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Fix mixed-width inside and dist range bounds failing randomization (#7875)

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This commit is contained in:
Yilou Wang
2026-07-07 11:26:19 -07:00
committed by GitHub
parent 87d77f0133
commit f1a8192a36
4 changed files with 244 additions and 26 deletions
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src/V3Randomize.cpp
+41 -20
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@@ -4453,6 +4453,39 @@ class RandomizeVisitor final : public VNVisitor {
return new AstConstraintIf{fl, condp, thenBodyp, nullptr};
}
static bool distBoundRefsRandVar(const AstNode* boundp) {
bool found = false;
boundp->foreach([&](const AstVarRef* vrefp) {
if (vrefp->varp()->rand().isRandomizable()) found = true;
});
return found;
}
// (distExpr >= lo) && (distExpr <= hi); signed comparisons for signed vars
static AstNodeExpr* newDistRangeMembership(AstDist* distp, const AstInsideRange* irp) {
FileLine* const fl = distp->fileline();
const bool isSigned = distp->exprp()->isSigned();
AstNodeExpr* const distExprGtep = distp->exprp()->cloneTreePure(false);
AstNodeExpr* const distExprLtep = distp->exprp()->cloneTreePure(false);
distExprGtep->user1(true);
distExprLtep->user1(true);
AstNodeExpr* const gep
= isSigned ? static_cast<AstNodeExpr*>(
new AstGteS{fl, distExprGtep, irp->lhsp()->cloneTreePure(false)})
: static_cast<AstNodeExpr*>(
new AstGte{fl, distExprGtep, irp->lhsp()->cloneTreePure(false)});
AstNodeExpr* const lep
= isSigned ? static_cast<AstNodeExpr*>(
new AstLteS{fl, distExprLtep, irp->rhsp()->cloneTreePure(false)})
: static_cast<AstNodeExpr*>(
new AstLte{fl, distExprLtep, irp->rhsp()->cloneTreePure(false)});
gep->user1(true);
lep->user1(true);
AstNodeExpr* const andp = new AstLogAnd{fl, gep, lep};
andp->user1(true);
return andp;
}
// Replace AstDist with weighted bucket selection via AstConstraintIf chain.
// Supports both constant and variable weight expressions.
void lowerDistConstraints(AstTask* taskp, AstNode* constrItemsp,
@@ -4577,25 +4610,7 @@ class RandomizeVisitor final : public VNVisitor {
for (const auto& bucket : buckets) {
AstNodeExpr* memberp;
if (const AstInsideRange* const irp = VN_CAST(bucket.rangep, InsideRange)) {
// (distExpr >= lo) && (distExpr <= hi); signed comparisons for signed vars
const bool isSigned = distp->exprp()->isSigned();
AstNodeExpr* const distExprGtep = distp->exprp()->cloneTreePure(false);
AstNodeExpr* const distExprLtep = distp->exprp()->cloneTreePure(false);
distExprGtep->user1(true);
distExprLtep->user1(true);
AstNodeExpr* const gep
= isSigned ? static_cast<AstNodeExpr*>(new AstGteS{
fl, distExprGtep, irp->lhsp()->cloneTreePure(false)})
: static_cast<AstNodeExpr*>(new AstGte{
fl, distExprGtep, irp->lhsp()->cloneTreePure(false)});
AstNodeExpr* const lep
= isSigned ? static_cast<AstNodeExpr*>(new AstLteS{
fl, distExprLtep, irp->rhsp()->cloneTreePure(false)})
: static_cast<AstNodeExpr*>(new AstLte{
fl, distExprLtep, irp->rhsp()->cloneTreePure(false)});
gep->user1(true);
lep->user1(true);
memberp = new AstLogAnd{fl, gep, lep};
memberp = newDistRangeMembership(distp, irp);
} else {
// distExpr == val
AstNodeExpr* const distExprCopyp = distp->exprp()->cloneTreePure(false);
@@ -4673,7 +4688,13 @@ class RandomizeVisitor final : public VNVisitor {
AstNode* chainp = nullptr;
for (int i = static_cast<int>(buckets.size()) - 1; i >= 0; --i) {
AstNodeExpr* constraintExprp;
if (const AstInsideRange* const irp = VN_CAST(buckets[i].rangep, InsideRange)) {
const AstInsideRange* const irp = VN_CAST(buckets[i].rangep, InsideRange);
if (irp
&& (distBoundRefsRandVar(irp->lhsp()) || distBoundRefsRandVar(irp->rhsp()))) {
// Bounds solved concurrently cannot pin a pre-solve value; softly
// prefer the symbolic range so the hard membership stays satisfiable
constraintExprp = newDistRangeMembership(distp, irp);
} else if (irp) {
// Pick distExpr = lo + rand64() % (hi - lo + 1) for a uniform value in range
AstNodeExpr* const distExprCopyp = distp->exprp()->cloneTreePure(false);
distExprCopyp->user1(true);