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Fix zero-size parameter (#7387 repair) (#7411) (#7418) 

Fixes #7411.
This commit is contained in:
em2machine 2026-04-13 13:19:11 -04:00 committed by GitHub
parent 369a315c27
commit fd7a3f4a16
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GPG Key ID: B5690EEEBB952194
3 changed files with 95 additions and 15 deletions
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48
src/V3Param.cpp
View File

@ -1396,8 +1396,7 @@ class ParamProcessor final {
}
AstConst* const exprp = VN_CAST(pinp->exprp(), Const);
AstConst* const origp = VN_CAST(modvarp->valuep(), Const);
// Width the pin value to match the port type so that the same
// logical value always produces the same specialization name.
// Width the pin to the port's type so equal values hash the same (#5479).
AstConst* normedNamep = nullptr;
if (exprp && !exprp->num().isDouble() && !exprp->num().isString()) {
AstVar* cloneVarp = modvarp->cloneTree(false);
@ -1406,21 +1405,41 @@ class ParamProcessor final {
VL_DO_DANGLING(oldValuep->deleteTree(), oldValuep);
}
cloneVarp->valuep(exprp->cloneTree(false));
// Clone the dtype and resolve VarRefs to other parameters
// with their already-constified pin values (e.g., N-1 in
// logic [N-1:0] becomes Const-1 which can be folded).
if (AstNodeDType* const origDTypep = modvarp->subDTypep()) {
AstNodeDType* const dtypeClonep = origDTypep->cloneTree(false);
dtypeClonep->foreach([&](AstVarRef* varrefp) {
for (AstPin* pp = paramsp; pp; pp = VN_AS(pp->nextp(), Pin)) {
if (pp->modVarp() == varrefp->varp()) {
if (AstConst* const constp = VN_CAST(pp->exprp(), Const)) {
varrefp->replaceWith(constp->cloneTree(false));
VL_DO_DANGLING(varrefp->deleteTree(), varrefp);
// Inline every param ref so widthing doesn't reach back into the template
// (#7411). Cycle detector for dependent parameters in the same module.
constexpr int maxSubstIters = 1000;
for (int it = 0; it < maxSubstIters; ++it) {
bool any = false;
dtypeClonep->foreach([&](AstVarRef* varrefp) {
AstVar* const targetp = varrefp->varp();
AstNode* replacep = nullptr;
for (AstPin* pp = paramsp; pp; pp = VN_AS(pp->nextp(), Pin)) {
if (pp->modVarp() == targetp) {
if (AstConst* const constp = VN_CAST(pp->exprp(), Const)) {
replacep = constp->cloneTree(false);
}
break;
}
break;
}
}
if (!replacep && targetp->valuep()) {
replacep = targetp->valuep()->cloneTree(false);
}
if (replacep) {
varrefp->replaceWith(replacep);
VL_DO_DANGLING(varrefp->deleteTree(), varrefp);
any = true;
}
});
if (!any) break;
}
// Bail if anything still points at the template.
dtypeClonep->foreach([&](AstVarRef* varrefp) {
varrefp->v3fatalSrc(
"Unresolved VarRef '"
<< varrefp->prettyName() << "' in pin dtype clone. Pin: "
<< pinp->prettyNameQ() << " of " << nodep->prettyNameQ());
});
if (cloneVarp->childDTypep())
cloneVarp->childDTypep()->unlinkFrBack()->deleteTree();
@ -1429,8 +1448,7 @@ class ParamProcessor final {
}
V3Const::constifyParamsEdit(cloneVarp);
if (AstConst* const widthedp = VN_CAST(cloneVarp->valuep(), Const)) {
// Set the constant's dtype to the port's widthed type
// so identical values hash the same in paramValueNumber.
// Stamp the port's type on the const so equal values hash the same.
if (cloneVarp->dtypep()) widthedp->dtypep(cloneVarp->dtypep());
widthedp->unlinkFrBack();
normedNamep = widthedp;

18
test_regress/t/t_param_localparam_recompute.py Executable file
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@ -0,0 +1,18 @@
#!/usr/bin/env python3
# DESCRIPTION: Verilator: Verilog Test driver/expect definition
#
# 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-FileCopyrightText: 2026 Wilson Snyder
# SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
import vltest_bootstrap
test.scenarios('simulator')
test.compile(verilator_flags2=["--binary", "-Wno-WIDTHEXPAND"])
test.execute()
test.passes()

44
test_regress/t/t_param_localparam_recompute.v Normal file
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@ -0,0 +1,44 @@
// DESCRIPTION: Verilator: Reproducer for issue #7411.
//
// when V3Param widths a pin value against the port dtype the widthing must not
// edit any referenced template vars in place. A dependent localparam like
// dirs_lp = dims_p*2+1 must still recompute from the overridden dims_p on
// each specialization. (basically - don't poison the template)
//
// 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-FileCopyrightText: 2026 Wilson Snyder
// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
module sub #(
parameter int dims_p = 2,
parameter int dirs_lp = dims_p*2 + 1,
parameter bit [1:0][dirs_lp-1:0][dirs_lp-1:0] matrix_p = '0
) ();
endmodule
module t;
localparam bit [1:0][4:0][4:0] big_matrix = '1;
localparam bit [1:0][2:0][2:0] small_matrix = '1;
// First instance processes matrix_p with the template's default dims_p=2.
// Before the fix, this froze dirs_lp on the template at 5.
sub #(.matrix_p(big_matrix)) s1 ();
// Second instance overrides dims_p=1, so dirs_lp must recompute to 3.
sub #(.dims_p(1), .matrix_p(small_matrix)) s2 ();
initial begin
if (s1.dirs_lp !== 5) begin
$write("%%Error: s1.dirs_lp=%0d expected 5\n", s1.dirs_lp);
$stop;
end
if (s2.dirs_lp !== 3) begin
$write("%%Error: s2.dirs_lp=%0d expected 3\n", s2.dirs_lp);
$stop;
end
$write("*-* All Finished *-*\n");
$finish;
end
endmodule