These are useful for formal verification with SBY where they can be used
to display solver chosen `rand const reg` signals and signals derived
from those.
The previous error message for non-constant initial $display statements
is downgraded to a log message. Constant initial $display statements
will be shown both during elaboration and become part of the RTLIL so
that the `sim` output is complete.
This makes tests/verilog/dynamic_range_lhs.v pass, after ensuring that
nowrshmsk is actually tested.
Stride is extracted from indexing of two-dimensional packed arrays and
variable slices on the form dst[i*stride +: width] = src, and is used
to optimize the generated CASE block.
Also uses less confusing variable names for indexing of lhs wires.
Compiling on GCC hid this bug as it optimized the nullptr call away as
undefined behavior, but running the SBY tests with a clang build hits
this error.
Instead of passing around in_lvalue/in_param flags to simplify, we make
the flags into properties of the AST nodes themselves. After the tree
is first parsed, we once do
ast->fixup_hierarchy_flags(true)
to walk the full hierarchy and set the flags to their initial correct
values. Then as long as one is using ->clone(), ->cloneInto() and the
AstNode constructor (with children passed to it) to modify the tree, the
flags will be kept in sync automatically. On the other hand if we are
modifying the children list of an existing node, we may need to call
node->fixup_hierarchy_flags()
to do a localized fixup. That fixup will update the flags on the node's
children, and will propagate the change down the tree if necessary.
clone() doesn't always retain the flags of the subtree being cloned. It
will produce a tree with a consistent setting of the flags, but the
root doesn't have in_param/in_lvalue set unless it's intrinsic to the
type of node being cloned (e.g. AST_PARAMETER). cloneInto() will make
sure the cloned subtree has the flags consistent with the new placement
in a hierarchy.
Add asserts to make sure the old and new way of determining the flags
agree.
The following commit will replace the way in_lvalue/in_param is being
tracked in the simplify code. Make tweaks in advance so that it will
be easier to make the old way and the new way agree.
These changes all should be innocuous.
The correct way of using the 'at_zero' regime of simplify is to perform
the simplification on a cloned AST subtree, otherwise the "at_zero"
evaluation seeps into the main tree.
Move the effect of the 'at_zero' flag to the cloning itself, so that
the simplify flag can be retired. We assume we can rely on id2ast in
the new clone method.
It's a repeating pattern to print an error message tied to an AST
node. Start using an 'input_error' helper for that. Among other
things this is beneficial in shortening the print lines, which tend
to be long.
(* nowrshmsk *) on a struct / union variable now affects dynamic
bit slice assignments to members of the struct / union.
(* nowrshmsk *) can in some cases yield significant resource savings; the
combination of pipeline shifting and indexed writes is an example of this.
Constructs similar to the one below can benefit from (* nowrshmsk *), and
in addition it is no longer necessary to split out the shift assignments
on separate lines in order to avoid the error message "ERROR: incompatible
mix of lookahead and non-lookahead IDs in LHS expression."
always_ff @(posedge clk) begin
if (rotate) begin
{ v5, v4, v3, v2, v1, v0 } <= { v4, v3, v2, v1, v0, v5 };
if (res) begin
v0.bytes <= '0;
end else if (w) begin
v0.bytes[addr] <= data;
end
end
end
This brings the metadata for packed arrays in packed structs
in line with the metadata for unpacked arrays, and correctly
handles the case when both lsb and msb in an address range are
non-zero.
Otherwise the AST_CELL simplification uses the wrong celltype before the
AST_CELLARRAY simplification has a chance to unroll it and change it to
the $array celltype.
This is primarily intended to enable the standard-permitted use of
module-scoped identifiers to refer to tasks and non-constant functions.
As a side-effect, this also adds support for the non-standard use of
module-scoped identifiers referring to constant functions, a feature
that is supported in some other tools, including Iverilog.
genrtlil.cc and simplify.cc had inconsistent and slightly broken
handling of signedness for array querying functions. These functions are
defined to return a signed result. Simplify always produced an unsigned
and genrtlil always a signed 32-bit result ignoring the context.
Includes tests for the the relvant edge cases for context dependent
conversions.
- Attempt to lookup a derived module if it potentially contains a port
connection with elaboration ambiguities
- Mark the cell if module has not yet been derived
- This can be extended to implement automatic hierarchical port
connections in a future change
- Root AST_PREFIX nodes are now subject to genblk expansion to allow
them to refer to a locally-visible generate block
- Part selects on AST_PREFIX member leafs can now refer to generate
block items (previously would not resolve and raise an error)
- Add source location information to AST_PREFIX nodes
The recent fix for case expression width detection causes the width of
the expressions to be queried before they are simplified. Because the
logic supporting module scope identifiers only existed in simplify,
looking them up would fail during width detection. This moves the logic
to a common helper used in both simplify() and detectSignWidthWorker().
- The case expression and case item expressions are extended to the
maximum width among them, and are only interpreted as signed if all of
them are signed
- Add overall width and sign detection for AST_CASE
- Add sign argument to genWidthRTLIL helper
- Coverage for both const and non-const case statements
From IEEE1364-2005, section 7.3 buf and not gates:
> These two logic gates shall have one input and one or more outputs.
> The last terminal in the terminal list shall connect to the input of the
> logic gate, and the other terminals shall connect to the outputs of
> the logic gate.
yosys does not follow this and instead interprets the first argument as
the output, the second as the input and ignores the rest.
This defers the simplification of globals so that globals in one file
may depend on globals in other files. Adds a simplify() call downstream
because globals are appended at the end.
- Simplify synthetic localparams for normal calls to update their width
- This step was inadvertently removed alongside `added_mod_children`
- Support redeclaration of constant function arguments
- `eval_const_function` never correctly handled this, but the issue
was not exposed in the existing tests until the recent change to
always attempt constant function evaluation when all-const args
are used
- Check asserts in const_arg_loop and const_func tests
- Add coverage for width mismatch error cases
This adds a mechanism for marking certain portions of elaboration as
occurring within unevaluated ternary branches. To enable elaboration of
the overall ternary, this also adds width detection for these
unelaborated function calls.
Elaboration now attempts constant evaluation of any function call with
only constant arguments, regardless of the context or contents of the
function. This removes the concept of "recommended constant evaluation"
which previously applied to functions with `for` loops or which were
(sometimes erroneously) identified as recursive. Any function call in a
constant context (e.g., `localparam`) or which contains a constant-only
procedural construct (`while` or `repeat`) in its body will fail as
before if constant evaluation does not succeed.
This change set contains a number of bug fixes and improvements related to
scoping and resolution in generate and procedural blocks. While many of the
frontend changes are interdependent, it may be possible bring the techmap
changes in under a separate PR.
Declarations within unnamed generate blocks previously encountered issues
because the data declarations were left un-prefixed, breaking proper scoping.
The LRM outlines behavior for generating names for unnamed generate blocks. The
original goal was to add this implicit labelling, but doing so exposed a number
of issues downstream. Additional testing highlighted other closely related scope
resolution issues, which have been fixed. This change also adds support for
block item declarations within unnamed blocks in SystemVerilog mode.
1. Unlabled generate blocks are now implicitly named according to the LRM in
`label_genblks`, which is invoked at the beginning of module elaboration
2. The Verilog parser no longer wraps explicitly named generate blocks in a
synthetic unnamed generate block to avoid creating extra hierarchy levels
where they should not exist
3. The techmap phase now allows special control identifiers to be used outside
of the topmost scope, which is necessary because such wires and cells often
appear in unlabeled generate blocks, which now prefix the declarations within
4. Some techlibs required modifications because they relied on the previous
invalid scope resolution behavior
5. `expand_genblock` has been simplified, now only expanding the outermost
scope, completely deferring the inspection and elaboration of nested scopes;
names are now resolved by looking in the innermost scope and stepping outward
6. Loop variables now always become localparams during unrolling, allowing them
to be resolved and shadowed like any other identifier
7. Identifiers in synthetic function call scopes are now prefixed and resolved
in largely the same manner as other blocks
before: `$func$\func_01$tests/simple/scopes.blk.v:60$5$\blk\x`
after: `\func_01$func$tests/simple/scopes.v:60$5.blk.x`
8. Support identifiers referencing a local generate scope nested more
than 1 level deep, i.e. `B.C.x` while within generate scope `A`, or using a
prefix of a current or parent scope, i.e. `B.C.D.x` while in `A.B`, `A.B.C`,
or `A.B.C.D`
9. Variables can now be declared within unnamed blocks in SystemVerilog mode
Addresses the following issues: 656, 2423, 2493
The changes in #2476 ensured that function inputs like `input x;`
retained their single-bit size when instantiated with a constant
argument and turned into a localparam. That change did not handle the
possibility for an input to be redeclared later on with an explicit
width, such as `integer x;`.
Catherine
Martin Povišer
uis
Dag Lem
Jannis Harder
Charlotte
Zachary Snow
Miodrag Milanovic
Kamil Rakoczy
Marcelina Kościelnicka
Xiretza
Claire Xen
Michael Singer
clairexen
Udi Finkelstein