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Support unbounded always [m:$] and strong s_always liveness (#7798)

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This commit is contained in:
Yilou Wang
2026-06-18 11:17:09 -04:00
committed by GitHub
parent 22b45f0fd7
commit a5a16cfbfd
15 changed files with 289 additions and 56 deletions
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src/V3Width.cpp
+23 -17
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@@ -1563,33 +1563,39 @@ class WidthVisitor final : public VNVisitor {
}
const bool loUnbounded = VN_IS(nodep->loBoundp(), Unbounded);
const bool hiUnbounded = VN_IS(nodep->hiBoundp(), Unbounded);
if (loUnbounded || hiUnbounded) {
if (nodep->isStrong()) {
nodep->v3error("s_always range must be bounded (IEEE 1800-2023 16.12.11)");
} else {
nodep->v3warn(E_UNSUPPORTED,
"Unsupported: unbounded always range (always [m:$])");
}
// Strong always must be bounded (IEEE 1800-2023 16.12.11: "the range
// for a strong always shall be bounded"). Weak always [m:$] is legal:
// an unbounded upper bound imposes no end-of-trace obligation.
if (nodep->isStrong() && (loUnbounded || hiUnbounded)) {
AstNode* const boundp = loUnbounded ? nodep->loBoundp() : nodep->hiBoundp();
boundp->v3error("s_always range must be bounded (IEEE 1800-2023 16.12.11)");
nodep->dtypeSetBit();
return;
}
if (loUnbounded) {
// Only the high bound may be $ (cycle_delay_const_range_expression).
nodep->loBoundp()->v3error("always range low bound must be a constant expression"
" (IEEE 1800-2023 16.12.11)");
nodep->dtypeSetBit();
return;
}
const AstConst* const loConstp = VN_CAST(nodep->loBoundp(), Const);
const AstConst* const hiConstp = VN_CAST(nodep->hiBoundp(), Const);
if (!loConstp) {
nodep->v3error("always range low bound must be a constant expression"
" (IEEE 1800-2023 16.12.11)");
nodep->loBoundp()->v3error("always range low bound must be a constant expression"
" (IEEE 1800-2023 16.12.11)");
}
if (!hiConstp) {
nodep->v3error("always range high bound must be a constant expression"
" (IEEE 1800-2023 16.12.11)");
if (!hiUnbounded && !hiConstp) {
nodep->hiBoundp()->v3error("always range high bound must be a constant expression"
" (IEEE 1800-2023 16.12.11)");
}
if (loConstp && loConstp->toSInt() < 0) {
nodep->v3error("always range low bound must be non-negative"
" (IEEE 1800-2023 16.12.11)");
nodep->loBoundp()->v3error("always range low bound must be non-negative"
" (IEEE 1800-2023 16.12.11)");
}
if (loConstp && hiConstp && hiConstp->toSInt() < loConstp->toSInt()) {
nodep->v3error("always range high bound must be >= low bound"
" (IEEE 1800-2023 16.12.11)");
if (!hiUnbounded && loConstp && hiConstp && hiConstp->toSInt() < loConstp->toSInt()) {
nodep->hiBoundp()->v3error("always range high bound must be >= low bound"
" (IEEE 1800-2023 16.12.11)");
}
bool hasPropertyOp = propp->isMultiCycleSva();
if (!hasPropertyOp) {