Add `--preproc-defines`.

Changes

@@ -27,6 +27,7 @@ Verilator 5.041 devel
 * Add NORETURN warning on functions without return values (#6534). [Alex Solomatnikov]
 * Add `--aslr` and `--no-aslr` options.
 * Add `$cpure` (#6580). [Igor Zaworski, Antmicro Ltd.]
+* Add `--preproc-defines`.
 * Deprecate sensitivity list on public_flat_rw attributes (#6443). [Geza Lore]
 * Deprecate clocker attribute and --clk option (#6463). [Geza Lore]
 * Deprecate '--make cmake' option (#6540). [Geza Lore]

bin/verilator

@@ -455,6 +455,7 @@ detailed descriptions of these arguments.
     --pipe-filter <command>     Filter all input through a script
     --prefix <topname>          Name of top-level class
     --preproc-comments          Include preprocessor comments in the output with -E
+    --preproc-defines           Include preprocessor defines in the output with -E
     --preproc-resolve           Include all found modules in the output with -E
     --preproc-token-limit       Maximum tokens on a line allowed by preprocessor
     --private                   Debugging; see docs

docs/guide/exe_verilator.rst

@@ -1280,6 +1280,10 @@ Summary:
 
    With :vlopt:`-E`, show comments in preprocessor output.
 
+.. option:: --preproc-defines
+
+   With :vlopt:`-E`, show defines and undefs in preprocessor output.
+
 .. option:: --preproc-resolve
 
    With :vlopt:`-E`, resolve referenced instance modules, to include

src/V3Options.cpp

@@ -1618,6 +1618,7 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc,
         m_prefix = valp;
     });
     DECL_OPTION("-preproc-comments", OnOff, &m_preprocComments);
+    DECL_OPTION("-preproc-defines", OnOff, &m_preprocDefines);
     DECL_OPTION("-preproc-resolve", OnOff, &m_preprocResolve);
     DECL_OPTION("-preproc-token-limit", CbVal, [this, fl](const char* valp) {
         m_preprocTokenLimit = std::atoi(valp);

src/V3Options.h

@@ -268,6 +268,7 @@ private:
     bool m_pinsScBigUint = false;   // main switch: --pins-sc-biguint
     bool m_pinsUint8 = false;       // main switch: --pins-uint8
     bool m_preprocComments = false;  // main switch: --preproc-comments
+    bool m_preprocDefines = false;  // main switch: --preproc-defines
     bool m_profC = false;           // main switch: --prof-c
     bool m_profCFuncs = false;      // main switch: --prof-cfuncs
     bool m_profExec = false;        // main switch: --prof-exec
@@ -555,6 +556,7 @@ public:
     bool pinsScBigUint() const VL_MT_SAFE { return m_pinsScBigUint; }
     bool pinsUint8() const { return m_pinsUint8; }
     bool preprocComments() const { return m_preprocComments; }
+    bool preprocDefines() const { return m_preprocDefines; }
     bool profC() const { return m_profC; }
     bool profCFuncs() const { return m_profCFuncs; }
     bool profExec() const { return m_profExec; }

src/V3PreProc.cpp

@@ -307,8 +307,14 @@ void V3PreProc::selfTest() VL_MT_DISABLED { V3PreExpr::selfTest(); }
 //*************************************************************************
 // Defines
 
-void V3PreProcImp::undef(const string& name) { m_defines.erase(name); }
+void V3PreProcImp::undef(const string& name) {
+    if (v3Global.opt.preprocOnly() && v3Global.opt.preprocDefines())
+        insertUnreadback("`undef " + name + "\n");
+    m_defines.erase(name);
+}
 void V3PreProcImp::undefineall() {
+    if (v3Global.opt.preprocOnly() && v3Global.opt.preprocDefines())
+        insertUnreadback("`undefineall\n");
     for (DefinesMap::iterator nextit, it = m_defines.begin(); it != m_defines.end(); it = nextit) {
         nextit = it;
         ++nextit;
@@ -348,6 +354,18 @@ FileLine* V3PreProcImp::defFileline(const string& name) {
 void V3PreProcImp::define(FileLine* fl, const string& name, const string& value,
                           const string& params, bool cmdline) {
     UINFO(4, "DEFINE '" << name << "' as '" << value << "' params '" << params << "'");
+    if (v3Global.opt.preprocOnly() && v3Global.opt.preprocDefines()) {
+        // Any newlines in the string must have backslash escape so can re-parse properly
+        // If there was a comment with backslash, it got stripped because IEEE says
+        // the backslash is not part of the value
+        string out;
+        out.reserve(value.size());
+        for (string::size_type pos = 0; pos < value.size(); ++pos) {
+            if (value[pos] == '\n' && (pos == 0 || value[pos - 1] != '\\')) out += '\\';
+            out += value[pos];
+        }
+        insertUnreadback("`define " + name + params + (out.empty() ? "" : " ") + out + "\n");
+    }
     if (!V3LanguageWords::isKeyword("`"s + name).empty()) {
         fl->v3error("Attempting to define built-in directive: '`" << name
                                                                   << "' (IEEE 1800-2023 22.5.1)");
@@ -1335,7 +1353,7 @@ int V3PreProcImp::getStateToken() {
             // DEFVALUE is terminated by a return, but lex can't return both tokens.
             // Thus, we emit a return here.
             yyourtext(s_newlines.c_str(), s_newlines.length());
-            return (VP_WHITE);
+            return VP_WHITE;
         }
         case ps_DEFPAREN: {
             if (tok == VP_TEXT && yyourleng() == 1 && yyourtext()[0] == '(') {

test_regress/t/t_preproc.out

@@ -1079,3 +1079,17 @@ string boo = "testx,ytest x x,y";
 string boo = "testtest x,y xquux(test)";
 
 `line 757 "t/t_preproc.v" 0
+ 
+ 
+
+`line 760 "t/t_preproc.v" 0
+ 
+ 
+
+
+
+
+
+
+
+`line 769 "t/t_preproc.v" 0

test_regress/t/t_preproc.v

@@ -753,3 +753,15 @@ predef `SV_COV_PARTIAL 2
 `quux(`bar(`a,`a))
 `quux(`baz(`a,`bar(x,`a)))
 `quux(`baz(`bar(`a,x), quux(`foo)))
+
+//======================================================================
+// Define with --preproc-defines needs to keep backslashes
+
+`define uvm_a(x) foo x bar
+`define uvm_imp_decl(SFX) \
+class uvm_master_imp``SFX  \
+  `uvm_a(SFX, RSP, t) // rsp \
+  \
+  `uvm_a(SFX, REQ, t) // req \
+  \
+endclass

test_regress/t/t_preproc_comments.out

@@ -1084,3 +1084,17 @@ string boo = "testx,ytest x x,y";
 string boo = "testtest x,y xquux(test)";
 
 `line 757 "t/t_preproc.v" 0
+//====================================================================== 
+// Define with --preproc-defines needs to keep backslashes 
+
+`line 760 "t/t_preproc.v" 0
+ 
+ 
+
+
+
+
+
+
+
+`line 769 "t/t_preproc.v" 0

test_regress/t/t_preproc_defines.py

@@ -0,0 +1,25 @@
+#!/usr/bin/env python3
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2024 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
+
+import vltest_bootstrap
+
+test.scenarios('vlt')
+test.top_filename = "t/t_preproc.v"
+
+stdout_filename = os.path.join(test.obj_dir, test.name + "__test.vpp")
+
+test.compile(verilator_flags2=['-DDEF_A0 -DPREDEF_COMMAND_LINE -E --preproc-defines'],
+             verilator_make_gmake=False,
+             make_top_shell=False,
+             make_main=False,
+             stdout_filename=stdout_filename)
+
+test.files_identical(stdout_filename, test.golden_filename)
+
+test.passes()

test_regress/t/t_preproc_dump_defines.out

@@ -27,5 +27,13 @@
 `define foo test
 `define quux(x) `qux(`"x`")
 `define qux(x) string boo = x;
+`define uvm_a(x) foo x bar
+`define uvm_imp_decl(SFX) \
+class uvm_master_imp``SFX  \
+  `uvm_a(SFX, RSP, t) 
+  \
+  `uvm_a(SFX, REQ, t) 
+  \
+endclass
 `define verilator 1
 `define verilator3 1