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Fix randomization of unreferenced rand members of unpacked structs (#7910) (#7911)

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Fixes #7910.
This commit is contained in:
Philip Axer
2026-07-21 07:42:04 -04:00
committed by GitHub
parent b34f685f70
commit 8113f1df7a
10 changed files with 390 additions and 30 deletions
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src/V3Randomize.cpp
+69 -26
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@@ -133,6 +133,13 @@ union RandomizeMode final {
int asInt; // Representation as int to be stored in nodep->user*
};
// Look through unpacked array dimensions to the element type
static AstNodeDType* arrayElementDTypep(AstNodeDType* dtypep) {
dtypep = dtypep->skipRefp();
while (dtypep->isNonPackedArray()) dtypep = dtypep->subDTypep()->skipRefp();
return dtypep;
}
//######################################################################
// Visitor that marks classes needing a randomize() method
@@ -783,6 +790,53 @@ class ConstraintExprVisitor final : public VNVisitor {
}
}
// Mark the one directly-referenced member; it must reach the solver even when it
// carries no rand qualifier (the constraint refers to it).
void markConstrainedRandMember(AstStructDType* const structp, const std::string& name) {
AstMemberDType* const memberp
= VN_CAST(m_memberMap.findMember(structp, name), MemberDType);
UASSERT_OBJ(memberp, structp, "Constraint references unknown struct member " << name);
memberp->markConstrainedRand(true);
}
// True when the aggregate is reached through rand-qualified struct members only
bool isRandQualifiedPath(const AstNodeExpr* nodep) {
while (nodep) {
if (const AstStructSel* const selp = VN_CAST(nodep, StructSel)) {
if (AstStructDType* const structp
= VN_CAST(selp->fromp()->dtypep()->skipRefp(), StructDType)) {
const AstMemberDType* const memberp
= VN_CAST(m_memberMap.findMember(structp, selp->name()), MemberDType);
if (memberp && !memberp->rand().isRandomizable()) return false;
}
nodep = selp->fromp();
} else if (const AstArraySel* const selp = VN_CAST(nodep, ArraySel)) {
nodep = selp->fromp();
} else if (const AstCMethodHard* const methodp = VN_CAST(nodep, CMethodHard)) {
nodep = methodp->fromp();
} else {
break;
}
}
return true;
}
// IEEE 1800-2023 18.4: all rand members of a rand unpacked struct are solved
// concurrently, so unreferenced rand members must still reach the solver.
static void markStructConstrainedRandRecurse(AstNodeDType* const dtypep) {
AstStructDType* const structp = VN_CAST(arrayElementDTypep(dtypep), StructDType);
if (!structp || structp->packed()) return;
structp->markConstrainedRand(true);
for (AstMemberDType* memberp = structp->membersp(); memberp;
memberp = VN_AS(memberp->nextp(), MemberDType)) {
// Non-rand members keep their value. TODO: randc members are solved as
// plain rand (uniform); per-member cyclic state is not generated for structs.
if (!memberp->rand().isRandomizable()) continue;
memberp->markConstrainedRand(true);
markStructConstrainedRandRecurse(memberp->subDTypep());
}
}
// Build full path for a MemberSel chain (e.g., "obj.l2.l3.l4")
std::string buildMemberPath(const AstMemberSel* const memberSelp) {
const AstNode* fromp = memberSelp->fromp();
@@ -1409,7 +1463,7 @@ class ConstraintExprVisitor final : public VNVisitor {
}
if (VN_IS(varp->dtypeSkipRefp(), StructDType)
&& !VN_AS(varp->dtypeSkipRefp(), StructDType)->packed()) {
VN_AS(varp->dtypeSkipRefp(), StructDType)->markConstrainedRand(true);
markStructConstrainedRandRecurse(varp->dtypeSkipRefp());
dimension = 1;
}
methodp->dtypeSetVoid();
@@ -1433,9 +1487,7 @@ class ConstraintExprVisitor final : public VNVisitor {
varRefp->classOrPackagep(classOrPackagep);
methodp->addPinsp(varRefp);
}
AstNodeDType* tmpDtypep = varp->dtypep();
while (tmpDtypep->isNonPackedArray()) tmpDtypep = tmpDtypep->subDTypep();
const size_t width = tmpDtypep->width();
const size_t width = arrayElementDTypep(varp->dtypep())->width();
methodp->addPinsp(
new AstConst{varp->dtypep()->fileline(), AstConst::Unsized64{}, width});
AstNodeExpr* const varnamep = new AstCExpr{varp->fileline(), AstCExpr::Pure{},
@@ -1917,16 +1969,12 @@ class ConstraintExprVisitor final : public VNVisitor {
m_structSel = true;
if (VN_IS(nodep->fromp()->dtypep()->skipRefp(), StructDType)) {
AstNodeExpr* const fromp = nodep->fromp();
if (VN_IS(fromp, StructSel)) {
VN_AS(fromp->dtypep()->skipRefp(), StructDType)->markConstrainedRand(true);
}
AstMemberDType* memberp = VN_AS(fromp->dtypep()->skipRefp(), StructDType)->membersp();
while (memberp) {
if (memberp->name() == nodep->name()) {
memberp->markConstrainedRand(true);
break;
} else
memberp = VN_CAST(memberp->nextp(), MemberDType);
AstStructDType* const structp = VN_AS(fromp->dtypep()->skipRefp(), StructDType);
markConstrainedRandMember(structp, nodep->name());
if (isRandQualifiedPath(fromp)) {
markStructConstrainedRandRecurse(fromp->dtypep());
} else {
structp->markConstrainedRand(true);
}
}
// Mark Random for structArray
@@ -1934,16 +1982,13 @@ class ConstraintExprVisitor final : public VNVisitor {
AstNodeExpr* const fromp = VN_IS(nodep->fromp(), ArraySel)
? VN_AS(nodep->fromp(), ArraySel)->fromp()
: VN_AS(nodep->fromp(), CMethodHard)->fromp();
AstStructDType* const dtypep
AstStructDType* const structp
= VN_AS(fromp->dtypep()->skipRefp()->subDTypep()->skipRefp(), StructDType);
dtypep->markConstrainedRand(true);
AstMemberDType* memberp = dtypep->membersp();
while (memberp) {
if (memberp->name() == nodep->name()) {
memberp->markConstrainedRand(true);
break;
} else
memberp = VN_CAST(memberp->nextp(), MemberDType);
markConstrainedRandMember(structp, nodep->name());
if (isRandQualifiedPath(fromp)) {
markStructConstrainedRandRecurse(fromp->dtypep()->skipRefp()->subDTypep());
} else {
structp->markConstrainedRand(true);
}
}
iterateChildren(nodep);
@@ -5412,9 +5457,7 @@ class RandomizeVisitor final : public VNVisitor {
dimension = dims.second;
}
AstNodeDType* tmpDtypep = arrVarp->dtypep();
while (tmpDtypep->isNonPackedArray()) tmpDtypep = tmpDtypep->subDTypep();
const size_t width = tmpDtypep->width();
const size_t width = arrayElementDTypep(arrVarp->dtypep())->width();
methodp->addPinsp(new AstConst{fl, AstConst::Unsized64{}, width});
AstNodeExpr* const varnamep = new AstCExpr{