to contact you by electronic and paper mail.
-
-  If the program does terminal interaction, make it output a short
-notice like this when it starts in an interactive mode:
-
-    <program>  Copyright (C) <year>  <name of author>
-    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
-    This is free software, and you are welcome to redistribute it
-    under certain conditions; type `show c' for details.
-
-The hypothetical commands `show w' and `show c' should show the appropriate
-parts of the General Public License.  Of course, your program's commands
-might be different; for a GUI interface, you would use an "about box".
-
-  You should also get your employer (if you work as a programmer) or school,
-if any, to sign a "copyright disclaimer" for the program, if necessary.
-For more information on this, and how to apply and follow the GNU GPL, see
-<http://www.gnu.org/licenses/>.
-
-  The GNU General Public License does not permit incorporating your program
-into proprietary programs.  If your program is a subroutine library, you
-may consider it more useful to permit linking proprietary applications with
-the library.  If this is what you want to do, use the GNU Lesser General
-Public License instead of this License.  But first, please read
-<http://www.gnu.org/philosophy/why-not-lgpl.html>.

LICENSE

@@ -1,7 +1,7 @@
                    GNU LESSER GENERAL PUBLIC LICENSE
                        Version 3, 29 June 2007
 
- Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
  Everyone is permitted to copy and distribute verbatim copies
  of this license document, but changing it is not allowed.
 

MANIFEST.SKIP

@@ -1,5 +1,9 @@
+\.ccache/
+\.clang-format
 \.clang-tidy
 \.git/
+\.git$
+\.github/
 \.svn/
 \.(bak|old)/
 \.(bak|old)$
@@ -13,28 +17,47 @@
 .*\.key
 .*\.vcd
 .*\.1
-/obj_dir/
+\.codacy\.yml
+\.travis\.yml
+/_build/
+/build/
 /obj_dbg/
+/obj_dir/
+/obj_dist/
+/obj_iv/
+/obj_ms/
 /obj_nc/
 /obj_opt/
 /obj_vcs/
 /obj_vlt/
 /obj_vltmt/
-/obj_dist/
-/INCA_libs/
+INCA_libs/
 /cov_work/
 /logs/
 ^Makefile$
+README.html
 bin/verilator_bin.*
 bin/verilator_coverage_bin.*
+docs/.*\.html$
+docs/_build/
+docs/clang-format.txt$
+docs/doxygen-doc/.*
+docs/spelling.txt
+examples/xml_py/copied/
+examples/xml_py/graph.*
+sonar-project.properties
 src/Makefile$
 src/Makefile_obj$
 include/verilated.mk$
 test_regress/.gdbinit$
+test_regress/transcript
+codecov.yml
 config.cache$
 config.status$
 verilator\.log
 verilator\.tex
+verilator-config.cmake$
+verilator-config-version.cmake$
 verilator.pc$
 verilator_bin.*
 verilator_coverage_bin.*
@@ -42,11 +65,12 @@ verilator_coverage_bin.*
 ncverilog.history
 autom4te\.cache/
 nodist/
+ci/
 /simv$
 /simv.daidir/
 /vc_hdrs.h$
 /csrc/
-doxygen-doc/.*
-obj_dir/.*
+obj_dir.*
 TAGS
+gmon.out
 .*~

Makefile.in

@@ -3,19 +3,15 @@
 #
 # This file is part of Verilator.
 #
-# Code available from: http://www.veripool.org/verilator
+# Code available from: https://verilator.org
 #
 #*****************************************************************************
 #
-# Copyright 2003-2018 by Wilson Snyder. This program is free software; you can
-# redistribute it and/or modify it under the terms of either the GNU
+# Copyright 2003-2021 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
-#
-# Verilator is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 #
 #****************************************************************************/
 #
@@ -48,6 +44,7 @@
 srcdir = @srcdir@
 VPATH = @srcdir@
 HOST = @HOST@
+EXEEXT = @EXEEXT@
 
 DOXYGEN = doxygen
 INSTALL = @INSTALL@
@@ -55,10 +52,12 @@ INSTALL_PROGRAM = @INSTALL_PROGRAM@
 INSTALL_DATA = @INSTALL_DATA@
 MAKEINFO = makeinfo
 POD2TEXT = pod2text
-POD2LATEXFIX = $(srcdir)/src/pod2latexfix
 MKINSTALLDIRS = $(SHELL) $(srcdir)/src/mkinstalldirs
 PERL = @PERL@
 
+# Version (for docs/guide/conf.py)
+PACKAGE_VERSION_NUMBER = @PACKAGE_VERSION_NUMBER@
+
 # Destination prefix for RPMs
 DESTDIR =
 
@@ -83,7 +82,7 @@ infodir = @infodir@
 pkgdatadir = @pkgdatadir@
 
 # Directory in which to install pkgconfig file
-# Generall ${prefix}/share/pkgconfig
+# Generally ${prefix}/share/pkgconfig
 pkgconfigdir = @pkgconfigdir@
 
 # Directory in which to install data across multiple architectures
@@ -93,7 +92,6 @@ datarootdir = @datarootdir@
 CFG_WITH_CCWARN = @CFG_WITH_CCWARN@
 CFG_WITH_DEFENV = @CFG_WITH_DEFENV@
 CFG_WITH_LONGTESTS = @CFG_WITH_LONGTESTS@
-CFG_WITH_THREADED = @CFG_WITH_THREADED@
 PACKAGE_VERSION = @PACKAGE_VERSION@
 
 #### End of system configuration section. ####
@@ -103,28 +101,58 @@ PACKAGE_VERSION = @PACKAGE_VERSION@
 
 SHELL = /bin/sh
 
-SUBDIRS = src test_regress \
-	examples/hello_world_c  examples/hello_world_sc \
-	examples/tracing_c  examples/tracing_sc \
+SUBDIRS = docs src test_regress \
+	examples/cmake_hello_c \
+	examples/cmake_hello_sc \
+	examples/cmake_tracing_c \
+	examples/cmake_tracing_sc \
+	examples/cmake_protect_lib \
+	examples/make_hello_c \
+	examples/make_hello_sc \
+	examples/make_tracing_c \
+	examples/make_tracing_sc \
+	examples/make_protect_lib \
+	examples/xml_py \
 
-INFOS = README README.html README.pdf internals.txt internals.html \
-        internals.pdf verilator.txt verilator.html verilator.pdf \
-	$(VL_INST_MAN_FILES)
+INFOS = verilator.html verilator.pdf
+
+INFOS_OLD = README README.html README.pdf
 
 # Files that can be generated, but should be up to date for a distribution.
 DISTDEP = info Makefile
 
-DISTFILES_INC = $(INFOS) .gitignore Artistic COPYING COPYING.LESSER \
+DISTFILES1 = $(INFOS) .gitignore \
 	*.in *.ac \
-	Changes TODO \
+	Artistic \
+	Changes \
+	LICENSE \
 	MANIFEST.SKIP \
+	README.rst \
+	verilator-config.cmake.in \
+	verilator-config-version.cmake.in \
 	bin/verilator \
+	bin/verilator_ccache_report \
 	bin/verilator_coverage \
 	bin/verilator_difftree \
 	bin/verilator_gantt \
 	bin/verilator_includer \
 	bin/verilator_profcfunc \
-	doxygen-mainpage doxygen.config verilator_logo.png \
+	docs/.gitignore \
+	docs/CONTRIBUTING.rst \
+	docs/CONTRIBUTORS \
+	docs/Makefile \
+	docs/_static/*.png \
+	docs/_static/css/* \
+	docs/bin/* \
+	docs/gen/* \
+	docs/guide/*.py \
+	docs/guide/*.rst \
+	docs/guide/figures/* \
+	docs/install.rst \
+	docs/internals.rst \
+	docs/internals.rst \
+	docs/verilated.dox \
+	docs/xml.rst \
 	install-sh configure *.pod \
 	include/*.[chv]* \
 	include/*.in \
@@ -134,17 +162,28 @@ DISTFILES_INC = $(INFOS) .gitignore Artistic COPYING COPYING.LESSER \
 	.*attributes */.*attributes  */*/.*attributes \
 	src/.*ignore src/*.in src/*.cpp src/*.[chly] \
 	src/astgen src/bisonpre src/*fix src/cppcheck_filtered \
+	src/config_rev \
 	src/vlcovgen src/mkinstalldirs \
 	src/.gdbinit \
 	src/*.pl src/*.pod \
 	examples/*/.*ignore examples/*/Makefile* \
-	examples/*/*.[chv]* examples/*/*.pl \
+	examples/*/*.[chv]* examples/*/vl_* \
+	examples/*/CMakeLists.txt \
+
+DISTFILES2 = \
 	test_*/.*ignore test_*/Makefile* test_*/*.cpp \
 	test_*/*.pl test_*/*.v test_*/*.vc test_*/*.vh \
+	test_regress/*.pl \
+	test_regress/Makefile \
+	test_regress/Makefile_obj \
+	test_regress/input.vc \
+	test_regress/CMakeLists.txt \
 	test_regress/t/t*/*.sv* \
 	test_regress/t/t*/*.v* \
 	test_regress/t/t*/*/*.sv* \
 	test_regress/t/t*/*/*.v* \
+	test_regress/t/t*/*.cpp \
+	test_regress/t/t*/CMakeLists.txt \
 	test_regress/t/*.cpp \
 	test_regress/t/*.h \
 	test_regress/t/*.dat \
@@ -156,6 +195,7 @@ DISTFILES_INC = $(INFOS) .gitignore Artistic COPYING COPYING.LESSER \
 
 INST_PROJ_FILES = \
 	bin/verilator \
+	bin/verilator_ccache_report \
 	bin/verilator_coverage \
 	bin/verilator_gantt \
 	bin/verilator_includer \
@@ -166,27 +206,28 @@ INST_PROJ_FILES = \
 	include/vltstd/*.[chv]* \
 
 INST_PROJ_BIN_FILES = \
-	bin/verilator_bin \
-	bin/verilator_bin_dbg \
-	bin/verilator_coverage_bin_dbg \
+	bin/verilator_bin$(EXEEXT) \
+	bin/verilator_bin_dbg$(EXEEXT) \
+	bin/verilator_coverage_bin_dbg$(EXEEXT) \
 
-DISTFILES := $(DISTFILES_INC)
+EXAMPLES_FIRST = \
+	examples/make_hello_c \
+	examples/make_hello_sc \
 
-ifeq ($(OBJCACHE_JOBS),)
-ifneq ($(OBJCACHE_HOSTS),)
-export OBJCACHE_JOBS := -j $(shell objcache --jobs "$(OBJCACHE_HOSTS)")
-endif
-endif
+EXAMPLES = $(EXAMPLES_FIRST) $(filter-out $(EXAMPLES_FIRST), $(sort $(wildcard examples/*)))
+
+# See uninstall also - don't put wildcards in this variable, it might uninstall other stuff
+VL_INST_MAN_FILES = verilator.1 verilator_coverage.1 verilator_gantt.1 verilator_profcfunc.1
 
 default: all
 all: all_nomsg msg_test
 all_nomsg: verilator_exe $(VL_INST_MAN_FILES)
 
 .PHONY:verilator_exe
-.PHONY:verilator_bin
-.PHONY:verilator_bin_dbg
-.PHONY:verilator_coverage_bin_dbg
-verilator_exe verilator_bin verilator_bin_dbg verilator_coverage_bin_dbg:
+.PHONY:verilator_bin$(EXEEXT)
+.PHONY:verilator_bin_dbg$(EXEEXT)
+.PHONY:verilator_coverage_bin_dbg$(EXEEXT)
+verilator_exe verilator_bin$(EXEEXT) verilator_bin_dbg$(EXEEXT) verilator_coverage_bin_dbg$(EXEEXT):
 	@echo ------------------------------------------------------------
 	@echo "making verilator in src"
 	$(MAKE) -C src $(OBJCACHE_JOBS)
@@ -200,7 +241,9 @@ msg_test: all_nomsg
 
 .PHONY: test
 ifeq ($(CFG_WITH_LONGTESTS),yes)	# Local... Else don't burden users
-test: smoke-test examples test_regress
+test: smoke-test test_regress
+# examples is part of test_regress's test_regress/t/t_a2_examples.pl
+# (because that allows it to run in parallel with other test_regress's)
 else
 test: smoke-test examples
 endif
@@ -211,79 +254,40 @@ endif
 	@echo
 
 smoke-test: all_nomsg
-	test_regress/t/t_a_first_cc.pl
-	test_regress/t/t_a_first_sc.pl
+	test_regress/t/t_a1_first_cc.pl
+	test_regress/t/t_a2_first_sc.pl
 
 test_regress: all_nomsg
 	$(MAKE) -C test_regress
 
 examples: all_nomsg
-	for p in examples/* ; do \
+	for p in $(EXAMPLES) ; do \
 	  $(MAKE) -C $$p VERILATOR_ROOT=`pwd` || exit 10; \
 	done
 
+.PHONY: docs
+docs: info
+
 info: $(INFOS)
 
-# Use --no-split to avoid creating filenames > 14 chars.
 %.1: ${srcdir}/bin/%
 	pod2man $< $@
 
-verilator.txt: ${srcdir}/bin/verilator
-	$(POD2TEXT) $< $@
-
-verilator.html: ${srcdir}/bin/verilator
-	pod2html $< >$@
+.PHONY: verilator.html
+verilator.html:
+	$(MAKE) -C docs html
 
 # PDF needs DIST variables; but having configure.ac as dependency isn't detected
-verilator.pdf: ${srcdir}/bin/verilator Makefile $(POD2LATEXFIX)
-	pod2latex --full --out verilator.tex $<
-	$(PERL) $(POD2LATEXFIX) "$(DISTTITLE)" "${DISTDATE}" < verilator.tex > verilator2.tex
-	mv verilator2.tex verilator.tex
-	pdflatex verilator.tex
-	pdflatex verilator.tex
-	-rm -f verilator.toc verilator.aux verilator.idx verilator.out
-
-README: README.pod
-	-rm -f $@
-	$(POD2TEXT) --loose $< > $@
-
-README.html: README.pod
-	pod2html $< >$@
-
-# PDF needs DIST variables; but having configure.ac as dependency isn't detected
-README.pdf: README.pod Makefile $(POD2LATEXFIX)
-	pod2latex --full --out README.tex $<
-	$(PERL) $(POD2LATEXFIX) "$(DISTTITLE) README File" "${DISTDATE}" < README.tex > README2.tex
-	mv README2.tex README.tex
-	pdflatex README.tex
-	pdflatex README.tex
-	-rm -f README.toc README.aux README.idx README.out
-
-internals.txt: internals.pod
-	-rm -f $@
-	$(POD2TEXT) --loose $< > $@
-
-internals.html: internals.pod
-	pod2html $< >$@
-
-# PDF needs DIST variables; but having configure.ac as dependency isn't detected
-internals.pdf: internals.pod Makefile $(POD2LATEXFIX)
-	pod2latex --full --out internals.tex $<
-	$(PERL) $(POD2LATEXFIX) "$(DISTTITLE) Internals Manual" "${DISTDATE}" < internals.tex > internals2.tex
-	mv internals2.tex internals.tex
-	pdflatex internals.tex
-	pdflatex internals.tex
-	-rm -f internals.toc internals.aux internals.idx internals.out
+.PHONY: verilator.pdf
+verilator.pdf: Makefile
+	$(MAKE) -C docs verilator.pdf
 
 # See uninstall also - don't put wildcards in this variable, it might uninstall other stuff
-VL_INST_BIN_FILES = verilator verilator_bin verilator_bin_dbg verilator_coverage_bin_dbg \
-	verilator_coverage verilator_gantt verilator_includer verilator_profcfunc
+VL_INST_BIN_FILES = verilator verilator_bin$(EXEEXT) verilator_bin_dbg$(EXEEXT) verilator_coverage_bin_dbg$(EXEEXT) \
+	verilator_ccache_report verilator_coverage verilator_gantt verilator_includer verilator_profcfunc
 # Some scripts go into both the search path and pkgdatadir,
 # so they can be found by the user, and under $VERILATOR_ROOT.
 
-# See uninstall also - don't put wildcards in this variable, it might uninstall other stuff
-VL_INST_MAN_FILES = verilator.1 verilator_coverage.1 verilator_gantt.1 verilator_profcfunc.1
-
 VL_INST_INC_BLDDIR_FILES = \
 	include/verilated_config.h \
 	include/verilated.mk \
@@ -296,6 +300,7 @@ VL_INST_INC_SRCDIR_FILES = \
 
 VL_INST_DATA_SRCDIR_FILES = \
 	examples/*/*.[chv]*  examples/*/Makefile* \
+	examples/*/CMakeLists.txt
 
 installbin:
 	$(MKINSTALLDIRS) $(DESTDIR)$(bindir)
@@ -303,11 +308,12 @@ installbin:
 	( cd ${srcdir}/bin ; $(INSTALL_PROGRAM) verilator_coverage $(DESTDIR)$(bindir)/verilator_coverage )
 	( cd ${srcdir}/bin ; $(INSTALL_PROGRAM) verilator_gantt $(DESTDIR)$(bindir)/verilator_gantt )
 	( cd ${srcdir}/bin ; $(INSTALL_PROGRAM) verilator_profcfunc $(DESTDIR)$(bindir)/verilator_profcfunc )
-	( cd bin ; $(INSTALL_PROGRAM) verilator_bin $(DESTDIR)$(bindir)/verilator_bin )
-	( cd bin ; $(INSTALL_PROGRAM) verilator_bin_dbg $(DESTDIR)$(bindir)/verilator_bin_dbg )
-	( cd bin ; $(INSTALL_PROGRAM) verilator_coverage_bin_dbg $(DESTDIR)$(bindir)/verilator_coverage_bin_dbg )
+	( cd bin ; $(INSTALL_PROGRAM) verilator_bin$(EXEEXT) $(DESTDIR)$(bindir)/verilator_bin$(EXEEXT) )
+	( cd bin ; $(INSTALL_PROGRAM) verilator_bin_dbg$(EXEEXT) $(DESTDIR)$(bindir)/verilator_bin_dbg$(EXEEXT) )
+	( cd bin ; $(INSTALL_PROGRAM) verilator_coverage_bin_dbg$(EXEEXT) $(DESTDIR)$(bindir)/verilator_coverage_bin_dbg$(EXEEXT) )
 	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/bin
 	( cd ${srcdir}/bin ; $(INSTALL_PROGRAM) verilator_includer $(DESTDIR)$(pkgdatadir)/bin/verilator_includer )
+	( cd ${srcdir}/bin ; $(INSTALL_PROGRAM) verilator_ccache_report $(DESTDIR)$(pkgdatadir)/bin/verilator_ccache_report )
 
 # Man files can either be part of the original kit, or built in current directory
 # So important we use $^ so VPATH is searched
@@ -327,16 +333,25 @@ installdata:
 	; for p in $(VL_INST_INC_SRCDIR_FILES) ; do \
 	  $(INSTALL_DATA) $$p $(DESTDIR)$(pkgdatadir)/$$p; \
 	done
-	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/hello_world_c
-	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/hello_world_sc
-	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/tracing_c
-	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/tracing_sc
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/make_hello_c
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/make_hello_sc
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/make_tracing_c
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/make_tracing_sc
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/make_protect_lib
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/cmake_hello_c
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/cmake_hello_sc
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/cmake_tracing_c
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/cmake_tracing_sc
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/cmake_protect_lib
+	$(MKINSTALLDIRS) $(DESTDIR)$(pkgdatadir)/examples/xml_py
 	cd $(srcdir) \
 	; for p in $(VL_INST_DATA_SRCDIR_FILES) ; do \
 	  $(INSTALL_DATA) $$p $(DESTDIR)$(pkgdatadir)/$$p; \
 	done
 	$(MKINSTALLDIRS) $(DESTDIR)$(pkgconfigdir)
 	$(INSTALL_DATA) verilator.pc $(DESTDIR)$(pkgconfigdir)
+	$(INSTALL_DATA) verilator-config.cmake $(DESTDIR)$(pkgdatadir)
+	$(INSTALL_DATA) verilator-config-version.cmake $(DESTDIR)$(pkgdatadir)
 
 # We don't trust rm -rf, so rmdir instead as it will fail if user put in other files
 uninstall:
@@ -347,14 +362,23 @@ uninstall:
 	-cd $(DESTDIR)$(pkgdatadir) && rm -f $(VL_INST_INC_SRCDIR_FILES)
 	-cd $(DESTDIR)$(pkgdatadir) && rm -f $(VL_INST_DATA_SRCDIR_FILES)
 	-rm $(DESTDIR)$(pkgconfigdir)/verilator.pc
+	-rm $(DESTDIR)$(pkgdatadir)/verilator-config.cmake
+	-rm $(DESTDIR)$(pkgdatadir)/verilator-config-version.cmake
 	-rmdir $(DESTDIR)$(pkgdatadir)/bin
 	-rmdir $(DESTDIR)$(pkgdatadir)/include/gtkwave
 	-rmdir $(DESTDIR)$(pkgdatadir)/include/vltstd
 	-rmdir $(DESTDIR)$(pkgdatadir)/include
-	-rmdir $(DESTDIR)$(pkgdatadir)/examples/hello_world_c
-	-rmdir $(DESTDIR)$(pkgdatadir)/examples/hello_world_sc
-	-rmdir $(DESTDIR)$(pkgdatadir)/examples/tracing_c
-	-rmdir $(DESTDIR)$(pkgdatadir)/examples/tracing_sc
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/make_hello_c
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/make_hello_sc
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/make_tracing_c
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/make_tracing_sc
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/make_protect_lib
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/cmake_hello_c
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/cmake_hello_sc
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/cmake_tracing_c
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/cmake_tracing_sc
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/cmake_protect_lib
+	-rmdir $(DESTDIR)$(pkgdatadir)/examples/xml_py
 	-rmdir $(DESTDIR)$(pkgdatadir)/examples
 	-rmdir $(DESTDIR)$(pkgdatadir)
 	-rmdir $(DESTDIR)$(pkgconfigdir)
@@ -367,34 +391,9 @@ install-here: installman ftp
 ifeq ($(VERILATOR_AUTHOR_SITE),1)	# Local... Else don't burden users
 DISTNAMEREV = $(shell sed -e '/DTVERSION/!d' -e 's/.*verilator_\([^"]*\).*/\1/' -e q ${srcdir}/src/config_rev.h)
 
-DIRPROJECT := $(shell project_dir --project)
 VERILATOR_CAD_DIR = $(CAD_DIR)/verilator/$(DISTNAMEREV)/$(DIRPROJECT_ARCH)
 INST_PROJ_CVS = cp_if_cvs_diff
 
-install-project: dist
-	@echo "Install-project to $(DIRPROJECT)"
-	strip bin/verilator_bin*
-	strip bin/verilator_coverage_bin*
-	$(MAKE) install-project-quick
-	for p in $(VL_INST_MAN_FILES) ; do \
-	  $(INSTALL_DATA) $$p $(DIRPROJECT_PREFIX)/man/man1/$$p; \
-	done
-	$(INST_PROJ_CVS) $(DISTNAME).tgz $(DIRPROJECT)/hw/utils/verilator/verilator.tgz
-	rm $(DISTNAME).tgz
-
-install-project-quick:
-ifeq ($(CFG_WITH_DEFENV),yes)
-	@echo "%Error: Reconfigure with './configure --disable-defenv' to avoid hardcoded paths."
-	false
-endif
-	@echo "Install-project-quick (no strip) to $(DIRPROJECT)"
-	for p in $(INST_PROJ_FILES) ; do \
-	  $(INST_PROJ_CVS) $$p $(DIRPROJECT)/hw/utils/verilator/$$p; \
-	done
-	for p in $(INST_PROJ_BIN_FILES) ; do \
-	  $(INST_PROJ_CVS) $$p $(DIRPROJECT)/hw/utils/verilator/$$p-$(DIRPROJECT_ARCH); \
-	done
-
 install-cadtools: dist
 	@echo "Install-project to $(CAD_DIR)"
 	strip bin/verilator_bin*
@@ -428,41 +427,104 @@ endif
 
 # Use --xml flag to see the cppcheck code to use for suppression
 CPPCHECK_CPP = $(wildcard \
+	$(srcdir)/examples/*/*.cpp \
 	$(srcdir)/include/*.cpp \
 	$(srcdir)/src/*.cpp )
 CPPCHECK_H = $(wildcard \
 	$(srcdir)/include/*.h \
 	$(srcdir)/src/*.h )
-CPPCHECK = src/cppcheck_filtered
+CPPCHECK_YL = $(wildcard \
+	$(srcdir)/src/*.y \
+	$(srcdir)/src/*.l )
+CPPCHECK = src/cppcheck_filtered cppcheck
 CPPCHECK_FLAGS = --enable=all --inline-suppr \
-	--suppress=unusedScopedObject --suppress=cstyleCast --suppress=useInitializationList
+	--suppress=unusedScopedObject --suppress=cstyleCast --suppress=useInitializationList \
+	--suppress=nullPointerRedundantCheck
 CPPCHECK_FLAGS += --xml
 CPPCHECK_DEP = $(subst .cpp,.cppcheck,$(CPPCHECK_CPP))
 CPPCHECK_INC = -I$(srcdir)/include -I$(srcdir)/src/obj_dbg -I$(srcdir)/src
 
 cppcheck: $(CPPCHECK_DEP)
 %.cppcheck: %.cpp
-	$(CPPCHECK) $(CPPCHECK_FLAGS) -DVL_DEBUG=1 -DVL_CPPCHECK=1 $(CPPCHECK_INC) $<
+	$(CPPCHECK) $(CPPCHECK_FLAGS) -DVL_DEBUG=1 -DVL_CPPCHECK=1 -DVL_THREADED=1 $(CPPCHECK_INC) $<
 
 CLANGTIDY = clang-tidy
-CLANGTIDY_FLAGS = -config=''
+CLANGTIDY_FLAGS = -config='' -checks='-fuchsia-*,-cppcoreguidelines-avoid-c-arrays,-cppcoreguidelines-init-variables'
 CLANGTIDY_DEP = $(subst .h,.h.tidy,$(CPPCHECK_H)) \
 	$(subst .cpp,.cpp.tidy,$(CPPCHECK_CPP))
+CLANGTIDY_DEFS = -DVL_DEBUG=1 -DVL_THREADED=1 -DVL_CPPCHECK=1
 
-clangtidy: $(CLANGTIDY_DEP)
+clang-tidy: $(CLANGTIDY_DEP)
 %.cpp.tidy: %.cpp
-	$(CLANGTIDY) $(CLANGTIDY_FLAGS) $< -- -DVL_DEBUG=1 -DVL_CPPCHECK=1 $(CPPCHECK_INC) | 2>&1 tee $@
+	$(CLANGTIDY) $(CLANGTIDY_FLAGS) $< -- $(CLANGTIDY_DEFS) $(CPPCHECK_INC) | 2>&1 tee $@
 %.h.tidy: %.h
-	$(CLANGTIDY) $(CLANGTIDY_FLAGS) $< -- -DVL_DEBUG=1 -DVL_CPPCHECK=1 $(CPPCHECK_INC) | 2>&1 tee $@
+	$(CLANGTIDY) $(CLANGTIDY_FLAGS) $< -- $(CLANGTIDY_DEFS) $(CPPCHECK_INC) | 2>&1 tee $@
 
 analyzer-src:
 	-rm -rf src/obj_dbg
-	scan-build $(MAKE) -k verilator_coverage_bin_dbg verilator_bin_dbg
+	scan-build $(MAKE) -k verilator_coverage_bin_dbg$(EXEEXT) verilator_bin_dbg$(EXEEXT)
 
 analyzer-include:
 	-rm -rf examples/*/obj*
 	scan-build $(MAKE) -k examples
 
+format: clang-format yapf format-pl-exec
+
+CLANGFORMAT = clang-format-11
+CLANGFORMAT_FLAGS = -i
+CLANGFORMAT_FILES = $(CPPCHECK_CPP) $(CPPCHECK_H) $(CPPCHECK_YL) test_regress/t/*.c* test_regress/t/*.h
+
+clang-format:
+	@$(CLANGFORMAT) --version | egrep 11.0 > /dev/null \
+		|| echo "*** You are not using clang-format 11.0, indents may differ from master's ***"
+	$(CLANGFORMAT) $(CLANGFORMAT_FLAGS) $(CLANGFORMAT_FILES)
+
+PY_PROGRAMS = \
+	bin/verilator_ccache_report \
+	examples/xml_py/vl_file_copy \
+	examples/xml_py/vl_hier_graph \
+	docs/guide/conf.py \
+	docs/bin/vl_sphinx_extract \
+	docs/bin/vl_sphinx_fix \
+	src/astgen \
+	src/bisonpre \
+	src/config_rev \
+	src/cppcheck_filtered \
+	src/flexfix \
+	src/vlcovgen \
+	test_regress/t/*.pf \
+	nodist/code_coverage \
+	nodist/dot_importer \
+	nodist/fuzzer/actual_fail \
+	nodist/fuzzer/generate_dictionary \
+	nodist/install_test \
+
+PY_FILES = \
+	$(PY_PROGRAMS) \
+	nodist/code_coverage.dat \
+
+YAPF = yapf3
+YAPF_FLAGS = -i
+
+yapf:
+	$(YAPF) $(YAPF_FLAGS) $(PY_FILES)
+
+FLAKE8 = flake8
+FLAKE8_FLAGS = \
+	--extend-exclude=fastcov.py \
+	--ignore=E123,E129,E251,E501,W503,W504,E701
+
+PYLINT = pylint
+PYLINT_FLAGS = --disable=R0801
+
+lint-py:
+	-$(FLAKE8) $(FLAKE8_FLAGS) $(PY_PROGRAMS)
+	-$(PYLINT) $(PYLINT_FLAGS) $(PY_PROGRAMS)
+
+format-pl-exec:
+	-chmod a+x test_regress/t/*.pl
+
+
 ftp: info
 
 install-msg:
@@ -472,7 +534,7 @@ install-msg:
 	@echo "Installed examples to $(DESTDIR)$(pkgdatadir)/examples"
 	@echo
 	@echo "For documentation see 'man verilator' or 'verilator --help'"
-	@echo "For forums and to report bugs see http://www.veripool.org/verilator"
+	@echo "For forums and to report bugs see https://verilator.org"
 	@echo
 
 IN_WILD := ${srcdir}/*.in ${srcdir}/*/*.in
@@ -511,11 +573,14 @@ clean mostlyclean distclean maintainer-clean::
 	rm -f *.pg *.pgs *.toc *.tp *.tps *.vr *.vrs *.idx
 	rm -f *.ev *.evs *.ov *.ovs *.cv *.cvs *.ma *.mas
 	rm -f *.tex
+	rm -rf examples/*/obj_dir* examples/*/logs
 	rm -rf test_*/obj_dir
-	rm -rf examples/*/obj_dir examples/*/logs
+	rm -rf nodist/fuzzer/dictionary
+	rm -rf nodist/obj_dir
+	rm -rf verilator.txt
 
 distclean maintainer-clean::
-	rm -f *.info* *.1 $(INFOS)
+	rm -f *.info* *.1 $(INFOS) $(INFOS_OLD) $(VL_INST_MAN_FILES)
 	rm -f Makefile config.status config.cache config.log TAGS
 	rm -f verilator_bin* verilator_coverage_bin*
 	rm -f bin/verilator_bin* bin/verilator_coverage_bin*
@@ -530,19 +595,17 @@ TAGS:	$(TAGFILES)
 .PHONY: doxygen
 
 doxygen:
-	$(DOXYGEN) doxygen.config
+	$(MAKE) -C docs doxygen
 
 ######################################################################
 # Test targets
 
 dist-file-list:
 	@echo "begin-dist-file-list:";  # Scripts look for this
-	@echo $(wildcard $(DISTFILES))
+	@echo $(wildcard $(DISTFILES1))
+	@echo $(wildcard $(DISTFILES2))
 	@echo "end-dist-file-list:";  # Scripts look for this
 
-print-cfg-with-threaded:
-	@echo $(CFG_WITH_THREADED)
-
 ######################################################################
 # Distributions
 
@@ -559,7 +622,12 @@ tag:
 # Don't depend on DISTFILES because there's no rule for "standards.info*".
 dist: $(DISTDEP) maintainer-copy
 	-rm -fr $(DISTNAME)
-	for file in $(DISTFILES); do \
+	for file in $(DISTFILES1); do \
+	  mkdir -p `dirname $(DISTNAME)/$$file` >/dev/null ; \
+	  ln $$file $(DISTNAME)/$$file \
+	  || { echo copying $$file instead; cp -p $$file $(DISTNAME)/$$file;}; \
+	done; true;
+	for file in $(DISTFILES2); do \
 	  mkdir -p `dirname $(DISTNAME)/$$file` >/dev/null ; \
 	  ln $$file $(DISTNAME)/$$file \
 	  || { echo copying $$file instead; cp -p $$file $(DISTNAME)/$$file;}; \

README.pod

@@ -1,211 +0,0 @@
-# DESCRIPTION: DOCUMENT source run through perl to produce README file
-# Use 'make README' to produce the output file
-
-=pod
-
-=head1 NAME
-
-This is the Verilator package README file.
-
-=head1 DISTRIBUTION
-
-http://www.veripool.org/verilator
-
-This package is Copyright 2003-2018 by Wilson Snyder.  (Report bugs to
-L<http://www.veripool.org/>.)
-
-Verilator is free software; you can redistribute it and/or modify it under
-the terms of either the GNU Lesser General Public License Version 3 or the
-Perl Artistic License Version 2.0.  (See the documentation for more
-details.)
-
-This program is distributed in the hope that it will be useful, but WITHOUT
-ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
-FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
-more details.
-
-=head1 DESCRIPTION
-
-Verilator converts synthesizable (generally not behavioral) Verilog code
-into C++ or SystemC code.  It is not a complete simulator, just a
-translator.
-
-Verilator is invoked with parameters similar to GCC or Synopsys's VCS.  It
-reads the specified Verilog code, lints it, and optionally adds coverage
-code.  For C++ format, it outputs .cpp and .h files.  For SystemC format,
-it outputs .cpp and .h files using the standard SystemC headers.
-
-The resulting files are then compiled with C++.  The user writes a little
-C++ wrapper file, which instantiates the top level module.  This is
-compiled in C++, and linked with the Verilated files.
-
-The resulting executable will perform the actual simulation.
-
-=head1 SUPPORTED SYSTEMS
-
-Verilator is developed and has primary testing on Ubuntu.  Versions have
-also built on Redhat Linux, Macs OS-X, HPUX and Solaris.  It should run
-with minor porting on any Linix-ish platform.  Verilator also works on
-Windows under Cygwin, and Windows under MinGW (gcc -mno-cygwin).  Verilated
-output (not Verilator itself) compiles under MSVC++ 2008 and newer.
-
-=head1 INSTALLATION
-
-For more details see
-L<http://www.veripool.org/projects/verilator/wiki/Installing>.
-
-If you will be modifying Verilator, you should use the "git" method as it
-will let you track changes.
-
-=over 4
-
-=item
-
-The latest version is available at L<http://www.veripool.org/verilator>.
-
-Download the latest package from that site, and decompress.
-
-    tar xvzf verilator_version.tgz
-
-=item
-
-If you will be using SystemC (vs straight C++ output), download SystemC
-from L<http://www.systemc.org>.  Follow their installation instructions.
-You will need to set SYSTEMC_INCLUDE to point to the include directory with
-systemc.h in it, and SYSTEMC_LIBDIR to points to the directory with
-libsystemc.a in it.  (Older installations may set SYSTEMC and SYSTEMC_ARCH
-instead.)
-
-=item
-
-To use Verilator you will need the C<perl>, C<make> (or C<gmake>), and
-C<g++> (or C<clang>) packages.
-
-To use Verilator LXT2 or FST tracing you will need the C<gtkwave> and C<libgz> (on
-Ubuntu C<zlibc> C<zlib1g> C<zlib1g-dev>) packages installed.
-
-To compile Verilator in addition to the above you need the C<flex>,
-C<bison> and C<texi2html> packages installed.
-
-=item
-
-C<cd> to the Verilator directory containing this README.
-
-=item
-
-You now have to decide how you're going to eventually install the kit.
-
-Note Verilator builds the current value of VERILATOR_ROOT, SYSTEMC_INCLUDE,
-and SYSTEMC_LIBDIR as defaults into the executable, so try to have them
-correct before configuring.
-
-=over 4
-
-=item 1.
-
-Our personal favorite is to always run Verilator from the kit directory.
-This allows the easiest experimentation and upgrading.  It's also how most
-EDA tools operate; to run you point to the tarball, no install is needed.
-
-    export VERILATOR_ROOT=`pwd`   # if your shell is bash
-    setenv VERILATOR_ROOT `pwd`   # if your shell is csh
-    ./configure
-
-=item 2.
-
-To install globally onto a "cad" disk with multiple versions of every tool,
-and add it to path using Modules/modulecmd:
-
-    unset VERILATOR_ROOT      # if your shell is bash
-    unsetenv VERILATOR_ROOT   # if your shell is csh
-    # For the tarball, use the version number instead of git describe
-    ./configure --prefix /CAD_DISK/verilator/`git describe | sed "s/verilator_//"`
-
-    After installing you'll want a module file like the following:
-
-    set install_root /CAD_DISK/verilator/{version-number-used-above}
-    unsetenv VERILATOR_ROOT
-    prepend-path PATH $install_root/bin
-    prepend-path MANPATH $install_root/man
-    prepend-path PKG_CONFIG_PATH $install_root/share/pkgconfig
-
-=item 3.
-
-The next option is to install it globally, using the normal system paths:
-
-    unset VERILATOR_ROOT      # if your shell is bash
-    unsetenv VERILATOR_ROOT   # if your shell is csh
-    ./configure
-
-=item 4.
-
-Alternatively you can configure a prefix that install will populate, as
-most GNU tools support:
-
-    unset VERILATOR_ROOT      # if your shell is bash
-    unsetenv VERILATOR_ROOT   # if your shell is csh
-    ./configure --prefix /opt/verilator-VERSION
-
-Then after installing you will need to add /opt/verilator-VERSION/bin to
-PATH.
-
-=back
-
-=item
-
-Type C<make> to compile Verilator.
-
-Type C<make test> to check the compilation.
-
-Configure with C<--enable-longtests> for more complete developer tests.
-Additional packages may be required for these tests.
-
-You may get a error about a typedef conflict for uint32_t.  Edit
-verilated.h to change the typedef to work, probably to @samp{typedef
-unsigned long uint32_t;}.
-
-=item
-
-If you used the VERILATOR_ROOT scheme you're done.  Programs should set the
-environment variable VERILATOR_ROOT to point to this distribution, then
-execute $VERILATOR_ROOT/bin/verilator, which will find the path to all
-needed files.
-
-If you used the prefix scheme, now do a C<make install>.  To run verilator,
-have the verilator binary directory in your PATH (this should already be
-true if using the default configure), and make sure VERILATOR_ROOT is not
-set.
-
-You may now wish to consult the examples directory. Type C<make> inside any
-example directory to run the example.
-
-=back
-
-=head1 USAGE DOCUMENTATION
-
-Detailed documentation and the man page can be seen by running:
-
-    bin/verilator --help
-
-or reading verilator.txt in the same directory as this README.
-
-=head1 DIRECTORY STRUCTURE
-
-The directories in the kit after de-taring are as follows:
-
-    bin/verilator               => Compiler Wrapper invoked to Verilate code
-    include/                    => Files that should be in your -I compiler path
-    include/verilated*.cpp      => Global routines to link into your simulator
-    include/verilated*.h        => Global headers
-    include/verilated.v         => Stub defines for linting
-    include/verilated.mk        => Common makefile
-    src/                        => Translator source code
-    examples/hello_world_c      => Example simple Verilog->C++ conversion
-    examples/hello_world_sc     => Example simple Verilog->SystemC conversion
-    examples/tracing_c          => Example Verilog->C++ with tracing
-    examples/tracing_sc         => Example Verilog->SystemC with tracing
-    test_regress                => Internal tests
-
-=head1 LIMITATIONS
-
-See verilator.txt (or execute C<bin/verilator --help>) for limitations.

README.rst

@@ -0,0 +1,151 @@
+.. Github doesn't render images unless absolute URL
+.. Do not know of a conditional tag, "only: github" nor "github display" works
+
+.. image:: https://img.shields.io/badge/License-LGPL%20v3-blue.svg
+    :target: https://www.gnu.org/licenses/lgpl-3.0]
+.. image:: https://img.shields.io/badge/License-Artistic%202.0-0298c3.svg
+    :target: https://opensource.org/licenses/Artistic-2.0
+.. image:: https://api.codacy.com/project/badge/Grade/fa78caa433c84a4ab9049c43e9debc6f
+    :target: https://www.codacy.com/gh/verilator/verilator
+.. image:: https://codecov.io/gh/verilator/verilator/branch/master/graph/badge.svg
+    :target: https://codecov.io/gh/verilator/verilator
+.. image:: https://github.com/verilator/verilator/workflows/build/badge.svg
+    :target: https://github.com/verilator/verilator/actions?query=workflow%3Abuild
+
+Welcome to Verilator
+====================
+
+.. list-table::
+
+   * - **Welcome to Verilator, the fastest Verilog/SystemVerilog simulator.**
+        * Accepts synthesizable Verilog or SystemVerilog
+        * Performs lint code-quality checks
+        * Compiles into multithreaded C++, or SystemC
+        * Creates XML to front-end your own tools
+     - |Logo|
+   * - |verilator multithreaded performance|
+     - **Fast**
+        * Outperforms many commercial simulators
+        * Single- and multi-threaded output models
+   * - **Widely Used**
+        * Wide industry and academic deployment
+        * Out-of-the-box support from Arm, and RISC-V vendor IP
+     - |verilator usage|
+   * - |verilator community|
+     - **Community Driven & Openly Licensed**
+        * Guided by the `CHIPS Alliance`_ and `Linux Foundation`_
+        * Open, and free as in both speech and beer
+        * More simulation for your verification budget
+   * - **Commercial Support Available**
+        * Commercial support contracts
+        * Design support contracts
+        * Enhancement contracts
+     - |verilator support|
+
+
+What Verilator Does
+===================
+
+Verilator is invoked with parameters similar to GCC or Synopsys's VCS.  It
+"Verilates" the specified Verilog or SystemVerilog code by reading it,
+performing lint checks, and optionally inserting assertion checks and
+coverage-analysis points. It outputs single- or multi-threaded .cpp and .h
+files, the "Verilated" code.
+
+The user writes a little C++/SystemC wrapper file, which instantiates the
+"Verilated" model of the user's top level module. These C++/SystemC files
+are then compiled by a C++ compiler (gcc/clang/MSVC++). The resulting
+executable performs the design simulation. Verilator also supports linking
+its generated libraries, optionally encrypted, into other simulators.
+
+Verilator may not be the best choice if you are expecting a full featured
+replacement for NC-Verilog, VCS or another commercial Verilog simulator, or
+if you are looking for a behavioral Verilog simulator e.g. for a quick
+class project (we recommend `Icarus Verilog`_ for this.) However, if you
+are looking for a path to migrate SystemVerilog to C++ or SystemC, or your
+team is comfortable writing just a touch of C++ code, Verilator is the tool
+for you.
+
+
+Performance
+===========
+
+Verilator does not simply convert Verilog HDL to C++ or SystemC. Rather,
+Verilator compiles your code into a much faster optimized and optionally
+thread-partitioned model, which is in turn wrapped inside a C++/SystemC
+module. The results are a compiled Verilog model that executes even on a
+single-thread over 10x faster than standalone SystemC, and on a single
+thread is about 100 times faster than interpreted Verilog simulators such
+as `Icarus Verilog`_. Another 2-10x speedup might be gained from
+multithreading (yielding 200-1000x total over interpreted simulators).
+
+Verilator has typically similar or better performance versus the
+closed-source Verilog simulators (Carbon Design Systems Carbonator,
+Modelsim, Cadence Incisive/NC-Verilog, Synopsys VCS, VTOC, and Pragmatic
+CVer/CVC). But, Verilator is open-sourced, so you can spend on computes
+rather than licenses. Thus Verilator gives you the best cycles/dollar.
+
+Installation & Documentation
+============================
+
+For more information:
+
+- `Verilator installation and package directory structure
+  <https://verilator.org/install>`_
+
+- `Verilator manual (HTML) <https://verilator.org/verilator_doc.html>`_,
+  or `Verilator manual (PDF) <https://verilator.org/verilator_doc.pdf>`_
+
+- `Subscribe to verilator announcements
+  <https://github.com/verilator/verilator-announce>`_
+
+- `Verilator forum <https://verilator.org/forum>`_
+
+- `Verilator issues <https://verilator.org/issues>`_
+
+
+Support
+=======
+
+Verilator is a community project, guided by the `CHIPS Alliance`_ under the
+`Linux Foundation`_.
+
+We appreciate and welcome your contributions in whatever form; please see
+`Contributing to Verilator
+<https://github.com/verilator/verilator/blob/master/docs/CONTRIBUTING.rst>`_.
+Thanks to our `Contributors and Sponsors
+<https://verilator.org/guide/latest/contributors.html>`_.
+
+Verilator also supports and encourages commercial support models and
+organizations; please see `Verilator Commercial Support
+<https://verilator.org/verilator_commercial_support>`_.
+
+
+Related Projects
+================
+
+- `GTKwave <http://gtkwave.sourceforge.net/>`_ - Waveform viewer for
+  Verilator traces.
+
+- `Icarus Verilog`_ - Icarus is a full featured interpreted Verilog
+  simulator. If Verilator does not support your needs, perhaps Icarus may.
+
+
+Open License
+============
+
+Verilator is Copyright 2003-2021 by Wilson Snyder. (Report bugs to
+`Verilator Issues <https://verilator.org/issues>`_.)
+
+Verilator is free software; you can redistribute it and/or modify it under
+the terms of either the GNU Lesser General Public License Version 3 or the
+Perl Artistic License Version 2.0. See the documentation for more details.
+
+.. _CHIPS Alliance: https://chipsalliance.org
+.. _Icarus Verilog: http://iverilog.icarus.com
+.. _Linux Foundation: https://www.linuxfoundation.org
+.. |Logo| image:: https://www.veripool.org/img/verilator_256_200_min.png
+.. |verilator multithreaded performance| image:: https://www.veripool.org/img/verilator_multithreaded_performance_bg-min.png
+.. |verilator usage| image:: https://www.veripool.org/img/verilator_usage_400x200-min.png
+.. |verilator community| image:: https://www.veripool.org/img/verilator_community_400x125-min.png
+.. |verilator support| image:: https://www.veripool.org/img/verilator_support_400x125-min.png

TODO

@@ -1,119 +0,0 @@
-// DESCRIPTION: Verilator: List of To Do issues.
-//
-// Copyright 2004-2018 by Wilson Snyder. This program is free software; you can
-// redistribute it and/or modify it under the terms of either the GNU
-// Lesser General Public License Version 3 or the Perl Artistic License
-// Version 2.0.
-
-* Language support:
-** Fix ordering of each bit separately in a signal (mips)
-   assign b[3:0] = b[7:4];  assign b[7:4] = in;
-** Support UDP gate primitives/ cell libraries
-   (have code for combos - problem is sequential udps)
-** Function to eval combo logic after /*verilator public*/ functions [gwaters]
-** Support generated clocks (correctness)
-** Recursive functions
-** Verilog configuration files
-** Expression coverage (see notes)
-** Better tristate support
-** UVM
-
-* Long-term Features
-** Assertions
-** Tristate support
-
-* Configure/Make/Install
-** Distribute with flex/bison already expanded?
-   Flex library not needed.  Probably too difficult to be worth it.
-
-* Testing:
-** Capture all inputs into global "rerun it" file
-** Code to make wrapper that sets signals, so can do comparison checks
-** New random program generator
-** Better graph viewer with search and zoom
-** Port and test against opencores.org code
-** // verilator debug in code so can see only tree affecting those nodes
-
-* Usability:
-** Detect and pre-remove most UNOPTFLATs
-** Better reporting of unopt problems, including what lines of code
-** Report more errors (all of them?) before exiting [Eugene Weber]
-** Auto-create scons config files
-** Print version/etc message at runtime. (4.000?)
-   Include number of lines of code, percent comments, code complexity measurement
-   <-80chars------------------------------------------------------------------->
-   Verilator 3.600 - The fast free open-sourced simulator.  Copyright 2001-2013.
-   Verilated #### modules, #### instances, ##### sigs,
-         #### non-comment lines, ##### ops, ### KB model size
-
-* Lint:
-** CDCRSTLOGIC should allow filtering with paths
-   "waive CDCRSTLOGIC --from a.b.sig  --to a.c.sig --via OR"
-
-* Internal Code:
-** A Visitor class that understands how to traverse data types
-** V3Graph should be templated container type, taking in Vertex + Edge types
-** Instead of string, have an VEncodedString/VIdString which contains __DOT__ish
-   things, to reduce bugs.  Also add _20 trailing space to \ encoded names.
-
-* Runtime:
-** New evalulation loop   ~/src/verilator/notes/event_loop.txt (4.000?)
-** Remove all private internal functions from top level wrapper header, move
-   to new level
-** Completely standalone simulation
-    main() records arguments for $test$plusvars
-    instantiates top,
-    does tracing  (support $dump?)
-    calls top->simulateForever()
-    exits
-
-* Performance:
-** Latch optimizations
-** Constant propagation
-   Extra cleaning AND:  1 & ((VARREF >> 1) | ((&VARREF >> 1) & VARREF))
-   Extra shift (perhaps due to clean): if (1 & CAST (VARREF >> #))
-** Gated clock and latch conversion to flops.  [JeanPaul Vanitegem]
-   Could propagate the AND into pos/negedges and let domaining optimize.
-** Negedge reset
-   Switch to remove negedges that don't matter
-   Can't remove async resets from control flops (like in syncronizers)
-** If all references to array have a constant index, blow up into separate signals-per-index
-** Bit-multiply for faster bit swapping and a=b[1,3,2] random bit reorderings.
-** Move _last sets and all other combo logic inside master
-   if() that triggers on all possible sense items
-** Rewrite and combine V3Life, V3Subst
-   If block temp only ever set in one place to constant, propagate it
-     Used in t_mem for array delayed assignments
-   Replace variables if set later in same cfunc branch
-     See for example duplicate sets of _narrow in cycle 90/91 of t_select_plusloop
-** Same assignment on both if branches
-   "if (a) { ... b=2; } else { ... b=2;}" -> "b=2; if ..."
-   Careful though, as b could appear in the statement or multiple times in statement
-   (Could just require exatly two 'b's in statement)
-** Simplify XOR/XNOR/AND/OR bit selection trees
-   Foo = A[1] ^ A[2] ^ A[3] etc are better as ^ ( A & 32'b...1110 )
-** Combine variables into wider elements
-   Parallel statements on different bits should become single signal
-   Variables that are always consumed in "parallel" can be joined
-** Duplicate assignments in gate optimization
-   Common to have many separate posedge blocks, each with identical
-   reset_r <= rst_in
-** If signal is used only once (not counting trace), always gate substitute
-   Don't merge if any combining would form circ logic (out goes back to in)
-** Multiple assignments each bit can become single assign with concat
-   Make sure a SEL of a CONCAT can get the single bit back.
-** Usually blocks/values
-   Enable only after certain time, so VL_TIME_I(32) > 0x1e gets eliminated out
-** Better ordering of a<=b, b<=c, put all refs to 'b' next to each other to optimize caching
-** I-cache packing improvements (what/how?)
-** Data cache organization (order of vars in class)
-   First have clocks,
-   then bools instead of uint32_t's
-   then based on what sense list they come from, all outputs, then all inputs
-   finally have any signals part of a "usually" block, or constant.
-** Rather then tracking widths, have a MSB...LSB of this expression
-   (or better, a bitmask of bits relevant in this expression)
-** Track recirculation and convert into clock-enables
-** Clock enables should become new clocking domains for speed
-** If floped(a) & flopped(b) and no other a&b, then instead flop(a&b).
-** Sort by output bitselects so can combine more assignments (see DDP example dx_dm signal)

bin/verilator_ccache_report

@@ -0,0 +1,94 @@
+#!/usr/bin/env python3
+# pylint: disable=C0103,C0114,C0115,C0116,C0123,C0301,R0902,R0913,R0914,R0912,R0915,W0621
+######################################################################
+
+import argparse
+import collections
+import pathlib
+import re
+
+from datetime import datetime
+
+parser = argparse.ArgumentParser(
+    allow_abbrev=False,
+    formatter_class=argparse.RawDescriptionHelpFormatter,
+    description="""Report ccache behavior of a Verilated model build.""",
+    epilog=
+    """Copyright 2002-2021 by Wilson Snyder. This program is free software; you
+can redistribute it and/or modify it under the terms of either the GNU
+Lesser General Public License Version 3 or the Perl Artistic License
+Version 2.0.
+
+SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0""")
+
+parser.add_argument('-o',
+                    type=argparse.FileType('w'),
+                    metavar="OUTFILE",
+                    required=True,
+                    help='output file')
+parser.add_argument('logdir', type=pathlib.Path, help='log directory')
+
+args = parser.parse_args()
+
+results = {}
+elapsed = {}
+
+
+def toDateTime(s):
+    return datetime.strptime(s, "%Y-%m-%dT%H:%M:%S.%f")
+
+
+for logfile in args.logdir.iterdir():
+    with logfile.open() as fh:
+        start = None
+        obj = None
+        for line in fh:
+            line = line.strip()
+            match = re.match(r'\[(\S+)\s.*Object file: (.*)$', line)
+            if match:
+                start = toDateTime(match.group(1))
+                obj = match.group(2)
+            match = re.match(r'\[(\S+)\s.*Result: (.*)$', line)
+            if match:
+                assert obj is not None
+                elapsed[obj] = toDateTime(match.group(1)) - start
+                results[obj] = match.group(2)
+
+args.o.write("#" * 80 + "\n")
+args.o.write("ccache report (from verilator_ccache_report) :\n")
+
+if not results:
+    args.o.write("\nAll object files up to date\n")
+else:
+    args.o.write("\nCompiled object files:\n")
+    wnames = max(len(_) for _ in results) + 1
+    wresults = max(len(_) for _ in results.values()) + 1
+    for k in sorted(results.keys()):
+        args.o.write("{:{wnames}} : {:{wresults}} : {}s\n".format(
+            k,
+            results[k],
+            elapsed[k].total_seconds(),
+            wnames=wnames,
+            wresults=wresults))
+
+    args.o.write("\nSummary:\n")
+    counts = collections.Counter(_ for _ in results.values())
+    total = sum(counts.values())
+    for k in sorted(counts.keys()):
+        c = counts[k]
+        args.o.write("{:{width}}| {} ({:.2%})\n".format(k,
+                                                        c,
+                                                        c / total,
+                                                        width=wresults))
+
+    args.o.write("\nLongest:\n")
+    longest = sorted(list(elapsed.items()),
+                     key=lambda kv: -kv[1].total_seconds())
+    for i, (k, v) in enumerate(longest):
+        args.o.write("{:{width}}| {}s\n".format(k,
+                                                v.total_seconds(),
+                                                width=wnames))
+        if i > 4:
+            break
+
+args.o.write("#" * 80 + "\n")

bin/verilator_coverage

@@ -1,29 +1,15 @@
-: # -*-Mode: perl;-*- use perl, wherever it is
-eval 'exec perl -wS $0 ${1+"$@"}'
-  if 0;
+#!/usr/bin/env perl
 ######################################################################
 #
-# Copyright 2003-2018 by Wilson Snyder. This program is free software; you
+# Copyright 2003-2021 by Wilson Snyder. This program is free software; you
 # can redistribute it and/or modify it under the terms of either the GNU
 # Lesser General Public License Version 3 or the Perl Artistic License
 # Version 2.0.
 #
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
 ######################################################################
 
 require 5.006_001;
 use warnings;
-BEGIN {
-    if ($ENV{DIRPROJECT} && $ENV{DIRPROJECT_PERL_BOOT}) {
-	# Magic to allow author testing of perl packages in local directory
-	require $ENV{DIRPROJECT}."/".$ENV{DIRPROJECT_PERL_BOOT};
-    }
-}
-
 use Getopt::Long;
 use FindBin qw($RealBin $RealScript);
 use IO::File;
@@ -56,12 +42,12 @@ foreach my $sw (@ARGV) {
 
 Getopt::Long::config("no_auto_abbrev","pass_through");
 if (! GetOptions (
-	  # Major operating modes
-	  "help"	=> \&usage,
-	  "debug:s"	=> \&debug,
-	  # "version!"	=> \&version,	# Also passthru'ed
-	  # Additional parameters
-	  "<>"		=> sub {},	# Ignored
+          # Major operating modes
+          "help"        => \&usage,
+          "debug:s"     => \&debug,
+          # "version!"  => \&version,   # Also passthru'ed
+          # Additional parameters
+          "<>"          => sub {},      # Ignored
     )) {
     pod2usage(-exitstatus=>2, -verbose=>0);
 }
@@ -73,7 +59,7 @@ run(verilator_coverage_bin()
 #----------------------------------------------------------------------
 
 sub usage {
-    pod2usage(-verbose=>2, -exitval=>2, -output=>\*STDOUT);
+    pod2usage(-verbose=>2, -exitval=>0, -output=>\*STDOUT);
 }
 
 sub debug {
@@ -90,25 +76,25 @@ sub verilator_coverage_bin {
     my $bin = "";
     # Use VERILATOR_ROOT if defined, else assume verilator_bin is in the search path
     my $basename = ($ENV{VERILATOR_COVERAGE_BIN}
-		    || "verilator_coverage_bin_dbg");
+                    || "verilator_coverage_bin_dbg");
     if (defined($ENV{VERILATOR_ROOT})) {
-	my $dir = $ENV{VERILATOR_ROOT};
+        my $dir = $ENV{VERILATOR_ROOT};
         if (-x "$dir/bin/$basename"
             || -x "$dir/bin/$basename.exe") {  # From a "make install" into VERILATOR_ROOT
-	    $bin = "$dir/bin/$basename";
-	} else {
-	    $bin = "$dir/$basename";  # From pointing to kit directory
-	}
+            $bin = "$dir/bin/$basename";
+        } else {
+            $bin = "$dir/$basename";  # From pointing to kit directory
+        }
     } else {
         if (-x "$RealBin/$basename"
             || -x "$RealBin/$basename.exe") {
-	    $bin = "$RealBin/$basename";  # From path/to/verilator with verilator_bin installed
-	} else {
-	    $bin = $basename;  # Find in PATH
-	}
-	# Note we don't look under bin/$basename which would be right if running
-	# in the kit dir. Running that would likely break, since
-	# VERILATOR_ROOT wouldn't be set and Verilator won't find internal files.
+            $bin = "$RealBin/$basename";  # From path/to/verilator with verilator_bin installed
+        } else {
+            $bin = $basename;  # Find in PATH
+        }
+        # Note we don't look under bin/$basename which would be right if running
+        # in the kit dir. Running that would likely break, since
+        # VERILATOR_ROOT wouldn't be set and Verilator won't find internal files.
     }
     return $bin;
 }
@@ -125,23 +111,28 @@ sub run {
     system($command);
     my $status = $?;
     if ($status) {
-	if ($! =~ /no such file or directory/i) {
-	    warn "%Error: verilator_coverage: Misinstalled, or VERILATOR_ROOT might need to be in environment\n";
-	}
-	if ($Debug) {  # For easy rerunning
-	    warn "%Error: export VERILATOR_ROOT=".($ENV{VERILATOR_ROOT}||"")."\n";
-	    warn "%Error: $command\n";
-	}
-	if ($status & 127) {
-	    if (($status & 127) == 8 || ($status & 127) == 11) { # SIGFPA or SIGSEGV
-		warn "%Error: Verilator_coverage internal fault, sorry.\n" if !$Debug;
-	    } elsif (($status & 127) == 6) {  # SIGABRT
-		warn "%Error: Verilator_coverage aborted.\n" if !$Debug;
-	    } else {
-		warn "%Error: Verilator_coverage threw signal $status.\n" if !$Debug;
-	    }
-	}
-	die "%Error: Command Failed $command\n";
+        if ($! =~ /no such file or directory/i) {
+            warn "%Error: verilator_coverage: Misinstalled, or VERILATOR_ROOT might need to be in environment\n";
+        }
+        if ($Debug) {  # For easy rerunning
+            warn "%Error: export VERILATOR_ROOT=".($ENV{VERILATOR_ROOT}||"")."\n";
+            warn "%Error: $command\n";
+        }
+        if ($status & 127) {
+            if (($status & 127) == 8 || ($status & 127) == 11) { # SIGFPA or SIGSEGV
+                warn "%Error: Verilator_coverage internal fault, sorry.\n" if !$Debug;
+            } elsif (($status & 127) == 6) {  # SIGABRT
+                warn "%Error: Verilator_coverage aborted.\n" if !$Debug;
+            } else {
+                warn "%Error: Verilator_coverage threw signal $status.\n" if !$Debug;
+            }
+        }
+        if ($status != 256 || $Debug) {  # i.e. not normal exit(1)
+            warn "%Error: Command Failed $command\n";
+        }
+        exit $! if $!;  # errno
+        exit $? >> 8 if $? >> 8;  # child exit status
+        exit 255;  # last resort
     }
 }
 
@@ -165,129 +156,53 @@ verilator_coverage - Verilator coverage analyzer
 
     verilator_coverage  -write merged.dat -read <datafiles>...
 
-Verilator_coverage processes Verilator coverage reports.
+    verilator_coverage  -write-info merged.info -read <datafiles>...
 
-With --anotate, it reads the specified data file and generates annotated
-source code with coverage metrics annotated.  If multiple coverage points
-exist on the same line, additional lines will be inserted to report the
-additional points.
+Verilator_coverage processes Verilated model-generated coverage reports.
 
-Additional Verilog-standard arguments specify the search paths necessary to
-find the source code that the coverage analysis was performed on.
+For documentation see
+L<https://verilator.org/guide/latest/exe_verilator_coverage.html>.
 
-To get correct coverage percentages, you may wish to read logs/coverage.dat
-into Emacs and do a M-x keep-lines to include only those statistics of
-interest.
+=head1 ARGUMENT SUMMARY
 
-For Verilog conditions that should never occur, you should add a $stop
-statement.  This will remove the coverage during the next build.
+    <filename>    Specify input data filename, default "coverage.dat"
+    --annotate <output_dir>       Directory name for source annotation.
+    --annotate-all                All files should be shown.
+    --annotate-min <count>        Minimum occurrence count for uncovered.
+    --help                        Displays this message and version and exits.
+    --rank                        Compute relative importance of tests.
+    --unlink                      With --write, unlink all inputs
+    --version                     Displays program version and exits.
+    --write <filename>            Write aggregate coverage results.
+    --write-info <filename.info>  Write lcov .info.
 
-=head1 ARGUMENTS
-
-=over 4
-
-=item I<filename>
-
-Specify input data file, may be repeated to read multiple inputs.  If no
-data file is specified, by default coverage.dat is read.
-
-=item --annotate I<output_directory>
-
-Sprcifies the directory name that source files with annotated coverage data
-should be written to.
-
-=item --annotate-all
-
-Specifies all files should be shown.  By default, only those source files
-which have low coverage are written to the output directory.
-
-=item --annotate-min I<count>
-
-Specifies the minimum occurrence count that should be flagged if the
-coverage point does not include a specified threshold.  Defaults to 10.
-
-=item --help
-
-Displays this message and program version and exits.
-
-=item --rank
-
-Print an experimental report listing the relative importance of each test
-in covering all of the coverage points.  The report shows "Covered" which
-indicates the number of points that test covers; a test is considered to
-cover a point if it has a bucket count of at least 1. The "rank" column has
-a higher number t indicate the test is more important, and rank 0 means the
-test does not need to be run to cover the points.  "RankPts" indicates the
-number of coverage points this test will contribute to overall coverage if
-all tests are run in the order of highest to lowest rank.
-
-=item --unlink
-
-When using --write to combine coverage data, unlink all input files after
-the output has been created.
-
-=item --version
-
-Displays program version and exits.
-
-=item --write I<filename>
-
-Specifies the aggregate coverage results, summed across all the files,
-should be written to the given filename.  This is useful in scripts to
-combine many sequential runs into one master coverage file.
-
-=back
-
-=head1 VERILOG ARGUMENTS
-
-The following arguments are compatible with GCC, VCS and most Verilog
-programs.
-
-=over 4
-
-=item +libext+I<ext>+I<ext>...
-
-Defines the extensions for Verilog files.
-
-=item +define+I<var>+I<value>
-=item -DI<var>=I<value>
-
-Defines the given variable.
-
-=item +incdir+I<dir>
-=item -II<dir>
-
-Specifies a directory for finding include files.
-
-=item -f I<file>
-
-Specifies a file containing additional command line arguments.
-
-=item -y I<dir>
-
-Specifies a module search directory.
-
-=back
+    +libext+I<ext>+I<ext>...      Extensions for Verilog files.
+    +define+I<var>+I<value>       Defines the given variable.
+    -DI<var>=I<value>             Defines the given variable.
+    +incdir+I<dir>                Add directory for finding include files.
+    -II<dir>                      Add directory for finding include files.
+    -y I<dir>                     Specifies module search directory.
 
 =head1 DISTRIBUTION
 
-The latest version is available from L<http://www.veripool.org/>.
+The latest version is available from L<https://verilator.org>.
 
-Copyright 2003-2018 by Wilson Snyder.  Verilator is free software; you can
-redistribute it and/or modify the Verilator internals under the terms of
-either the GNU Lesser General Public License Version 3 or the Perl Artistic
-License Version 2.0.
+Copyright 2003-2021 by Wilson Snyder. This program is free software; you
+can redistribute it and/or modify the Verilator internals under the terms
+of either the GNU Lesser General Public License Version 3 or the Perl
+Artistic License Version 2.0.
 
-=head1 AUTHORS
-
-Wilson Snyder <[email protected]>
+SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 
 =head1 SEE ALSO
 
-C<verilator>
+C<verilator>, C<lcov>
 
 L<verilator_coverage --help> which is the source for this document.
 
+and L<https://verilator.org/guide/latest/exe_verilator_coverage.html> for
+detailed documentation.
+
 =cut
 
 ######################################################################

bin/verilator_difftree

@@ -1,10 +1,7 @@
-: # -*-Mode: perl;-*- use perl, wherever it is
-eval 'exec perl -wS $0 ${1+"$@"}'
-  if 0;
+#!/usr/bin/env perl
 # See copyright, etc in below POD section.
 ######################################################################
 
-require 5.006_001;
 use warnings;
 use Getopt::Long;
 use IO::File;
@@ -12,22 +9,6 @@ use Pod::Usage;
 use strict;
 use vars qw($Debug);
 
-#======================================================================
-
-# Old version 1 dump nodes with no dtypep's
-our %Ver1_Non_Dtyped = map {$_ => 1} qw(
-  ACTIVE ALWAYS ALWAYSPOST ALWAYSPUBLIC ATTROF BEGIN BREAK CASE CASEITEM
-  CCALL CELL CELLINLINE CFILE CFUNC CHANGEDET CLOCKING COMMENT CONTINUE
-  COVERDECL COVERINC COVERTOGGLE CRETURN CSTMT DEFPARAM DISABLE DISPLAY DOT
-  DPIEXPORT FCLOSE FFLUSH FINAL FINISH FOPEN GENCASE GENERATE GENFOR GENIF
-  IF IMPLICIT INITARRAY INITIAL JUMPGO JUMPLABEL MODULE NETLIST
-  NOTFOUNDMODULE PACKAGE PACKAGEIMPORT PARSEREF PIN PORT PRAGMA PRIMITIVE
-  PSLASSERT PSLCOVER PSLDEFCLOCK PULL RANGE READMEM REPEAT RETURN SCCTOR
-  SCDTOR SCHDR SCIMP SCIMPHDR SCINT SCOPE SELBIT SELEXTRACT SELMINUS
-  SELPLUS SENGATE SENITEM SENTREE SFORMAT SFORMATF STOP SYSIGNORE SYSTEMT
-  TASK TASKREF TEXT TOPSCOPE TYPEDEFFWD TYPETABLE UCSTMT UDPTABLE
-  UDPTABLELINE UNTILSTABLE VASSERT WHILE );
-
 #======================================================================
 # main
 
@@ -38,11 +19,11 @@ my $Opt_Lineno = 1;
 autoflush STDOUT 1;
 autoflush STDERR 1;
 Getopt::Long::config("no_auto_abbrev");
-if (! GetOptions (
-	  "help"	=> \&usage,
-	  "debug"	=> \&debug,
-	  "<>"		=> \&parameter,
-	  "lineno!"	=> \$Opt_Lineno,
+if (! GetOptions(
+          "help"        => \&usage,
+          "debug"       => \&debug,
+          "<>"          => \&parameter,
+          "lineno!"     => \$Opt_Lineno,
     )) {
     die "%Error: Bad usage, try 'verilator_difftree --help'\n";
 }
@@ -68,22 +49,22 @@ sub diff_dir {
     my %files;
 
     foreach my $fn (glob("$a/*.tree")) {
-	(my $base = $fn) =~ s!.*/!!;
-	$files{$base}{a} = $fn;
+        (my $base = $fn) =~ s!.*/!!;
+        $files{$base}{a} = $fn;
     }
     foreach my $fn (glob("$b/*.tree")) {
-	(my $base = $fn) =~ s!.*/!!;
-	$files{$base}{b} = $fn;
+        (my $base = $fn) =~ s!.*/!!;
+        $files{$base}{b} = $fn;
     }
     my $any;
     foreach my $base (sort (keys %files)) {
-	my $a = $files{$base}{a};
-	my $b = $files{$base}{b};
-	next if !$a || !$b;
-	print "="x70,"\n";
-	print "= $a <-> $b\n";
-	diff_file($a,$b);
-	$any = 1;
+        my $a = $files{$base}{a};
+        my $b = $files{$base}{b};
+        next if !$a || !$b;
+        print "="x70,"\n";
+        print "= $a <-> $b\n";
+        diff_file($a,$b);
+        $any = 1;
     }
     $any or warn("%Warning: No .tree files found that have similar base names:\n    "
                  .join("\n    ", sort keys %files),"\n");
@@ -101,7 +82,7 @@ sub diff_file {
     my $vera = version_from($a);
     my $verb = version_from($b);
     my $verCvt = (($vera < 0x3900 && $verb >= 0x3900)
-		  || ($vera >= 0x3900 && $verb < 0x3900));
+                  || ($vera >= 0x3900 && $verb < 0x3900));
 
     filter($a, $tmp_a, $verCvt);
     filter($b, $tmp_b, $verCvt);
@@ -115,8 +96,8 @@ sub version_from {
     # Return dump format
     my $f1 = IO::File->new ($fn) or die "%Error: $! $fn,";
     while (defined (my $line=$f1->getline())) {
-	last if $. > 10;
-	return hex $1 if $line =~ /\(format (0x[0-9.]+)\)/;
+        last if $. > 10;
+        return hex $1 if $line =~ /\(format (0x[0-9.]+)\)/;
     }
     return 1.0;
 }
@@ -130,36 +111,27 @@ sub filter {
     my $f2 = IO::File->new ($fn2,"w") or die "%Error: $! $fn2,";
     while (defined (my $line=$f1->getline())) {
       same_line:
-	next if $line =~ / This=/;
-	$line =~ s/0x[a-f0-9]+/0x/g;
-	$line =~ s/<e[0-9]+\#?>/<e>/g;
-	$line =~ s/{[a-z]*\d+}/{}/g if !$Opt_Lineno;
-	if ($verCvt) {
-	    next if $line =~ /^     NETLIST/;
-	    $line =~ s!\@dt=0x\(G?/?([^)]+)\)!$1!g;  # NEW: @dt -> OLD: non @dt format
-	    #					     # Below Ver1_Non_Dtyped may replace above further
-	    if ($line =~ /: ([A-Z]+) /) {
-		my $type = $1;
-		next if $type =~ 'DTYPE';
-		if ($type eq 'TYPETABLE' || $type eq 'RANGE') {
-		    $line =~ /^(\s+\S+:) /; my $prefix = $1;
-		    while (defined ($line=$f1->getline())) {
-			next if $line =~ /^\s+[a-z]/;  # Table body
-			next if $line =~ /^${prefix}[0-9]:/;
-			goto same_line;
-		    }
-		    next;
-		}
-		if ($Ver1_Non_Dtyped{$type}) {
-		    $line =~ s! w[0-9]+!!g;
-		}
-	    }
-	    $line =~ s!\@dt=0$!NoW!g;   # NEW: dt=null -> common format
-	    $line =~ s!\@dt=0 !NoW !g;  # NEW: dt=null -> common format
-	    $line =~ s! s?w0$! NoW!g;   # OLD: no width -> common format
-	    $line =~ s! s?w0 ! NoW !g;  # OLD: no width -> common format
-	}
-	print $f2 $line;
+        next if $line =~ / This=/;
+        $line =~ s/0x[a-f0-9]+/0x/g;
+        $line =~ s/<e[0-9]+\#?>/<e>/g;
+        $line =~ s/{[a-z]*\d+}/{}/g if !$Opt_Lineno;
+        if ($verCvt) {
+            next if $line =~ /^     NETLIST/;
+            if ($line =~ /: ([A-Z]+) /) {
+                my $type = $1;
+                next if $type =~ 'DTYPE';
+                if ($type eq 'TYPETABLE' || $type eq 'RANGE') {
+                    $line =~ /^(\s+\S+:) /; my $prefix = $1;
+                    while (defined ($line=$f1->getline())) {
+                        next if $line =~ /^\s+[a-z]/;  # Table body
+                        next if $line =~ /^${prefix}[0-9]:/;
+                        goto same_line;
+                    }
+                    next;
+                }
+            }
+        }
+        print $f2 $line;
     }
     $f1->close;
     $f2->close;
@@ -168,8 +140,8 @@ sub filter {
 #----------------------------------------------------------------------
 
 sub usage {
-    pod2usage(-verbose=>2, -exitval=>2, -output=>\*STDOUT);
-    exit(1);
+    pod2usage(-verbose=>2, -exitval=>0, -output=>\*STDOUT);
+    exit(1);  # Unreachable
 }
 
 sub debug {
@@ -179,11 +151,11 @@ sub debug {
 sub parameter {
     my $param = shift;
     if (!defined $Opt_A) {
-	$Opt_A = $param;
+        $Opt_A = $param;
     } elsif (!defined $Opt_B) {
-	$Opt_B = $param;
+        $Opt_B = $param;
     } else {
-	die "%Error: Unknown parameter: $param\n";
+        die "%Error: Unknown parameter: $param\n";
     }
 }
 
@@ -234,11 +206,14 @@ Do not show differences in line numbering.
 
 =head1 DISTRIBUTION
 
-The latest version is available from L<http://www.veripool.org/verilator>.
+The latest version is available from L<https://verilator.org>.
 
-Copyright 2005-2018 by Wilson Snyder.  This package is free software; you can
-redistribute it and/or modify it under the terms of either the GNU Lesser
-General Public License Version 3 or the Perl Artistic License Version 2.0.
+Copyright 2005-2021 by Wilson Snyder. This program is free software; you
+can redistribute it and/or modify it under the terms of either the GNU
+Lesser General Public License Version 3 or the Perl Artistic License
+Version 2.0.
+
+SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 
 =head1 AUTHORS
 
@@ -248,6 +223,8 @@ Wilson Snyder <[email protected]>
 
 C<verilator>
 
+and L<https://verilator.org/verilator_doc.html> for detailed documentation.
+
 =cut
 
 ######################################################################

bin/verilator_gantt

@@ -1,11 +1,9 @@
-: # -*-Mode: perl;-*- use perl, wherever it is
-eval 'exec perl -wS $0 ${1+"$@"}'
-  if 0;
+#!/usr/bin/env perl
 # See copyright, etc in below POD section.
 ######################################################################
 
-use strict;
 use warnings;
+use strict;
 use Getopt::Long;
 use IO::File;
 use Pod::Usage;
@@ -43,8 +41,8 @@ exit(0);
 #######################################################################
 
 sub usage {
-    pod2usage(-verbose=>2, -exitval=>2, -output=>\*STDOUT);
-    exit(1);
+    pod2usage(-verbose=>2, -exitval=>0, -output=>\*STDOUT);
+    exit(1);  # Unreachable
 }
 
 sub parameter {
@@ -62,6 +60,7 @@ sub process {
     my $filename = shift;
 
     read_data($filename);
+    read_cpuinfo();
     report();
 }
 
@@ -72,7 +71,7 @@ sub read_data {
 
     %Global = (rdtsc_cycle_time => 0);
 
-    my $fh = IO::File->new ($filename) or die "%Error: $! $filename,";
+    my $fh = IO::File->new("<$filename") or die "%Error: $! $filename,";
     while (my $line = $fh->getline) {
         if ($line =~ m/VLPROF mtask\s(\d+)\sstart\s(\d+)\send\s(\d+)\selapsed\s(\d+)\spredict_time\s(\d+)\scpu\s(\d+)\son thread (\d+)/) {
             my $mtask = $1;
@@ -115,6 +114,27 @@ sub read_data {
     }
 }
 
+sub read_cpuinfo {
+    my $filename = "/proc/cpuinfo";
+    my $fh = IO::File->new("<$filename") or return;
+    my $cpu;
+    while (my $line = $fh->getline) {
+        chomp $line;
+        if ($line =~ m/^processor\s*:\s*(\d+)\s*$/) {
+            $cpu = $1;
+        }
+        if ($cpu && $line =~ m/^([a-z_ ]+)\s*:\s*(.*)$/) {
+            my ($term, $value) = ($1, $2);
+            $term =~ s/\s+$//;
+            $term =~ s/\s+/_/;
+            $value =~ s/\s+$//;
+            $Global{cpuinfo}{$cpu}{$term} = $value;
+        }
+    }
+}
+
+#######################################################################
+
 sub report {
     print "Verilator Gantt report\n";
 
@@ -125,13 +145,13 @@ sub report {
     }
 
     my $nthreads = scalar keys %Threads;
-    $Global{cpus}{cpu_time} = {};
+    $Global{cpus} = {};
     foreach my $thread (keys %Threads) {
         # Make potentially multiple characters per column
         foreach my $start (keys %{$Threads{$thread}}) {
             my $cpu = $Threads{$thread}{$start}{cpu};
             my $elapsed = $Threads{$thread}{$start}{end} - $start;
-            $Global{cpus}{cpu_time}{$cpu} += $elapsed;
+            $Global{cpus}{$cpu}{cpu_time} += $elapsed;
         }
     }
 
@@ -158,14 +178,15 @@ sub report {
     print "\nAnalysis:\n";
     printf "  Total threads             = %d\n", $nthreads;
     printf "  Total mtasks              = %d\n", scalar(keys %Mtasks);
-    printf "  Total cpus used           = %d\n", scalar(keys %{$Global{cpus}});
+    my $ncpus = scalar(keys %{$Global{cpus}});
+    printf "  Total cpus used           = %d\n", $ncpus;
     printf "  Total yields              = %d\n", $Global{stats}{yields};
     printf "  Total eval time           = %d rdtsc ticks\n", $Global{last_end};
     printf "  Longest mtask time        = %d rdtsc ticks\n", $long_mtask_time;
     printf "  All-thread mtask time     = %d rdtsc ticks\n", $mt_mtask_time;
-    my $long_efficiency = $long_mtask_time/($Global{last_end});
+    my $long_efficiency = $long_mtask_time/($Global{last_end} || 1);
     printf "  Longest-thread efficiency = %0.1f%%\n", $long_efficiency*100;
-    my $mt_efficiency = $mt_mtask_time/($Global{last_end}*$nthreads);
+    my $mt_efficiency = $mt_mtask_time/($Global{last_end}*$nthreads || 1);
     printf "  All-thread efficiency     = %0.1f%%\n", $mt_efficiency*100;
     printf "  All-thread speedup        = %0.1f\n", $mt_efficiency*$nthreads;
     if ($Global{rdtsc_cycle_time} > 0) {
@@ -199,17 +220,72 @@ sub report {
     }
 
     print "\nStatistics:\n";
-    print "  min log(p2e) = $min_p2e  from mtask $min_mtask (predict $Mtasks{$min_mtask}{predict}, elapsed $Mtasks{$min_mtask}{elapsed})\n";
-    print "  max log(p2e) = $max_p2e  from mtask $max_mtask (predict $Mtasks{$max_mtask}{predict}, elapsed $Mtasks{$max_mtask}{elapsed})\n";
+    printf "  min log(p2e) = %0.3f", $min_p2e;
+    print "  from mtask $min_mtask (predict $Mtasks{$min_mtask}{predict},";
+    print " elapsed $Mtasks{$min_mtask}{elapsed})\n";
+    printf "  max log(p2e) = %0.3f", $max_p2e;
+    print "  from mtask $max_mtask (predict $Mtasks{$max_mtask}{predict},";
+    print " elapsed $Mtasks{$max_mtask}{elapsed})\n";
 
     my $stddev = stddev(\@p2e_ratios);
     my $mean = mean(\@p2e_ratios);
-    print "  mean = " . ($mean) . "\n";
-    print "  stddev = " . ($stddev) . "\n";
-    print "  e ^ stddev = " . exp($stddev). "\n";
+    printf "  mean = %0.3f\n", $mean;
+    printf "  stddev = %0.3f\n", $stddev;
+    printf "  e ^ stddev = %0.3f\n", exp($stddev);
+
+    report_cpus();
+
+    if ($nthreads > $ncpus) {
+        print "\n";
+        print "%Warning: There were fewer CPUs ($ncpus) then threads ($nthreads).\n";
+        print "        : See docs on use of numactl.\n";
+    } else {
+        if ($Global{cpu_socket_cores_warning}) {
+            print "\n";
+            print "%Warning: Multiple threads scheduled on same hyperthreaded core.\n";
+            print "        : See docs on use of numactl.\n";
+        }
+        if ($Global{cpu_sockets_warning}) {
+            print "\n";
+            print "%Warning: Threads scheduled on multiple sockets.\n";
+            print "        : See docs on use of numactl.\n";
+        }
+    }
     print "\n";
 }
 
+sub report_cpus {
+    print "\nCPUs:\n";
+    # Test - show all cores
+    # for (my $i=0; $i<73; ++$i) { $Global{cpus}{$i} ||= {cpu_time => 0}; }
+
+    $Global{cpu_sockets} ||= {};
+    $Global{cpu_socket_cores} ||= {};
+
+    foreach my $cpu (sort {$a <=> $b} keys %{$Global{cpus}}) {
+        printf "  cpu %d: ", $cpu;
+        printf "cpu_time=%d", $Global{cpus}{$cpu}{cpu_time};
+
+        my $socket = $Global{cpuinfo}{$cpu}{physical_id};
+        $Global{cpu_sockets}{$socket}++ if defined $socket;
+        printf " socket=%d", $socket if defined $socket;
+
+        my $core = $Global{cpuinfo}{$cpu}{core_id};
+        $Global{cpu_socket_cores}{$socket."__".$core}++ if defined $socket && defined $core;
+        printf " core=%d", $core if defined $core;
+
+        my $model = $Global{cpuinfo}{$cpu}{model_name};
+        printf "  %s", $model if defined $model;
+        print "\n";
+    }
+
+    $Global{cpu_sockets_warning} = 1
+        if (scalar keys %{$Global{cpu_sockets}} > 1);
+    foreach my $scn (values %{$Global{cpu_socket_cores}}) {
+        $Global{cpu_socket_cores_warning} = 1 if $scn > 1;
+    }
+}
+
 sub report_graph {
     my $time_per = $Opt_Time_Per_Char;
     if ($time_per == 0) {
@@ -221,6 +297,7 @@ sub report_graph {
         }
         # One more step so we can fit more labels
         $time_per = int($time_per/2);
+        $time_per ||= 1;
     }
 
     my ($graph, $conflicts) = _make_graph($time_per);
@@ -458,100 +535,39 @@ verilator_gantt - Create Gantt chart of multi-threaded execution
 
 =head1 SYNOPSIS
 
-Creates a visual representation to help analyze Verilator multithreaded
-simulation performance, by showing when each macro-task starts and ends,
-and showing when each thread is busy or idle.
+Verilator_gantt creates a visual representation to help analyze Verilator
+multithreaded simulation performance, by showing when each macro-task
+starts and ends, and showing when each thread is busy or idle.
 
-The generated Gantt chart has time on the X-axis. Times shown are to the
-scale printed, i.e. a certain about of time for each character width.  The
-Y-axis shows threads, each thread's execution is shown on one line.  That
-line shows "[" at the position in time when it executes.
+For documentation see
+L<https://verilator.org/guide/latest/exe_verilator_gantt.html>.
 
-Following the "[" is the cpu number the task executed on, followed by zero
-or more "-" to make the width of the characters match the scaled execution
-time, followed by a "]".  If the scale is too small, the cpu number and
-mtask number will not be printed.  If the scale is very small, a "&"
-indicates multiple mtasks started at that time position.
+=head1 ARGUMENT SUMMARY
 
-Also creates a value change dump (VCD) format dump file which may be viewed
-in a waveform viewer (e.g. C<GTKWave>).  See below.
-
-=head1 USAGE
-
-  Build with --prof-threads.
-
-  Run a sim with +verilator+prof+threads+window 2.
-
-  This will create profile_threads.dat.
-
-  Then run:
-
-  verilator_gantt profile_threads.dat
-
-  The report will be printed on standard output, this also generates
-  profile_threads.vcd
-
-  View profile_threads.vcd in a waveform viewer.
-
-=head1 VCD SIGNALS
-
-In waveforms there are the following signals. Most signals the "decimal"
-format will remove the leading zeros and make the traces easier to read.
-
-parallelism: The number of mtasks active at this time, for best performance
-this will match the thread count. You may want to use an "analog step"
-format to view this signal.
-
-cpu#_thread: For the given CPU number, the thread number executing.
-
-mtask#_cpu; For the given mtask id, the CPU it is executing on.
-
-thread#_mtask: For the given thread number, the mtask id executing.
-
-=head1 ARGUMENTS
-
-=over 4
-
-=item I<filename>
-
-The filename to read data from, defaults to "profile_threads.dat".
-
-=item --help
-
-Displays this message and program version and exits.
-
-=item --scale I<n>
-
-On the X-axis of the generated Gantt chart, each character represents this
-many time units. (On x86, time units are rdtsc ticks.)  Defaults to 0,
-which will automatically compute a reasonable scale where no two mtasks
-need to fit into same character width's worth of scaled time.
-
-=item --no-vcd
-
-=item --vcd I<filename>
-
-Set output filename for vcd dump, or disable. Default is
-verilator_gantt.vcd.
-
-=back
+    <filename>    Filename to read data from, default "profile_threads.dat".
+    --help        Displays this message and program version and exits.
+    --scale I<n>  Number of characters per time step.
+    --no-vcd      Do not create a VCD file.
+    --vcd <filename>   Set output filename for vcd dump, default "verilator_gantt.vcd."
 
 =head1 DISTRIBUTION
 
-The latest version is available from L<http://www.veripool.org/>.
+The latest version is available from L<https://verilator.org>.
 
-Copyright 2018-2018 by Wilson Snyder.  Verilator is free software; you can
-redistribute it and/or modify it under the terms of either the GNU Lesser
-General Public License Version 3 or the Perl Artistic License Version 2.0.
+Copyright 2018-2021 by Wilson Snyder. This program is free software; you
+can redistribute it and/or modify it under the terms of either the GNU
+Lesser General Public License Version 3 or the Perl Artistic License
+Version 2.0.
 
-=head1 AUTHORS
-
-Wilson Snyder <[email protected]>
+SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 
 =head1 SEE ALSO
 
 C<verilator>
 
+and L<https://verilator.org/guide/latest/exe_verilator_gantt.html> for
+detailed documentation.
+
 =cut
 
 ######################################################################

bin/verilator_includer

@@ -1,11 +1,11 @@
-: # -*-Mode: perl;-*- use perl, wherever it is
-eval 'exec perl -wS $0 ${1+"$@"}'
-  if 0;
+#!/usr/bin/env perl
 # DESCRIPTION: Print include statements for each ARGV
 #
-# Copyright 2003-2018 by Wilson Snyder. This package is free software; you can
-# redistribute it and/or modify it under the terms of either the GNU Lesser
-# General Public License Version 3 or the Perl Artistic License Version 2.0.
+# Copyright 2003-2021 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 ######################################################################
 
 require 5.005;

bin/verilator_profcfunc

@@ -1,6 +1,4 @@
-: # -*-Mode: perl;-*- use perl, wherever it is
-eval 'exec perl -wS $0 ${1+"$@"}'
-  if 0;
+#!/usr/bin/env perl
 # See copyright, etc in below POD section.
 ######################################################################
 
@@ -24,11 +22,11 @@ my $Opt_File;
 autoflush STDOUT 1;
 autoflush STDERR 1;
 Getopt::Long::config("no_auto_abbrev");
-if (! GetOptions (
-		  "help"	=> \&usage,
-		  "debug"	=> \&debug,
-		  "<>"		=> \&parameter,
-		  )) {
+if (! GetOptions(
+          "help"        => \&usage,
+          "debug"       => \&debug,
+          "<>"          => \&parameter,
+    )) {
     die "%Error: Bad usage, try 'verilator_profcfunc --help'\n";
 }
 
@@ -39,8 +37,8 @@ profcfunc($Opt_File);
 #----------------------------------------------------------------------
 
 sub usage {
-    pod2usage(-verbose=>2, -exitval=>2, -output=>\*STDOUT);
-    exit(1);
+    pod2usage(-verbose=>2, -exitval=>0, -output=>\*STDOUT);
+    exit(1);  # Unreachable
 }
 
 sub debug {
@@ -50,9 +48,9 @@ sub debug {
 sub parameter {
     my $param = shift;
     if (!defined $Opt_File) {
-	$Opt_File = $param;
+        $Opt_File = $param;
     } else {
-	die "%Error: Unknown parameter: $param\n";
+        die "%Error: Unknown parameter: $param\n";
     }
 }
 
@@ -66,13 +64,13 @@ sub profcfunc {
     my %funcs;
 
     while (defined (my $line=$fh->getline())) {
-	#                  %time      cumesec   selfsec     calls     {stuff}   name
-	if ($line =~ /^\s*([0-9.]+)\s+[0-9.]+\s+([0-9.]+)\s+([0-9.]+)\s+[^a-zA-Z_]*([a-zA-Z_].*)$/) {
-	    my $pct=$1; my $sec=$2; my $calls=$3; my $func=$4;
-	    $funcs{$func}{pct} += $pct;
-	    $funcs{$func}{sec} += $sec;
-	    $funcs{$func}{calls} += $calls;
-	}
+        #                  %time      cumesec   selfsec     calls     {stuff}   name
+        if ($line =~ /^\s*([0-9.]+)\s+[0-9.]+\s+([0-9.]+)\s+([0-9.]+)\s+[^a-zA-Z_]*([a-zA-Z_].*)$/) {
+            my $pct=$1; my $sec=$2; my $calls=$3; my $func=$4;
+            $funcs{$func}{pct} += $pct;
+            $funcs{$func}{sec} += $sec;
+            $funcs{$func}{calls} += $calls;
+        }
         # Older gprofs have no call column for single-call functions
         #                  %time      cumesec   selfsec      {stuff}   name
         elsif ($line =~ /^\s*([0-9.]+)\s+[0-9.]+\s+([0-9.]+)\s+[^a-zA-Z_]*([a-zA-Z_].*)$/) {
@@ -88,10 +86,10 @@ sub profcfunc {
     my %pointer_mods;
     my %verilated_mods;
     foreach my $func (keys %funcs) {
-	if ($func =~ /(.*)::_eval\(([a-zA-Z_0-9]+__Syms).*\)$/) {
-	    $verilated_mods{$1} = qr/^$1/;
-	    $pointer_mods{$2} = $1;
-	}
+        if ($func =~ /(.*)::_eval\(([a-zA-Z_0-9]+__Syms).*\)$/) {
+            $verilated_mods{$1} = qr/^$1/;
+            $pointer_mods{$2} = $1;
+        }
     }
     #print Dumper(\%pointer_mods, \%verilated_mods);
 
@@ -99,72 +97,72 @@ sub profcfunc {
     my %vfuncs;
     my %groups;
     foreach my $func (keys %funcs) {
-	my $pct = $funcs{$func}{pct};
-	my $vfunc = $func;
-	my $design;
+        my $pct = $funcs{$func}{pct};
+        my $vfunc = $func;
+        my $design;
 
-	if ($func =~ /\(([a-zA-Z_0-9]+__Syms)/) {
-	    $design = $pointer_mods{$1};
-	}
+        if ($func =~ /\(([a-zA-Z_0-9]+__Syms)/) {
+            $design = $pointer_mods{$1};
+        }
 
-	foreach my $vde (keys %verilated_mods) {
-	    last if $design;
-	    if ($func =~ /$verilated_mods{$vde}/) {
-		$design=$vde;
-		last;
-	    }
-	}
+        foreach my $vde (keys %verilated_mods) {
+            last if $design;
+            if ($func =~ /$verilated_mods{$vde}/) {
+                $design=$vde;
+                last;
+            }
+        }
 
-	if ($vfunc =~ /__PROF__([a-zA-Z_0-9]+)__l?([0-9]+)\(/) {
-	    $vfunc     = sprintf("VBlock    %s:%d", $1, $2);
-	    $groups{type}{"Verilog Blocks under $design"} += $pct;
-	    $groups{design}{$design} += $pct;
-	    $groups{module}{$1} += $pct;
-	} else {
-	    if ($design) {
-		$vfunc = sprintf("VCommon   %s", $func);
-		$groups{type}{"Common code under $design"} += $pct;
-		$groups{design}{$design} += $pct;
-		$groups{module}{$design." common code"} += $pct;
-	    } elsif ($func =~ /^VL_[A-Z0-9_]+/
-		     || $func =~ /^_?vl_[a-zA-Z0-9_]+/
-		     || $func =~ /^verilated/i) {
-		$vfunc = sprintf("VLib      %s", $func);
-		$groups{type}{'VLib'} += $pct;
-		$groups{design}{'VLib'} += $pct;
-		$groups{module}{'VLib'} += $pct;
-	    } elsif ($func =~ /^_mcount_private/) {
-		$vfunc = sprintf("Prof      %s", $func);
-		$groups{type}{'Prof'} += $pct;
-		$groups{design}{'Prof'} += $pct;
-		$groups{module}{'Prof'} += $pct;
-	    } else {
-		$vfunc = sprintf("C++       %s", $func);
-		$groups{type}{'C++'} += $pct;
-		$groups{design}{'C++'} += $pct;
-		$groups{module}{'C++'} += $pct;
-	    }
-	}
-	$vfuncs{$vfunc} = $funcs{$func};
+        if ($vfunc =~ /__PROF__([a-zA-Z_0-9]+)__l?([0-9]+)\(/) {
+            $vfunc     = sprintf("VBlock    %s:%d", $1, $2);
+            $groups{type}{"Verilog Blocks under $design"} += $pct;
+            $groups{design}{$design} += $pct;
+            $groups{module}{$1} += $pct;
+        } else {
+            if ($design) {
+                $vfunc = sprintf("VCommon   %s", $func);
+                $groups{type}{"Common code under $design"} += $pct;
+                $groups{design}{$design} += $pct;
+                $groups{module}{$design." common code"} += $pct;
+            } elsif ($func =~ /^VL_[A-Z0-9_]+/
+                     || $func =~ /^_?vl_[a-zA-Z0-9_]+/
+                     || $func =~ /^verilated/i) {
+                $vfunc = sprintf("VLib      %s", $func);
+                $groups{type}{'VLib'} += $pct;
+                $groups{design}{'VLib'} += $pct;
+                $groups{module}{'VLib'} += $pct;
+            } elsif ($func =~ /^_mcount_private/) {
+                $vfunc = sprintf("Prof      %s", $func);
+                $groups{type}{'Prof'} += $pct;
+                $groups{design}{'Prof'} += $pct;
+                $groups{module}{'Prof'} += $pct;
+            } else {
+                $vfunc = sprintf("C++       %s", $func);
+                $groups{type}{'C++'} += $pct;
+                $groups{design}{'C++'} += $pct;
+                $groups{module}{'C++'} += $pct;
+            }
+        }
+        $vfuncs{$vfunc} = $funcs{$func};
     }
 
 
     foreach my $type (qw(type design module)) {
-	my $missing = 100;
-	foreach (sort (keys %{$groups{$type}})) {
-	    $missing -= $groups{$type}{$_};
-	}
-	if ($missing) {
-	    $groups{$type}{"\377Unaccounted for/rounding error"} = $missing;
-	}
+        my $missing = 100;
+        foreach (sort (keys %{$groups{$type}})) {
+            $missing -= $groups{$type}{$_};
+        }
+        if ($missing) {
+            $groups{$type}{"\377Unaccounted for/rounding error"} = $missing;
+        }
 
-	print("Overall summary by $type:\n");
-	printf("  %-6s  %s\n","% time",$type);
-	foreach my $what (sort (keys %{$groups{$type}})) {
-	    (my $pwhat = $what) =~ s/^\377//;  # Just used to establish sort order
-	    printf("  %6.2f  %s\n", $groups{$type}{$what}, $pwhat);
-	}
-	print("\n");
+        print("Overall summary by $type:\n");
+        printf("  %-6s  %s\n","% time",$type);
+        foreach my $what (sort (keys %{$groups{$type}})) {
+            (my $pwhat = $what) =~ s/^\377//;  # Just used to establish sort order
+            printf("  %6.2f  %s\n", $groups{$type}{$what}, $pwhat);
+        }
+        print("\n");
     }
 
     print("Verilog code profile:\n");
@@ -181,14 +179,14 @@ sub profcfunc {
 
     my $cume = 0;
     foreach my $func (sort {$vfuncs{$b}{sec} <=> $vfuncs{$a}{sec}
-			    || $a cmp $b}
-		      (keys %vfuncs)) {
-	$cume += $vfuncs{$func}{sec};
-	printf +("%6.2f %9.2f %8.2f %8d   %s\n",
-		 $vfuncs{$func}{pct},
-		 $cume, $vfuncs{$func}{sec},
-		 $vfuncs{$func}{calls},
-		 $func);
+                            || $a cmp $b}
+                      (keys %vfuncs)) {
+        $cume += $vfuncs{$func}{sec};
+        printf +("%6.2f %9.2f %8.2f %8d   %s\n",
+                 $vfuncs{$func}{pct},
+                 $cume, $vfuncs{$func}{sec},
+                 $vfuncs{$func}{calls},
+                 $func);
     }
 }
 
@@ -204,7 +202,7 @@ verilator_profcfunc - Read gprof report created with --prof-cfuncs
 =head1 SYNOPSIS
 
   verilator --prof-cfuncs ....
-  gcc --ggdb -pg ....
+  gcc ....
   {run executable}
   gprof
   verilator_profcfuncs gprof.out
@@ -212,36 +210,36 @@ verilator_profcfunc - Read gprof report created with --prof-cfuncs
 =head1 DESCRIPTION
 
 Verilator_profcfunc reads a profile report created by gprof.  The names of
-the functions are then transformed, assuming the user used verilator's
+the functions are then transformed, assuming the user used Verilator's
 --prof-cfuncs, and a report printed showing the percentage of time, etc,
 in each Verilog block.
 
-=head1 ARGUMENTS
+For documentation see
+L<https://verilator.org/guide/latest/exe_verilator_profcfuncs.html>.
 
-=over 4
+=head1 ARGUMENT SUMMARY
 
-=item --help
-
-Displays this message and program version and exits.
-
-=back
+    <filename>  Input file (gprof.out)
+    --help      Display this help
 
 =head1 DISTRIBUTION
 
-The latest version is available from L<http://www.veripool.org/>.
+The latest version is available from L<https://verilator.org>.
 
-Copyright 2007-2018 by Wilson Snyder.  Verilator is free software; you can
-redistribute it and/or modify it under the terms of either the GNU Lesser
-General Public License Version 3 or the Perl Artistic License Version 2.0.
+Copyright 2007-2021 by Wilson Snyder. This program is free software; you
+can redistribute it and/or modify it under the terms of either the GNU
+Lesser General Public License Version 3 or the Perl Artistic License
+Version 2.0.
 
-=head1 AUTHORS
-
-Wilson Snyder <[email protected]>
+SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 
 =head1 SEE ALSO
 
 C<verilator>
 
+and L<https://verilator.org/guide/latest/exe_verilator_profcfuncs.html> for
+detailed documentation.
+
 =cut
 
 ######################################################################

ci/ci-ccache-maint.bash

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# DESCRIPTION: Verilator: CI ccache maintenance
+#
+# Copyright 2020 by Geza Lore. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+#
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+################################################################################
+# This script is run in 'before_script', once ccache has been set up.
+################################################################################
+
+set -e
+set -x
+
+# Show version
+ccache --version
+
+# Flush ccache if requested in commit message
+COMMIT="${CI_PULL_REQUEST_SHA:-$CI_COMMIT}"
+if git log --format=%B -n 1 "$COMMIT" | grep -q -i '\[CI\s\+ccache\s\+clear\]'; then
+  echo "Flushing ccache due to commit message"
+  ccache -C
+fi
+
+# Dump stats, then zero stats
+ccache -s -z

ci/ci-install.bash

@@ -0,0 +1,114 @@
+#!/usr/bin/env bash
+# DESCRIPTION: Verilator: CI dependency install script
+#
+# Copyright 2020 by Geza Lore. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+#
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+################################################################################
+# This script runs in the 'install' phase of all jobs, in all stages. We try to
+# minimize the time spent in this by selectively installing only the components
+# required by the particular build stage.
+################################################################################
+
+set -e
+set -x
+
+cd $(dirname "$0")/..
+
+fatal() {
+  echo "ERROR: $(basename "$0"): $1" >&2; exit 1;
+}
+
+if [ "$CI_M32" = "0" ]; then
+  unset CI_M32
+elif [ "$CI_M32" != "1" ]; then
+  fatal "\$CI_M32 must be '0' or '1'";
+fi
+
+if [ "$CI_OS_NAME" = "linux" ]; then
+  MAKE=make
+elif [ "$CI_OS_NAME" = "osx" ]; then
+  MAKE=make
+elif [ "$CI_OS_NAME" = "freebsd" ]; then
+  MAKE=gmake
+else
+  fatal "Unknown os: '$CI_OS_NAME'"
+fi
+
+install-vcddiff() {
+  TMP_DIR="$(mktemp -d)"
+  git clone https://github.com/veripool/vcddiff "$TMP_DIR"
+  git -C "${TMP_DIR}" checkout e5664be5fe39d353bf3fcb50aa05214ab7ed4ac4
+  "$MAKE" -C "${TMP_DIR}"
+  sudo cp "${TMP_DIR}/vcddiff" /usr/local/bin
+}
+
+if [ "$CI_BUILD_STAGE_NAME" = "build" ]; then
+  ##############################################################################
+  # Dependencies of jobs in the 'build' stage, i.e.: packages required to
+  # build Verilator
+
+  if [ "$CI_OS_NAME" = "linux" ]; then
+    sudo apt-get update
+    sudo apt-get install libfl-dev libgoogle-perftools-dev ccache
+    if [ "$CI_RUNS_ON" = "ubuntu-20.04" ]; then
+      sudo apt-get install libsystemc libsystemc-dev
+    fi
+    if [ "$COVERAGE" = 1 ]; then
+      yes yes | sudo cpan -fi Parallel::Forker
+    fi
+    if [ "$CI_M32" = 1 ]; then
+      sudo apt-get install gcc-multilib g++-multilib
+    fi
+  elif [ "$CI_OS_NAME" = "osx" ]; then
+    brew update
+    brew install ccache perl gperftools
+  elif [ "$CI_OS_NAME" = "freebsd" ]; then
+    sudo pkg install -y autoconf bison ccache gmake perl5
+  else
+    fatal "Unknown os: '$CI_OS_NAME'"
+  fi
+
+  if [ -n "$CCACHE_DIR" ]; then
+    mkdir -p "$CCACHE_DIR" && ./ci/ci-ccache-maint.bash
+  fi
+elif [ "$CI_BUILD_STAGE_NAME" = "test" ]; then
+  ##############################################################################
+  # Dependencies of jobs in the 'test' stage, i.e.: packages required to
+  # run the tests
+
+  if [ "$CI_OS_NAME" = "linux" ]; then
+    sudo apt-get update
+    # libfl-dev needed for internal coverage's test runs
+    sudo apt-get install gdb gtkwave lcov libfl-dev ccache
+    if [ "$CI_RUNS_ON" = "ubuntu-20.04" ]; then
+      sudo apt-get install libsystemc-dev
+    fi
+    if [ "$CI_M32" = 1 ]; then
+      sudo apt-get install lib32z1-dev gcc-multilib g++-multilib
+    fi
+  elif [ "$CI_OS_NAME" = "osx" ]; then
+    brew update
+    # brew cask install gtkwave # fst2vcd hangs at launch, so don't bother
+    brew install ccache perl
+  elif [ "$CI_OS_NAME" = "freebsd" ]; then
+    # fst2vcd fails with "Could not open '<input file>', exiting."
+    sudo pkg install -y ccache gmake perl5 python3
+  else
+    fatal "Unknown os: '$CI_OS_NAME'"
+  fi
+  # Common installs
+  if [ "$CI_RUNS_ON" != "ubuntu-14.04" ]; then
+    CI_CPAN_REPO=https://cpan.org
+  fi
+  yes yes | sudo cpan -M $CI_CPAN_REPO -fi Parallel::Forker
+  install-vcddiff
+else
+  ##############################################################################
+  # Unknown build stage
+  fatal "Unknown build stage: '$CI_BUILD_STAGE_NAME'"
+fi

ci/ci-script.bash

@@ -0,0 +1,193 @@
+#!/usr/bin/env bash
+# DESCRIPTION: Verilator: CI main job script
+#
+# Copyright 2020 by Geza Lore. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+#
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+################################################################################
+# This is the main script executed in the 'script' phase by all jobs. We use a
+# single script to keep the CI setting simple. We pass job parameters via
+# environment variables using 'env' keys.
+################################################################################
+
+set -e
+set -x
+
+fatal() {
+  echo "ERROR: $(basename "$0"): $1" >&2; exit 1;
+}
+
+if [ "$CI_M32" = "0" ]; then
+  unset CI_M32
+elif [ "$CI_M32" != "1" ]; then
+  fatal "\$CI_M32 must be '0' or '1'";
+fi
+
+if [ "$CI_OS_NAME" = "linux" ]; then
+  export MAKE=make
+  NPROC=$(nproc)
+elif [ "$CI_OS_NAME" = "osx" ]; then
+  export MAKE=make
+  NPROC=$(sysctl -n hw.logicalcpu)
+elif [ "$CI_OS_NAME" = "freebsd" ]; then
+  export MAKE=gmake
+  NPROC=$(sysctl -n hw.ncpu)
+else
+  fatal "Unknown os: '$CI_OS_NAME'"
+fi
+
+if [ "$CI_BUILD_STAGE_NAME" = "build" ]; then
+  ##############################################################################
+  # Build verilator
+
+  if [ "$COVERAGE" != 1 ]; then
+    autoconf
+    ./configure --enable-longtests --enable-ccwarn ${CI_M32:+--enable-m32}
+    ccache -z
+    "$MAKE" -j "$NPROC" -k
+    ccache -s
+    if [ "$CI_OS_NAME" = "osx" ]; then
+      file bin/verilator_bin
+      file bin/verilator_bin_dbg
+      md5 bin/verilator_bin
+      md5 bin/verilator_bin_dbg
+      stat bin/verilator_bin
+      stat bin/verilator_bin_dbg
+    fi
+  else
+    nodist/code_coverage --stages 0-2
+  fi
+elif [ "$CI_BUILD_STAGE_NAME" = "test" ]; then
+  ##############################################################################
+  # Run tests
+
+  export VERILATOR_TEST_NO_CONTRIBUTORS=1  # Separate workflow check
+
+  if [ "$CI_OS_NAME" = "osx" ]; then
+    export VERILATOR_TEST_NO_GDB=1  # Pain to get GDB to work on OS X
+    # TODO below may no longer be requried as configure checks for -pg
+    export VERILATOR_TEST_NO_GPROF=1  # Apple Clang has no -pg
+    # export PATH="/Applications/gtkwave.app/Contents/Resources/bin:$PATH" # fst2vcd
+    file bin/verilator_bin
+    file bin/verilator_bin_dbg
+    md5 bin/verilator_bin
+    md5 bin/verilator_bin_dbg
+    stat bin/verilator_bin
+    stat bin/verilator_bin_dbg
+    # For some reason, the dbg exe is corrupted by this point ('file' reports
+    # it as data rather than a Mach-O). Unclear if this is an OS X issue or
+    # CI's. Remove the file and re-link...
+    rm bin/verilator_bin_dbg
+    "$MAKE" -j "$NPROC" -k
+  elif [ "$CI_OS_NAME" = "freebsd" ]; then
+    export VERILATOR_TEST_NO_GDB=1 # Disable for now, ideally should run
+    # TODO below may no longer be requried as configure checks for -pg
+    export VERILATOR_TEST_NO_GPROF=1 # gprof is a bit different on FreeBSD, disable
+  fi
+
+  # Run sanitize on Ubuntu 20.04 only
+  [ "$CI_RUNS_ON" = 'ubuntu-20.04' ] && [ "$CI_M32" = "" ] && sanitize='--sanitize' || sanitize=''
+
+  # Run the specified test
+  ccache -z
+  case $TESTS in
+    dist-vlt-0)
+      "$MAKE" -C test_regress SCENARIOS="--dist --vlt $sanitize" DRIVER_HASHSET=--hashset=0/3
+      ;;
+    dist-vlt-1)
+      "$MAKE" -C test_regress SCENARIOS="--dist --vlt $sanitize" DRIVER_HASHSET=--hashset=1/3
+      ;;
+    dist-vlt-2)
+      "$MAKE" -C test_regress SCENARIOS="--dist --vlt $sanitize" DRIVER_HASHSET=--hashset=2/3
+      ;;
+    vltmt-0)
+      "$MAKE" -C test_regress SCENARIOS=--vltmt DRIVER_HASHSET=--hashset=0/2
+      ;;
+    vltmt-1)
+      "$MAKE" -C test_regress SCENARIOS=--vltmt DRIVER_HASHSET=--hashset=1/2
+      ;;
+    coverage-all)
+      nodist/code_coverage --stages 1-
+      ;;
+    coverage-dist)
+      nodist/code_coverage --stages 1- --scenarios=--dist
+      ;;
+    coverage-vlt-0)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=0/10
+      ;;
+    coverage-vlt-1)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=1/10
+      ;;
+    coverage-vlt-2)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=2/10
+      ;;
+    coverage-vlt-3)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=3/10
+      ;;
+    coverage-vlt-4)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=4/10
+      ;;
+    coverage-vlt-5)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=5/10
+      ;;
+    coverage-vlt-6)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=6/10
+      ;;
+    coverage-vlt-7)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=7/10
+      ;;
+    coverage-vlt-8)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=8/10
+      ;;
+    coverage-vlt-9)
+      nodist/code_coverage --stages 1- --scenarios=--vlt --hashset=9/10
+      ;;
+    coverage-vltmt-0)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=0/10
+      ;;
+    coverage-vltmt-1)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=1/10
+      ;;
+    coverage-vltmt-2)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=2/10
+      ;;
+    coverage-vltmt-3)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=3/10
+      ;;
+    coverage-vltmt-4)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=4/10
+      ;;
+    coverage-vltmt-5)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=5/10
+      ;;
+    coverage-vltmt-6)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=6/10
+      ;;
+    coverage-vltmt-7)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=7/10
+      ;;
+    coverage-vltmt-8)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=8/10
+      ;;
+    coverage-vltmt-9)
+      nodist/code_coverage --stages 1- --scenarios=--vltmt --hashset=9/10
+      ;;
+    *)
+      fatal "Unknown test: $TESTS"
+      ;;
+  esac
+  ccache -s
+
+  # Upload coverage data
+  if [[ $TESTS == coverage-* ]]; then
+    bash <(cat ci/coverage-upload.sh) -f nodist/obj_dir/coverage/app_total.info
+  fi
+else
+  ##############################################################################
+  # Unknown build stage
+  fatal "Unknown build stage: '$CI_BUILD_STAGE_NAME'"
+fi

ci/docker/buildenv/Dockerfile

@@ -0,0 +1,56 @@
+# DESCRIPTION: Dockerfile for env to build and fully test Verilator
+#
+# Copyright 2020 by Stefan Wallentowitz. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+FROM ubuntu:20.04
+
+RUN apt-get update \
+    && DEBIAN_FRONTEND=noninteractive \
+       apt-get install --no-install-recommends -y \
+                        autoconf \
+                        bc \
+                        bison \
+                        build-essential \
+                        ca-certificates \
+                        ccache \
+                        clang \
+                        cmake \
+                        flex \
+                        gdb \
+                        git \
+                        gtkwave \
+                        libfl2 \
+                        libfl-dev \
+                        libgoogle-perftools-dev \
+                        libsystemc \
+                        libsystemc-dev \
+                        numactl \
+                        perl \
+                        python3 \
+                        wget \
+                        zlibc \
+                        zlib1g \
+                        zlib1g-dev \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /tmp
+
+RUN cpan install -fi Parallel::Forker
+
+RUN git clone https://github.com/veripool/vcddiff.git && \
+    make -C vcddiff && \
+    cp -p vcddiff/vcddiff /usr/local/bin/vcddiff && \
+    rm -rf vcddiff
+
+COPY build.sh /tmp/build.sh
+
+ENV VERILATOR_AUTHOR_SITE=1
+
+WORKDIR /work
+
+ENTRYPOINT [ "/tmp/build.sh" ]

ci/docker/buildenv/README.rst

@@ -0,0 +1,63 @@
+Verilator Build Docker Container
+================================
+
+This Verilator Build Docker Container is set up to compile and test a
+Verilator build. It uses the following parameters:
+
+-  Source repository (default: https://github.com/verilator/verilator)
+
+-  Source revision (default: master)
+
+-  Compiler (GCC 9.3.0, clang 10.0.0, default: 9.3.0)
+
+The container is published as ``verilator/verilator-buildenv`` on `docker
+hub
+<https://hub.docker.com/repository/docker/verilator/verilator-buildenv>`__.
+
+To run the basic build using the current Verilator master:
+
+::
+
+   docker run -ti verilator/verilator-buildenv
+
+To also run tests:
+
+::
+
+   docker run -ti verilator/verilator-buildenv test
+
+To change the compiler:
+
+::
+
+   docker run -ti -e CC=clang-10 -e CXX=clang++-10 verilator/verilator-buildenv test
+
+The tests that involve gdb are not working due to security restrictions.
+To run those too:
+
+::
+
+   docker run -ti -e CC=clang-10 -e CXX=clang++-10 --cap-add=SYS_PTRACE --security-opt seccomp=unconfined verilator/verilator-buildenv test
+
+Rather then building using a remote git repository you may prefer to use a
+working copy on the local filesystem. Mount the local working copy path as
+a volume and use that in place of git. When doing this be careful to have
+all changes committed to the local git area. To build the current HEAD from
+top of a repository:
+
+::
+
+   docker run -ti -v ${PWD}:/tmp/repo -e REPO=/tmp/repo -e REV=`git rev-parse --short HEAD` --cap-add=SYS_PTRACE --security-opt seccomp=unconfined verilator/verilator-buildenv test
+
+
+Rebuilding
+----------
+
+To rebuild the Verilator-buildenv docker image, run:
+
+::
+
+   docker build .
+
+This will also build SystemC under all supported compiler variants to
+reduce the SystemC testing time.

ci/docker/buildenv/build.sh

@@ -0,0 +1,25 @@
+#!/bin/bash -e
+# DESCRIPTION: Build Verilator (inside container)
+#
+# Copyright 2020 by Stefan Wallentowitz. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+: "${REPO:=https://github.com/verilator/verilator}"
+: "${REV:=master}"
+: "${CC:=gcc}"
+: "${CXX:=g++}"
+
+SRCS=$PWD/verilator
+
+git clone "$REPO" "$SRCS"
+cd "$SRCS"
+git checkout "$REV"
+autoconf
+./configure --enable-longtests
+make -j $(nproc)
+if [ "${1:-''}" == "test" ]; then
+    make test
+fi

ci/docker/run/Dockerfile

@@ -0,0 +1,51 @@
+# DESCRIPTION: Dockerfile for image to run Verilator inside
+#
+# Copyright 2020 by Stefan Wallentowitz. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+FROM ubuntu:20.04
+
+RUN apt-get update \
+    && DEBIAN_FRONTEND=noninteractive \
+    && apt-get install --no-install-recommends -y \
+                        autoconf \
+                        bc \
+                        bison \
+                        build-essential \
+                        ca-certificates \
+                        ccache \
+                        flex \
+                        git \
+                        libfl-dev \
+                        libgoogle-perftools-dev \
+                        perl \
+                        python3 \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/*
+
+ARG REPO=https://github.com/verilator/verilator
+ARG SOURCE_COMMIT=master
+
+WORKDIR /tmp
+
+# Add an exception for the linter, we want to cd here in one layer
+# to reduce the number of layers (and thereby size).
+# hadolint ignore=DL3003
+RUN git clone "${REPO}" verilator && \
+    cd verilator && \
+    git checkout "${SOURCE_COMMIT}" && \
+    autoconf && \
+    ./configure && \
+    make -j "$(nproc)" && \
+    make install && \
+    cd .. && \
+    rm -r verilator
+
+COPY verilator-wrap.sh /usr/local/bin/verilator-wrap.sh
+
+WORKDIR /work
+
+ENTRYPOINT [ "/usr/local/bin/verilator-wrap.sh" ]

ci/docker/run/README.rst

@@ -0,0 +1,73 @@
+Verilator Executable Docker Container
+=====================================
+
+The Verilator Executable Docker Container allows you to run Verilator
+easily as a docker image, e.g.:
+
+::
+
+   docker run -ti verilator/verilator:latest --version
+
+This will install the container, run the latest Verilator and print
+Verilator's version.
+
+Containers are automatically built for all released versions, so you may
+easily compare results across versions, e.g.:
+
+::
+
+   docker run -ti verilator/verilator:4.030 --version
+
+Verilator needs to read and write files on the local system. To simplify
+this process, use the ``verilator-docker`` convenience script. This script
+takes the version number, and all remaining arguments are passed through to
+Verilator. e.g.:
+
+::
+
+   ./verilator-docker 4.030 --version
+
+or
+
+::
+
+   ./verilator-docker 4.030 --cc test.v
+
+If you prefer not to use ``verilator-docker`` you must give the container
+access to your files as a volume with appropriate user rights.  For example
+to Verilate test.v:
+
+::
+
+   docker run -ti -v ${PWD}:/work --user $(id -u):$(id -g) verilator/verilator:latest --cc test.v
+
+This method can only access files below the current directory. An
+alternative is setup the volume ``-workdir``.
+
+You can also work in the container by setting the entrypoint (don't forget
+to mount a volume if you want your work persistent):
+
+::
+
+   docker run -ti --entrypoint /bin/bash verilator/verilator:latest
+
+You can also use the container to build Verilator at a specific commit:
+
+::
+
+   docker build --build-arg SOURCE_COMMIT=<commit> .
+
+
+Internals
+---------
+
+The Dockerfile builds Verilator and removes the tree when completed to
+reduce the image size. The entrypoint is set as a wrapper script
+(``verilator-wrap.sh``). That script 1. calls Verilator, and 2. copies the
+Verilated runtime files to the ``obj_dir`` or the ``-Mdir``
+respectively. This allows the user to have the files to they may later
+build the C++ output with the matching runtime files. The wrapper also
+patches the Verilated Makefile accordingly.
+
+There is also a hook defined that is run by docker hub via automated
+builds.

ci/docker/run/hooks/build

@@ -0,0 +1,10 @@
+#!/bin/bash
+# DESCRIPTION: Docker hub hook to pass SOURCE_COMMIT
+#
+# Copyright 2020 by Stefan Wallentowitz. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+docker build --build-arg SOURCE_COMMIT=${SOURCE_COMMIT} -f $DOCKERFILE_PATH -t $IMAGE_NAME .

ci/docker/run/hooks/post_push

@@ -0,0 +1,13 @@
+#!/bin/bash
+# DESCRIPTION: Docker hub hook to tag the latest release (stable)
+#
+# Copyright 2020 by Stefan Wallentowitz. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+if [ "$SOURCE_BRANCH"="stable" ]; then
+    docker tag $IMAGE_NAME $DOCKER_REPO:latest
+    docker push $DOCKER_REPO:latest
+fi

ci/docker/run/verilator-docker

@@ -0,0 +1,11 @@
+#!/bin/bash
+# DESCRIPTION: Wrap a verilator call to run a docker container
+#
+# Copyright 2020 by Stefan Wallentowitz. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+docker pull verilator/verilator:$1 >/dev/null
+docker run -ti -v ${PWD}:/work --user $(id -u):$(id -g) verilator/verilator:$1 "${@:2}"

ci/docker/run/verilator-wrap.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+# DESCRIPTION: Wrap a Verilator call and copy vlt includes
+#              (inside docker container)
+#
+# Copyright 2020 by Stefan Wallentowitz. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+perl /usr/local/bin/verilator "$@"
+status=$?
+if [ $status -ne 0 ]; then
+    exit $status
+fi
+
+# Check if user set an obj_dir
+obj_dir=$(echo " $@" | grep -oP '\s--Mdir\s*\K\S+')
+if [ "$obj_dir" == "" ]; then
+    obj_dir="obj_dir"
+fi
+
+# If the run was successful: Copy required files to allow build without this container
+if [ -e ${obj_dir} ]; then
+    # Copy files required for the build
+    mkdir -p ${obj_dir}/vlt
+    cp -r /usr/local/share/verilator/bin ${obj_dir}/vlt
+    cp -r /usr/local/share/verilator/include ${obj_dir}/vlt
+    # Point Makefile to that folder
+    sed -i 's/VERILATOR_ROOT = \/usr\/local\/share\/verilator/VERILATOR_ROOT = vlt/g' ${obj_dir}/*.mk
+fi

codecov.yml

@@ -0,0 +1,38 @@
+# DESCRIPTION: codecov.io config
+#
+# Copyright 2020-2021 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+####################
+# Validate:
+#  curl --data-binary @codecov.yml https://codecov.io/validate
+
+codecov:
+  require_ci_to_pass: no
+
+coverage:
+  precision: 2
+  round: down
+  range: "50...100"
+  ignore:
+    - "ci"
+    - "docs"
+    - "examples"
+    - "include/gtkwave"
+    - "include/vltstd"
+    - "test_regress"
+
+parsers:
+  gcov:
+    branch_detection:
+      conditional: yes
+      loop: yes
+      method: no
+      macro: no
+
+comment:
+  layout: "reach,diff,flags,tree"
+  behavior: default
+  require_changes: yes

configure.ac

@@ -1,21 +1,27 @@
 # DESCRIPTION: Process this file with autoconf to produce a configure script.
 #
-# Copyright 2003-2018 by Wilson Snyder. Verilator is free software; you can
-# redistribute it and/or modify it under the terms of either the GNU Lesser
+# Copyright 2003-2021 by Wilson Snyder. Verilator is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU Lesser
 # General Public License Version 3 or the Perl Artistic License Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
 
 #AC_INIT([Verilator],[#.### YYYY-MM-DD])
 #AC_INIT([Verilator],[#.### devel])
-AC_INIT([Verilator],[4.008 2018-12-01],
-        [https://www.veripool.org/verilator],
-        [verilator],[https://www.veripool.org/verilator])
+AC_INIT([Verilator],[4.210 2021-07-07],
+        [https://verilator.org],
+        [verilator],[https://verilator.org])
 # When releasing, also update header of Changes file
 # and commit using "devel release" or "Version bump" message
+# Then 'make maintainer-dist'
 
 AC_CONFIG_HEADER(src/config_build.h)
-AC_CONFIG_FILES(Makefile src/Makefile src/Makefile_obj include/verilated.mk include/verilated_config.h verilator.pc)
+AC_CONFIG_FILES(Makefile src/Makefile src/Makefile_obj include/verilated.mk include/verilated_config.h verilator.pc verilator-config.cmake verilator-config-version.cmake)
 
+# Version
 AC_MSG_RESULT([configuring for $PACKAGE_STRING])
+PACKAGE_VERSION_NUMBER=`AS_ECHO("$PACKAGE_VERSION") | sed 's/ .*//g'`
+AC_SUBST(PACKAGE_VERSION_NUMBER)
+AC_DEFINE_UNQUOTED([PACKAGE_VERSION_NUMBER_STRING],["$PACKAGE_VERSION_NUMBER"],[Package version as a number])
 
 # Ignore automake flags passed by Ubuntu builds
 AC_ARG_ENABLE([dependency-tracking],
@@ -25,11 +31,71 @@ AC_ARG_ENABLE([maintainer-mode],
 AC_ARG_ENABLE([silent-rules],
               [AS_HELP_STRING([--disable-silent-rules], [ignored])])
 
+# Flag to enable linking specific libraries statically
+AC_MSG_CHECKING(whether to perform partial static linking of Verilator binary)
+AC_ARG_ENABLE([partial-static],
+              [AS_HELP_STRING([--disable-partial-static],
+                              [By default, for Verilation performance, Verilator
+                               is linked against some of its dependencies
+                               statically. Use this to link the Verilator binary
+                               fully dynamically.])],
+              [case "${enableval}" in
+                yes) CFG_ENABLE_PARTIAL_STATIC=yes ;;
+                no)  CFG_ENABLE_PARTIAL_STATIC=no ;;
+                *)   AC_MSG_ERROR([bad value '${enableval}' for --disable-partial-static]) ;;
+               esac],
+               CFG_ENABLE_PARTIAL_STATIC=yes)
+AC_MSG_RESULT($CFG_ENABLE_PARTIAL_STATIC)
+
+# Flag to enable linking Verilator with tcmalloc if available
+AC_MSG_CHECKING(whether to use tcmalloc)
+AC_ARG_ENABLE([tcmalloc],
+              [AS_HELP_STRING([--enable-tcmalloc],
+                              [Use libtcmalloc_minimal for faster dynamic memory
+                               management in Verilator binary @<:@default=check@:>@])],
+              [case "${enableval}" in
+                yes) CFG_WITH_TCMALLOC=yes ;;
+                no)  CFG_WITH_TCMALLOC=no ;;
+                *)   AC_MSG_ERROR([bad value '${enableval}' for --enable-tcmalloc]) ;;
+               esac],
+              [CFG_WITH_TCMALLOC=check;])
+AC_MSG_RESULT($CFG_WITH_TCMALLOC)
+
+# Flag to enable -m32 build
+AC_MSG_CHECKING(whether to use -m32)
+AC_ARG_ENABLE([m32],
+              [AS_HELP_STRING([--enable-m32],
+                              [Use -m32 for all compilation and link,
+                               including Verialtor and generated models.])],
+              [case "${enableval}" in
+                yes) CFG_ENABLE_M32=yes ;;
+                no)  CFG_ENABLE_M32=no ;;
+                *)   AC_MSG_ERROR([bad value '${enableval}' for --enable-m32]) ;;
+               esac],
+               CFG_ENABLE_M32=no)
+AC_MSG_RESULT($CFG_ENABLE_M32)
+
+# Flag to enable coverage build
+AC_MSG_CHECKING(whether to build for coverage collection)
+AC_ARG_ENABLE([coverage],
+              [AS_HELP_STRING([--enable-coverage],
+                              [Build Verilator for code coverage collection.
+                               For developers only.])],
+              [case "${enableval}" in
+                yes) CFG_ENABLE_COVERAGE=yes ;;
+                no)  CFG_ENABLE_COVERAGE=no ;;
+                *)   AC_MSG_ERROR([bad value '${enableval}' for --enable-coverage]) ;;
+               esac],
+               CFG_ENABLE_COVERAGE=no)
+AC_MSG_RESULT($CFG_ENABLE_COVERAGE)
+
 # Special Substitutions - CFG_WITH_DEFENV
 AC_MSG_CHECKING(whether to use hardcoded paths)
 AC_ARG_ENABLE([defenv],
               [AS_HELP_STRING([--disable-defenv],
-                              [disable using some hardcoded data paths extracted from some default environment variables (the default is to use hardcoded paths)])],
+                              [disable using some hardcoded data paths extracted
+                              from some default environment variables (the default
+                              is to use hardcoded paths) in Verilator binary])],
               [case "${enableval}" in
                 yes) CFG_WITH_DEFENV=yes ;;
                 no)  CFG_WITH_DEFENV=no ;;
@@ -43,7 +109,8 @@ AC_MSG_RESULT($CFG_WITH_DEFENV)
 AC_MSG_CHECKING(whether to show and stop on compilation warnings)
 AC_ARG_ENABLE([ccwarn],
               [AS_HELP_STRING([--enable-ccwarn],
-                              [enable showing and stopping on compilation warnings])],
+                              [enable showing and stopping on compilation warnings
+                               in Verilator binrary and Verilated makefiles])],
               [case "${enableval}" in
                 yes) CFG_WITH_CCWARN=yes ;;
                 no)  CFG_WITH_CCWARN=no ;;
@@ -75,26 +142,11 @@ AC_ARG_ENABLE([longtests],
 AC_SUBST(CFG_WITH_LONGTESTS)
 AC_MSG_RESULT($CFG_WITH_LONGTESTS)
 
-# CFG_WITH_PREC11
-AC_MSG_CHECKING(whether allow pre-C++11)
-AC_ARG_ENABLE([prec11],
-              [AS_HELP_STRING([--enable-prec11],
-                              [enable pre-C++11 compilers])],
-              [case "${enableval}" in
-                yes) CFG_WITH_PREC11=yes ;;
-                no)  CFG_WITH_PREC11=no ;;
-                *)   AC_MSG_ERROR([bad value ${enableval} for --enable-prec11]) ;;
-               esac],
-              [CFG_WITH_PREC11=no;]
-              )
-AC_SUBST(CFG_WITH_PREC11)
-AC_MSG_RESULT($CFG_WITH_PREC11)
-
-# Compiler flags
-CFLAGS=-I${includedir}
-CPPFLAGS=-I${includedir}
-CXXFLAGS=-I${includedir}
-LDFLAGS=-L${libdir}
+# Compiler flags (ensure they are not empty to avoid configure defaults)
+CFLAGS+=" "
+CPPFLAGS+=" "
+CXXFLAGS+=" "
+LDFLAGS+=" "
 
 # Checks for programs.
 AC_PROG_CC
@@ -111,18 +163,40 @@ AC_RUN_IFELSE(
     AC_MSG_RESULT(no);AC_MSG_ERROR([a working C++ compiler is required]),
     AC_MSG_RESULT(yes))
 
+AC_CHECK_PROG(AR,ar,ar)
+if test "x$AR" = "x" ; then
+   AC_MSG_ERROR([Cannot find "ar" in your PATH, please install it])
+fi
+
 AC_PATH_PROG(PERL,perl)
 if test "x$PERL" = "x" ; then
    AC_MSG_ERROR([Cannot find "perl" in your PATH, please install it])
 fi
+
+AC_PATH_PROG(PYTHON3,python3)
+if test "x$PYTHON3" = "x" ; then
+   AC_MSG_ERROR([Cannot find "python3" in your PATH, please install it])
+fi
+
 AC_PATH_PROG(LEX,flex)
 if test "x$LEX" = "x" ; then
    AC_MSG_ERROR([Cannot find "flex" in your PATH, please install it])
 fi
+flex_version=$($LEX --version | head -1)
+AC_MSG_RESULT([$LEX --version = $flex_version])
+
 AC_PATH_PROG(YACC,bison)
 if test "x$YACC" = "x" ; then
    AC_MSG_ERROR([Cannot find "bison" in your PATH, please install it])
 fi
+bison_version=$($YACC --version | head -1)
+AC_MSG_RESULT([$YACC --version = $bison_version])
+
+AC_CHECK_PROG(OBJCACHE,ccache,ccache)
+if test "x$OBJCACHE" != "x" ; then
+  objcache_version=$($OBJCACHE --version | head -1)
+  AC_MSG_RESULT([objcache is $OBJCACHE --version = $objcache_version])
+fi
 
 # Checks for libraries.
 
@@ -170,24 +244,34 @@ AC_DEFUN([_MY_CXX_CHECK_FLAG],
     CXXFLAGS="$ACO_SAVE_CXXFLAGS"
    ])
 
+AC_DEFUN([_MY_CXX_CHECK_IFELSE],
+   [# _MY_CXX_CHECK_IFELSE(option,action-if-supported,action-if-not-supported)
+    # Check if compiler supports specific option. If it does,
+    # do action-if-supported, otherwise do action-if-not-supported
+    _MY_CXX_CHECK_FLAG($1)
+    if test "$_my_result" = "yes" ; then
+      true
+      $2
+    else
+      true
+      $3
+    fi
+   ])
+
 AC_DEFUN([_MY_CXX_CHECK_SET],
-   [# _MY_CXX_CHECK_SET(variable,flag) -- Check if compiler supports specific options
-    # If it does, set variable to flag, only if not previously set
+   [# _MY_CXX_CHECK_SET(variable,option)
+    # Check if compiler supports specific option. If it does,
+    # set variable to option, only if not previously set.
     if test "$$1" = ""; then
-       _MY_CXX_CHECK_FLAG($2)
-       if test "$_my_result" = "yes" ; then
-          $1="$2"
-       fi
+       _MY_CXX_CHECK_IFELSE($2, $1="$2")
     fi
    ])
 
 AC_DEFUN([_MY_CXX_CHECK_OPT],
-   [# _MY_CXX_CHECK_OPT(flag) -- Check if compiler supports specific options
-    # If it does, append flag to variable
-    _MY_CXX_CHECK_FLAG($2)
-    if test "$_my_result" = "yes" ; then
-       $1="$$1 $2"
-    fi
+   [# _MY_CXX_CHECK_OPT(variable,option)
+    # Check if compiler supports specific option. If it does,
+    # append option to variable
+    _MY_CXX_CHECK_IFELSE($2, $1="$$1 $2")
    ])
 
 AC_DEFUN([_MY_LDLIBS_CHECK_FLAG],
@@ -209,24 +293,68 @@ AC_DEFUN([_MY_LDLIBS_CHECK_FLAG],
     LIBS="$ACO_SAVE_LIBS"
    ])
 
-AC_DEFUN([_MY_LDLIBS_CHECK_OPT],
-   [# _MY_LDLIBS_CHECK_OPT(flag) -- Check if linker supports specific options
-    # If it does, append flag to variable
-    _MY_LDLIBS_CHECK_FLAG($2)
+AC_DEFUN([_MY_LDLIBS_CHECK_IFELSE],
+   [# _MY_LDLIBS_CHECK_IFELSE(flag,action-if-supported,action-if-not-supported)
+    # Check if linker supports specific flag, if it does do action-if-supported
+    # otherwise do action-if-not-supported
+    _MY_LDLIBS_CHECK_FLAG($1)
     if test "$_my_result" = "yes" ; then
-       $1="$$1 $2"
+      true
+      $2
+    else
+      true
+      $3
     fi
    ])
 
+AC_DEFUN([_MY_LDLIBS_CHECK_OPT],
+   [# _MY_LDLIBS_CHECK_OPT(variable, flag) -- Check if linker supports specific
+    # options. If it does, append flag to variable.
+    _MY_LDLIBS_CHECK_IFELSE($2, $1="$$1 $2")
+   ])
+
+# When using -m32. Check this first as later checks may fail with the -m32 flag.
+if test "$CFG_ENABLE_M32" = "yes"; then
+  _MY_CXX_CHECK_IFELSE(
+    -m32,
+    [CXX="$CXX -m32"],
+    [AC_MSG_ERROR([--enable-m32 was given but compiler does not support -m32])])
+fi
+
+# Similarly, add the coverage flags early as they influence later checks.
+if test "$CFG_ENABLE_COVERAGE" = "yes"; then
+  _MY_CXX_CHECK_OPT(CXX,--coverage)
+  # Otherwise inline may not show as uncovered
+  #  If we use this then e.g. verilated.h functions properly show up
+  #  if unused.
+  #  However, VerilatedSerialize::write then changes from covered
+  #  to uncovered (in G++ 9.3.0) even with all inlining turned off.
+  #  Having false negative coverage is more effort then missing negatives.
+  #  Also this seems to explode the runtime (since a lot more data).
+  #  _MY_CXX_CHECK_OPT(CXX,-fkeep-inline-functions)
+  # Otherwise static may not show as uncovered
+  _MY_CXX_CHECK_OPT(CXX,-fkeep-static-functions)
+  # Exceptions can pollute the branch coverage data
+  _MY_CXX_CHECK_OPT(CXX,-fno-exceptions)
+  # Define-out some impossible stuff
+  _MY_CXX_CHECK_OPT(CXX,-DVL_GCOV)
+fi
+
+# Compiler flags to enable profiling
+_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_PROFILE,-pg)
+AC_SUBST(CFG_CXXFLAGS_PROFILE)
+
 # Flag to select newest language standard supported
 # Macros work such that first option that passes is the one we take
-# gnu++17 code is clean, but SystemC in 2018 doesn't link with it (bug1339)
-# gnu++14 is the newest that Verilator supports
+# Currently enabled gnu++14/c++14 due to packaged SystemC dependency
+# gnu++17 is the newest that Verilator supports
 # std++03 is the oldest that Verilator supports
+#_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=gnu++20)
 #_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=gnu++17)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=gnu++14)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=gnu++11)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=gnu++03)
+#_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=c++20)
 #_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=c++17)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=c++14)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_NEWEST,-std=c++11)
@@ -237,11 +365,13 @@ AC_SUBST(CFG_CXXFLAGS_STD_NEWEST)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=c++03)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=c++11)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=c++14)
-#_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=std++17)
+#_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=c++17)
+#_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=c++20)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=gnu++03)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=gnu++11)
 _MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=gnu++14)
 #_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=gnu++17)
+#_MY_CXX_CHECK_SET(CFG_CXXFLAGS_STD_OLDEST,-std=gnu++20)
 AC_SUBST(CFG_CXXFLAGS_STD_OLDEST)
 
 # Flags for compiling Verilator internals including parser, and Verilated files
@@ -256,7 +386,6 @@ AC_SUBST(CFG_CXXFLAGS_WEXTRA)
 _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_SRC,-Qunused-arguments)
 _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_SRC,-faligned-new)
 _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_SRC,-Wno-unused-parameter)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_SRC,-Wno-undefined-bool-conversion)
 _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_SRC,-Wno-shadow)
 AC_SUBST(CFG_CXXFLAGS_SRC)
 
@@ -267,38 +396,111 @@ _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_PARSER,-Wno-parentheses-equality)
 _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_PARSER,-Wno-unused)
 AC_SUBST(CFG_CXXFLAGS_PARSER)
 
+# Flags for compiling the debug version of Verilator (in addition to above CFG_CXXFLAGS_SRC)
+if test "$CFG_ENABLE_COVERAGE" = "no"; then # Do not optimize for the coverage build
+_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_DEBUG,-Og)
+fi
+_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_DEBUG,-ggdb)
+_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_DEBUG,-gz)
+AC_SUBST(CFG_CXXFLAGS_DEBUG)
+
+# Flags for linking the debug version of Verilator (in addition to above CFG_LDFLAGS_SRC)
+_MY_LDLIBS_CHECK_OPT(CFG_LDFLAGS_DEBUG,-gz)
+AC_SUBST(CFG_LDFLAGS_DEBUG)
+
 # Flags for Verilated makefile
 # For example, -Wno-div-by-zero isn't in 4.1.2
 # Random code often does / 0.  Unfortunately VL_DIV_I(0,0) will warn
 # without this flag, even though there's a conditional to prevent the divide.
 # We still don't add no-div-by-zero as it throws message to stdout, though doesn't die.
 #_MY_CXX_CHECK_OPT(-Wno-div-by-zero)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-faligned-new)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-fbracket-depth=4096)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Qunused-arguments)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Wno-bool-operation)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Wno-parentheses-equality)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Wno-sign-compare)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Wno-uninitialized)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Wno-unused-but-set-variable)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Wno-unused-parameter)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Wno-unused-variable)
-_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-Wno-shadow)
+# For some reason -faligned-new does not work under Travis w/ clang but the
+# configure test doesn't catch this either
+AS_IF([test "x$TRAVIS_COMPILER" != xclang], [_MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,-faligned-new)])
+CFG_CXX_FLAGS_CMAKE="-faligned-new"
+m4_foreach([cflag],[
+        [-fbracket-depth=4096],
+        [-fcf-protection=none],
+        [-mno-cet],
+        [-Qunused-arguments],
+        [-Wno-bool-operation],
+        [-Wno-tautological-bitwise-compare],
+        [-Wno-parentheses-equality],
+        [-Wno-sign-compare],
+        [-Wno-uninitialized],
+        [-Wno-unused-but-set-variable],
+        [-Wno-unused-parameter],
+        [-Wno-unused-variable],
+        [-Wno-shadow]],[
+    _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_NO_UNUSED,cflag)
+    # CMake will test what flags work itself, so pass all flags through to it
+    CFG_CXX_FLAGS_CMAKE="$CFG_CXX_FLAGS_CMAKE cflag"
+    ])
 AC_SUBST(CFG_CXXFLAGS_NO_UNUSED)
+AC_SUBST(CFG_CXX_FLAGS_CMAKE)
 
 # Find multithread linker flags
-_MY_LDLIBS_CHECK_OPT(CFG_LDLIBS_THREADS,-mt)
-_MY_LDLIBS_CHECK_OPT(CFG_LDLIBS_THREADS,-pthread)
-_MY_LDLIBS_CHECK_OPT(CFG_LDLIBS_THREADS,-lpthread)
-_MY_LDLIBS_CHECK_OPT(CFG_LDLIBS_THREADS,-latomic)
+m4_foreach([ldflag], [
+        [-mt],
+        [-pthread],
+        [-lpthread],
+        [-latomic]],[
+    _MY_LDLIBS_CHECK_OPT(CFG_LDLIBS_THREADS,ldflag)
+    # CMake will test what flags work itself, so pass all flags through to it
+    CFG_LDFLAGS_THREADS_CMAKE="$CFG_LDFLAGS_THREADS_CMAKE ldflag"
+    ])
 AC_SUBST(CFG_LDLIBS_THREADS)
+AC_SUBST(CFG_LDFLAGS_THREADS_CMAKE)
 
-# Set CFG_WITH_THREADED if can support threading
-AC_MSG_CHECKING(whether $CXX supports Verilated threads)
-ACO_SAVE_CXXFLAGS="$CXXFLAGS"
-CXXFLAGS="$CXXFLAGS $CFG_CXXFLAGS_STD_NEWEST $CFG_CXXFLAGS_NO_UNUSED"
-AC_LINK_IFELSE(
-     [AC_LANG_PROGRAM([#include <thread>], [[ ]])],
+# When linking partially statically
+if test "$CFG_ENABLE_PARTIAL_STATIC" = "yes"; then
+  _MY_LDLIBS_CHECK_OPT(CFG_LDFLAGS_SRC, -static-libgcc)
+  _MY_LDLIBS_CHECK_OPT(CFG_LDFLAGS_SRC, -static-libstdc++)
+  _MY_LDLIBS_CHECK_OPT(CFG_LDFLAGS_SRC, -Xlinker -gc-sections)
+  LTCMALLOC=-l:libtcmalloc_minimal.a
+else
+  LTCMALLOC=-ltcmalloc_minimal
+fi
+AC_SUBST(CFG_LDFLAGS_SRC)
+
+# The pthread library is required by tcmalloc, so add it if it exists. If it
+# does not, the tcmalloc check below will fail anyway, and linking against
+# pthreads is harmless otherwise.
+CFG_LIBS="$LIBS $CFG_LIBS"
+_MY_LDLIBS_CHECK_OPT(CFG_LIBS, -lpthread)
+
+# Check libraries for MingW
+_MY_LDLIBS_CHECK_OPT(CFG_LIBS, -lbcrypt)
+_MY_LDLIBS_CHECK_OPT(CFG_LIBS, -lpsapi)
+
+# Check if tcmalloc is available based on --enable-tcmalloc
+_MY_LDLIBS_CHECK_IFELSE(
+  $LTCMALLOC,
+  [if test "$CFG_WITH_TCMALLOC" != "no"; then
+    CFG_LIBS="$LTCMALLOC $CFG_LIBS";
+    # If using tcmalloc, add some extra options to make the compiler not assume
+    # it is using it's own versions of the standard library functions
+    _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_SRC,-fno-builtin-malloc)
+    _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_SRC,-fno-builtin-calloc)
+    _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_SRC,-fno-builtin-realloc)
+    _MY_CXX_CHECK_OPT(CFG_CXXFLAGS_SRC,-fno-builtin-free)
+   fi],
+  [if test "$CFG_WITH_TCMALLOC" = "yes"; then
+    AC_MSG_ERROR([--enable-tcmalloc was given but test for ${LTCMALLOC} failed])
+   fi])
+AC_SUBST(CFG_LIBS)
+
+# Need C++11 at least
+#Alternative: AX_CXX_COMPILE_STDCXX([11])
+AC_DEFUN([_MY_CXX_CHECK_CXX_VER],
+   [# _MY_CXX_CHECK_CXX_VER(flag) -- Check if compiler runs C++11
+    # Set $_my_result
+    AC_LINK_IFELSE(
+     [AC_LANG_PROGRAM([#include <thread>
+#if (__cplusplus < 201103L)
+# error "Too old"
+#endif
+    ], [[ ]])],
      [_my_result=yes
       if test -s conftest.err; then
         if grep -e "$1" conftest.err >/dev/null; then
@@ -306,24 +508,24 @@ AC_LINK_IFELSE(
         fi
       fi],
      [_my_result=no])
-CFG_WITH_THREADED=$_my_result
-AC_SUBST(CFG_WITH_THREADED)
-AC_MSG_RESULT($CFG_WITH_THREADED)
+   ])
 
-# Check compiler flag
-if test "$CFG_WITH_THREADED" = "no" ; then
-   if test "$CFG_WITH_PREC11" = "no" ; then
-      AC_MSG_NOTICE([[]])
-      AC_MSG_ERROR([[the $CXX compiler appears to not support C++11.
+AC_MSG_CHECKING(whether $CXX supports C++11)
+_MY_CXX_CHECK_CXX_VER()
+AC_MSG_RESULT($_my_result)
+if test "$_my_result" = "no" ; then
+   CXXFLAGS="$CXXFLAGS $CFG_CXXFLAGS_STD_NEWEST"
+   CFG_CXX_FLAGS_CMAKE="$CFG_CXX_FLAGS_CMAKE $CFG_CXXFLAGS_STD_NEWEST"
+   AC_MSG_CHECKING(whether $CXX supports C++11 with $CFG_CXXFLAGS_STD_NEWEST)
+   _MY_CXX_CHECK_CXX_VER()
+   AC_MSG_RESULT($_my_result)
+fi
+if test "$_my_result" = "no" ; then
+   AC_MSG_NOTICE([[]])
+   AC_MSG_ERROR([[the $CXX compiler appears to not support C++11.
 
-Verilator plans to require a C++11 or newer compiler in a future release,
-unless sufficient people report problems. Therefore, if you do not have a
-C++11 compiler, please post a message to
-https://www.veripool.org/boards/3/topics/2580-Verilator-Requiring-C-11-compiler
-indicating your OS and when you think C++11 might be ok, and then rerun
-configure with the --enable-prec11 argument. Thanks.]])
+Verilator requires a C++11 or newer compiler.]])
 
-   fi
 fi
 
 # Checks for library functions.
@@ -331,6 +533,24 @@ AC_CHECK_MEMBER([struct stat.st_mtim.tv_nsec],
     [AC_DEFINE([HAVE_STAT_NSEC],[1],[Defined if struct stat has st_mtim.tv_nsec])],
     [], [#include <sys/stat.h>])
 
+# HAVE_SYSTEMC
+# - If found the default search path has it, so support is always enabled.
+# - If not found or not system-wide, user can set SYSTEMC_INCLUDE.
+# AC_CHECK_HEADERS seems to not locate on Travis-CI but include does work.
+AC_MSG_CHECKING([whether SystemC is found (in system path)])
+ACO_SAVE_LIBS="$LIBS"
+LIBS="$LIBS -lsystemc"
+AC_LINK_IFELSE(
+    [AC_LANG_PROGRAM([[#include <systemc.h>
+                     extern "C" int sc_main(int argc, char* argv[]) {}
+                     ]],[[sc_version()]])],
+    [_my_result=yes
+     AC_DEFINE([HAVE_SYSTEMC],[1],[Defined if have SystemC library])],
+    [_my_result=no])
+AC_MSG_RESULT($_my_result)
+LIBS="$ACO_SAVE_LIBS"
+AC_SUBST(HAVE_SYSTEMC)
+
 # Checks for system services
 
 # Other install directories

docs/.gitignore

@@ -0,0 +1,4 @@
+*.1
+*.html
+*.pdf
+_build

docs/CONTRIBUTING.rst

@@ -0,0 +1,92 @@
+Contributing to Verilator
+=========================
+
+Thanks for using Verilator! We welcome your contributions in whatever form.
+
+This contributing document contains some suggestions that may make
+contributions flow more efficiently.
+
+
+Did you find a bug?
+-------------------
+
+- Please **Ensure the bug was not already reported** by searching
+  `Verilator Issues <https://verilator.org/issues>`__.
+
+- If you're unable to find an open issue addressing the problem, `open a
+  new Verilator issue <https://verilator.org/issues/new>`__.
+
+  - Be sure to include a **code sample** or an **executable test case**
+    demonstrating the bug and expected behavior that is not occurring.
+
+  - The ideal example works against other simulators, and is in the
+    test_regress/t test format, as described in `docs/internals
+    <internals.rst>`__.
+
+
+Did you write a patch that fixes a bug?
+---------------------------------------
+
+- Please `Open a new issue <https://verilator.org/issues/new>`__.
+
+- You may attach a patch to the issue, or (preferred) may request a
+  GitHub pull request.
+
+  - Verilator uses GitHub Actions to provide continuous integration.  You
+    may want to enable Actions on your GitHub branch to ensure your changes
+    keep the tests passing. See `docs/internals <internals.rst>`__.
+
+- Your source-code contributions must be certified as open source,
+  under the `Developer Certificate of
+  Origin <https://developercertificate.org/>`__. On your first
+  contribution, you must either:
+
+  - Have your patch include the addition of your name to `docs/CONTRIBUTORS
+    <CONTRIBUTORS>`__ (preferred).
+
+  - Use "git -s" as part of your commit. This adds a "signed-of-by"
+    attribute which will certify your contribution as described in the
+    `Signed-of-By convention
+    <https://github.com/wking/signed-off-by/blob/master/Documentation/SubmittingPatches>`__.
+
+  - Email, or post in an issue a statement that you certify your
+    contributions.
+
+  - In any of these cases your name will be added to `docs/CONTRIBUTORS
+    <CONTRIBUTORS>`__ and you are agreeing all future contributions are
+    also certified.
+
+  - We occasionally accept contributions where people do not want their
+    name published. Please email us; you must still privately certify your
+    contribution.
+
+- Your test contributions are generally considered released into the
+  Creative Commons Public Domain (CC0), unless you request otherwise or
+  put a GNU/Artistic license on your file.
+
+- Most important is we get your patch. If you’d like to clean up
+  indentation and related issues ahead of our feedback, that is
+  appreciated; please see the coding conventions in `docs/internals
+  <internals.rst>`__.
+
+
+Do you have questions?
+----------------------
+
+- Please see FAQ section and rest of the `Verilator
+  manual <https://verilator.org/verilator_doc.html>`__, or `Verilator
+  manual (PDF) <https://verilator.org/verilator_doc.pdf>`__.
+
+- Ask any question in the `Verilator forum
+  <https://verilator.org/forum>`__.
+
+
+Code of Conduct
+---------------
+
+- Our contributors and participants pledge to make participation in our
+  project and our community a positive experience for everyone. We follow
+  the `Contributor Covenant version 1.4
+  <https://www.contributor-covenant.org/version/1/4/code-of-conduct/>`__.
+
+Thanks!

docs/CONTRIBUTORS

@@ -0,0 +1,101 @@
+The contributors listed below have certified their Verilator contributions
+under the Developer Certificate of Origin (https://developercertificate.org/).
+
+Please see the Verilator manual for 200+ additional contributors. Thanks to all.
+
+Ahmed El-Mahmoudy
+Alex Chadwick
+Àlex Torregrosa
+Ameya Vikram Singh
+Andreas Kuster
+Chris Randall
+Conor McCullough
+Dan Petrisko
+David Horton
+David Metz
+David Stanford
+David Turner
+Drew Taussig
+Driss Hafdi
+Edgar E. Iglesias
+Eric Rippey
+Fan Shupei
+Felix Yan
+Garrett Smith
+Geza Lore
+Gianfranco Costamagna
+Glen Gibb
+Graham Rushton
+Harald Heckmann
+Howard Su
+Huang Rui
+HyungKi Jeong
+Iztok Jeras
+James Hanlon
+James Hutchinson
+James Pallister
+Jamey Hicks
+Jan Van Winkel
+Jean Berniolles
+Jeremy Bennett
+John Coiner
+John Demme
+Jonathan Drolet
+Josh Redford
+Julien Margetts
+Kaleb Barrett
+Kanad Kanhere
+Kevin Kiningham
+Krzysztof Bieganski
+Kuba Ober
+Ludwig Rogiers
+Lukasz Dalek
+Maarten De Braekeleer
+Maciej Sobkowski
+Marco Widmer
+Markus Krause
+Marlon James
+Marshal Qiao
+Martin Schmidt
+Matthew Ballance
+Michael Killough
+Mike Popoloski
+Miodrag Milanović
+Morten Borup Petersen
+Nandu Raj
+Nathan Kohagen
+Nathan Myers
+Patrick Stewart
+Paul Wright
+Peter Horvath
+Peter Monsson
+Philipp Wagner
+Pierre-Henri Horrein
+Pieter Kapsenberg
+Piotr Binkowski
+Qingyao Sun
+Rafal Kapuscik
+Richard Myers
+Rupert Swarbrick
+Samuel Riedel
+Sean Cross
+Sebastien Van Cauwenberghe
+Sergi Granell
+Stefan Wallentowitz
+Stephen Henry
+Tim Snyder
+Tobias Rosenkranz
+Tobias Wölfel
+Todd Strader
+Tomasz Gorochowik
+Tymoteusz Blazejczyk
+Udi Finkelstein
+Unai Martinez-Corral
+Vassilis Papaefstathiou
+Veripool API Bot
+Victor Besyakov
+Wilson Snyder
+Yossi Nivin
+Yuri Victorovich
+Yutetsu TAKATSUKASA
+Yves Mathieu

docs/Makefile

@@ -0,0 +1,82 @@
+#*****************************************************************************
+# DESCRIPTION: Verilator documentation: Makefile pre-configure version
+#
+# This file is part of Verilator.
+#
+# Code available from: https://verilator.org
+#
+# Copyright 2003-2021 by Wilson Snyder. This program is free software; you
+# can redistribute it and/or modify it under the terms of either the GNU
+# Lesser General Public License Version 3 or the Perl Artistic License
+# Version 2.0.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+#
+######################################################################
+#
+# This file is intended only to be called from the top-level Verilator Makefile.
+
+RST2HTML = rst2html
+PYTHON3 = python3
+DOXYGEN = doxygen
+SPHINXOPTS ?= -c guide
+SPHINXBUILD ?= sphinx-build
+
+SOURCEDIR = guide
+BUILDDIR = _build
+
+######################################################################
+
+.SUFFIXES:
+
+default:
+	@echo "error: make not supported here, run 'make docs' from Verilator top-level"
+
+######################################################################
+# Intermediate rules
+
+vl-extract: ../bin/verilator ../Changes
+	mkdir -p _build/gen
+	$(PYTHON3) bin/vl_sphinx_extract ../bin/verilator
+	sed 's/`/\&96;/g' < ../Changes > _build/gen/Changes
+
+######################################################################
+# HTML
+
+server: html
+	cd _build/html && $(PYTHON3) -m http.server
+
+%.html: %.rst
+	$(RST2HTML) $< $@
+
+######################################################################
+# PDF
+
+.PHONY: verilator.pdf
+
+verilator.pdf: pdf
+pdf:
+	$(MAKE) vl-extract
+	$(MAKE) latex
+	$(PYTHON3) bin/vl_sphinx_fix _build
+	$(MAKE) -C _build/latex
+	cp _build/latex/verilator.pdf ..
+
+######################################################################
+
+html latex linkcheck spelling::
+	$(MAKE) vl-extract
+	$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
+	$(PYTHON3) bin/vl_sphinx_fix _build
+
+help:
+	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS)
+
+clean mostlyclean distclean maintainer-clean::
+	rm -f $(SCRIPTS) *.tmp
+	rm -f *.aux *.cp *.cps *.dvi *.fn *.fns *.ky *.kys *.log
+	rm -f *.pg *.pgs *.toc *.tp *.tps *.vr *.vrs *.idx
+	rm -f *.ev *.evs *.ov *.ovs *.cv *.cvs *.ma *.mas
+	rm -f *.tex
+
+distclean maintainer-clean::
+	rm -f *.info* *.1 *.html *.pdf $(INFOS)

docs/_static/css/vlt_sphinx.css

@@ -0,0 +1,25 @@
+/* Verilator blue #008fd7; set in html */
+
+.wy-side-nav-search > div.version {
+  color: #111;
+}
+
+.fa-github::before,
+.icon-github::before {
+  content: "";
+}
+
+.fa-home::before,
+.icon-home::before {
+  content: "";
+}
+
+.fa-arrow-circle-right::before,
+.icon-circle-arrow-right::before {
+  content: "";
+}
+
+.fa-arrow-circle-left::before,
+.icon-circle-arrow-left::before {
+  content: "";
+}

docs/bin/vl_sphinx_extract

@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+# pylint: disable=C0112,C0114,C0115,C0116,C0301,R0201,R0903
+# -*- Python -*- See copyright, etc below
+######################################################################
+
+import argparse
+import re
+
+#######################################################################
+
+
+class VlSphinxExtract:
+    debug = 0
+    SkipBasenames = {}
+
+    def process(self, filename):
+        with open(filename) as fhr:
+            fhw = None
+            for line in fhr:
+                # =for VL_SPHINX_EXTRACT "file_to_write_to"
+                match = re.search(r'VL_SPHINX_EXTRACT +"([^"]+)"', line)
+                if match:
+                    outname = match.group(1)
+                    print("Writing %s" % outname)
+                    fhw = open(outname, "w")
+                    fhw.write(
+                        ".. comment: generated by vl_sphinx_extract from " +
+                        filename + "\n")
+                    fhw.write(".. code-block::\n")
+                elif re.match(r'^[=a-zA-Z0-9_]', line):
+                    fhw = None
+                elif fhw:
+                    fhw.write(line)
+
+
+#######################################################################
+
+parser = argparse.ArgumentParser(
+    allow_abbrev=False,
+    formatter_class=argparse.RawDescriptionHelpFormatter,
+    description="""Read a file and extract documentation data.""",
+    epilog=
+    """ Copyright 2021-2021 by Wilson Snyder.  This package is free software;
+you can redistribute it and/or modify it under the terms of either the GNU
+Lesser General Public License Version 3 or the Perl Artistic License
+Version 2.0.
+
+SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0""")
+
+parser.add_argument('--debug',
+                    action='store_const',
+                    const=9,
+                    help='enable debug')
+parser.add_argument('path', help='path to extract from')
+Args = parser.parse_args()
+
+o = VlSphinxExtract()
+o.debug = Args.debug
+o.process(Args.path)
+
+######################################################################
+# Local Variables:
+# compile-command: "./vl_sphinx_extract --debug ../../bin/verilator"
+# End:

docs/bin/vl_sphinx_fix

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+# pylint: disable=C0112,C0114,C0115,C0116,C0301,R0903
+# -*- Python -*- See copyright, etc below
+######################################################################
+
+import argparse
+import os
+import re
+
+#######################################################################
+
+
+class VlSphinxFix:
+    debug = 0
+    SkipBasenames = {}
+
+    def process(self, path):
+        if os.path.isdir(path):
+            for basefile in os.listdir(path):
+                file = os.path.join(path, basefile)
+                if ((basefile != ".") and (basefile != "..")
+                        and basefile not in self.SkipBasenames
+                        and not os.path.islink(file)):
+                    self.process(file)
+        elif re.search(r'\.(html|tex)$', path):
+            self._edit(path)
+
+    def _edit(self, filename):
+        is_html = re.search(r'\.(html)$', filename)
+        with open(filename) as fhr:
+            origfile = fhr.read()
+            wholefile = origfile
+            # Option doesn't like spaces, so we use
+            # :option:`/*verilator&32;metacomment*/`
+            wholefile = re.sub(r'verilator-32-', r'verilator-', wholefile)
+            if is_html:
+                wholefile = re.sub(r'&32;', r' ', wholefile)
+                wholefile = re.sub(r'&96;', r'`', wholefile)
+            else:
+                wholefile = re.sub(r'&32;', r' ', wholefile)
+                wholefile = re.sub(r'&96;', r'`', wholefile)
+            if wholefile != origfile:
+                if self.debug:
+                    print("Edit %s" % filename)
+                tempname = filename + ".tmp"
+                with open(tempname, "w") as fhw:
+                    fhw.write(wholefile)
+                os.rename(tempname, filename)
+
+
+#######################################################################
+
+parser = argparse.ArgumentParser(
+    allow_abbrev=False,
+    formatter_class=argparse.RawDescriptionHelpFormatter,
+    description="""Post-process Sphinx HTML.""",
+    epilog=
+    """ Copyright 2021-2021 by Wilson Snyder.  This package is free software;
+you can redistribute it and/or modify it under the terms of either the GNU
+Lesser General Public License Version 3 or the Perl Artistic License
+Version 2.0.
+
+SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0""")
+
+parser.add_argument('--debug',
+                    action='store_const',
+                    const=9,
+                    help='enable debug')
+parser.add_argument('path', help='path to edit')
+Args = parser.parse_args()
+
+o = VlSphinxFix()
+o.debug = Args.debug
+o.process(Args.path)
+
+######################################################################
+# Local Variables:
+# compile-command: "./vl_sphinx_fix --debug _build"
+# End:

docs/gen/ex_MULTIDRIVEN_faulty.rst

@@ -0,0 +1,11 @@
+.. comment: generated by t_lint_multidriven_bad
+.. code-block:: sv
+   :linenos:
+   :emphasize-lines: 2,5
+
+      always @(posedge clk) begin
+         out2[7:0] <= d0;  // <--- Warning
+      end
+      always @(negedge clk) begin
+         out2[15:8] <= d0;  // <--- Warning
+      end

docs/gen/ex_MULTIDRIVEN_msg.rst

@@ -0,0 +1,6 @@
+.. comment: generated by t_lint_multidriven_bad
+.. code-block::
+
+   %Warning-MULTIDRIVEN: example.v:1:22 Signal has multiple driving blocks with different clocking: 'out2'
+                         example.v:1:7 ... Location of first driving block
+                         example.v:1:7 ... Location of other driving block

docs/gen/ex_USERERROR_faulty.rst

@@ -0,0 +1,4 @@
+.. comment: generated by t_assert_comp_bad
+.. code-block:: sv
+
+         $error("User elaboration-time error");

docs/gen/ex_USERERROR_msg.rst

@@ -0,0 +1,4 @@
+.. comment: generated by t_assert_comp_bad
+.. code-block::
+
+   %Warning-USERERROR: example.v:1:7 User elaboration-time error

docs/gen/ex_USERFATAL_faulty.rst

@@ -0,0 +1,4 @@
+.. comment: generated by t_assert_comp_bad
+.. code-block:: sv
+
+         $fatal(0, "User elaboration-time fatal");

docs/gen/ex_USERFATAL_msg.rst

@@ -0,0 +1,4 @@
+.. comment: generated by t_assert_comp_bad
+.. code-block::
+
+   %Warning-USERFATAL: example.v:1:7 User elaboration-time fatal

docs/gen/ex_USERINFO_faulty.rst

@@ -0,0 +1,4 @@
+.. comment: generated by t_assert_comp_bad
+.. code-block:: sv
+
+         $info("User elaboration-time info");

docs/gen/ex_USERINFO_msg.rst

@@ -0,0 +1,4 @@
+.. comment: generated by t_assert_comp_bad
+.. code-block::
+
+   -Info: example.v:1:7 User elaboration-time info

docs/gen/ex_USERWARN_faulty.rst

@@ -0,0 +1,4 @@
+.. comment: generated by t_assert_comp_bad
+.. code-block:: sv
+
+         $warning("User elaboration-time warning");

docs/gen/ex_USERWARN_msg.rst

@@ -0,0 +1,4 @@
+.. comment: generated by t_assert_comp_bad
+.. code-block::
+
+   %Warning-USERWARN: example.v:1:7 User elaboration-time warning

docs/gen/ex_VARHIDDEN_faulty.rst

@@ -0,0 +1,8 @@
+.. comment: generated by t_var_bad_hide_docs
+.. code-block:: sv
+   :linenos:
+   :emphasize-lines: 2
+
+   module t;
+      integer t;  //<--- Warning ('t' hidden by module 't')
+   endmodule

docs/gen/ex_VARHIDDEN_msg.rst

@@ -0,0 +1,5 @@
+.. comment: generated by t_var_bad_hide_docs
+.. code-block::
+
+   %Warning-VARHIDDEN: example.v:2:12 Declaration of signal hides declaration in upper scope: 't'
+                       example.v:1:8 ... Location of original declaration

docs/gen/ex_WIDTH_1_faulty.rst

@@ -0,0 +1,8 @@
+.. comment: generated by t_lint_width_docs_bad
+.. code-block:: sv
+   :linenos:
+   :emphasize-lines: 3
+
+      int array[5];
+      bit [1:0] rd_addr;
+      wire int rd_value = array[rd_addr];  //<--- Warning

docs/gen/ex_WIDTH_1_fixed.rst

@@ -0,0 +1,5 @@
+.. comment: generated by t_lint_width_docs_bad
+.. code-block:: sv
+   :emphasize-lines: 1
+
+      wire int rd_value = array[{1'b0, rd_addr}];  //<--- Fixed

docs/gen/ex_WIDTH_1_msg.rst

@@ -0,0 +1,4 @@
+.. comment: generated by t_lint_width_docs_bad
+.. code-block::
+
+   %Warning-WIDTH: example.v:3:29 Bit extraction of array[4:0] requires 3 bit index, not 2 bits.

docs/guide/changes.rst

@@ -0,0 +1,16 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+****************
+Revision History
+****************
+
+.. COMMENT above header must use ### so there is an extra level of headers
+   here so the index won't show the huge list of revisions when clicking on
+   "Revision History" in the sidebar.
+
+Changes are contained in the :file:`Changes` file of the distribution, and
+also summarized below.  To subscribe to new versions see `Verilator
+Announcements <https://github.com/verilator/verilator-announce>`_.
+
+.. include:: ../_build/gen/Changes

docs/guide/conf.py

@@ -0,0 +1,228 @@
+# pylint: disable=C0103,C0114,C0116,E0402,W0622
+#
+# Configuration file for Verilator's Sphinx documentation builder.
+# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+#
+# This file only contains overridden options. For a full list:
+# https://www.sphinx-doc.org/en/master/usage/configuration.html
+#
+# ----------------------------------------------------------------------
+# -- Path setup
+
+from datetime import datetime
+import os
+import re
+import sys
+sys.path.insert(0, os.path.abspath('./_ext'))
+
+import sphinx_rtd_theme  # pylint: disable=wrong-import-position,
+
+
+def get_vlt_version():
+    filename = "../../Makefile"
+    with open(filename) as fh:
+        for line in fh:
+            match = re.search(r"PACKAGE_VERSION_NUMBER *= *([a-z0-9.]+)", line)
+            if match:
+                return match.group(1)
+    return "unknown"
+
+
+def setup(app):
+    app.add_css_file('css/vlt_sphinx.css')
+
+
+# ----------------------------------------------------------------------
+# -- Project information
+
+project = 'Verilator'
+copyright = '2021 by Wilson Snyder, under LGPL-3.0 or Artistic-2.0'
+author = 'Wilson Snyder'
+
+# The master toctree document.
+master_doc = "index"
+
+version = get_vlt_version()
+release = get_vlt_version()
+
+rst_prolog = """
+.. role:: vlopt(option)
+"""
+
+# ----------------------------------------------------------------------
+# -- General configuration
+
+# Add any Sphinx extension module names here, as strings. They can be
+# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
+# ones.
+# To install:
+#   sudo install enchant
+#   sudo pip3 install sphinx sphinx_rtd_theme breathe sphinxcontrib-spelling
+# We keep this list empty for now to avoid needing dependencies
+extensions = []
+# extensions = ['breathe', 'sphinxcontrib.spelling']
+
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+# This pattern also affects html_static_path and html_extra_path.
+exclude_patterns = [
+    '_build', 'Thumbs.db', '.DS_Store', 'internals.rst', 'xml.rst', 'gen/ex_*',
+    'CONTRIBUTING.rst'
+]
+
+# Warn about refs
+nitpicky = True
+nitpicky_ignore = []
+
+# Number figures for referencing
+numfig = True
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = "sphinx"
+
+# The suffix(es) of source filenames.
+# You can specify multiple suffix as a list of string:
+source_suffix = [".rst"]
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# Date format to ISO
+today_fmt = datetime.now().strftime("%F")
+
+# If true, `todo` and `todoList` produce output, else they produce nothing.
+todo_include_todos = True
+
+# Could use this for internals<->guide references
+# intersphinx_mapping = { 'sphinx': ('https://sphinx-doc.org/', None), }
+
+# ----------------------------------------------------------------------
+# -- Options for HTML output
+
+# html_baseurl =
+
+html_domain_indices = False
+
+html_logo = "../_static/verilator_192_150_min.png"
+
+html_theme = 'sphinx_rtd_theme'
+html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
+
+html_theme_options = {
+    'analytics_id': 'G-D27B0C9QEB',
+    'logo_only': True,
+    'style_nav_header_background': "#45acf8",  # Default is #2980B9
+    # 'canonical_url':
+}
+
+html_context = {
+    'display_github': True,
+    'github_user': 'verilator',
+    'github_repo': 'verilator',
+    'github_version': 'master/docs/guide/',
+}
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['../_static']
+
+# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
+html_show_sphinx = False
+
+html_copy_source = False
+html_show_sourcelink = False
+
+html_use_index = False
+
+html_favicon = "../_static/verilator_32x32_min.png"
+
+# Custom sidebar templates, maps document names to template names.
+# html_sidebars
+
+# Add any extra paths that contain custom files (such as robots.txt or
+# .htaccess) here, relative to this directory. These files are copied
+# directly to the root of the documentation.
+# html_extra_path = []
+
+# Additional templates that should be rendered to pages, maps page names to
+# template names.
+# html_additional_pages = {}
+
+# ----------------------------------------------------------------------
+# -- Options for Latex output
+
+latex_logo = "../_static/verilator_logo.png"
+
+latex_elements = {
+    'extraclassoptions': 'openany,oneside',
+    'papersize': 'letterpaper',
+    'makeindex': '',
+    'printindex': '',
+    # 'pointsize': '10pt',
+    # 'preamble': '',
+}
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title,
+#  author, documentclass [howto, manual, or own class]).
+# latex_documents = [
+#    (
+#        master_doc,
+#        "Verilog-to-Routing.tex",
+#        "Verilog-to-Routing Documentation",
+#        "VTR Developers",
+#        "manual",
+#    ),
+# ]
+
+# For "manual" documents, if this is true, then toplevel headings are parts,
+# not chapters.
+# latex_use_parts = False
+
+# If true, show page references after internal links.
+# latex_show_pagerefs = False
+
+# If true, show URL addresses after external links.
+# latex_show_urls = False
+
+latex_domain_indices = False
+
+# ----------------------------------------------------------------------
+# -- Options for manual page output
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+# man_pages = [(master_doc, "verilog-to-routing", "Verilog-to-Routing Documentation", [author], 1)]
+
+# If true, show URL addresses after external links.
+# man_show_urls = False
+
+# ----------------------------------------------------------------------
+# -- Options for spelling
+
+spelling_word_list_filename = ['spelling.txt']
+spelling_ignore_contributor_names = True
+
+# ----------------------------------------------------------------------
+# -- Options for doxygen
+
+# if shutil.which("doxygen"):
+#    breathe_projects = {
+#        "verilated": "../_build/doxygen/verilated/xml",
+#    }
+#    breathe_default_project = "verilated"
+#
+#    if not os.environ.get("SKIP_DOXYGEN", None) == "True":
+#        for prjname, prjdir in breathe_projects.items():
+#            print("Generating doxygen files for {}...".format(prjname))
+#            os.makedirs(prjdir, exist_ok=True)
+#            cmd = "cd ../_doxygen && doxygen {}.dox".format(prjname)
+#            subprocess.call(cmd, shell=True)
+#    else:
+#        for prjname, prjdir in breathe_projects.items():
+#            assert os.path.exists(prjdir) == True, "Regenerate doxygen XML for {}".format(prjname)
+
+breathe_projects = {"verilated": "_build/doxygen/verilated/xml/"}
+breathe_default_project = "verilated"
+breathe_default_members = ('members')

docs/guide/connecting.rst

@@ -0,0 +1,516 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+.. _Connecting:
+
+******************************
+Connecting to Verilated Models
+******************************
+
+Structure of the Verilated Model
+================================
+
+Verilator outputs a :file:`{prefix}.h` header file which defines a class
+named :code:`{prefix}` which represents the generated model the user is
+supposed to instantiate.  This model class defines the interface of the
+Verilated model.
+
+Verilator will additionally create a :file:`{prefix}.cpp` file, together
+with additional .h and .cpp files for internals.  See the :file:`examples`
+directory in the kit for examples.  See :ref:`Files Read/Written` for
+information on all the files Verilator might output.
+
+The output of Verilator will contain a :file:`{prefix}.mk` file that may be
+used with Make to build a :file:`{prefix}__ALL.a` library with all required
+objects in it.
+
+The generated model class file manages all internal state required by the
+model, and exposes the following interface that allows interaction with the
+model:
+
+* Top level IO ports are exposed as references to the appropriate internal
+  equivalents.
+
+* Public top level module instances are exposed as pointers to allow access
+  to :code:`/* verilator public */` items.
+
+* The root of the design hierarchy (as in SystemVerilog :code:`$root`) is
+  exposed via the :code:`rootp` member pointer to allow access to model
+  internals, including :code:`/* verilator public_flat */` items.
+
+
+.. _Porting from pre 4.210:
+
+Model interface changes in version 4.210
+------------------------------------------
+
+Starting from version 4.210, the model class is an interface object.
+
+Up until Verilator version 4.204 inclusive, the generated model class was
+also the instance of the top level instance in the design hierarchy (what
+you would refer to with :code:`$root` in SystemVerilog).  This meant that
+all internal variables that were implemented by Verilator in the root scope
+were accessible as members of the model class itself.  Note there were often
+many such variable due to module inlining, including :code:`/* verilator
+public_flat */` items.
+
+This means that user code that accesses internal signals in the model
+(likely including :code:`/* verilator public_flat */` signals, as they are
+often inlined into the root scope) will need to be updated as follows:
+
+* No change required for accessing top level IO signals. These are directly
+  accessible in the model class via references.
+
+* No change required for accessing :code:`/* verilator public */` items.
+  These are directly accessible via sub-module pointers in the model class.
+
+* Accessing any other internal members, including
+  :code:`/* verilator public_flat */` items requires the following changes:
+
+  * Additionally include :file:`{prefix}___024root.h`. This header defines
+    type of the :code:`rootp` pointer within the model class. Note the
+    :code:`__024` substring is the Verilator escape sequence for the
+    :code:`$` character, i.e.: :code:`rootp` points to the Verilated
+    SystemVerilog :code:`$root` scope.
+
+  * Replace :code:`modelp->internal->member->lookup` references with
+    :code:`modelp->rootp->internal->member->lookup` references, which
+    contain one additional indirection via the :code:`rootp` pointer.
+
+
+.. _Connecting to C++:
+
+Connecting to C++
+=================
+
+In C++ output mode (:vlopt:`--cc`), the Verilator generated model class is a
+simple C++ class.  The user must write a C++ wrapper and main loop for the
+simulation, which instantiates the model class, and link with the Verilated
+model.  Here is a simple example:
+
+.. code-block:: C++
+
+         #include <verilated.h>          // Defines common routines
+         #include <iostream>             // Need std::cout
+         #include "Vtop.h"               // From Verilating "top.v"
+
+         Vtop *top;                      // Instantiation of model
+
+         vluint64_t main_time = 0;       // Current simulation time
+         // This is a 64-bit integer to reduce wrap over issues and
+         // allow modulus.  This is in units of the timeprecision
+         // used in Verilog (or from --timescale-override)
+
+         double sc_time_stamp() {        // Called by $time in Verilog
+             return main_time;           // converts to double, to match
+                                         // what SystemC does
+         }
+
+         int main(int argc, char** argv) {
+             Verilated::commandArgs(argc, argv);   // Remember args
+
+             top = new Vtop;             // Create model
+
+             top->reset_l = 0;           // Set some inputs
+
+             while (!Verilated::gotFinish()) {
+                 if (main_time > 10) {
+                     top->reset_l = 1;   // Deassert reset
+                 }
+                 if ((main_time % 10) == 1) {
+                     top->clk = 1;       // Toggle clock
+                 }
+                 if ((main_time % 10) == 6) {
+                     top->clk = 0;
+                 }
+                 top->eval();            // Evaluate model
+                 cout << top->out << endl;       // Read a output
+                 main_time++;            // Time passes...
+             }
+
+             top->final();               // Done simulating
+             //    // (Though this example doesn't get here)
+             delete top;
+         }
+
+
+Note top level IO signals are read and written as members of the model.  You
+call the :code:`eval()` method to evaluate the model.  When the simulation is
+complete call the :code:`final()` method to execute any SystemVerilog final
+blocks, and complete any assertions. See :ref:`Evaluation Loop`.
+
+
+Connecting to SystemC
+=====================
+
+In SystemC output mode (:vlopt:`--sc`), the Verilator generated model class
+is a SystemC SC_MODULE.  This module will attach directly into a SystemC
+netlist as an instantiation.
+
+The SC_MODULE gets the same pinout as the Verilog module, with the
+following type conversions: Pins of a single bit become bool.  Pins 2-32
+bits wide become uint32_t's.  Pins 33-64 bits wide become sc_bv's or
+vluint64_t's depending on the :vlopt:`--no-pins64` option.  Wider pins
+become sc_bv's.  (Uints simulate the fastest so are used where possible.)
+
+Model internals, including lower level sub-modules are not pure SystemC
+code.  This is a feature, as using the SystemC pin interconnect scheme
+everywhere would reduce performance by an order of magnitude.
+
+
+Direct Programming Interface (DPI)
+==================================
+
+Verilator supports SystemVerilog Direct Programming Interface import and
+export statements.  Only the SystemVerilog form ("DPI-C") is supported, not
+the original Synopsys-only DPI.
+
+DPI Example
+-----------
+
+In the SYSTEMC example above, if you wanted to import C++ functions into
+Verilog, put in our.v:
+
+.. code-block::
+
+    import "DPI-C" function int add (input int a, input int b);
+
+    initial begin
+       $display("%x + %x = %x", 1, 2, add(1,2));
+    endtask
+
+Then after Verilating, Verilator will create a file Vour__Dpi.h with the
+prototype to call this function:
+
+.. code-block:: C++
+
+     extern int add(int a, int b);
+
+From the sc_main.cpp file (or another .cpp file passed to the Verilator
+command line, or the link), you'd then:
+
+.. code-block:: C++
+
+     #include "svdpi.h"
+     #include "Vour__Dpi.h"
+     int add(int a, int b) { return a+b; }
+
+
+DPI System Task/Functions
+-------------------------
+
+Verilator extends the DPI format to allow using the same scheme to
+efficiently add system functions.  Simply use a dollar-sign prefixed system
+function name for the import, but note it must be escaped.
+
+.. code-block:: sv
+
+    export "DPI-C" function integer \$myRand;
+
+    initial $display("myRand=%d", $myRand());
+
+Going the other direction, you can export Verilog tasks so they can be
+called from C++:
+
+.. code-block:: sv
+
+    export "DPI-C" task publicSetBool;
+
+    task publicSetBool;
+       input bit in_bool;
+       var_bool = in_bool;
+    endtask
+
+Then after Verilating, Verilator will create a file Vour__Dpi.h with the
+prototype to call this function:
+
+.. code-block:: C++
+
+     extern void publicSetBool(svBit in_bool);
+
+From the sc_main.cpp file, you'd then:
+
+.. code-block:: C++
+
+     #include "Vour__Dpi.h"
+     publicSetBool(value);
+
+Or, alternatively, call the function under the design class.  This isn't
+DPI compatible but is easier to read and better supports multiple designs.
+
+.. code-block:: C++
+
+     #include "Vour__Dpi.h"
+     Vour::publicSetBool(value);
+     // or top->publicSetBool(value);
+
+Note that if the DPI task or function accesses any register or net within
+the RTL, it will require a scope to be set. This can be done using the
+standard functions within svdpi.h, after the module is instantiated, but
+before the task(s) and/or function(s) are called.
+
+For example, if the top level module is instantiated with the name "dut"
+and the name references within tasks are all hierarchical (dotted) names
+with respect to that top level module, then the scope could be set with
+
+.. code-block:: C++
+
+     #include "svdpi.h"
+     ...
+     svSetScope(svGetScopeFromName("TOP.dut"));
+
+(Remember that Verilator adds a "TOP" to the top of the module hierarchy.)
+
+Scope can also be set from within a DPI imported C function that has been
+called from Verilog by querying the scope of that function. See the
+sections on DPI Context Functions and DPI Header Isolation below and the
+comments within the svdpi.h header for more information.
+
+
+DPI Imports that access signals
+-------------------------------
+
+If a DPI import accesses a signal through the VPI Verilator will not be
+able to know what variables are accessed and may schedule the code
+inappropriately.  Ideally pass the values as inputs/outputs so the VPI is
+not required.  Alternatively a workaround is to use a non-inlined task as a
+wrapper:
+
+.. code-block::
+
+     logic din;
+
+     // This DPI function will read "din"
+     import "DPI-C" context function void dpi_that_accesses_din();
+
+     always @(...)
+        dpi_din_args(din);
+
+     task dpi_din_args(input din);
+        /* verilator no_inline_task */
+        dpi_that_accesses_din();
+     endtask
+
+
+DPI Display Functions
+---------------------
+
+Verilator allows writing $display like functions using this syntax:
+
+.. code-block::
+
+    import "DPI-C" function void
+          \$my_display(input string formatted /*verilator sformat*/ );
+
+The :option:`/*verilator&32;sformat*/` metacomment indicates that this
+function accepts a $display like format specifier followed by any number of
+arguments to satisfy the format.
+
+
+DPI Context Functions
+---------------------
+
+Verilator supports IEEE DPI Context Functions.  Context imports pass the
+simulator context, including calling scope name, and filename and line
+number to the C code.  For example, in Verilog:
+
+.. code-block::
+
+    import "DPI-C" context function int dpic_line();
+    initial $display("This is line %d, again, line %d\n", `line, dpic_line());
+
+This will call C++ code which may then use the svGet\* functions to read
+information, in this case the line number of the Verilog statement that
+invoked the dpic_line function:
+
+.. code-block:: C++
+
+    int dpic_line() {
+        // Get a scope:  svScope scope = svGetScope();
+
+        const char* scopenamep = svGetNameFromScope(scope);
+        assert(scopenamep);
+
+        const char* filenamep = "";
+        int lineno = 0;
+        if (svGetCallerInfo(&filenamep, &lineno)) {
+            printf("dpic_line called from scope %s on line %d\n",
+               scopenamep, lineno);
+            return lineno;
+        } else {
+            return 0;
+        }
+    }
+
+See the IEEE Standard for more information.
+
+
+DPI Header Isolation
+--------------------
+
+Verilator places the IEEE standard header files such as svdpi.h into a
+separate include directory, vltstd (VeriLaTor STandarD).  When compiling
+most applications $VERILATOR_ROOT/include/vltstd would be in the include
+path along with the normal $VERILATOR_ROOT/include.  However, when
+compiling Verilated models into other simulators which have their own
+svdpi.h and similar standard files with different contents, the vltstd
+directory should not be included to prevent picking up incompatible
+definitions.
+
+
+Public Functions
+----------------
+
+Instead of DPI exporting, there's also Verilator public functions, which
+are slightly faster, but less compatible.
+
+
+Verification Procedural Interface (VPI)
+=======================================
+
+Verilator supports a limited subset of the VPI.  This subset allows
+inspection, examination, value change callbacks, and depositing of values
+to public signals only.
+
+VPI is enabled with the Verilator :vlopt:`--vpi` option.
+
+To access signals via the VPI, Verilator must be told exactly which signals
+are to be accessed.  This is done using the Verilator public pragmas
+documented below.
+
+Verilator has an important difference from an event based simulator; signal
+values that are changed by the VPI will not immediately propagate their
+values, instead the top level header file's :code:`eval()` method must be
+called.  Normally this would be part of the normal evaluation (i.e. the
+next clock edge), not as part of the value change.  This makes the
+performance of VPI routines extremely fast compared to event based
+simulators, but can confuse some test-benches that expect immediate
+propagation.
+
+Note the VPI by its specified implementation will always be much slower
+than accessing the Verilator values by direct reference
+(structure->module->signame), as the VPI accessors perform lookup in
+functions at simulation runtime requiring at best hundreds of instructions,
+while the direct references are evaluated by the compiler and result in
+only a couple of instructions.
+
+For signal callbacks to work the main loop of the program must call
+:code:`VerilatedVpi::callValueCbs()`.
+
+
+.. _VPI Example:
+
+VPI Example
+-----------
+
+In the below example, we have readme marked read-only, and writeme which if
+written from outside the model will have the same semantics as if it
+changed on the specified clock edge.
+
+.. code-block:: bash
+
+     cat >our.v <<'EOF'
+       module our (input clk);
+          reg readme   /*verilator public_flat_rd*/;
+          reg writeme  /*verilator public_flat_rw @(posedge clk) */;
+          initial $finish;
+       endmodule
+     EOF
+
+There are many online tutorials and books on the VPI, but an example that
+accesses the above signal "readme" would be:
+
+.. code-block:: bash
+
+     cat >sim_main.cpp <<'<<EOF'
+       #include "Vour.h"
+       #include "verilated.h"
+       #include "verilated_vpi.h"  // Required to get definitions
+
+       vluint64_t main_time = 0;   // See comments in first example
+       double sc_time_stamp() { return main_time; }
+
+       void read_and_check() {
+           vpiHandle vh1 = vpi_handle_by_name((PLI_BYTE8*)"TOP.our.readme", NULL);
+           if (!vh1) vl_fatal(__FILE__, __LINE__, "sim_main", "No handle found");
+           const char* name = vpi_get_str(vpiName, vh1);
+           printf("Module name: %s\n", name);  // Prints "readme"
+
+           s_vpi_value v;
+           v.format = vpiIntVal;
+           vpi_get_value(vh1, &v);
+           printf("Value of v: %d\n", v.value.integer);  // Prints "readme"
+       }
+
+       int main(int argc, char** argv, char** env) {
+           Verilated::commandArgs(argc, argv);
+           Vour* top = new Vour;
+           Verilated::internalsDump();  // See scopes to help debug
+           while (!Verilated::gotFinish()) {
+               top->eval();
+               VerilatedVpi::callValueCbs();  // For signal callbacks
+               read_and_check();
+           }
+           delete top;
+           return 0;
+       }
+     EOF
+
+
+.. _Evaluation Loop:
+
+Wrappers and Model Evaluation Loop
+==================================
+
+When using SystemC, evaluation of the Verilated model is managed by the
+SystemC kernel, and for the most part can be ignored.  When using C++, the
+user must call :code:`eval()`, or :code:`eval_step()` and
+:code:`eval_end_step()`.
+
+1. When there is a single design instantiated at the C++ level that needs
+to evaluate within a given context, call :code:`designp->eval()`.
+
+2. When there are multiple designs instantiated at the C++ level that need
+to evaluate within a context, call :code:`first_designp->eval_step()` then
+:code:`->eval_step()` on all other designs.  Then call
+:code:`->eval_end_step()` on the first design then all other designs.  If
+there is only a single design, you would call :code:`eval_step()` then
+:code:`eval_end_step()`; in fact :code:`eval()` described above is just a
+wrapper which calls these two functions.
+
+When :code:`eval()` (or :code:`eval_step()`) is called Verilator looks for
+changes in clock signals and evaluates related sequential always blocks,
+such as computing always_ff @ (posedge...) outputs.  Then Verilator
+evaluates combinatorial logic.
+
+Note combinatorial logic is not computed before sequential always blocks
+are computed (for speed reasons). Therefore it is best to set any non-clock
+inputs up with a separate :code:`eval()` call before changing clocks.
+
+Alternatively, if all always_ff statements use only the posedge of clocks,
+or all inputs go directly to always_ff statements, as is typical, then you
+can change non-clock inputs on the negative edge of the input clock, which
+will be faster as there will be fewer :code:`eval()` calls.
+
+For more information on evaluation, see :file:`docs/internals.rst` in the
+distribution.
+
+
+Verilated and VerilatedContext
+==============================
+
+Multiple Verilated models may be part of the same simulation context, that
+is share a VPI interface, sense of time, and common settings.  This common
+simulation context information is stored in a ``VerilatedContext``
+structure.  If a ``VerilatedContext`` is not created prior to creating a
+model, a default global one is created automatically.
+
+The ``Verilated::`` methods, including the ``Verilated::commandArgs`` call
+shown above, simply call VerilatedContext methods using the default global
+VerilatedContext.  (Technically they operate on the last one used by a
+given thread.)  If you are using multiple simulation contexts you should
+not use the Verilated:: methods, and instead always use VerilatedContext
+methods called on the appropriate VerilatedContext object.
+
+For methods available under Verilated and VerilatedContext see
+:file:`include/verilated.h` in the distribution.

docs/guide/contributing.rst

@@ -0,0 +1,68 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+*******************************
+Contributing and Reporting Bugs
+*******************************
+
+Announcements
+=============
+
+To get notified of new releases and other important announcements, go to
+`Verilator announcement repository
+<https://github.com/verilator/verilator-announce>`__ and follow the
+instructions there.
+
+
+Reporting Bugs
+==============
+
+First, check the :ref:`Language Limitations` section.
+
+Next, try the :vlopt:`--debug` option.  This will enable additional
+internal assertions, and may help identify the problem.
+
+Finally, reduce your code to the smallest possible routine that exhibits
+the bug.  Even better, create a test in the :file:`test_regress/t`
+directory, as follows:
+
+.. code-block:: bash
+
+       cd test_regress
+       cp -p t/t_EXAMPLE.pl t/t_BUG.pl
+       cp -p t/t_EXAMPLE.v t/t_BUG.v
+
+There are many hints on how to write a good test in the
+:file:`test_regress/driver.pl` documentation which can be seen by running:
+
+.. code-block:: bash
+
+       cd $VERILATOR_ROOT  # Need the original distribution kit
+       test_regress/driver.pl --help
+
+Edit :file:`t/t_BUG.pl` to suit your example; you can do anything you want
+in the Verilog code there; just make sure it retains the single clk input
+and no outputs.  Now, the following should fail:
+
+.. code-block:: bash
+
+       cd $VERILATOR_ROOT  # Need the original distribution kit
+       cd test_regress
+       t/t_BUG.pl  # Run on Verilator
+       t/t_BUG.pl --debug # Run on Verilator, passing --debug to Verilator
+       t/t_BUG.pl --vcs  # Run on VCS simulator
+       t/t_BUG.pl --nc|--iv|--ghdl  # Likewise on other simulators
+
+The test driver accepts a number of options, many of which mirror the main
+Verilator options. For example the previous test could have been run with
+debugging enabled.  The full set of test options can be seen by running
+:command:`driver.pl --help` as shown above.
+
+Finally, report the bug at `Verilator Issues
+<https://verilator.org/issues>`_.  The bug will become publicly visible; if
+this is unacceptable, mail the bug report to ``[email protected]``.
+
+
+.. Contributing
+.. ============
+.. include:: ../CONTRIBUTING.rst

docs/guide/contributors.rst

@@ -0,0 +1,155 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+************************
+Contributors and Origins
+************************
+
+Authors
+=======
+
+When possible, please instead report bugs at `Verilator Issues
+<https://verilator.org/issues>`_.
+
+Primary author is Wilson Snyder <[email protected]>.
+
+Major concepts by Paul Wasson, Duane Galbi, John Coiner and Jie Xu.
+
+
+Contributors
+============
+
+Many people have provided ideas and other assistance with Verilator.
+
+Verilator is receiving major development support from the `CHIPS Alliance
+<https://chipsalliance.org>`_.
+
+Previous major corporate sponsors of Verilator, by providing significant
+contributions of time or funds included include: Atmel Corporation, Cavium
+Inc., Compaq Corporation, Digital Equipment Corporation, Embecosm Ltd.,
+Hicamp Systems, Intel Corporation, Mindspeed Technologies Inc., MicroTune
+Inc., picoChip Designs Ltd., Sun Microsystems Inc., Nauticus Networks Inc.,
+and SiCortex Inc.
+
+The people who have contributed major functionality are: Byron Bradley,
+Jeremy Bennett, Lane Brooks, John Coiner, Duane Galbi, Geza Lore, Todd
+Strader, Stefan Wallentowitz, Paul Wasson, Jie Xu, and Wilson Snyder.
+Major testers included Jeff Dutton, Jonathon Donaldson, Ralf Karge, David
+Hewson, Iztok Jeras, Wim Michiels, Alex Solomatnikov, Sebastien Van
+Cauwenberghe, Gene Weber, and Clifford Wolf.
+
+Some of the people who have provided ideas, and feedback for Verilator
+include: David Addison, Nikana Anastasiadis, Vasu Arasanipalai, Jens Arm,
+Tariq B. Ahmad, Sharad Bagri, Matthew Ballance, Andrew Bardsley, Matthew
+Barr, Geoff Barrett, Kaleb Barrett, Julius Baxter, Jeremy Bennett, Michael
+Berman, Jean Berniolles, Victor Besyakov, Moinak Bhattacharyya, Krzysztof
+Bieganski, David Binderman, Piotr Binkowski, Johan Bjork, David Black,
+Tymoteusz Blazejczyk, Daniel Bone, Morten Borup Petersen, Gregg Bouchard,
+Christopher Boumenot, Nick Bowler, Byron Bradley, Bryan Brady, Charlie
+Brej, J Briquet, Lane Brooks, John Brownlee, Jeff Bush, Lawrence Butcher,
+Tony Bybell, Iru Cai, Ted Campbell, Chris Candler, Lauren Carlson, Donal
+Casey, Alex Chadwick, Terry Chen, Yi-Chung Chen, Enzo Chi, Robert A. Clark,
+Ryan Clarke, Allan Cochrane, John Coiner, Gianfranco Costamagna, Sean
+Cross, George Cuan, Joe DErrico, Lukasz Dalek, Gunter Dannoritzer, Ashutosh
+Das, Maarten De Braekeleer, Bernard Deadman, Alberto Del Rio, John Demme,
+Mike Denio, John Deroo, Philip Derrick, John Dickol, Ruben Diez, Danny
+Ding, Jacko Dirks, Ivan Djordjevic, Jonathon Donaldson, Sebastian Dressler,
+Alex Duller, Jeff Dutton, Tomas Dzetkulic, Richard E George, Edgar
+E. Iglesias, Usuario Eda, Charles Eddleston, Chandan Egbert, Jan Egil Ruud,
+Joe Eiler, Ahmed El-Mahmoudy, Trevor Elbourne, Mats Engstrom, Charles Eric
+LaForest, Robert Farrell, Eugen Fekete, Fabrizio Ferrandi, Udi Finkelstein,
+Brian Flachs, Andrea Foletto, Bob Fredieu, Duane Galbi, Benjamin Gartner,
+Christian Gelinek, Peter Gerst, Glen Gibb, Michael Gielda, Barbara Gigerl,
+Shankar Giri, Dan Gisselquist, Petr Gladkikh, Sam Gladstone, Andrew
+Goessling, Amir Gonnen, Chitlesh Goorah, Tomasz Gorochowik, Kai Gossner,
+Sergi Granell, Al Grant, Alexander Grobman, Xuan Guo, Driss Hafdi, Neil
+Hamilton, James Hanlon, Oyvind Harboe, Jannis Harder, Junji Hashimoto,
+Thomas Hawkins, Mitch Hayenga, Harald Heckmann, Robert Henry, Stephen
+Henry, David Hewson, Jamey Hicks, Joel Holdsworth, Andrew Holme, Hiroki
+Honda, Alex Hornung, Pierre-Henri Horrein, David Horton, Peter Horvath, Jae
+Hossell, Kuoping Hsu, Alan Hunter, James Hutchinson, Anderson Ignacio da
+Silva, Jamie Iles, Thomas J Whatson, Ben Jackson, Mark Jackson Pulver,
+Shareef Jalloq, Marlon James, Krzysztof Jankowski, HyungKi Jeong, Iztok
+Jeras, James Johnson, Christophe Joly, Franck Jullien, James Jung, Mike
+Kagen, Arthur Kahlich, Kaalia Kahn, Guy-Armand Kamendje, Vasu Kandadi,
+Kanad Kanhere, Patricio Kaplan, Pieter Kapsenberg, Rafal Kapuscik, Ralf
+Karge, Dan Katz, Sol Katzman, Ian Kennedy, Michael Killough, Jonathan
+Kimmitt, Olof Kindgren, Kevin Kiningham, Dan Kirkham, Sobhan Klnv, Gernot
+Koch, Jack Koenig, Soon Koh, Nathan Kohagen, Steve Kolecki, Brett Koonce,
+Will Korteland, Wojciech Koszek, Varun Koyyalagunta, Markus Krause, David
+Kravitz, Roland Kruse, Andreas Kuster, Sergey Kvachonok, Ed Lander, Steve
+Lang, Stephane Laurent, Walter Lavino, Christian Leber, Larry Lee, Igor
+Lesik, John Li, Eivind Liland, Charlie Lind, Andrew Ling, Jiuyang Liu, Paul
+Liu, Derek Lockhart, Jake Longo, Geza Lore, Arthur Low, Stefan Ludwig, Dan
+Lussier, Fred Ma, Duraid Madina, Odd Magne Reitan, Affe Mao, Julien
+Margetts, Mark Marshall, Alfonso Martinez, Unai Martinez-Corral, Yves
+Mathieu, Patrick Maupin, Conor McCullough, Jason McMullan, Elliot Mednick,
+Wim Michiels, Miodrag Milanovic, Peter Monsson, Sean Moore, Dennis
+Muhlestein, John Murphy, Matt Myers, Nathan Myers, Richard Myers, Dimitris
+Nalbantis, Peter Nelson, Bob Newgard, Paul Nitza, Yossi Nivin, Pete Nixon,
+Lisa Noack, Mark Nodine, Kuba Ober, Andreas Olofsson, Baltazar Ortiz,
+Aleksander Osman, Don Owen, James Pallister, Vassilis Papaefstathiou, Brad
+Parker, Dan Petrisko, Maciej Piechotka, David Pierce, Cody Piersall,
+Dominic Plunkett, David Poole, Mike Popoloski, Roman Popov, Rich Porter,
+Niranjan Prabhu, Usha Priyadharshini, Prateek Puri, Marshal Qiao, Nandu
+Raj, Danilo Ramos, Chris Randall, Anton Rapp, Josh Redford, Frederic
+Requin, Dustin Richmond, Samuel Riedel, Eric Rippey, Oleg Rodionov, Ludwig
+Rogiers, Paul Rolfe, Arjen Roodselaar, Tobias Rosenkranz, Huang Rui, Denis
+Rystsov, John Sanguinetti, Galen Seitz, Joseph Shaker, Salman Sheikh, Yu
+Sheng Lin, Hao Shi, Mike Shinkarovsky, Rafael Shirakawa, Jeffrey Short, Fan
+Shupei, Rodney Sinclair, Steven Slatter, Brian Small, Garrett Smith, Tim
+Snyder, Wilson Snyder, Maciej Sobkowski, Stan Sokorac, Alex Solomatnikov,
+Wei Song, Art Stamness, David Stanford, John Stevenson, Pete Stevenson,
+Patrick Stewart, Rob Stoddard, Todd Strader, John Stroebel, Sven Stucki,
+Howard Su, Emerson Suguimoto, Gene Sullivan, Wai Sum Mong, Qingyao Sun,
+Renga Sundararajan, Rupert Swarbrick, Yutetsu Takatsukasa, Thierry Tambe,
+Drew Taussig, Peter Tengstrand, Wesley Terpstra, Rui Terra, Stefan Thiede,
+Gary Thomas, Ian Thompson, Kevin Thompson, Mike Thyer, Hans Tichelaar,
+Viktor Tomov, Steve Tong, Alex Torregrosa, Michael Tresidder, David Turner,
+Neil Turton, Cong Van Nguyen, Hans Van Antwerpen, Jan Van Winkel, Sebastien
+Van Cauwenberghe, Laurens van Dam, Leendert van Doorn, Srini Vemuri, Yuri
+Victorovich, Bogdan Vukobratovic, Holger Waechtler, Philipp Wagner, Stefan
+Wallentowitz, Shawn Wang, Paul Wasson, Greg Waters, Thomas Watts, Eugene
+Weber, David Welch, Martin Whitaker, Marco Widmer, Leon Wildman, Daniel
+Wilkerson, Gerald Williams, Trevor Williams, Jeff Winston, Joshua Wise,
+Clifford Wolf, Tobias Wolfel, Johan Wouters, Paul Wright, Junyi Xi, Ding
+Xiaoliang, Jie Xu, Mandy Xu, Yinan Xu, Luke Yang, Amir Yazdanbakhsh, and
+Keyi Zhang.
+
+Thanks to them, and all those we've missed including above, or wished to
+remain anonymous.
+
+Historical Origins
+==================
+
+Verilator was conceived in 1994 by Paul Wasson at the Core Logic Group at
+Digital Equipment Corporation.  The Verilog code that was converted to C
+was then merged with a C based CPU model of the Alpha processor and
+simulated in a C based environment called CCLI.
+
+In 1995 Verilator started being used also for Multimedia and Network
+Processor development inside Digital.  Duane Galbi took over active
+development of Verilator, and added several performance enhancements.  CCLI
+was still being used as the shell.
+
+In 1998, through the efforts of existing DECies, mainly Duane Galbi,
+Digital graciously agreed to release the source code.  (Subject to the code
+not being resold, which is compatible with the GNU Public License.)
+
+In 2001, Wilson Snyder took the kit, and added a SystemC mode, and called
+it Verilator2.  This was the first packaged public release.
+
+In 2002, Wilson Snyder created Verilator 3.000 by rewriting Verilator from
+scratch in C++.  This added many optimizations, yielding about a 2-5x
+performance gain.
+
+In 2009, major SystemVerilog and DPI language support was added.
+
+In 2018, Verilator 4.000 was released with multithreaded support.
+
+In 2019, Verilator joined the `CHIPS Alliance
+<https://chipsalliance.org>`_.
+
+Currently, various language features and performance enhancements are added
+as the need arises.  Verilator is now about 3x faster than in 2002, and is
+faster than most (if not every) other simulator.

docs/guide/copyright.rst

@@ -0,0 +1,19 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+*********
+Copyright
+*********
+
+The latest version of Verilator is available from `https://verilator.org
+<https://verilator.org>`_.
+
+Copyright 2003-2021 by Wilson Snyder. This program is free software; you
+can redistribute it and/or modify the Verilator internals under the terms
+of either the GNU Lesser General Public License Version 3 or the Perl
+Artistic License Version 2.0.
+
+All Verilog and C++/SystemC code quoted within this documentation file are
+released as Creative Commons Public Domain (CC0).  Many example files and
+test files are likewise released under CC0 into effectively the Public
+Domain as described in the files themselves.

docs/guide/deprecations.rst

@@ -0,0 +1,20 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+Deprecations
+============
+
+The following deprecated items are scheduled for future removal:
+
+C++11 compiler support
+  Verilator currently requires C++11 or newer compilers.  Verilator will
+  require C++14 or newer compilers for both compiling Verilator and
+  compiling Verilated models no sooner than January 2022.
+
+Configuration File -msg
+  The :vlopt:`lint_off` "-msg" option has been replaced with the "-rule"
+  option.  "-msg" is planned for removal no sooner than January 2021.
+
+XML locations
+  The XML "fl" attribute has been replaced with the "loc" attribute.  "fl"
+  is planned for removal no sooner than January 2021.

docs/guide/environment.rst

@@ -0,0 +1,93 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+Environment
+===========
+
+This section describes the environment variables used by Verilator and
+associated programs.
+
+.. option:: LD_LIBRARY_PATH
+
+   A generic Linux/OS variable specifying what directories have shared
+   object (.so) files.  This path should include SystemC and any other
+   shared objects needed at simulation runtime.
+
+.. option:: MAKE
+
+   Names the executable of the make command invoked when using the
+   :vlopt:`--build` option.  Some operating systems may require "gmake" to
+   this variable to launch GNU make.  If this variable is not specified,
+   "make" is used.
+
+.. option:: OBJCACHE
+
+   Optionally specifies a caching or distribution program to place in front
+   of all runs of the C++ compiler.  For example, "ccache".  If using
+   :command:`distcc` or :command:`icecc`/:command:`icecream`, they would
+   generally be run under :command:`ccache`; see the documentation for
+   those programs.  If OBJCACHE is not set, and at configure time ccache
+   was present, ccache will be used as a default.
+
+.. option:: SYSTEMC
+
+   Deprecated.  Used only if :option:`SYSTEMC_INCLUDE` or
+   :option:`SYSTEMC_LIBDIR` is not set.  If set, specifies the directory
+   containing the SystemC distribution.  If not specified, it will come
+   from a default optionally specified at configure time (before Verilator
+   was compiled).
+
+.. option:: SYSTEMC_ARCH
+
+   Deprecated.  Used only if :option:`SYSTEMC_LIBDIR` is not set.
+   Specifies the architecture name used by the SystemC kit.  This is the
+   part after the dash in the "lib-{...}" directory name created by a
+   :command:`make` in the SystemC distribution.  If not set, Verilator will
+   try to intuit the proper setting, or use the default optionally
+   specified at configure time (before Verilator was compiled).
+
+.. option:: SYSTEMC_CXX_FLAGS
+
+   Specifies additional flags that are required to be passed to GCC when
+   building the SystemC model.  System 2.3.0 may need this set to
+   "-pthread".
+
+.. option:: SYSTEMC_INCLUDE
+
+   If set, specifies the directory containing the systemc.h header file. If
+   not specified, it will come from a default optionally specified at
+   configure time (before Verilator was compiled), or computed from
+   SYSTEMC/include.
+
+.. option:: SYSTEMC_LIBDIR
+
+   If set, specifies the directory containing the libsystemc.a library. If
+   not specified, it will come from a default optionally specified at
+   configure time (before Verilator was compiled), or computed from
+   SYSTEMC/lib-SYSTEMC_ARCH.
+
+.. option:: VERILATOR_BIN
+
+   If set, specifies an alternative name of the ``verilator`` binary.  May
+   be used for debugging and selecting between multiple operating system
+   builds.
+
+.. option:: VERILATOR_COVERAGE_BIN
+
+   If set, specifies an alternative name of the ``verilator_coverage``
+   binary.  May be used for debugging and selecting between multiple
+   operating system builds.
+
+.. option:: VERILATOR_GDB
+
+   If set, the command to run when using the :vlopt:`--gdb` option, such as
+   "ddd".  If not specified, it will use "gdb".
+
+.. option:: VERILATOR_ROOT
+
+   Specifies the directory containing the distribution kit.  This is used
+   to find the executable, Perl library, and include files.  If not
+   specified, it will come from a default optionally specified at configure
+   time (before Verilator was compiled).  It should not be specified if
+   using a pre-compiled Verilator package as the hard-coded value should be
+   correct.  See :ref:`Installation`.

docs/guide/example_cc.rst

@@ -0,0 +1,92 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+.. _Example C++ Execution:
+
+Example C++ Execution
+=====================
+
+We'll compile this example into C++.  For an extended and commented version
+of what this C++ code is doing, see
+:file:`examples/make_tracing_c/sim_main.cpp` in the distribution.
+
+.. include:: example_common_install.rst
+
+Now, let's create an example Verilog, and C++ wrapper file:
+
+.. code-block:: bash
+
+     mkdir test_our
+     cd test_our
+
+     cat >our.v <<'EOF'
+       module our;
+          initial begin $display("Hello World"); $finish; end
+       endmodule
+     EOF
+
+     cat >sim_main.cpp <<'EOF'
+       #include "Vour.h"
+       #include "verilated.h"
+       int main(int argc, char** argv, char** env) {
+           VerilatedContext* contextp = new VerilatedContext;
+           contextp->commandArgs(argc, argv);
+           Vour* top = new Vour{contextp};
+           while (!contextp->gotFinish()) { top->eval(); }
+           delete top;
+           delete contextp;
+           return 0;
+       }
+     EOF
+
+Now we run Verilator on our little example.
+
+.. code-block:: bash
+
+     verilator -Wall --cc --exe --build sim_main.cpp our.v
+
+Breaking this command down:
+
+#. :vlopt:`-Wall` so Verilator has stronger lint warnings
+   enabled.
+
+#. :vlopt:`--cc` to get C++ output (versus e.g. SystemC
+   or only linting).
+
+#. :vlopt:`--exe`, along with our :command:`sim_main.cpp` wrapper file, so
+   the build will create an executable instead of only a library.
+
+#. :vlopt:`--build` so Verilator will call make itself. This is we don't
+   need to manually call make as a separate step. You can also write your
+   own compile rules, and run make yourself as we show in :ref:`Example
+   SystemC Execution`.)
+
+#. An finally, :command:`our.v` which is our SystemVerilog design file.
+
+Once Verilator completes we can see the generated C++ code under the
+:file:`obj_dir` directory.
+
+.. code-block:: bash
+
+     ls -l obj_dir
+
+(See :ref:`Files Read/Written` for descriptions of some of the files that
+were created.)
+
+And now we run it:
+
+.. code-block:: bash
+
+     obj_dir/Vour
+
+And we get as output:
+
+.. code-block:: bash
+
+     Hello World
+     - our.v:2: Verilog $finish
+
+Really, you're better off using a Makefile to run the steps for you so when
+your source changes it will automatically run all of the appropriate steps.
+To aid this Verilator can create a makefile dependency file.  For examples
+that do this see the :file:`examples` directory in the distribution.

docs/guide/example_common_install.rst

@@ -0,0 +1,16 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+First you need Verilator installed, see :ref:`Installation`. In brief, if
+you installed Verilator using the package manager of your operating system,
+or did a :command:`make install` to place Verilator into your default path,
+you do not need anything special in your environment, and should not have
+VERILATOR_ROOT set.  However, if you installed Verilator from sources and
+want to run Verilator out of where you compiled Verilator, you need to
+point to the kit:
+
+.. code-block:: bash
+
+     # See above; don't do this if using an OS-distributed Verilator
+     export VERILATOR_ROOT=/path/to/where/verilator/was/installed
+     export PATH=$VERILATOR_ROOT/bin:$PATH

docs/guide/example_dist.rst

@@ -0,0 +1,40 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+.. _Examples in the Distribution:
+
+Examples in the Distribution
+============================
+
+See the ``examples/`` directory that is part of the distribution, and
+is installed (in a OS-specific place, often in e.g.
+``/usr/local/share/verilator/examples``).  These examples include:
+
+examples/make_hello_c
+   Example GNU-make simple Verilog->C++ conversion
+examples/make_hello_sc
+   Example GNU-make simple Verilog->SystemC conversion
+examples/make_tracing_c
+   Example GNU-make Verilog->C++ with tracing
+examples/make_tracing_sc
+   Example GNU-make Verilog->SystemC with tracing
+examples/make_protect_lib
+   Example using --protect-lib
+examples/cmake_hello_c
+   Example building make_hello_c with CMake
+examples/cmake_hello_sc
+   Example building make_hello_sc with CMake
+examples/cmake_tracing_c
+   Example building make_tracing_c with CMake
+examples/cmake_tracing_sc
+   Example building make_tracing_sc with CMake
+examples/cmake_protect_lib
+   Example building make_protect_lib with CMake
+
+To run an example copy the example to a new directory and run it.
+
+::
+
+      cp -rp {path_to}/examples/make_hello_c make_hello_c
+      cd make_hello_c
+      make

docs/guide/example_sc.rst

@@ -0,0 +1,73 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+.. _Example SystemC Execution:
+
+Example SystemC Execution
+=========================
+
+This is an example similar to the :ref:`Example C++ Execution`, but using
+SystemC. We'll also explicitly run make.
+
+.. include:: example_common_install.rst
+
+Now, let's create an example Verilog, and SystemC wrapper file:
+
+.. code-block:: bash
+
+     mkdir test_our_sc
+     cd test_our_sc
+
+     cat >our.v <<'EOF'
+       module our (clk);
+          input clk;  // Clock is required to get initial activation
+          always @(posedge clk)
+             begin $display("Hello World"); $finish; end
+       endmodule
+     EOF
+
+     cat >sc_main.cpp <<'EOF'
+       #include "Vour.h"
+       int sc_main(int argc, char** argv) {
+           Verilated::commandArgs(argc, argv);
+           sc_clock clk{"clk", 10, SC_NS, 0.5, 3, SC_NS, true};
+           Vour* top = new Vour{"top"};
+           top->clk(clk);
+           while (!Verilated::gotFinish()) { sc_start(1, SC_NS); }
+           delete top;
+           return 0;
+       }
+     EOF
+
+Now we run Verilator on our little example:
+
+.. code-block:: bash
+
+     verilator -Wall --sc --exe sc_main.cpp our.v
+
+This example does not use --build, therefore we need to explicitly compile
+it:
+
+.. code-block:: bash
+
+     make -j -C obj_dir -f Vour.mk Vour
+
+And now we run it:
+
+.. code-block:: bash
+
+     obj_dir/Vour
+
+And we get, after the SystemC banner, the same output as the C++ example:
+
+.. code-block:: bash
+
+     SystemC 2.3.3-Accellera
+
+     Hello World
+     - our.v:4: Verilog $finish
+
+Really, you're better off using a Makefile to run the steps for you so when
+your source changes it will automatically run all of the appropriate steps.
+For examples that do this see the :file:`examples` directory in the
+distribution.

docs/guide/examples.rst

@@ -0,0 +1,22 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+.. _Examples:
+
+========
+Examples
+========
+
+This section covers the following examples:
+
+* :ref:`Example C++ Execution`
+* :ref:`Example SystemC Execution`
+* :ref:`Examples in the Distribution`
+
+.. toctree::
+   :maxdepth: 1
+   :hidden:
+
+   example_cc.rst
+   example_sc.rst
+   example_dist.rst

docs/guide/exe_sim.rst

@@ -0,0 +1,89 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+.. _Simulation Runtime Arguments:
+
+Simulation Runtime Arguments
+============================
+
+The following are the arguments that may be passed to a Verilated
+executable, provided that executable calls
+:code:`Verilated::commandArgs()`.
+
+All simulation runtime arguments begin with "+verilator", so that the
+user's executable may skip over all "+verilator" arguments when parsing its
+command line.
+
+Summary:
+
+   .. include:: ../_build/gen/args_verilated.rst
+
+
+.. option:: +verilator+debug
+
+   Enable simulation runtime debugging.  Equivalent to
+   :vlopt:`+verilator+debugi+4 <+verilator+debugi+\<value\>>`.
+
+.. option:: +verilator+debugi+<value>
+
+   Enable simulation runtime debugging at the provided level.
+
+.. option:: +verilator+error+limit+<value>
+
+   Set number of non-fatal errors (e.g. assertion failures) before exiting
+   simulation runtime. Also affects number of $stop calls needed before
+   exit. Defaults to 1.
+
+.. option:: +verilator+help
+
+   Display help and exit.
+
+.. option:: +verilator+prof+threads+file+<filename>
+
+   When a model was Verilated using :vlopt:`--prof-threads`, sets the
+   simulation runtime filename to dump to.  Defaults to
+   :file:`profile_threads.dat`.
+
+.. option:: +verilator+prof+threads+start+<value>
+
+   When a model was Verilated using :vlopt:`--prof-threads`, the simulation
+   runtime will wait until $time is at this value (expressed in units of
+   the time precision), then start the profiling warmup, then
+   capturing. Generally this should be set to some time that is well within
+   the normal operation of the simulation, i.e. outside of reset. If 0, the
+   dump is disabled. Defaults to 1.
+
+.. option:: +verilator+prof+threads+window+<value>
+
+   When a model was Verilated using :vlopt:`--prof-threads`, after $time
+   reaches :vlopt:`+verilator+prof+threads+start+\<value\>`, Verilator will
+   warm up the profiling for this number of eval() calls, then will capture
+   the profiling of this number of eval() calls.  Defaults to 2, which
+   makes sense for a single-clock-domain module where it's typical to want
+   to capture one posedge eval() and one negedge eval().
+
+.. option:: +verilator+rand+reset+<value>
+
+   When a model was Verilated using :vlopt:`--x-initial unique
+   <--x-initial>`, sets the simulation runtime initialization technique.  0
+   = Reset to zeros. 1 = Reset to all-ones.  2 = Randomize.  See
+   :ref:`Unknown States`.
+
+.. option:: +verilator+seed+<value>
+
+   For $random and :vlopt:`--x-initial unique <--x-initial>`, set the
+   simulation runtime random seed value.  If zero or not specified picks a
+   value from the system random number generator.
+
+.. option:: +verilator+noassert
+
+   Disable assert checking per runtime argument. This is the same as
+   calling :code:`Verilated::assertOn(false)` in the model.
+
+.. option:: +verilator+V
+
+   Shows the verbose version, including configuration information.
+
+.. option:: +verilator+version
+
+   Displays program version and exits.

docs/guide/exe_verilator_coverage.rst

@@ -0,0 +1,114 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+verilator_coverage
+==================
+
+Verilator_coverage processes Verilated model-generated coverage reports.
+
+With --annotate, it reads the specified coverage data file and generates
+annotated source code with coverage metrics annotated.  If multiple
+coverage points exist on the same source code line, additional lines will
+be inserted to report the additional points.
+
+Additional Verilog-XL-style standard arguments specify the search paths
+necessary to find the source code that the coverage analysis was performed
+on.
+
+To filter those items to be included in coverage, you may read
+logs/coverage.dat into an editor and do a M-x keep-lines to include only
+those statistics of interest and save to a new .dat file.
+
+For Verilog conditions that should never occur, either add a $stop
+statement to the appropriate statement block, or see
+:option:`/*verilator&32;coverage_off*/`.  This will remove the coverage
+points after the model is re-Verilated.
+
+For an overview of use of verilator_coverage, see :ref:`Coverage Analysis`.
+
+
+verilator_coverage Example Usage
+--------------------------------
+
+..
+
+    verilator_coverage --help
+    verilator_coverage --version
+
+    verilator_coverage --annotate <obj>
+
+    verilator_coverage  -write merged.dat -read <datafiles>...
+
+    verilator_coverage  -write-info merged.info -read <datafiles>...
+
+
+verilator_coverage Arguments
+----------------------------
+
+.. program:: verilator_coverage
+
+.. option:: <filename>
+
+Specifies the input coverage data file.  Multiple filenames may be provided
+to read multiple inputs.  If no data file is specified, by default
+"coverage.dat" will be read.
+
+.. option:: --annotate <output_directory>
+
+Specifies the directory name that source files with annotated coverage data
+should be written to.
+
+.. option:: --annotate-all
+
+Specifies all files should be shown.  By default, only those source files
+which have low coverage are written to the output directory.
+
+.. option:: --annotate-min <count>
+
+Specifies if the coverage point does not include the count number of
+coverage hits, then the coverage point will be considered above the
+threashold, and the coverage report will put a "%" to indicate the coverage
+is not sufficient.  Defaults to 10.
+
+.. option:: --help
+
+Displays a help summary, the program version, and exits.
+
+.. option:: --rank
+
+Prints an experimental report listing the relative importance of each test
+in covering all of the coverage points.  The report shows "Covered" which
+indicates the number of points that test covers; a test is considered to
+cover a point if it has a bucket count of at least 1. The "rank" column has
+a higher number t indicate the test is more important, and rank 0 means the
+test does not need to be run to cover the points.  "RankPts" indicates the
+number of coverage points this test will contribute to overall coverage if
+all tests are run in the order of highest to lowest rank.
+
+.. option:: --unlink
+
+With :option:`--write`, unlink all input files after the output
+has been successfully created.
+
+.. option:: --version
+
+Displays program version and exits.
+
+.. option:: --write <filename>
+
+Specifies the aggregate coverage results, summed across all the files,
+should be written to the given filename in verilator_coverage data format.
+This is useful for use in scripts to combine many coverage data files
+(likely generated from random test runs) into one master coverage file.
+
+.. option:: --write-info <filename.info>
+
+Specifies the aggregate coverage results, summed across all the files,
+should be written to the given filename in :command:`lcov` .info format.
+This may be used to feed into :command:`lcov` to aggregate or generate
+reports.
+
+The info format loses data compared to the Verilator coverage data format;
+the info will all forms of coverage converted to line style coverage, and
+if there are multiple coverage points on a single line, the minimum
+coverage across those points will be used to report coverage of the line.

docs/guide/exe_verilator_gantt.rst

@@ -0,0 +1,76 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+verilator_gantt
+===============
+
+Verilator_gantt creates a visual representation to help analyze Verilator
+multithreaded simulation performance, by showing when each macro-task
+starts and ends, and showing when each thread is busy or idle.
+
+For an overview of use of verilator_gantt, see :ref:`Profiling`.
+
+Gantt Chart Contents
+--------------------
+
+The generated Gantt chart has time on the X-axis. Times shown are to the
+scale printed, i.e. a certain about of time for each character width.  The
+Y-axis shows threads, each thread's execution is shown on one line.  That
+line shows "[" at the position in time when it executes.
+
+Following the "[" is the CPU number the task executed on, followed by zero
+or more "-" to make the width of the characters match the scaled execution
+time, followed by a "]".  If the scale is too small, the CPU number and
+mtask number will not be printed.  If the scale is very small, a "&"
+indicates multiple mtasks started at that time position.
+
+Also creates a value change dump (VCD) format dump file which may be viewed
+in a waveform viewer (e.g. C<GTKWave>).  See below.
+
+Gantt Chart VCD Signals
+-----------------------
+
+In waveforms there are the following signals. Most signals the "decimal"
+format will remove the leading zeros and make the traces easier to read.
+
+parallelism
+  The number of mtasks active at this time, for best performance this will
+  match the thread count. You may want to use an "analog step" format to
+  view this signal.
+
+cpu#_thread
+  For the given CPU number, the thread number executing.
+
+mtask#_cpu
+  For the given mtask id, the CPU it is executing on.
+
+thread#_mtask
+  For the given thread number, the mtask id executing.
+
+verilator_gantt Arguments
+-------------------------
+
+.. program:: verilator_gantt
+
+.. option:: <filename>
+
+The filename to read data from, defaults to "profile_threads.dat".
+
+.. option:: --help
+
+Displays a help summary, the program version, and exits.
+
+.. option:: --scale <n>
+
+Sets the number of time units per character on the X-axis of the generated
+Gantt chart.  (On x86, time units are rdtsc ticks.)  Defaults to 0, which
+will automatically compute a reasonable scale where no two mtasks need to
+fit into same character width's worth of scaled time.
+
+.. option:: --no-vcd
+
+Disables creating a .vcd file.
+
+.. option:: --vcd <filename>
+
+Sets the output filename for vcd dump. Default is "verilator_gantt.vcd".

docs/guide/exe_verilator_profcfuncs.rst

@@ -0,0 +1,25 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+verilator_profcfuncs
+====================
+
+Verilator_profcfunc reads a profile report created by gprof.  The names of
+the functions are then transformed, assuming the user used Verilator's
+--prof-cfuncs, and a report printed showing the percentage of time, etc, in
+each Verilog block.
+
+For an overview of use of verilator_profcfuncs, see :ref:`Profiling`.
+
+verilator_profcfuncs Arguments
+------------------------------
+
+.. program:: verilator_profcfuncs
+
+.. option:: <filename>
+
+The :command:`gprof`-generated filename to read data from. Typically "gprof.out".
+
+.. option:: --help
+
+Displays a help summary, the program version, and exits.

docs/guide/executables.rst

@@ -0,0 +1,19 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+*********************************
+Executable and Argument Reference
+*********************************
+
+This section describes the executables that are part of Verilator, and the
+options to each executable.
+
+.. toctree::
+   :maxdepth: 1
+   :hidden:
+
+   exe_verilator.rst
+   exe_verilator_coverage.rst
+   exe_verilator_gantt.rst
+   exe_verilator_profcfuncs.rst
+   exe_sim.rst

docs/guide/extensions.rst

@@ -0,0 +1,495 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+*******************
+Language Extensions
+*******************
+
+The following additional constructs are the extensions Verilator supports
+on top of standard Verilog code.  Using these features outside of comments
+or "`ifdef`"'s may break other tools.
+
+.. option:: `__FILE__
+
+   The :option:`\`__FILE__` define expands to the current filename as a
+   string, like C++'s __FILE__.  This Verilator feature added in 2006 was
+   incorporated into the IEEE 1800-2009 standard.
+
+.. option:: `__LINE__
+
+   The :option:`\`__LINE__` define expands to the current filename as a
+   string, like C++'s __LINE__.  This Verilator feature added in 2006 was
+   incorporated into the IEEE 1800-2009 standard.
+
+.. option:: `error [string]
+
+   This will report an error when encountered, like C++'s #error.
+
+.. option:: $c([string], ...);
+
+   The string will be embedded directly in the output C++ code at the point
+   where the surrounding Verilog code is compiled.  It may either be a
+   standalone statement (with a trailing ; in the string), or a function
+   that returns up to a 32-bit number (without a trailing ;). This can be
+   used to call C++ functions from your Verilog code.
+
+   String arguments will be put directly into the output C++ code, except
+   the word 'this' (i.e.: the object pointer) might be replaced with a
+   different pointer as Verilator might implement logic with non-member
+   functions. For this reason, any references to class members must be made
+   via an explicit 'this->' pointer dereference.
+
+   Expression arguments will have the code to evaluate the expression
+   inserted.  Thus to call a C++ function, :code:`$c("func(",a,")")` will
+   result in :code:`func(a)` in the output C++ code.  For input arguments,
+   rather than hard-coding variable names in the string
+   :code:`$c("func(a)")`, instead pass the variable as an expression
+   ::code:`$c("func(",a,")")`.  This will allow the call to work inside
+   Verilog functions where the variable is flattened out, and also enable
+   other optimizations.
+
+   If you will be reading or writing any Verilog variables inside the C++
+   functions, the Verilog signals must be declared with
+   :option:`/*verilator&32;public*/` metacomments.
+
+   You may also append an arbitrary number to $c, generally the width of
+   the output; :code:`signal_32_bits = $c32("...");`.  This allows for
+   compatibility with other simulators which require a differently named
+   PLI function name for each different output width.
+
+.. option:: $display, $write, $fdisplay, $fwrite, $sformat, $swrite
+
+   Format arguments may use C fprintf sizes after the % escape.  Per the
+   Verilog standard, %x prints a number with the natural width, and %0x
+   prints a number with minimum width.  Verilator extends this so %5x
+   prints 5 digits per the C standard (this is unspecified in Verilog, but
+   was incorporated into the 1800-2009).
+
+.. option:: `coverage_block_off
+
+   Specifies the entire begin/end block should be ignored for coverage
+   analysis.  Must be inside a code block, e.g. within a begin/end pair.
+   Same as :option:`coverage_block_off` in :ref:`Configuration Files`.
+
+.. option:: `systemc_header
+
+   Take remaining text up to the next :option:`\`verilog` or
+   :option:`\`systemc_... <\`systemc_header>` mode switch and place it
+   verbatim into the output .h file's header.  Must be placed as a module
+   item, e.g. directly inside a module/endmodule pair. Despite the name of
+   this macro, this also works in pure C++ code.
+
+.. option:: `systemc_ctor
+
+   Take remaining text up to the next :option:`\`verilog` or
+   :option:`\`systemc_... <\`systemc_header>` mode switch and place it
+   verbatim into the C++ class constructor.  Must be placed as a module
+   item, e.g. directly inside a module/endmodule pair. Despite the name of
+   this macro, this also works in pure C++ code.
+
+.. option:: `systemc_dtor
+
+   Take remaining text up to the next :option:`\`verilog` or
+   :option:`\`systemc_... <\`systemc_header>` mode switch and place it
+   verbatim into the C++ class destructor.  Must be placed as a module
+   item, e.g. directly inside a module/endmodule pair. Despite the name of
+   this macro, this also works in pure C++ code.
+
+.. option:: `systemc_interface
+
+   Take remaining text up to the next :option:`\`verilog` or
+   :option:`\`systemc_... <\`systemc_header>` mode switch and place it
+   verbatim into the C++ class interface.  Must be placed as a module item,
+   e.g. directly inside a module/endmodule pair. Despite the name of this
+   macro, this also works in pure C++ code.
+
+.. option:: `systemc_imp_header
+
+   Take remaining text up to the next :option:`\`verilog` or
+   :option:`\`systemc_... <\`systemc_header>` mode switch and place it
+   verbatim into the header of all files for this C++ class implementation.
+   Must be placed as a module item, e.g. directly inside a module/endmodule
+   pair. Despite the name of this macro, this also works in pure C++ code.
+
+.. option:: `systemc_implementation
+
+   Take remaining text up to the next :option:`\`verilog` or
+   :option:`\`systemc_... <\`systemc_header>` mode switch and place it
+   verbatim into a single file of the C++ class implementation.  Must be
+   placed as a module item, e.g. directly inside a module/endmodule
+   pair. Despite the name of this macro, this also works in pure C++ code.
+
+   If you will be reading or writing any Verilog variables in the C++
+   functions, the Verilog signals must be declared with a
+   :option:`/*verilator&32;public*/` metacomment.  See also the public task
+   feature; writing an accessor may result in cleaner code.
+
+.. option:: `SYSTEMVERILOG
+
+   The SYSTEMVERILOG, SV_COV_START and related standard defines are set by
+   default when :vlopt:`--language <--language>` is "1800-\*".
+
+.. option:: `VERILATOR
+
+.. option:: `verilator
+
+.. option:: `verilator3
+
+   The VERILATOR, verilator and verilator3 defines are set by default so
+   you may "\`ifdef" around tool specific constructs.
+
+.. option:: `verilator_config
+
+   Take remaining text up to the next :option:`\`verilog` mode switch and
+   treat it as Verilator configuration commands.  See :ref:`Configuration Files`.
+
+.. option:: `verilog
+
+   Switch back to processing Verilog code after a
+   :option:`\`systemc_... <\`systemc_header>` mode switch.  The Verilog
+   code returns to the last language mode specified with
+   "\`begin_keywords", or SystemVerilog if none was specified.
+
+.. option:: /*verilator&32;clock_enable*/
+
+   Used after a signal declaration to indicate the signal is used to gate a
+   clock, and the user takes responsibility for insuring there are no races
+   related to it. (Typically by adding a latch, and running static timing
+   analysis.) For example:
+
+   .. code-block:: sv
+
+         reg enable_r /*verilator clock_enable*/;
+         wire gated_clk = clk & enable_r;
+         always_ff @(posedge clk)
+            enable_r <= enable_early;
+
+   The clock_enable attribute will cause the clock gate to be ignored in
+   the scheduling algorithm, sometimes required for correct clock behavior,
+   and always improving performance.  It's also a good idea to enable the
+   :option:`IMPERFECTSCH` warning, to ensure all clock enables are properly
+   recognized.
+
+   Same as :option:`clock_enable` configuration file option.
+
+.. option:: /*verilator&32;clocker*/
+
+.. option:: /*verilator&32;no_clocker*/
+
+   Used after a signal declaration to indicate the signal is used as clock
+   or not. This information is used by Verilator to mark the signal as
+   clocker and propagate the clocker attribute automatically to derived
+   signals. See :vlopt:`--clk`.
+
+   Same as :option:`clocker` and :option:`no_clocker` in configuration
+   files.
+
+.. option:: /*verilator&32;coverage_block_off*/
+
+   Specifies the entire begin/end block should be ignored for coverage
+   analysis purposes.
+
+   Same as :option:`coverage_block_off` configuration file option.
+
+.. option:: /*verilator&32;coverage_off*/
+
+   Specifies that following lines of code should have coverage disabled.
+   Often used to ignore an entire module for coverage analysis purposes.
+
+.. option:: /*verilator&32;coverage_on*/
+
+   Specifies that following lines of code should have coverage re-enabled
+   (if appropriate :vlopt:`--coverage` flags are passed) after being
+   disabled earlier with :option:`/*verilator&32;coverage_off*/`.
+
+
+.. _verilator_hier_block:
+
+.. option:: /*verilator&32;hier_block*/
+
+   Specifies that the module is a unit of hierarchical Verilation.  This
+   metacomment must be between :code:`module module_name(...);` and
+   :code:`endmodule`.  The module will not be inlined nor uniquified for
+   each instance in hierarchical Verilation.  Note that the metacomment is
+   ignored unless the :vlopt:`--hierarchical` option is specified.
+
+   See :ref:`Hierarchical Verilation`.
+
+.. option:: /*verilator&32;inline_module*/
+
+   Specifies the module the comment appears in may be inlined into any
+   modules that use this module.  This is useful to speed up simulation
+   runtime.  Note if using :vlopt:`--public` that signals under inlined
+   submodules will be named :code:`{submodule}__DOT__{subsignal}` as C++
+   does not allow "." in signal names.
+
+   Same as :option:`inline` configuration file option.
+
+.. option:: /*verilator&32;isolate_assignments*/
+
+   Used after a signal declaration to indicate the assignments to this
+   signal in any blocks should be isolated into new blocks.  When there is
+   a large combinatorial block that is resulting in an ``UNOPTFLAT``
+   warning, attaching this to the signal causing a false loop may clear up
+   the problem.
+
+   IE, with the following:
+
+   .. code-block:: sv
+
+         reg splitme /* verilator isolate_assignments*/;
+         // Note the placement of the semicolon above
+         always_comb begin
+           if (....) begin
+              splitme = ....;
+              other assignments
+           end
+         end
+
+   Verilator will internally split the block that assigns to "splitme" into
+   two blocks:
+
+   It would then internally break it into (sort of):
+
+   .. code-block:: sv
+
+         // All assignments excluding those to splitme
+         always_comb begin
+           if (....) begin
+              other assignments
+           end
+         end
+         // All assignments to splitme
+         always_comb begin
+           if (....) begin
+              splitme = ....;
+           end
+         end
+
+   Same as :option:`isolate_assignments` configuration file option.
+
+.. option:: /*verilator&32;lint_off <msg>*/
+
+   Disable the specified warning message for any warnings following the
+   comment.
+
+.. option:: /*verilator&32;lint_on <msg>*/
+
+   Re-enable the specified warning message for any warnings following the
+   comment.
+
+.. option:: /*verilator&32;lint_restore*/
+
+   After a :code:`/*verilator&32;lint_save*/`, pop the stack containing lint
+   message state.  Often this is useful at the bottom of include files.
+
+.. option:: /*verilator&32;lint_save*/
+
+   Push the current state of what lint messages are turned on or turned off
+   to a stack.  Later meta-comments may then lint_on or lint_off specific
+   messages, then return to the earlier message state by using
+   :code:`/*verilator&32;lint_restore*/`.  For example:
+
+   .. code-block:: sv
+
+         // verilator lint_save
+         // verilator lint_off WIDTH
+         ...  // code needing WIDTH turned off
+         // verilator lint_restore
+
+   If WIDTH was on before the lint_off, it will now be restored to on, and
+   if it was off before the lint_off it will remain off.
+
+.. option:: /*verilator&32;no_inline_module*/
+
+   Specifies the module the comment appears in should not be inlined into
+   any modules that use this module.
+
+   Same as :option:`no_inline` configuration file option.
+
+.. option:: /*verilator&32;no_inline_task*/
+
+   Used in a function or task variable definition section to specify the
+   function or task should not be inlined into where it is used.  This may
+   reduce the size of the final executable when a task is used a very large
+   number of times.  For this flag to work, the task and tasks below it
+   must be pure; they cannot reference any variables outside the task
+   itself.
+
+   Same as :option:`no_inline` configuration file option.
+
+.. option:: /*verilator&32;public*/ (on parameter)
+
+   Used after a parameter declaration to indicate the emitted C code should
+   have the parameter values visible. Due to C++ language restrictions,
+   this may only be used on 64-bit or narrower integral enumerations.
+
+   .. code-block:: sv
+
+         parameter [2:0] PARAM /*verilator public*/ = 2'b0;
+
+.. option:: /*verilator&32;public*/ (on typedef enum)
+
+   Used after an enum typedef declaration to indicate the emitted C code
+   should have the enum values visible. Due to C++ language restrictions,
+   this may only be used on 64-bit or narrower integral enumerations.
+
+   .. code-block:: sv
+
+         typedef enum logic [2:0] { ZERO = 3'b0 } pub_t /*verilator public*/;
+
+.. option:: /*verilator&32;public*/ (on variable)
+
+   Used after an input, output, register, or wire declaration to indicate
+   the signal should be declared so that C code may read or write the value
+   of the signal.  This will also declare this module public, otherwise use
+   :code:`/*verilator&32;public_flat*/`.
+
+   Instead of using public variables, consider instead making a DPI or
+   public function that accesses the variable.  This is nicer as it
+   provides an obvious entry point that is also compatible across
+   simulators.
+
+   Same as :option:`public` configuration file option.
+
+.. option:: /*verilator&32;public*/ (on task/function)
+
+   Used inside the declaration section of a function or task declaration to
+   indicate the function or task should be made into a C++ function, public
+   to outside callers.  Public tasks will be declared as a void C++
+   function, public functions will get the appropriate non-void (bool,
+   uint32_t, etc) return type.  Any input arguments will become C++
+   arguments to the function.  Any output arguments will become C++
+   reference arguments.  Any local registers/integers will become function
+   automatic variables on the stack.
+
+   Wide variables over 64 bits cannot be function returns, to avoid
+   exposing complexities.  However, wide variables can be input/outputs;
+   they will be passed as references to an array of 32-bit numbers.
+
+   Generally, only the values of stored state (flops) should be written, as
+   the model will NOT notice changes made to variables in these functions.
+   (Same as when a signal is declared public.)
+
+   You may want to use DPI exports instead, as it's compatible with other
+   simulators.
+
+   Same as :option:`public` configuration file option.
+
+.. option:: /*verilator&32;public_flat*/ (on variable)
+
+   Used after an input, output, register, or wire declaration to indicate
+   the signal should be declared so that C code may read or write the value
+   of the signal.  This will not declare this module public, which means
+   the name of the signal or path to it may change based upon the module
+   inlining which takes place.
+
+   Same as :option:`public_flat` configuration file option.
+
+.. option:: /*verilator&32;public_flat_rd*/ (on variable)
+
+   Used after an input, output, register, or wire declaration to indicate
+   the signal should be declared public_flat (see above), but read-only.
+
+   Same as :option:`public_flat_rd` configuration file option.
+
+.. option:: /*verilator&32;public_flat_rw @(<edge_list>)*/ (on variable)
+
+   Used after an input, output, register, or wire declaration to indicate
+   the signal should be declared public_flat_rd (see above), and also
+   writable, where writes should be considered to have the timing specified
+   by the given sensitivity edge list.  Set for all variables, ports and
+   wires using the :vlopt:`--public-flat-rw` option.
+
+   Same as :option:`public_flat_rw` configuration file option.
+
+.. option:: /*verilator&32;public_module*/
+
+   Used after a module statement to indicate the module should not be
+   inlined (unless specifically requested) so that C code may access the
+   module.  Verilator automatically sets this attribute when the module
+   contains any public signals or \`systemc_ directives.  Also set for all
+   modules when using the :vlopt:`--public` option.
+
+   Same as :option:`public` configuration file option.
+
+.. option:: /*verilator&32;sc_clock*/
+
+   Deprecated and ignored.  Previously used after an input declaration to
+   indicate the signal should be declared in SystemC as a sc_clock instead
+   of a bool.  This was needed in SystemC 1.1 and 1.2 only; versions 2.0
+   and later do not require clock pins to be sc_clocks and this is no
+   longer needed and is ignored.
+
+.. option:: /*verilator&32;sc_bv*/
+
+   Used after a port declaration.  It sets the port to be of
+   :code:`sc_bv<{width}>` type, instead of bool, vluint32_t or vluint64_t.
+   This may be useful if the port width is parameterized and the
+   instantiating C++ code wants to always have a sc_bv so it can accept any
+   width.  In general you should avoid using this attribute when not
+   necessary as with increasing usage of sc_bv the performance decreases
+   significantly.
+
+   Same as :option:`sc_bv` configuration file option.
+
+.. option:: /*verilator&32;sformat*/
+
+   Attached to the final argument of type "input string" of a function or
+   task to indicate the function or task should pass all remaining
+   arguments through $sformatf.  This allows creation of DPI functions with
+   $display like behavior.  See the :file:`test_regress/t/t_dpi_display.v`
+   file for an example.
+
+   Same as :option:`sformat` configuration file option.
+
+.. option:: /*verilator&32;split_var*/
+
+   Attached to a variable or a net declaration to break the variable into
+   multiple pieces typically to resolve ``UNOPTFLAT`` performance issues.
+   Typically the variables to attach this to are recommended by Verilator
+   itself, see :option:`UNOPTFLAT`.
+
+   For example, Verilator will internally convert a variable with the
+   metacomment such as:
+
+   .. code-block:: sv
+
+         logic [7:0] x [0:1]  /*verilator split_var*/;
+
+   To:
+
+   .. code-block:: sv
+
+         logic [7:0] x__BRA__0__KET__ /*verilator split_var*/;
+         logic [7:0] x__BRA__1__KET__ /*verilator split_var*/;
+
+   Note that the generated packed variables retain the split_var
+   metacomment because they may be split into further smaller pieces
+   according to the access patterns.
+
+   This only supports unpacked arrays, packed arrays, and packed structs of
+   integer types (reg, logic, bit, byte, int...); otherwise if a split was
+   requested but cannot occur a SPLITVAR warning is issued.  Splitting
+   large arrays may slow down the Verilation speed, so use this only on
+   variables that require it.
+
+   Same as :option:`split_var` configuration file option.
+
+.. option:: /*verilator&32;tag <text...>*/
+
+   Attached after a variable or structure member to indicate opaque (to
+   Verilator) text that should be passed through to the XML output as a tag,
+   for use by downstream applications.
+
+.. option:: /*verilator&32;tracing_off*/
+
+   Disable waveform tracing for all future signals that are declared in
+   this module, or instances below this module.  Often this is placed just
+   after a primitive's module statement, so that the entire module and
+   instances below it are not traced.
+
+.. option:: /*verilator&32;tracing_on*/
+
+   Re-enable waveform tracing for all future signals or instances that are
+   declared.

docs/guide/faq.rst

@@ -0,0 +1,497 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+******************************
+FAQ/Frequently Asked Questions
+******************************
+
+.. Extra heading level here so sidebar index looks nice
+
+Questions
+=========
+
+Can I contribute?
+"""""""""""""""""
+
+Please contribute!  Just submit a pull request, or raise an issue to
+discuss if looking for something to help on.  For more information see our
+contributor agreement.
+
+
+How widely is Verilator used?
+"""""""""""""""""""""""""""""
+
+Verilator is used by many of the largest silicon design companies, large
+organizations such as CERN, and even by college student projects.
+
+Verilator is one of the "big 4" simulators, meaning one of the 4 main
+SystemVerilog simulators available, namely the closed-source products Synopsys
+VCS (tm), Mentor Questa/ModelSim (tm), Cadence
+Xcelium/Incisive/NC-Verilog/NC-Sim (tm), and the open-source Verilator.
+The three closed-source offerings are often collectively called the "big 3"
+simulators.
+
+
+Does Verilator run under Windows?
+"""""""""""""""""""""""""""""""""
+
+Yes, using Cygwin.  Verilated output also compiles under Microsoft Visual
+C++, but this is not tested every release.
+
+
+Can you provide binaries?
+"""""""""""""""""""""""""
+
+You can install Verilator via the system package manager (apt, yum, etc.)
+on many Linux distributions, including Debian, Ubuntu, SuSE, RedHat, and
+others.  These packages are provided by the Linux distributions and
+generally will lag the version of the mainline Verilator repository.  If no
+binary package is available for your distribution, how about you set one
+up?
+
+
+How can it be faster than (name-a-big-3-closed-source-simulator)?
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+Generally, the implied part of the question is "... with all of the
+manpower they can put into developing it."
+
+Most simulators have to be compliant with the complete IEEE 1364 (Verilog)
+and IEEE 1800 (SystemVerilog) standards, meaning they have to be event
+driven.  This prevents them from being able to reorder blocks and make
+netlist-style optimizations, which are where most of the gains come from.
+
+You should not be scared by non-compliance.  Your synthesis tool isn't
+compliant with the whole standard to start with, so your simulator need not
+be either.  Verilator is closer to the synthesis interpretation, so this is
+a good thing for getting working silicon.
+
+
+Will Verilator output remain under my own license/copyright?
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+Yes, it's just like using GCC on your programs; this is why Verilator uses
+the "GNU **Lesser** Public License Version 3" instead of the more typical
+"GNU Public License".  See the licenses for details, but in brief, if you
+change Verilator itself or the header files Verilator includes, you must
+make the source code available under the GNU Lesser Public License.
+However, Verilator output (the Verilated code) only "include"s the licensed
+files, and so you are **not** required to open-source release any output
+from Verilator.
+
+You also have the option of using the Perl Artistic License, which again
+does not require you to release your Verilog or generated code, and also
+allows you to modify Verilator for internal use without distributing the
+modified version.  But please contribute back to the community!
+
+One limit is that you cannot under either license release a closed-source
+Verilog simulation product incorporating Verilator. That is you can have a
+commercial product, but must make the source code available.
+
+As is standard with Open Source, contributions back to Verilator will be
+placed under the Verilator copyright and LGPL/Artistic license.  Small test
+cases will be released into the public domain so they can be used anywhere,
+and large tests under the LGPL/Artistic, unless requested otherwise.
+
+
+Why is running Verilator (to create a model) so slow?
+"""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+Verilator may require more memory than the resulting simulator will
+require, as Verilator internally creates all of the state of the resulting
+generated simulator in order to optimize it.  If it takes more than a few
+minutes or so (and you're not using :vlopt:`--debug` since debug mode is
+disk bound), see if your machine is paging; most likely you need to run it
+on a machine with more memory. Very large designs are known to have topped
+64 GB resident set size.  Alternatively, see :ref:`Hierarchical Verilation`.
+
+
+How do I generate waveforms (traces) in C++?
+""""""""""""""""""""""""""""""""""""""""""""
+
+See also the next question for tracing in SystemC mode.
+
+A. Pass the :vlopt:`--trace` option to Verilator, and in your top level C
+   code, call ``Verilated::traceEverOn(true)``.  Then you may use
+   ``$dumpfile`` and ``$dumpvars`` to enable traces, same as with any
+   Verilog simulator. See ``examples/make_tracing_c`` in the distribution.
+
+B. Or, for finer-grained control, or C++ files with multiple Verilated
+   modules you may also create the trace purely from C++.  Create a
+   VerilatedVcdC object, and in your main loop right after ``eval()`` call
+   ``trace_object->dump(contextp->time())`` every time step, and finally
+   call ``trace_object->close()``.
+
+   .. code-block:: C++
+      :emphasize-lines: 1,5-8,12
+
+      #include "verilated_vcd_c.h"
+      ...
+      int main(int argc, char** argv, char** env) {
+          const std::unique_ptr<VerilatedContext> contextp{new VerilatedContext};
+          ...
+          Verilated::traceEverOn(true);
+          VerilatedVcdC* tfp = new VerilatedVcdC;
+          topp->trace(tfp, 99);  // Trace 99 levels of hierarchy
+          tfp->open("obj_dir/t_trace_ena_cc/simx.vcd");
+          ...
+          while (contextp->time() < sim_time && !contextp->gotFinish()) {
+              contextp->timeInc(1);
+              topp->eval();
+              tfp->dump(contextp->time());
+          }
+          tfp->close();
+      }
+
+You also need to compile :file:`verilated_vcd_c.cpp` and add it to your
+link, preferably by adding the dependencies in your Makefile's
+:code:`$(VK_GLOBAL_OBJS)` link rule.  This is done for you if using the
+Verilator :vlopt:`--exe` option.
+
+you can call :code:`trace_object->trace()` on multiple Verilated objects
+with the same trace file if you want all data to land in the same output
+file.
+
+
+How do I generate waveforms (traces) in SystemC?
+""""""""""""""""""""""""""""""""""""""""""""""""
+
+A. Pass the :vlopt:`--trace` option to Verilator, and in your top level
+   :code:`sc_main()`, call :code:`Verilated::traceEverOn(true)`.  Then you
+   may use :code:`$dumpfile` and code:`$dumpvars` to enable traces, same as
+   with any Verilog simulator, see the non-SystemC example in
+   :file:`examples/make_tracing_c`. This will trace only the module
+   containing the :code:`$dumpvar`.
+
+B. Or, you may create a trace purely from SystemC, which may trace all
+   Verilated designs in the SystemC model. Create a VerilatedVcdSc object
+   as you would create a normal SystemC trace file.  For an example, see
+   the call to ``VerilatedVcdSc`` in the
+   :file:`examples/make_tracing_sc/sc_main.cpp` file of the distribution,
+   and below.
+
+C. Alternatively you may use the C++ trace mechanism described in the
+   previous question, note the timescale and timeprecision will be
+   inherited from your SystemC settings.
+
+   .. code-block:: C++
+      :emphasize-lines: 1,5-8
+
+      #include "verilated_vcd_sc.h"
+      ...
+      int main(int argc, char** argv, char** env) {
+          ...
+          Verilated::traceEverOn(true);
+          VerilatedVcdSc* tfp = new VerilatedVcdSc;
+          topp->trace(tfp, 99);  // Trace 99 levels of hierarchy
+          tfp->open("obj_dir/t_trace_ena_cc/simx.vcd");
+          ...
+          sc_start(1);
+          ...
+          tfp->close();
+      }
+
+
+
+You also need to compile :file:`verilated_vcd_sc.cpp` and
+:file:`verilated_vcd_c.cpp` and add them to your link, preferably by adding
+the dependencies in your Makefile's :code:`$(VK_GLOBAL_OBJS)` link rule.
+This is done for you if using the Verilator :vlopt:`--exe` option.
+
+You can call :code:`->trace()` on multiple Verilated objects with the same
+trace file if you want all data to land in the same output file.
+
+When using SystemC 2.3, the SystemC library must have been built with the
+experimental simulation phase callback based tracing disabled. This is
+disabled by default when building SystemC with its configure based build
+system, but when building SystemC with CMake, you must pass
+``-DENABLE_PHASE_CALLBACKS_TRACING=OFF`` to disable this feature.
+
+
+How do I generate FST waveforms (traces) in C++ or SystemC?
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+FST is a trace file format developed by GTKWave.  Verilator provides basic
+FST support.  To dump traces in FST format, add the :vlopt:`--trace-fst`
+option to Verilator and either A. use :code:`$dumpfile & $dumpvars` in
+Verilog as described in the VCD example above,
+
+Or, in C++ change the include described in the VCD example above:
+
+.. code-block:: C++
+
+      #include "verilated_fst_c.h"
+      VerilatedFstC* tfp = new VerilatedFstC;
+
+
+Or, in SystemC change the include described in the VCD example above:
+
+.. code-block:: C++
+
+      #include "verilated_fst_sc.h"
+      VerilatedFstC* tfp = new VerilatedFstSc;
+
+
+Note that currently supporting both FST and VCD in a single simulation is
+impossible, but such requirement should be rare.  You can however ifdef
+around the trace format in your C++ main loop, and select VCD or FST at
+build time, should you require.
+
+
+How do I view waveforms (aka dumps or traces)?
+""""""""""""""""""""""""""""""""""""""""""""""
+
+Verilator creates standard VCD (Value Change Dump) and FST files.  VCD
+files are viewable with the open source GTKWave (recommended) or Dinotrace
+(legacy) programs, or any of the many closed-source offerings; FST is
+supported only by GTKWave.
+
+
+How do I speed up writing large waveform (trace) files?
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+A. Instead of calling ``VerilatedVcdC->open`` or ``$dumpvars`` at the
+   beginning of time, delay calling it until the time stamp where you want
+   tracing to begin.
+
+B. Add the :option:`/*verilator&32;tracing_off*/` metacomment to any very
+   low level modules you never want to trace (such as perhaps library
+   cells).
+
+C. Use the :vlopt:`--trace-depth` option to limit the depth of tracing, for
+   example :vlopt:`--trace-depth 1 <--trace-depth>` to see only the top
+   level signals.
+
+D. You can also consider using FST tracing instead of VCD. FST dumps are a
+   fraction of the size of the equivalent VCD. FST tracing can be slower
+   than VCD tracing, but it might be the only option if the VCD file size
+   is prohibitively large.
+
+E. Be sure you write your trace files to a local solid-state drive, instead
+   of to a network drive.  Network drives are generally far slower.
+
+
+Where is the translate_off command?  (How do I ignore a construct?)
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+Translate on/off pragmas are generally a bad idea, as it's easy to have
+mismatched pairs, and you can't see what another tool sees by just
+preprocessing the code.  Instead, use the preprocessor; Verilator defines
+the ``\`VERILATOR`` define for you, so just wrap the code in an ifndef
+region:
+
+ .. code-block:: sv
+    :emphasize-lines: 1
+
+    `ifndef VERILATOR
+       Something_Verilator_Dislikes;
+    `endif
+
+Most synthesis tools similarly define SYNTHESIS for you.
+
+
+Why do I get "unexpected 'do'" or "unexpected 'bit'" errors?
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+The words \ ``do``\ , \ ``bit``\ , \ ``ref``\ , \ ``return``\ , and others
+are reserved keywords in SystemVerilog.  Older Verilog code might use these
+as identifiers.  You should change your code to not use them to ensure it
+works with newer tools.  Alternatively, surround them by the Verilog
+2005/SystemVerilog begin_keywords pragma to indicate Verilog 2001 code.
+
+.. code-block:: sv
+   :emphasize-lines: 1
+
+   `begin_keywords "1364-2001"
+      integer bit; initial bit = 1;
+   `end_keywords
+
+
+If you want the whole design to be parsed as Verilog 2001, see the
+:vlopt:`--default-language` option.
+
+
+How do I prevent my assertions from firing during reset?
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+Call :code:`Verilated::assertOn(false)` before you first call the model,
+then turn it back on after reset.  It defaults to true.  When false, all
+assertions controlled by :vlopt:`--assert` are disabled.
+
+
+Why do I get "undefined reference to sc_time_stamp()?
+"""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+In Verilator 4.200 and later, using the timeInc function is recommended
+instead.  See the :ref:`Connecting to C++` examples.  Some linkers (MSVC++)
+still require :code:`sc_time_stamp()` to be defined, either define this
+with :code:`double sc_time_stamp() { return 0; }` or compile the Verilated
+code with :code:`-CFLAGS -DVL_TIME_CONTEXT`.
+
+Prior to Verilator 4.200, the :code:`sc_time_stamp()` function needs to be
+defined in C++ (non SystemC) to return the current simulation time.
+
+
+Why do I get "undefined reference to \`VL_RAND_RESET_I' or \`Verilated::...'"?
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+You need to link your compiled Verilated code against the
+:code:`verilated.cpp` file found in the include directory of the Verilator
+kit.  This is one target in the ``$(VK_GLOBAL_OBJS)`` make variable, which
+should be part of your Makefile's link rule.  If you use :vlopt:`--exe`,
+this is done for you.
+
+
+Is the PLI supported?
+"""""""""""""""""""""
+
+Only somewhat.  More specifically, the common PLI-ish calls $display,
+$finish, $stop, $time, $write are converted to C++ equivalents.  You can
+also use the "import DPI" SystemVerilog feature to call C code (see the
+chapter above).  There is also limited VPI access to public signals.
+
+If you want something more complex, since Verilator emits standard C++
+code, you can simply write your own C++ routines that can access and modify
+signal values without needing any PLI interface code, and call it with
+$c("{any_c++_statement}").
+
+See the :ref:`Connecting` section.
+
+
+How do I make a Verilog module that contain a C++ object?
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+You need to add the object to the structure that Verilator creates, then
+use $c to call a method inside your object.  The
+:file:`test_regress/t/t_extend_class` files in the distribution show an
+example of how to do this.
+
+
+How do I get faster build times?
+""""""""""""""""""""""""""""""""
+
+* When running make, pass the make variable VM_PARALLEL_BUILDS=1 so that
+  builds occur in parallel. Note this is now set by default if an output
+  file was large enough to be split due to the :vlopt:`--output-split`
+  option.
+
+* Verilator emits any infrequently executed "cold" routines into separate
+  __Slow.cpp files. This can accelerate compilation as optimization can be
+  disabled on these routines. See the OPT_FAST and OPT_SLOW make variables
+  and :ref:`Benchmarking & Optimization`.
+
+* Use a recent compiler.  Newer compilers tend to be faster.
+
+* Compile in parallel on many machines and use caching; see the web for the
+  ccache, distcc and icecream packages. ccache will skip GCC runs between
+  identical source builds, even across different users.  If ccache was
+  installed when Verilator was built it is used, or see OBJCACHE
+  environment variable to override this. Also see the
+  :vlopt:`--output-split` option and :ref: `Profiling ccache efficiency`
+
+* To reduce the compile time of classes that use a Verilated module (e.g. a
+  top CPP file) you may wish to add a
+  :option:`/*verilator&32;no_inline_module*/` metacomment to your top level
+  module. This will decrease the amount of code in the model's Verilated
+  class, improving compile times of any instantiating top level C++ code,
+  at a relatively small cost of execution performance.
+
+* Use :ref:`hierarchical verilation`.
+
+
+Why do so many files need to recompile when I add a signal?
+"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+Adding a new signal requires the symbol table to be recompiled.  Verilator
+uses one large symbol table, as that results in 2-3 less assembly
+instructions for each signal access.  This makes the execution time 10-15%
+faster, but can result in more compilations when something changes.
+
+
+How do I access Verilog functions/tasks in C?
+"""""""""""""""""""""""""""""""""""""""""""""
+
+Use the SystemVerilog Direct Programming Interface.  You write a Verilog
+function or task with input/outputs that match what you want to call in
+with C.  Then mark that function as a DPI export function.  See the DPI
+chapter in the IEEE Standard.
+
+
+How do I access C++ functions/tasks in Verilog?
+"""""""""""""""""""""""""""""""""""""""""""""""
+
+Use the SystemVerilog Direct Programming Interface.  You write a Verilog
+function or task with input/outputs that match what you want to call in
+with C.  Then mark that function as a DPI import function.  See the DPI
+chapter in the IEEE Standard.
+
+
+How do I access signals in C?
+"""""""""""""""""""""""""""""
+
+The best thing to do is to make a SystemVerilog "export DPI" task or
+function that accesses that signal, as described in the DPI chapter in the
+manual and DPI tutorials on the web.  This will allow Verilator to better
+optimize the model and should be portable across simulators.
+
+If you really want raw access to the signals, declare the signals you will
+be accessing with a :option:`/*verilator&32;public*/` metacomment before
+the closing semicolon.  Then scope into the C++ class to read the value of
+the signal, as you would any other member variable.
+
+Signals are the smallest of 8-bit unsigned chars (equivalent to uint8_t),
+16-bit unsigned shorts (uint16_t), 32-bit unsigned longs (uint32_t), or
+64-bit unsigned long longs (uint64_t) that fits the width of the signal.
+Generally, you can use just uint32_t's for 1 to 32 bits, or vluint64_t for
+1 to 64 bits, and the compiler will properly up-convert smaller entities.
+Note even signed ports are declared as unsigned; you must sign extend
+yourself to the appropriate signal width.
+
+Signals wider than 64 bits are stored as an array of 32-bit uint32_t's.
+Thus to read bits 31:0, access signal[0], and for bits 63:32, access
+signal[1].  Unused bits (for example bit numbers 65-96 of a 65-bit vector)
+will always be zero.  If you change the value you must make sure to pack
+zeros in the unused bits or core-dumps may result, because Verilator strips
+array bound checks where it believes them to be unnecessary to improve
+performance.
+
+In the SYSTEMC example above, if you had in our.v:
+
+ .. code-block:: sv
+
+      input clk /*verilator public*/;
+      // Note the placement of the semicolon above
+
+From the sc_main.cpp file, you'd then:
+
+ .. code-block:: C++
+
+      #include "Vour.h"
+      #include "Vour_our.h"
+      cout << "clock is " << top->our->clk << endl;
+
+
+In this example, clk is a bool you can read or set as any other variable.
+The value of normal signals may be set, though clocks shouldn't be changed
+by your code or you'll get strange results.
+
+
+Should a module be in Verilog or SystemC?
+"""""""""""""""""""""""""""""""""""""""""
+
+Sometimes there is a block that just interconnects instances, and have a
+choice as to if you write it in Verilog or SystemC.  Everything else being
+equal, best performance is when Verilator sees all of the design.  So, look
+at the hierarchy of your design, labeling instances as to if they are
+SystemC or Verilog.  Then:
+
+* A module with only SystemC instances below must be SystemC.
+
+* A module with a mix of Verilog and SystemC instances below must be
+  SystemC. (As Verilator cannot connect to lower-level SystemC instances.)
+
+* A module with only Verilog instances below can be either, but for best
+  performance should be Verilog.  (The exception is if you have a design
+  that is instantiated many times; in this case Verilating one of the lower
+  modules and instantiating that Verilated instances multiple times into a
+  SystemC module *may* be faster.)

docs/guide/files.rst

@@ -0,0 +1,147 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+*****
+Files
+*****
+
+.. _Files in the Distribution:
+
+Files in the Git Tree
+=====================
+
+The following is a summary of the files in the Git Tree (distribution) of
+Verilator:
+
+::
+
+   Changes                     => Version history
+   README.rst                  => This document
+   bin/verilator               => Compiler wrapper invoked to Verilate code
+   docs/                       => Additional documentation
+   examples/                   => Examples (see manual for descriptions)
+   include/                    => Files that should be in your -I compiler path
+   include/verilated*.cpp      => Global routines to link into your simulator
+   include/verilated*.h        => Global headers
+   include/verilated.mk        => Common Makefile
+   src/                        => Translator source code
+   test_regress                => Internal tests
+
+
+.. _Files Read/Written:
+
+Files Read/Written
+==================
+
+All output files are placed in the output directory specified with the
+:vlopt:`--Mdir` option, or "obj_dir" if not specified.
+
+Verilator creates the following files in the output directory:
+
+For --cc/--sc, it creates:
+
+.. list-table::
+
+   * - *{prefix}*\ .cmake
+     - CMake include script for compiling (from --make cmake)
+   * - *{prefix}*\ .mk
+     - Make include file for compiling (from --make gmake)
+   * - *{prefix}*\ _classes.mk
+     - Make include file with class names (from --make gmake)
+   * - *{prefix}*\ _hier.mk
+     - Make file for hierarchy blocks (from --make gmake)
+   * - *{prefix|*\ _hierMkArgs.f
+     - Arguments for hierarchical Verilation (from --make gmake)
+   * - *{prefix}*\ _hierCMakeArgs.f
+     - Arguments for hierarchical Verilation (from --make cmake)
+   * - *{prefix}*\ .h
+     - Model header
+   * - *{prefix}*\ .cpp
+     - Model C++ file
+   * - *{prefix}*\ ___024root.h
+     - Top level (SystemVerilog $root) internal header file
+   * - *{prefix}*\ ___024root.cpp
+     - Top level (SystemVerilog $root) internal C++ file
+   * - *{prefix}*___024root*{__n}*\ .cpp
+     - Additional top level internal C++ files (from --output-split)
+   * - *{prefix}*\ ___024root__Slow\ *{__n}*\ .cpp
+     - Infrequent cold routines
+   * - *{prefix}*\ ___024root__Trace{__n}*\ .cpp
+     - Wave file generation code (from --trace)
+   * - *{prefix}*\ ___024root__Trace__Slow{__n}*\ .cpp
+     - Wave file generation code (from --trace)
+   * - *{prefix}*\ __Dpi.h
+     - DPI import and export declarations (from --dpi)
+   * - *{prefix}*\ __Dpi.cpp
+     - Global DPI export wrappers (from --dpi)
+   * - *{prefix}*\ __Dpi_Export\ *{__n}\ .cpp
+     - DPI export wrappers scoped to this particular model (from --dpi)
+   * - *{prefix}*\ __Inlines.h
+     - Inline support functions
+   * - *{prefix}*\ __Syms.h
+     - Global symbol table header
+   * - *{prefix}*\ __Syms.cpp
+     - Global symbol table C++
+   * - *{prefix}{each_verilog_module}*\ .h
+     - Lower level internal header files
+   * - *{prefix}{each_verilog_module}*\ .cpp
+     - Lower level internal C++ files
+   * - *{prefix}{each_verilog_module}{__n}*\ .cpp
+     - Additional lower C++ files (from --output-split)
+
+For --hierarchy mode, it creates:
+
+.. list-table::
+
+   * - V\ *{hier_block}*\ /
+     - Directory to Verilate each hierarchy block (from --hierarchy)
+   * - *{prefix}*\ __hierVer.d
+     - Make dependencies of the top module (from --hierarchy)
+   * - *{prefix}*\ __hier.dir
+     - Directory to store .dot, .vpp, .tree of top module (from --hierarchy)
+
+In certain debug and other modes, it also creates:
+
+.. list-table::
+
+   * - *{prefix}*\ .xml
+     - XML tree information (from --xml)
+   * - *{prefix}*\ __cdc.txt
+     - Clock Domain Crossing checks (from --cdc)
+   * - *{prefix}*\ __stats.txt
+     - Statistics (from --stats)
+   * - *{prefix}*\ __idmap.txt
+     - Symbol demangling (from --protect-ids)
+   * - *{prefix}*\ __ver.d
+     - Make dependencies (from -MMD)
+   * - *{prefix}*\ __verFiles.dat
+     - Timestamps (from --skip-identical)
+   * - *{prefix}{misc}*\ .dot
+     - Debugging graph files (from --debug)
+   * - *{prefix}{misc}*\ .tree
+     - Debugging files (from --debug)
+   * - {mod_prefix}_{each_verilog_module}*{__n}*\ .vpp
+     - Pre-processed verilog (from --debug)
+
+After running Make, the C++ compiler may produce the following:
+
+.. list-table::
+
+   * - verilated{misc}*\ .d
+     - Intermediate dependencies
+   * - verilated{misc}*\ .o
+     - Intermediate objects
+   * - {mod_prefix}{misc}*\ .d
+     - Intermediate dependencies
+   * - {mod_prefix}{misc}*\ .o
+     - Intermediate objects
+   * - *{prefix}*\
+     - Final executable (from --exe)
+   * - *{prefix}*\ __ALL.a
+     - Library of all Verilated objects
+   * - *{prefix}*\ __ALL.cpp
+     - Include of all code for single compile
+   * - *{prefix}{misc}*\ .d
+     - Intermediate dependencies
+   * - *{prefix}{misc}*\ .o
+     - Intermediate objects

docs/guide/index.rst

@@ -0,0 +1,41 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+######################
+Verilator User's Guide
+######################
+
+.. toctree::
+   :maxdepth: 2
+   :caption: Getting Started
+
+   overview.rst
+   examples.rst
+   install.rst
+
+
+.. toctree::
+   :maxdepth: 2
+   :caption: User's Guide
+
+   verilating.rst
+   connecting.rst
+   simulating.rst
+   contributing.rst
+   faq.rst
+
+
+.. toctree::
+   :maxdepth: 1
+   :caption: Reference Guide
+
+   languages.rst
+   extensions.rst
+   executables.rst
+   warnings.rst
+   files.rst
+   environment.rst
+   deprecations.rst
+   contributors.rst
+   changes.rst
+   copyright.rst

docs/guide/install.rst

@@ -0,0 +1,321 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+.. _Installation:
+
+************
+Installation
+************
+
+This section discusses how to install Verilator.
+
+.. _Package Manager Quick Install:
+
+Package Manager Quick Install
+=============================
+
+Using a distribution's package manager is the easiest way to get
+started. (Note packages are unlikely to have the most recent version, so
+:ref:`Git Install`, might be a better alternative.) To install as a
+package:
+
+::
+
+   apt-get install verilator   # On Ubuntu
+
+
+.. _Git Install:
+
+Git Quick Install
+=================
+
+Installing Verilator from Git provides the most flexibility. For additional
+options and details see :ref:`Detailed Build Instructions` below.
+
+In brief, to install from git:
+
+::
+
+   # Prerequisites:
+   #sudo apt-get install git perl python3 make autoconf g++ flex bison ccache
+   #sudo apt-get install libgoogle-perftools-dev numactl perl-doc
+   #sudo apt-get install libfl2  # Ubuntu only (ignore if gives error)
+   #sudo apt-get install libfl-dev  # Ubuntu only (ignore if gives error)
+   #sudo apt-get install zlibc zlib1g zlib1g-dev  # Ubuntu only (ignore if gives error)
+
+   git clone https://github.com/verilator/verilator   # Only first time
+   ## Note the URL above is not a page you can see with a browser, it's for git only
+
+   # Every time you need to build:
+   unsetenv VERILATOR_ROOT  # For csh; ignore error if on bash
+   unset VERILATOR_ROOT  # For bash
+   cd verilator
+   git pull        # Make sure git repository is up-to-date
+   git tag         # See what versions exist
+   #git checkout master      # Use development branch (e.g. recent bug fixes)
+   #git checkout stable      # Use most recent stable release
+   #git checkout v{version}  # Switch to specified release version
+
+   autoconf        # Create ./configure script
+   ./configure     # Configure and create Makefile
+   make -j         # Build Verilator itself
+   sudo make install
+
+
+.. _Detailed Build Instructions:
+
+Detailed Build Instructions
+===========================
+
+This section describes details of the build process, and assumes you are
+building from Git. For using a pre-built binary for your Linux
+distribution, see instead :ref:`Package Manager Quick Install`.
+
+
+OS Requirements
+---------------
+
+Verilator is developed and has primary testing on Ubuntu, with additional
+testing on FreeBSD and Apple OS-X. Versions have also built on Redhat
+Linux, HPUX and Solaris. It should run with minor porting on any
+GNU/Linux-ish platform. Verilator also works on Windows under Cygwin, and
+Windows under MinGW (gcc -mno-cygwin). Verilated output (not Verilator
+itself) compiles under all the options above, plus using MSVC++.
+
+
+Install Prerequisites
+---------------------
+
+To build or run Verilator you need these standard packages:
+
+::
+
+   sudo apt-get install git perl python3 make
+   sudo apt-get install g++  # Alternatively, clang
+   sudo apt-get install libgz  # Non-Ubuntu (ignore if gives error)
+   sudo apt-get install libfl2  # Ubuntu only (ignore if gives error)
+   sudo apt-get install libfl-dev  # Ubuntu only (ignore if gives error)
+   sudo apt-get install zlibc zlib1g zlib1g-dev  # Ubuntu only (ignore if gives error)
+
+To build or run the following are optional but should be installed for good
+performance:
+
+::
+
+   sudo apt-get install ccache  # If present at build, needed for run
+   sudo apt-get install libgoogle-perftools-dev numactl perl-doc
+
+To build Verilator you will need to install these packages; these do not
+need to be present to run Verilator:
+
+::
+
+   sudo apt-get install git autoconf flex bison
+
+Those developing Verilator itself may also want these (see internals.rst):
+
+::
+
+   sudo apt-get install gdb graphviz cmake clang clang-format-11 gprof lcov
+   sudo pip3 install sphinx sphinx_rtd_theme breathe
+   cpan install Pod::Perldoc
+   cpan install Parallel::Forker
+
+
+Install SystemC
+^^^^^^^^^^^^^^^
+
+If you will be using SystemC (vs straight C++ output), download `SystemC
+<https://www.accellera.org/downloads/standards/systemc>`__.  Follow their
+installation instructions. You will need to set the
+:option:`SYSTEMC_INCLUDE` environment variable to point to the include
+directory with ``systemc.h`` in it, and set the :option:`SYSTEMC_LIBDIR`
+environment variable to point to the directory with ``libsystemc.a`` in it.
+
+
+Install GTKWave
+^^^^^^^^^^^^^^^
+
+To make use of Verilator FST tracing you will want `GTKwave
+<http://gtkwave.sourceforge.net/>`__ installed, however this is not
+required at Verilator build time.
+
+
+Obtain Sources
+--------------
+
+Get the sources from the git repository: (You need do this only once,
+ever.)
+
+::
+
+   git clone https://github.com/verilator/verilator   # Only first time
+   ## Note the URL above is not a page you can see with a browser, it's for git only
+
+Enter the checkout and determine what version/branch to use:
+
+::
+
+   cd verilator
+   git pull        # Make sure we're up-to-date
+   git tag         # See what versions exist
+   #git checkout master      # Use development branch (e.g. recent bug fix)
+   #git checkout stable      # Use most recent release
+   #git checkout v{version}  # Switch to specified release version
+
+
+Auto Configure
+--------------
+
+Create the configuration script:
+
+::
+
+   autoconf        # Create ./configure script
+
+
+Eventual Installation Options
+-----------------------------
+
+Before configuring the build, you have to decide how you're going to
+eventually install Verilator onto your system. Verilator will be compiling
+the current value of the environment variables :option:`VERILATOR_ROOT`,
+:option:`SYSTEMC_INCLUDE`, and :option:`SYSTEMC_LIBDIR` as defaults into
+the executable, so they must be correct before configuring.
+
+These are the installation options:
+
+
+1. Run-in-Place from VERILATOR_ROOT
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Our personal favorite is to always run Verilator in-place from its Git
+directory. This allows the easiest experimentation and upgrading, and
+allows many versions of Verilator to co-exist on a system.
+
+::
+
+   export VERILATOR_ROOT=`pwd`   # if your shell is bash
+   setenv VERILATOR_ROOT `pwd`   # if your shell is csh
+   ./configure
+   # Running will use files from $VERILATOR_ROOT, so no install needed
+
+Note after installing (below steps), a calling program or shell must set
+the environment variable :option:`VERILATOR_ROOT` to point to this Git
+directory, then execute ``$VERILATOR_ROOT/bin/verilator``, which will find
+the path to all needed files.
+
+
+2. Install into a specific location
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+You may eventually be installing onto a project/company-wide "CAD" tools
+disk that may support multiple versions of every tool. Tell configure the
+eventual destination directory name.  We recommend the destination location
+include the Verilator version name:
+
+::
+
+   unset VERILATOR_ROOT      # if your shell is bash
+   unsetenv VERILATOR_ROOT   # if your shell is csh
+   # For the tarball, use the version number instead of git describe
+   ./configure --prefix /CAD_DISK/verilator/`git describe | sed "s/verilator_//"`
+
+Note after installing (below steps), if you use `modulecmd
+<http://modules.sourceforge.net/>`__, you'll want a module file like the
+following:
+
+::
+
+   set install_root /CAD_DISK/verilator/{version-number-used-above}
+   unsetenv VERILATOR_ROOT
+   prepend-path PATH $install_root/bin
+   prepend-path MANPATH $install_root/man
+   prepend-path PKG_CONFIG_PATH $install_root/share/pkgconfig
+
+
+3. Install into a Specific Path
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+You may eventually install Verilator into a specific installation prefix,
+as most GNU tools support:
+
+::
+
+   unset VERILATOR_ROOT      # if your shell is bash
+   unsetenv VERILATOR_ROOT   # if your shell is csh
+   ./configure --prefix /opt/verilator-VERSION
+
+Then after installing (below steps) you will need to add
+``/opt/verilator-VERSION/bin`` to your ``$PATH`` environment variable.
+
+
+4. Install System Globally
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The final option is to eventually install Verilator globally, using
+configure's default system paths:
+
+::
+
+   unset VERILATOR_ROOT      # if your shell is bash
+   unsetenv VERILATOR_ROOT   # if your shell is csh
+   ./configure
+
+Then after installing (below) the binaries should be in a location that is
+already in your ``$PATH`` environment variable.
+
+
+Configure
+---------
+
+The command to configure the package was described in the previous step.
+Developers should configure to have more complete developer tests.
+Additional packages may be required for these tests.
+
+::
+
+   export VERILATOR_AUTHOR_SITE=1    # Put in your .bashrc
+   ./configure --enable-longtests  ...above options...
+
+
+Compile
+-------
+
+Compile Verilator:
+
+::
+
+   make -j
+
+
+Test
+----
+
+Check the compilation by running self-tests:
+
+::
+
+   make test
+
+
+Install
+-------
+
+If you used any install option other than the `1. Run-in-Place from
+VERILATOR_ROOT <#_1_run_in_place_from_verilator_root>`__ scheme, install
+the files:
+
+::
+
+   make install
+
+
+.. Docker Build Environment
+
+.. include:: ../../ci/docker/buildenv/README.rst
+
+
+.. Docker Run Environment
+
+.. include:: ../../ci/docker/run/README.rst

docs/guide/languages.rst

@@ -0,0 +1,477 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+***************
+Input Languages
+***************
+
+This section describes the languages Verilator takes as input.  See also
+:ref:`Configuration Files`.
+
+
+Language Standard Support
+=========================
+
+Verilog 2001 (IEEE 1364-2001) Support
+-------------------------------------
+
+Verilator supports most Verilog 2001 language features.  This includes
+signed numbers, "always @\*", generate statements, multidimensional arrays,
+localparam, and C-style declarations inside port lists.
+
+
+Verilog 2005 (IEEE 1364-2005) Support
+-------------------------------------
+
+Verilator supports most Verilog 2005 language features.  This includes the
+\`begin_keywords and \`end_keywords compiler directives, $clog2, and the
+uwire keyword.
+
+
+SystemVerilog 2005 (IEEE 1800-2005) Support
+-------------------------------------------
+
+Verilator supports ==? and !=? operators, ++ and -- in some contexts,
+$bits, $countbits, $countones, $error, $fatal, $info, $isunknown, $onehot,
+$onehot0, $unit, $warning, always_comb, always_ff, always_latch, bit, byte,
+chandle, const, do-while, enum, export, final, import, int, interface,
+logic, longint, modport, package, program, shortint, struct, time, typedef,
+union, var, void, priority case/if, and unique case/if.
+
+It also supports .name and .\* interconnection.
+
+Verilator partially supports concurrent assert and cover statements; see
+the enclosed coverage tests for the syntax which is allowed.
+
+Verilator has limited support for class and related object-oriented
+constructs.
+
+
+SystemVerilog 2012 (IEEE 1800-2012) Support
+-------------------------------------------
+
+Verilator implements a full SystemVerilog-compliant preprocessor, including
+function call-like preprocessor defines, default define arguments,
+\`__FILE__, \`__LINE__ and \`undefineall.
+
+
+SystemVerilog 2017 (IEEE 1800-2017) Support
+-------------------------------------------
+
+Verilator supports the 2017 "for" loop constructs, and several minor
+cleanups IEEE made in 1800-2017.
+
+
+Verilog AMS Support
+-------------------
+
+Verilator implements a very small subset of Verilog AMS (Verilog Analog and
+Mixed-Signal Extensions) with the subset corresponding to those VMS
+keywords with near equivalents in the Verilog 2005 or SystemVerilog 2009
+languages.
+
+AMS parsing is enabled with :vlopt:`--language VAMS <--language>` or
+:vlopt:`--language 1800+VAMS <--language>`.
+
+At present Verilator implements ceil, exp, floor, ln, log, pow, sqrt,
+string, and wreal.
+
+
+Synthesis Directive Assertion Support
+-------------------------------------
+
+With the :vlopt:`--assert` option, Verilator reads any :code:`//synopsys
+full_case` or :code:`//synopsys parallel_case` directives.  The same
+applies to any :code:`//ambit synthesis`, :code:`//cadence` or
+:code:`//pragma` directives of the same form.
+
+When these synthesis directives are discovered, Verilator will either
+formally prove the directive to be true, or failing that, will insert the
+appropriate code to detect failing cases at simulation runtime and print an
+"Assertion failed" error message.
+
+Verilator likewise also asserts any "unique" or "priority" SystemVerilog
+keywords on case statement, as well as "unique" on if statements.  However,
+"priority if" is currently simply ignored.
+
+
+.. _Language Limitations:
+
+Language Limitations
+====================
+
+This section describes the language limitations of Verilator. Many of these
+restrictions are by intent.
+
+Synthesis Subset
+----------------
+
+Verilator supports the Synthesis subset with other verification constructs
+being added over time. Verilator also simulates events as Synopsys's Design
+Compiler would; namely given a block of the form:
+
+.. code-block:: sv
+
+        always @(x) y = x & z;
+
+This will recompute y when there is even a potential for change in x or a
+change in z, that is when the flops computing x or z evaluate (which is
+what Design Compiler will synthesize.)  A compliant simulator would only
+calculate y if x changes.  We recommend using always_comb to make the code
+run the same everywhere.  Also avoid putting $displays in combo blocks, as
+they may print multiple times when not desired, even on compliant
+simulators as event ordering is not specified.
+
+
+Signal Naming
+-------------
+
+To avoid conflicts with C symbol naming, any character in a signal name
+that is not alphanumeric nor a single underscore will be replaced by __0hh
+where hh is the hex code of the character. To avoid conflicts with
+Verilator's internal symbols, any double underscore are replaced with
+___05F (5F is the hex code of an underscore.)
+
+
+Bind
+----
+
+sVerilator only supports bind to a target module name, not to an
+instance path.
+
+
+Class
+-----
+
+Verilator class support is limited but in active development.  Verilator
+supports members, and methods. Verilator does not support class static
+members, class extend, or class parameters.
+
+
+Dotted cross-hierarchy references
+---------------------------------
+
+Verilator supports dotted references to variables, functions and tasks in
+different modules. The portion before the dot must have a constant value;
+for example a[2].b is acceptable, while a[x].b is generally not.
+
+References into generated and arrayed instances use the instance names
+specified in the Verilog standard; arrayed instances are named
+``{instanceName}[{instanceNumber}]`` in Verilog, which becomes
+``{instanceName}__BRA__{instanceNumber}__KET__`` inside the generated C++
+code.
+
+
+Latches
+-------
+
+Verilator is optimized for edge sensitive (flop based) designs.  It will
+attempt to do the correct thing for latches, but most performance
+optimizations will be disabled around the latch.
+
+
+Structures and Unions
+---------------------
+
+Presently Verilator only supports packed structs and packed unions.  Rand
+and randc tags on members are simply ignored.  All structures and unions
+are represented as a single vector, which means that generating one member
+of a structure from blocking, and another from non-blocking assignments is
+unsupported.
+
+
+Time
+----
+
+All delays (#) are ignored, as they are in synthesis.
+
+
+.. _Unknown States:
+
+Unknown States
+--------------
+
+Verilator is mostly a two state simulator, not a four state simulator.
+However, it has two features which uncover most initialization bugs
+(including many that a four state simulator will miss.)
+
+Identity comparisons (=== or !==) are converted to standard ==/!= when
+neither side is a constant.  This may make the expression yield a different
+result compared to a four state simulator.  An === comparison to X will
+always be false, so that Verilog code which checks for uninitialized logic
+will not fire.
+
+Assigning X to a variable will actually assign a constant value as
+determined by the :vlopt:`--x-assign` option.  This allows runtime
+randomization, thus if the value is actually used, the random value should
+cause downstream errors.  Integers also get randomized, even though the
+Verilog 2001 specification says they initialize to zero.  Note however that
+randomization happens at initialization time and hence during a single
+simulation run, the same constant (but random) value will be used every
+time the assignment is executed.
+
+All variables, depending on :vlopt:`--x-initial` setting, are typically
+randomly initialized using a function.  By running several random
+simulation runs you can determine that reset is working correctly.  On the
+first run, have the function initialize variables to zero.  On the second,
+have it initialize variables to one.  On the third and following runs have
+it initialize them randomly.  If the results match, reset works.  (Note
+this is what the hardware will really do.)  In practice, just setting all
+variables to one at startup finds most problems (since typically control
+signals are active-high).
+
+:vlopt:`--x-assign` applies to variables explicitly initialized or assigned
+an X. Uninitialized clocks are initialized to zero, while all other state
+holding variables are initialized to a random value.  Event driven
+simulators will generally trigger an edge on a transition from X to 1
+(posedge) or X to 0 (negedge). However, by default, since clocks are
+initialized to zero, Verilator will not trigger an initial negedge. Some
+code (particularly for reset) may rely on X->0 triggering an edge. The
+:vlopt:`--x-initial-edge` option enables this behavior. Comparing runs with
+and without this option will find such problems.
+
+
+Tri/Inout
+---------
+
+Verilator converts some simple tristate structures into two state.  Pullup,
+pulldown, bufif0, bufif1, notif0, notif1, pmos, nmos, tri0 and tri1 are
+also supported.  Simple comparisons with :code:`=== 1'bz` are also
+supported.
+
+An assignment of the form:
+
+.. code-block:: sv
+
+        inout driver;
+        wire driver = (enable) ? output_value : 1'bz;
+
+Will be converted to:
+
+.. code-block:: sv
+
+        input driver;       // Value being driven in from "external" drivers
+        output driver__en;  // True if driven from this module
+        output driver__out; // Value being driven from this module
+
+External logic will be needed to combine these signals with any external
+drivers.
+
+Tristate drivers are not supported inside functions and tasks; an inout
+there will be considered a two state variable that is read and written
+instead of a four state variable.
+
+
+Functions & Tasks
+-----------------
+
+All functions and tasks will be inlined (will not become functions in C.)
+The only support provided is for simple statements in tasks (which may
+affect global variables).
+
+Recursive functions and tasks are not supported.  All inputs and outputs
+are automatic, as if they had the Verilog 2001 "automatic" keyword
+prepended.  (If you don't know what this means, Verilator will do what you
+probably expect, what C does. The default behavior of Verilog is
+different.)
+
+
+Generated Clocks
+----------------
+
+Verilator attempts to deal with generated and gated clocks correctly,
+however some cases cause problems in the scheduling algorithm which is
+optimized for performance.  The safest option is to have all clocks as
+primary inputs to the model, or wires directly attached to primary inputs.
+For proper behavior clock enables may also need the
+:option:`/*verilator&32;clock_enable*/` metacomment.
+
+
+Gate Primitives
+---------------
+
+The 2-state gate primitives (and, buf, nand, nor, not, or, xnor, xor) are
+directly converted to behavioral equivalents.  The 3-state and MOS gate
+primitives are not supported.  Tables are not supported.
+
+
+Specify blocks
+--------------
+
+All specify blocks and timing checks are ignored. All min:typ:max delays
+use the typical value.
+
+
+Array Initialization
+--------------------
+
+When initializing a large array, you need to use non-delayed assignments.
+Verilator will tell you when this needs to be fixed; see the BLKLOOPINIT
+error for more information.
+
+
+Array Out of Bounds
+-------------------
+
+Writing a memory element that is outside the bounds specified for the array
+may cause a different memory element inside the array to be written
+instead.  For power-of-2 sized arrays, Verilator will give a width warning
+and the address.  For non-power-of-2-sizes arrays, index 0 will be written.
+
+Reading a memory element that is outside the bounds specified for the array
+will give a width warning and wrap around the power-of-2 size.  For
+non-power-of-2 sizes, it will return a unspecified constant of the
+appropriate width.
+
+
+Assertions
+----------
+
+Verilator is beginning to add support for assertions.  Verilator currently
+only converts assertions to simple :code:`if (...) error` statements, and
+coverage statements to increment the line counters described in the
+coverage section.
+
+Verilator does not support SEREs yet.  All assertion and coverage
+statements must be simple expressions that complete in one cycle.
+
+
+Encrypted Verilog
+-----------------
+
+Open source simulators like Verilator are unable to use encrypted RTL
+(i.e. IEEE P1735).  Talk to your IP vendor about delivering IP blocks via
+Verilator's :vlopt:`--protect-lib` feature.
+
+
+Language Keyword Limitations
+============================
+
+This section describes specific limitations for each language keyword.
+
+.. Hack to get long definition list:
+.. |cmdslong1| replace:: \`__FILE__, \`__LINE__, \`begin_keywords,
+   \`begin_keywords, \`begin_keywords, \`begin_keywords, \`begin_keywords,
+   \`define, \`else, \`elsif, \`end_keywords, \`endif, \`error, \`ifdef,
+   \`ifndef, \`include, \`line, \`systemc_ctor, \`systemc_dtor,
+   \`systemc_header, \`systemc_imp_header, \`systemc_implementation,
+   \`systemc_interface, \`undef, \`verilog
+
+|cmdslong1|
+  Fully supported.
+
+
+.. Hack to get long definition list:
+
+.. |cmdslong2| replace:: always, always_comb, always_ff, always_latch, and,
+   assign, begin, buf, byte, case, casex, casez, default, defparam,
+   do-while, else, end, endcase, endfunction, endgenerate, endmodule,
+   endspecify, endtask, final, for, function, generate, genvar, if,
+   initial, inout, input, int, integer, localparam, logic, longint,
+   macromodule, module, nand, negedge, nor, not, or, output, parameter,
+   posedge, reg, scalared, shortint, signed, supply0, supply1, task, time,
+   tri, typedef, var, vectored, while, wire, xnor, xor
+
+|cmdslong2|
+  Generally supported.
+
+++, -- operators
+  Increment/decrement can only be used as standalone statements or in
+  certain limited cases.
+
+'{} operator
+  Assignment patterns with order based, default, constant integer (array)
+  or member identifier (struct/union) keys are supported.  Data type keys
+  and keys which are computed from a constant expression are not supported.
+
+\`uselib
+  Uselib, a vendor specific library specification method, is ignored along
+  with anything following it until the end of that line.
+
+cast operator
+  Casting is supported only between simple scalar types, signed and
+  unsigned, not arrays nor structs.
+
+chandle
+  Treated as a "longint"; does not yet warn about operations that are
+  specified as illegal on chandles.
+
+disable
+  Disable statements may be used only if the block being disabled is a
+  block the disable statement itself is inside.  This was commonly used to
+  provide loop break and continue functionality before SystemVerilog added
+  the break and continue keywords.
+
+inside
+  Inside expressions may not include unpacked array traversal or $ as an
+  upper bound.  Case inside and case matches are also unsupported.
+
+interface
+  Interfaces and modports, including with generated data types are
+  supported.  Generate blocks around modports are not supported, nor are
+  virtual interfaces nor unnamed interfaces.
+
+shortreal
+  Short floating point (shortreal) numbers are converted to real. Most
+  other simulators either do not support float, or convert likewise.
+
+specify specparam
+  All specify blocks and timing checks are ignored.
+
+uwire
+  Verilator does not perform warning checking on uwires, it treats the
+  uwire keyword as if it were the normal wire keyword.
+
+$bits, $countbits, $countones, $finish, $isunknown, $onehot, $onehot0, $signed, $stime, $stop, $time, $unsigned,
+  Generally supported.
+
+$dump/$dumpports and related
+  $dumpfile or $dumpports will create a VCD or FST file (which is based on
+  the :vlopt:`--trace` option given when the model was Verilated). This
+  will take effect starting at the next eval() call.  If you have multiple
+  Verilated designs under the same C model, then this will dump signals
+  only from the design containing the $dumpvars.
+
+  $dumpvars and $dumpports module identifier is ignored; the traced
+  instances will always start at the top of the design. The levels argument
+  is also ignored, use tracing_on/tracing_off pragmas instead.
+
+  $dumpportson/$dumpportsoff/$dumpportsall/$dumpportslimit filename
+  argument is ignored, only a single trace file may be active at once.
+
+  $dumpall/$dumpportsall, $dumpon/$dumpportson, $dumpoff/$dumpportsoff, and
+  $dumplimit/$dumpportlimit are currently ignored.
+
+$error, $fatal, $info, $warning.
+  Generally supported.
+
+$exit, $finish, $stop
+  The rarely used optional parameter to $finish and $stop is ignored. $exit
+  is aliased to $finish.
+
+$fopen, $fclose, $fdisplay, $ferror, $feof, $fflush, $fgetc, $fgets, $fscanf, $fwrite, $fscanf, $sscanf
+  Generally supported.
+
+$fullskew, $hold, $nochange, $period, $recovery, $recrem, $removal, $setup, $setuphold, $skew, $timeskew, $width
+  All specify blocks and timing checks are ignored.
+
+$random, $urandom, $urandom_range
+  Use :vlopt:`+verilator+seed+\<value\>` runtime option to set the seed if
+  there is no $random nor $urandom optional argument to set the seed.
+  There is one random seed per C thread, not per module for $random, nor
+  per object for random stability of $urandom/$urandom_range.
+
+$readmemb, $readmemh
+  Read memory commands are supported.  Note Verilator and the Verilog
+  specification does not include support for readmem to multi-dimensional
+  arrays.
+
+$test$plusargs, $value$plusargs
+  Supported, but the instantiating C++/SystemC wrapper must call
+
+  .. code-block:: C++
+
+        Verilated::commandArgs(argc, argv);
+
+  to register the command line before calling $test$plusargs or
+  $value$plusargs.

docs/guide/overview.rst

@@ -0,0 +1,55 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+********
+Overview
+********
+
+Welcome to Verilator!
+
+The Verilator package converts Verilog [#]_ and SystemVerilog [#]_ hardware
+description language (HDL) designs into a C++ or SystemC model that after
+compiling can be executed.  Verilator is not a traditional simulator, but a
+compiler.
+
+Verilator is typically used as follows:
+
+1. The :command:`verilator` executable is invoked with parameters similar
+to GCC, or other simulators such as Cadence Verilog-XL/NC-Verilog, or
+Synopsys VCS.  Verilator reads the specified SystemVerilog code, lints it,
+optionally adds coverage and waveform tracing support, and compiles the
+design into a source level multithreaded C++ or SystemC "model".  The
+resulting model's C++ or SystemC code is output as .cpp and .h files. This
+is referred to as "Verilating" and the process is "to Verilate"; the output
+is a "Verilated" model.
+
+2. For simulation, a small user written C++ wrapper file is required, the
+"wrapper".  This wrapper defines the C++ standard function "main()" which
+instantiates the Verilated model as a C++/SystemC object.
+
+3. The user C++ wrapper, the files created by Verilator, a "runtime
+library" provided by Verilator, and if applicable SystemC libraries are
+then compiled using a C++ compiler to create a simulation executable.
+
+4. The resulting executable will perform the actual simulation, during
+"simulation runtime".
+
+5. If appropriately enabled, the executable may also generate waveform
+traces of the design that may be viewed.  It may also create coverage
+analysis data for post-analysis.
+
+The best place to get started is to try the :ref:`Examples`.
+
+
+.. [#] Verilog is defined by the `Institute of Electrical and Electronics
+       Engineers (IEEE) Standard for Verilog Hardware Description
+       Language`, Std. 1364, released in 1995, 2001, and 2005.  The
+       Verilator documentation uses the shorthand e.g. "IEEE 1394-2005" to
+       refer to the e.g. 2005 version of this standard.
+
+.. [#] SystemVerilog is defined by the `Institute of Electrical and
+       Electronics Engineers (IEEE) Standard for SystemVerilog - Unified
+       Hardware Design, Specification, and Verification Language`, Standard
+       1800, released in 2005, 2009, 2012, and 2017.  The Verilator
+       documentation uses the shorthand e.g. "IEEE 1800-2017" to refer to
+       the e.g. 2017 version of this standard.

docs/guide/simulating.rst

@@ -0,0 +1,379 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+.. _Simulating:
+
+************************************
+Simulating (Verilated-Model Runtime)
+************************************
+
+This section describes items related to simulating, that using a Verilated
+model's executable.  For the runtime arguments to a simulated model, see
+:ref:`Simulation Runtime Arguments`.
+
+
+.. _Benchmarking & Optimization:
+
+Benchmarking & Optimization
+===========================
+
+For best performance, run Verilator with the :vlopt:`-O3`
+:vlopt:`--x-assign fast <--x-assign>` :vlopt:`--x-initial fast
+<--x-initial>` :vlopt:`--noassert <--assert>` options.  The :vlopt:`-O3`
+option will require longer time to run Verilator, and :vlopt:`--x-assign
+fast <--x-assign>` :vlopt:`--x-initial fast <--x-assign>` may increase the
+risk of reset bugs in trade for performance; see the above documentation
+for these options.
+
+If using Verilated multithreaded, use ``numactl`` to ensure you are using
+non-conflicting hardware resources. See :ref:`Multithreading`.
+
+Minor Verilog code changes can also give big wins.  You should not have any
+UNOPTFLAT warnings from Verilator.  Fixing these warnings can result in
+huge improvements; one user fixed their one UNOPTFLAT warning by making a
+simple change to a clock latch used to gate clocks and gained a 60%
+performance improvement.
+
+Beyond that, the performance of a Verilated model depends mostly on your
+C++ compiler and size of your CPU's caches. Experience shows that large
+models are often limited by the size of the instruction cache, and as such
+reducing code size if possible can be beneficial.
+
+The supplied $VERILATOR_ROOT/include/verilated.mk file uses the OPT,
+OPT_FAST, OPT_SLOW and OPT_GLOBAL variables to control optimization. You
+can set these when compiling the output of Verilator with Make, for
+example:
+
+.. code-block:: bash
+
+     make OPT_FAST="-Os -march=native" -f Vour.mk Vour__ALL.a
+
+OPT_FAST specifies optimization options for those parts of the model that
+are on the fast path. This is mostly code that is executed every
+cycle. OPT_SLOW applies to slow-path code, which executes rarely, often
+only once at the beginning or end of simulation. Note that OPT_SLOW is
+ignored if VM_PARALLEL_BUILDS is not 1, in which case all generated code
+will be compiled in a single compilation unit using OPT_FAST. See also the
+Verilator :vlopt:`--output-split` option. The OPT_GLOBAL variable applies
+to common code in the runtime library used by Verilated models (shipped in
+$VERILATOR_ROOT/include). Additional C++ files passed on the verilator
+command line use OPT_FAST. The OPT variable applies to all compilation
+units in addition to the specific "OPT" variables described above.
+
+You can also use the :vlopt:`-CFLAGS` and/or :vlopt:`-LDFLAGS` options on
+the verilator command line to pass arguments directly to the compiler or
+linker.
+
+The default values of the "OPT" variables are chosen to yield good
+simulation speed with reasonable C++ compilation times. To this end,
+OPT_FAST is set to "-Os" by default. Higher optimization such as "-O2" or
+"-O3" may help (though often they provide only a very small performance
+benefit), but compile times may be excessively large even with medium sized
+designs. Compilation times can be improved at the expense of simulation
+speed by reducing optimization, for example with OPT_FAST="-O0". Often good
+simulation speed can be achieved with OPT_FAST="-O1 -fstrict-aliasing" but
+with improved compilation times. Files controlled by OPT_SLOW have little
+effect on performance and therefore OPT_SLOW is empty by default
+(equivalent to "-O0") for improved compilation speed. In common use-cases
+there should be little benefit in changing OPT_SLOW.  OPT_GLOBAL is set to
+"-Os" by default and there should rarely be a need to change it. As the
+runtime library is small in comparison to a lot of Verilated models,
+disabling optimization on the runtime library should not have a serious
+effect on overall compilation time, but may have detrimental effect on
+simulation speed, especially with tracing. In addition to the above, for
+best results use OPT="-march=native", the latest Clang compiler (about 10%
+faster than GCC), and link statically.
+
+Generally the answer to which optimization level gives the best user
+experience depends on the use case and some experimentation can pay
+dividends. For a speedy debug cycle during development, especially on large
+designs where C++ compilation speed can dominate, consider using lower
+optimization to get to an executable faster. For throughput oriented use
+cases, for example regressions, it is usually worth spending extra
+compilation time to reduce total CPU time.
+
+If you will be running many simulations on a single model, you can
+investigate profile guided optimization. With GCC, using GCC's
+"-fprofile-arcs", then GCC's "-fbranch-probabilities" will yield another
+15% or so.
+
+Modern compilers also support link-time optimization (LTO), which can help
+especially if you link in DPI code. To enable LTO on GCC, pass "-flto" in
+both compilation and link. Note LTO may cause excessive compile times on
+large designs.
+
+Unfortunately, using the optimizer with SystemC files can result in
+compilation taking several minutes. (The SystemC libraries have many little
+inlined functions that drive the compiler nuts.)
+
+If you are using your own makefiles, you may want to compile the Verilated
+code with ``--MAKEFLAGS -DVL_INLINE_OPT=inline``. This will inline
+functions, however this requires that all cpp files be compiled in a single
+compiler run.
+
+You may uncover further tuning possibilities by profiling the Verilog code.
+See :ref:`profiling`.
+
+When done optimizing, please let the author know the results.  We like to
+keep tabs on how Verilator compares, and may be able to suggest additional
+improvements.
+
+
+.. _Coverage Analysis:
+
+Coverage Analysis
+=================
+
+Verilator supports adding code to the Verilated model to support
+SystemVerilog code coverage.  With :vlopt:`--coverage`, Verilator enables
+all forms of coverage:
+
+* :ref:`User Coverage`
+* :ref:`Line Coverage`
+* :ref:`Toggle Coverage`
+
+When a model with coverage is executed, it will create a coverage file for
+collection and later analysis, see :ref:`Coverage Collection`.
+
+
+.. _User Coverage:
+
+Functional Coverage
+-------------------
+
+With :vlopt:`--coverage` or :vlopt:`--coverage-user`, Verilator will
+translate functional coverage points which the user has inserted manually
+into the SystemVerilog design, into the Verilated model.
+
+Currently, all functional coverage points are specified using SystemVerilog
+assertion syntax which must be separately enabled with :vlopt:`--assert`.
+
+For example, the following SystemVerilog statement will add a coverage
+point, under the coverage name "DefaultClock":
+
+.. code-block:: sv
+
+    DefaultClock: cover property (@(posedge clk) cyc==3);
+
+
+.. _Line Coverage:
+
+Line Coverage
+-------------
+
+With :vlopt:`--coverage` or :vlopt:`--coverage-line`, Verilator will
+automatically add coverage analysis at each code flow change point (e.g. at
+branches).  At each such branch a unique counter is incremented.  At the
+end of a test, the counters along with the filename and line number
+corresponding to each counter are written into the coverage file.
+
+Verilator automatically disables coverage of branches that have a $stop in
+them, as it is assumed $stop branches contain an error check that should
+not occur.  A :option:`/*verilator&32;coverage_block_off*/` metacomment
+will perform a similar function on any code in that block or below, or
+:option:`/*verilator&32;coverage_off*/` and
+:option:`/*verilator&32;coverage_on*/` will disable and enable coverage
+respectively around a block of code.
+
+Verilator may over-count combinatorial (non-clocked) blocks when those
+blocks receive signals which have had the UNOPTFLAT warning disabled; for
+most accurate results do not disable this warning when using coverage.
+
+
+.. _Toggle Coverage:
+
+Toggle Coverage
+---------------
+
+With :vlopt:`--coverage` or :vlopt:`--coverage-toggle`, Verilator will
+automatically add toggle coverage analysis  into the Verilated model.
+
+Every bit of every signal in a module has a counter inserted.  The counter
+will increment on every edge change of the corresponding bit.
+
+Signals that are part of tasks or begin/end blocks are considered local
+variables and are not covered.  Signals that begin with underscores (see
+:vlopt:`--coverage-underscore`), are integers, or are very wide (>256 bits
+total storage across all dimensions, see :vlopt:`--coverage-max-width`) are
+also not covered.
+
+Hierarchy is compressed, such that if a module is instantiated multiple
+times, coverage will be summed for that bit across **all** instantiations
+of that module with the same parameter set.  A module instantiated with
+different parameter values is considered a different module, and will get
+counted separately.
+
+Verilator makes a minimally-intelligent decision about what clock domain
+the signal goes to, and only looks for edges in that clock domain.  This
+means that edges may be ignored if it is known that the edge could never be
+seen by the receiving logic.  This algorithm may improve in the future.
+The net result is coverage may be lower than what would be seen by looking
+at traces, but the coverage is a more accurate representation of the
+quality of stimulus into the design.
+
+There may be edges counted near time zero while the model stabilizes.  It's
+a good practice to zero all coverage just before releasing reset to prevent
+counting such behavior.
+
+A :option:`/*verilator&32;coverage_off*/`
+:option:`/*verilator&32;coverage_on*/` metacomment pair can be used around
+signals that do not need toggle analysis, such as RAMs and register files.
+
+
+.. _Coverage Collection:
+
+Coverage Collection
+-------------------
+
+When any coverage flag was used to Verilate, Verilator will add appropriate
+coverage point insertions into the model and collect the coverage data.
+
+To get the coverage data from the model, in the user wrapper code,
+typically at the end once a test passes, call
+:code:`Verilated::coveragep()->write` with an argument of the filename for
+the coverage data file to write coverage data to (typically
+"logs/coverage.dat").
+
+Run each of your tests in different directories, potentially in parallel.
+Each test will create a :file:`logs/coverage.dat` file.
+
+After running all of the tests, execute the :command:`verilator_coverage`
+command, passing arguments pointing to the filenames of all of the
+individual coverage files.  :command:`verilator_coverage` will reads the
+:file:`logs/coverage.dat` file(s), and create an annotated source code
+listing showing code coverage details.
+
+:command:`verilator_coverage` may also be used for test grading, that is
+computing which tests are important to fully cover the design.
+
+For an example, see the :file:`examples/make_tracing_c/logs` directory.
+Grep for lines starting with '%' to see what lines Verilator believes need
+more coverage.
+
+Additional options of :command:`verilator_coverage` allow for merging of
+coverage data files or other transformations.
+
+Info files can be written by verilator_coverage for import to
+:command:`lcov`.  This enables use of :command:`genhtml` for HTML reports
+and importing reports to sites such as `https://codecov.io
+<https://codecov.io>`_.
+
+
+.. _Profiling:
+
+Code Profiling
+==============
+
+The Verilated model may be code-profiled using GCC or Clang's C++ profiling
+mechanism.  Verilator provides additional flags to help map the resulting
+C++ profiling results back to the original Verilog code responsible for the
+profiled C++ code functions.
+
+To use profiling:
+
+#. Use Verilator's :vlopt:`--prof-cfuncs`.
+#. Build and run the simulation model.
+#. The model will create gmon.out.
+#. Run :command:`gprof` to see where in the C++ code the time is spent.
+#. Run the gprof output through the :command:`verilator_profcfunc` program
+   and it will tell you what Verilog line numbers on which most of the time
+   is being spent.
+
+
+.. _Thread Profiling:
+
+Thread Profiling
+================
+
+When using multithreaded mode (:vlopt:`--threads`), it is useful to see
+statistics and visualize how well the multiple CPUs are being utilized.
+
+With the :vlopt:`--prof-threads` option, Verilator will:
+
+* Add code to the Verilated model to record the start and end time of each
+  macro-task across a number of calls to eval. (What is a macro-task?  See
+  the Verilator internals document (:file:`docs/internals.rst` in the
+  distribution.)
+
+* Add code to save profiling data in non-human-friendly form to the file
+  specified with :vlopt:`+verilator+prof+threads+file+\<filename\>`.
+
+The :command:`verilator_gantt` program may then be run to transform the
+saved profiling file into a nicer visual format and produce some related
+statistics.
+
+.. figure:: figures/fig_gantt_min.png
+
+   Example verilator_gantt output, as viewed with GTKWave.
+
+   The parallelism shows the number of CPUs being used at a given moment.
+
+   The cpu_thread section shows which thread is executing on each of the physical CPUs.
+
+   The thread_mtask section shows which macro-task is running on a given thread.
+
+For more information see :command:`verilator_gantt`.
+
+.. _Profiling ccache efficiency:
+
+Profiling ccache efficiency
+===========================
+
+The Verilator generated Makefile provides support for basic profiling of
+ccache behavior during the build. This can be used to track down files that
+might be unnecessarily rebuilt, though as of today even small code changes
+will usually require rebuilding a large number of files. Improving ccache
+efficiency during the edit/compile/test loop is an active area of
+development.
+
+To get a basic report of how well ccache is doing, add the `ccache-report`
+target when invoking the generated Makefile:
+
+.. code-block:: bash
+
+     make -C obj_dir -f Vout.mk Vout ccache-report
+
+This will print a report based on all executions of ccache during this
+invocation of Make. The report is also written to a file, in this example
+`obj_dir/Vout__cache_report.txt`.
+
+To use the `ccache-report` target, at least one other explicit build target
+must be specified, and OBJCACHE must be set to 'ccache'.
+
+This feature is currently experimental and might change in subsequent
+releases.
+
+.. _Save/Restore:
+
+Save/Restore
+============
+
+The intermediate state of a Verilated model may be saved, so that it may
+later be restored.
+
+To enable this feature, use :vlopt:`--savable`.  There are limitations in
+what language features are supported along with :vlopt:`--savable`; if you
+attempt to use an unsupported feature Verilator will throw an error.
+
+To use save/restore, the user wrapper code must create a VerilatedSerialize
+or VerilatedDeserialze object then calling the :code:`<<` or :code:`>>`
+operators on the generated model and any other data the process needs
+saved/restored.  These functions are not thread safe, and are typically
+called only by a main thread.
+
+For example:
+
+.. code-block:: C++
+
+     void save_model(const char* filenamep) {
+         VerilatedSave os;
+         os.open(filenamep);
+         os << main_time;  // user code must save the timestamp, etc
+         os << *topp;
+     }
+     void restore_model(const char* filenamep) {
+         VerilatedRestore os;
+         os.open(filenamep);
+         os >> main_time;
+         os >> *topp;
+     }

docs/guide/verilating.rst

@@ -0,0 +1,492 @@
+.. Copyright 2003-2021 by Wilson Snyder.
+.. SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
+
+**********
+Verilating
+**********
+
+Verilator may be used in five major ways:
+
+* With the :vlopt:`--cc` or :vlopt:`--sc` options, Verilator will translate
+  the design into C++ or SystemC code respectively.  See :ref:`C++ and
+  SystemC Generation`.
+
+* With the :vlopt:`--lint-only` option, Verilator will lint the design to
+  check for warnings but will not typically create any output files.
+
+* With the :vlopt:`--xml-only` option, Verilator will create XML output
+  that may be used to feed into other user-designed tools.  See
+  :file:`docs/xml.rst` in the distribution.
+
+* With the :vlopt:`-E` option, Verilator will preprocess the code according
+  to IEEE preprocessing rules, and write the output to standard out. This
+  is useful to feed other tools, and to debug how "\`define" statements are
+  expanded.
+
+
+.. _C++ and SystemC Generation:
+
+C++ and SystemC Generation
+==========================
+
+Verilator will translate a SystemVerilog design into C++ with the
+:vlopt:`--cc` option, or into SystemC with the :vlopt:`--sc` option.
+
+When using these options:
+
+#. Verilator reads the input Verilog code, determines all "top modules" that
+   is modules or programs that are not used as instances under other cells.
+   If :vlopt:`--top-module` is used, then that determines the top module and
+   all other top modules are removed, otherwise a :vlopt:`MULTITOP` warning
+   is given.
+
+#. Verilator writes the C++/SystemC code to output files into the
+   :vlopt:`--Mdir` option-specified directory, or defaults to "obj_dir".
+   The prefix is set with :vlopt:`--prefix`, or defaults to the name of the
+   top module.
+
+#. If :vlopt:`--exe` is used, Verilator creates makefiles to generate a
+   simulation executable, otherwise it creates makefiles to generate an
+   archive (.a) containing the objects.
+
+#. If :vlopt:`--build` option was used, it calls :ref:`GNU Make` or
+   :ref:`CMake` to build the model.
+
+Once a model is built it is then typically run, see :ref:`Simulating`.
+
+
+.. _Hierarchical Verilation:
+
+Hierarchical Verilation
+=======================
+
+Large designs may take long (e.g. 10+ minutes) and huge memory (e.g. 100+
+GB) to Verilate.  In hierarchical mode, the user manually selects some
+large lower-level hierarchy blocks to separate from the larger design. For
+example a core may be the hierarchy block, and separated out of a
+multi-core SoC.
+
+Verilator is run in hierarchical mode on the whole SoC.  Verilator will
+make two models, one for the CPU hierarchy block, and one for the SoC.  The
+Verialted code for the SoC will automatically call the CPU Verilated model.
+
+The current hierarchical Verilation is based on protect-lib. Each hierarchy
+block is Verilated to a protect-lib. User modules of the hierarchy blocks
+will see a tiny wrapper generated by protect-lib instead of the actual
+design.
+
+
+Usage
+-----
+
+Users need to mark one or more moderate size module as hierarchy block(s).
+There are two ways to mark a module:
+
+* Write :option:`/*verilator&32;hier_block*/` metacomment in HDL code.
+
+* Add a :option:`hier_block` line in a the :ref:`Configuration Files`.
+
+Then pass the :vlopt:`--hierarchical` option to Verilator
+
+Compilation is the same as when not using hierarchical mode.
+
+.. code-block:: bash
+
+    make -C obj_dir -f Vtop_module_name.mk
+
+
+Limitations
+-----------
+
+Hierarchy blocks have some limitations including:
+
+* The hierarchy block cannot be accessed using dot (.) from upper module(s)
+  or other hierarchy blocks.
+
+* Signals in the block cannot be traced.
+
+* Modport cannot be used at the hierarchical block boundary.
+
+* The simulation speed is likely to not be as fast as flat Verilation, in
+  which all modules are globally scheduled.
+
+* Generated clocks may not work correctly if they are generated in the
+  hierarchical model and pass up into another hierarchical model or the top
+  module.
+
+But, the following usage is supported:
+
+* Nested hierarchy blocks. A hierarchy block may instantiate other
+  hierarchy blocks.
+
+* Parameterized hierarchy block. Parameters of a hierarchy block can be
+  overridden using :code:`#(.param_name(value))` construct.
+
+
+.. _Overlapping Verilation and Compilation:
+
+Overlapping Verilation and Compilation
+--------------------------------------
+
+Verilator needs to run 2 + *N* times in hierarchical Verilation, where *N*
+is the number of hierarchy blocks. One of the two is for the top module
+which refers wrappers of all other hierarchy blocks.  The second one of the
+two is the initial run that searches modules marked with
+:option:`/*verilator&32;hier_block*/` metacomment and creates a plan and
+write in :file:`{prefix}_hier.mk`.  This initial run internally invokes
+other *N* + 1 runs, so you don't have to care about these *N* + 1 times of
+run. The additional *N* is the Verilator run for each hierarchical block.
+
+If ::vlopt:`-j {jobs} <-j>` option is specified, Verilation for hierarchy
+blocks runs in parallel.
+
+If :vlopt:`--build` option is specified, C++ compilation also runs as soon
+as a hierarchy block is Verilated. C++ compilation and Verilation for other
+hierarchy blocks run simultaneously.
+
+
+Cross Compilation
+=================
+
+Verilator supports cross-compiling Verilated code.  This is generally used
+to run Verilator on a Linux system and produce C++ code that is then compiled
+on Windows.
+
+Cross compilation involves up to three different OSes.  The build system is
+where you configured and compiled Verilator, the host system where you run
+Verilator, and the target system where you compile the Verilated code and
+run the simulation.
+
+Currently, Verilator requires the build and host system type to be the
+same, though the target system type may be different.  To support this,
+:command:`./configure` and make Verilator on the build system.  Then, run
+Verilator on the host system.  Finally, the output of Verilator may be
+compiled on the different target system.
+
+To support this, none of the files that Verilator produces will reference
+any configure generated build-system specific files, such as
+:file:`config.h` (which is renamed in Verilator to :file:`config_build.h`
+to reduce confusion.)  The disadvantage of this approach is that
+:file:`include/verilatedos.h` must self-detect the requirements of the
+target system, rather than using configure.
+
+The target system may also require edits to the Makefiles, the simple
+Makefiles produced by Verilator presume the target system is the same type
+as the build system.
+
+
+.. _Multithreading:
+
+Multithreading
+==============
+
+Verilator supports multithreaded simulation models.
+
+With :vlopt:`--no-threads`, the default, the model is not thread safe, and
+any use of more than one thread calling into one or even different
+Verilated models may result in unpredictable behavior. This gives the
+highest single thread performance.
+
+With :vlopt:`--threads 1 <--threads>`, the generated model is single
+threaded, however the support libraries are multithread safe. This allows
+different instantiations of model(s) to potentially each be run under a
+different thread. All threading is the responsibility of the user's C++
+testbench.
+
+With :vlopt:`--threads {N} <--threads>`, where N is at least 2, the
+generated model will be designed to run in parallel on N threads. The
+thread calling eval() provides one of those threads, and the generated
+model will create and manage the other N-1 threads. It's the client's
+responsibility not to oversubscribe the available CPU cores. Under CPU
+oversubscription, the Verilated model should not livelock nor deadlock,
+however, you can expect performance to be far worse than it would be with
+proper ratio of threads and CPU cores.
+
+The remainder of this section describe behavior with :vlopt:`--threads 1
+<--threads>` or :vlopt:`--threads {N} <--threads>` (not
+:vlopt:`--no-threads`).
+
+:code:`VL_THREADED` is defined in the C++ code when compiling a threaded
+Verilated module, causing the Verilated support classes become threadsafe.
+
+The thread used for constructing a model must be the same thread that calls
+:code:`eval()` into the model, this is called the "eval thread". The thread
+used to perform certain global operations such as saving and tracing must
+be done by a "main thread". In most cases the eval thread and main thread
+are the same thread (i.e. the user's top C++ testbench runs on a single
+thread), but this is not required.
+
+The :vlopt:`--trace-threads` options can be used to produce trace dumps
+using multiple threads. If :vlopt:`--trace-threads` is set without
+:vlopt:`--threads`, then :vlopt:`--trace-threads` will imply
+:vlopt:`--threads 1 <--threads>`, i.e.: the support libraries will be
+thread safe.
+
+With :vlopt:`--trace-threads 0 <--trace-threads>`, trace dumps are produced
+on the main thread. This again gives the highest single thread performance.
+
+With :vlopt:`--trace-threads {N} <--trace-threads>`, where N is at least 1,
+N additional threads will be created and managed by the trace files (e.g.:
+VerilatedVcdC or VerilatedFstC), to generate the trace dump. The main
+thread will be released to proceed with execution as soon as possible,
+though some blocking of the main thread is still necessary while capturing
+the trace. Different trace formats can utilize a various number of
+threads. See the :vlopt:`--trace-threads` option.
+
+When running a multithreaded model, the default Linux task scheduler often
+works against the model, by assuming threads are short lived, and thus
+often schedules threads using multiple hyperthreads within the same
+physical core. For best performance use the :command:`numactl` program to
+(when the threading count fits) select unique physical cores on the same
+socket. The same applies for :vlopt:`--trace-threads` as well.
+
+As an example, if a model was Verilated with :vlopt:`--threads 4
+<--threads>`, we consult:
+
+.. code-block:: bash
+
+    egrep 'processor|physical id|core id' /proc/cpuinfo
+
+To select cores 0, 1, 2, and 3 that are all located on the same socket (0)
+but different physical cores.  (Also useful is :command:`numactl
+--hardware`, or :command:`lscpu` but those doesn't show Hyperthreading
+cores.) Then we execute:
+
+.. code-block:: bash
+
+    numactl -m 0 -C 0,1,2,3 -- verilated_executable_name
+
+This will limit memory to socket 0, and threads to cores 0, 1, 2, 3,
+(presumably on socket 0) optimizing performance.  Of course this must be
+adjusted if you want another simulator using e.g. socket 1, or if you
+Verilated with a different number of threads.  To see what CPUs are
+actually used, use :vlopt:`--prof-threads`.
+
+
+Multithreaded Verilog and Library Support
+-----------------------------------------
+
+$display/$stop/$finish are delayed until the end of an eval() call in order
+to maintain ordering between threads. This may result in additional tasks
+completing after the $stop or $finish.
+
+If using :vlopt:`--coverage`, the coverage routines are fully thread safe.
+
+If using the DPI, Verilator assumes pure DPI imports are thread safe,
+balancing performance versus safety. See :vlopt:`--threads-dpi`.
+
+If using :vlopt:`--savable`, the save/restore classes are not multithreaded
+and must be called only by the eval thread.
+
+If using :vlopt:`--sc`, the SystemC kernel is not thread safe, therefore
+the eval thread and main thread must be the same.
+
+If using :vlopt:`--trace`, the tracing classes must be constructed and
+called from the main thread.
+
+If using :vlopt:`--vpi`, since SystemVerilog VPI was not architected by
+IEEE to be multithreaded, Verilator requires all VPI calls are only made
+from the main thread.
+
+
+.. _GNU Make:
+
+GNU Make
+========
+
+Verilator defaults to creating GNU Make makefiles for the model.  Verilator
+will call make automatically when the :vlopt:'--build' option is used.
+
+If calling Verilator from a makefile, the :vlopt:'-MMD' option will create
+a dependency file which will allow Make to only run Verilator if input
+Verilog files change.
+
+.. _CMake:
+
+CMake
+=====
+
+Verilator can be run using CMake, which takes care of both running
+Verilator and compiling the output. There is a CMake example in the
+examples/ directory. The following is a minimal CMakeLists.txt that would
+build the code listed in :ref:`Example C++ Execution`
+
+.. code-block:: CMake
+
+     project(cmake_example)
+     find_package(verilator HINTS $ENV{VERILATOR_ROOT})
+     add_executable(Vour sim_main.cpp)
+     verilate(Vour SOURCES our.v)
+
+:code:`find_package` will automatically find an installed copy of
+Verilator, or use a local build if VERILATOR_ROOT is set.
+
+It is recommended to use CMake >= 3.12 and the Ninja generator, though
+other combinations should work. To build with CMake, change to the folder
+containing CMakeLists.txt and run:
+
+.. code-block:: bash
+
+     mkdir build
+     cd build
+     cmake -GNinja ..
+     ninja
+
+Or to build with your system default generator:
+
+.. code-block:: bash
+
+     mkdir build
+     cd build
+     cmake ..
+     cmake --build .
+
+If you're building the example you should have an executable to run:
+
+.. code-block:: bash
+
+     ./Vour
+
+The package sets the CMake variables verilator_FOUND, VERILATOR_ROOT and
+VERILATOR_BIN to the appropriate values, and also creates a verilate()
+function. verilate() will automatically create custom commands to run
+Verilator and add the generated C++ sources to the target specified.
+
+Verilate in CMake
+-----------------
+
+.. code-block:: CMake
+
+     verilate(target SOURCES source ... [TOP_MODULE top] [PREFIX name]
+              [TRACE] [TRACE_FST] [SYSTEMC] [COVERAGE]
+              [INCLUDE_DIRS dir ...] [OPT_SLOW ...] [OPT_FAST ...]
+              [OPT_GLOBAL ..] [DIRECTORY dir] [THREADS num]
+              [TRACE_THREADS num] [VERILATOR_ARGS ...])
+
+Lowercase and ... should be replaced with arguments, the uppercase parts
+delimit the arguments and can be passed in any order, or left out entirely
+if optional.
+
+verilate(target ...) can be called multiple times to add other Verilog
+modules to an executable or library target.
+
+When generating Verilated SystemC sources, you should also include the
+SystemC include directories and link to the SystemC libraries.
+
+.. describe:: target
+
+   Name of a target created by add_executable or add_library.
+
+.. describe:: COVERAGE
+
+   Optional. Enables coverage if present, equivalent to "VERILATOR_ARGS
+   --coverage"
+
+.. describe:: DIRECTORY
+
+   Optional. Set the verilator output directory. It is preferable to use
+   the default, which will avoid collisions with other files.
+
+.. describe:: INCLUDE_DIRS
+
+   Optional. Sets directories that Verilator searches (same as -y).
+
+.. describe:: OPT_SLOW
+
+   Optional. Set compiler options for the slow path. You may want to reduce
+   the optimization level to improve compile times with large designs.
+
+.. describe:: OPT_FAST
+
+   Optional. Set compiler options for the fast path.
+
+.. describe:: OPT_GLOBAL
+
+   Optional. Set compiler options for the common runtime library used by
+   Verilated models.
+
+.. describe:: PREFIX
+
+   Optional. Sets the Verilator output prefix. Defaults to the name of the
+   first source file with a "V" prepended. Must be unique in each call to
+   verilate(), so this is necessary if you build a module multiple times
+   with different parameters. Must be a valid C++ identifier, i.e. contains
+   no white space and only characters A-Z, a-z, 0-9 or _.
+
+.. describe:: SOURCES
+
+   List of Verilog files to Verilate. Must have at least one file.
+
+.. describe:: SYSTEMC
+
+   Optional. Enables SystemC mode, defaults to C++ if not specified.
+
+   When using Accellera's SystemC with CMake support, a CMake target is
+   available that simplifies the SystemC steps. This will only work if the
+   SystemC installation can be found by CMake. This can be configured by
+   setting the CMAKE_PREFIX_PATH variable during CMake configuration.
+
+   Don't forget to set the same C++ standard for the Verilated sources as
+   the SystemC library. This can be specified using the SYSTEMC_CXX_FLAGS
+   environment variable.
+
+.. describe:: THREADS
+
+   Optional. Generated a multi-threaded model, same as "--threads".
+
+.. describe:: TRACE_THREADS
+
+   Optional. Generated multi-threaded trace dumping, same as
+   "--trace-threads".
+
+.. describe:: TOP_MODULE
+
+   Optional. Sets the name of the top module. Defaults to the name of the
+   first file in the SOURCES array.
+
+.. describe:: TRACE
+
+   Optional. Enables VCD tracing if present, equivalent to "VERILATOR_ARGS
+   --trace".
+
+.. describe:: TRACE_FST
+
+   Optional. Enables FST tracing if present, equivalent to "VERILATOR_ARGS
+   --trace-fst".
+
+.. describe:: VERILATOR_ARGS
+
+   Optional. Extra arguments to Verilator. Do not specify :vlopt:`--Mdir`
+   or :vlopt:`--prefix` here, use DIRECTORY or PREFIX.
+
+
+SystemC Link in CMake
+---------------------
+
+Verilator's CMake support provides a convenience function to automatically
+find and link to the SystemC library.  It can be used as:
+
+.. code-block:: CMake
+
+     verilator_link_systemc(target)
+
+where target is the name of your target.
+
+The search paths can be configured by setting some variables:
+
+.. describe:: SYSTEMC_INCLUDE
+
+   Sets the direct path to the SystemC includes.
+
+.. describe:: SYSTEMC_LIBDIR
+
+   Sets the direct path to the SystemC libraries.
+
+.. describe:: SYSTEMC_ROOT
+
+   Sets the installation prefix of an installed SystemC library.
+
+.. describe:: SYSTEMC
+
+   Sets the installation prefix of an installed SystemC library. (Same as
+   SYSTEMC_ROOT).