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Fix rand_mode(0) on sub-object members not preventing solver write-back (#7272)

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This commit is contained in:
Yilou Wang
2026-03-17 15:09:14 -04:00
committed by GitHub
parent 316fb02c60
commit 8925762077
7 changed files with 196 additions and 2 deletions
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src/V3Randomize.cpp
+68 -1
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@@ -1328,7 +1328,6 @@ class ConstraintExprVisitor final : public VNVisitor {
methodp->addPinsp(varnamep);
methodp->addPinsp(
new AstConst{varp->dtypep()->fileline(), AstConst::Unsized64{}, dimension});
// Don't pass randMode.index for global constraints with membersel
if (randMode.usesMode && !(isGlobalConstrained && membersel)) {
methodp->addPinsp(
new AstConst{varp->fileline(), AstConst::Unsized64{}, randMode.index});
@@ -1347,7 +1346,52 @@ class ConstraintExprVisitor final : public VNVisitor {
UASSERT_OBJ(initTaskp, classp, "No new() in class");
}
}
// For globalConstrained sub-object members with rand_mode:
// Always call write_var (keeps variable in solver for constraint
// evaluation), but toggle disabled state so the solver skips
// write-back when rand_mode is off.
initTaskp->addStmtsp(methodp->makeStmt());
if (isGlobalConstrained && membersel && randMode.usesMode) {
AstNodeModule* const varClassp = VN_AS(varp->user2p(), NodeModule);
AstVar* const subRandModeVarp = VN_AS(varClassp->user2p(), Var);
if (subRandModeVarp) {
AstNodeExpr* const parentAccess = membersel->fromp()->cloneTree(false);
AstMemberSel* const randModeSel
= new AstMemberSel{varp->fileline(), parentAccess, subRandModeVarp};
randModeSel->dtypep(subRandModeVarp->dtypep());
AstCMethodHard* const atp
= new AstCMethodHard{varp->fileline(), randModeSel, VCMethod::ARRAY_AT,
new AstConst{varp->fileline(), randMode.index}};
atp->dtypeSetUInt32();
// rand_mode ON: clear disabled state
AstCMethodHard* const enablep = new AstCMethodHard{
varp->fileline(),
new AstVarRef{varp->fileline(), VN_AS(m_genp->user2p(), NodeModule),
m_genp, VAccess::READWRITE},
VCMethod::RANDOMIZER_CLEAR_VAR_DISABLED};
enablep->dtypeSetVoid();
AstNodeExpr* const ennp
= new AstCExpr{varp->fileline(), AstCExpr::Pure{},
"\"" + smtName + "\"", varp->width()};
ennp->dtypep(varp->dtypep());
enablep->addPinsp(ennp);
// rand_mode OFF: set disabled state
AstCMethodHard* const disablep = new AstCMethodHard{
varp->fileline(),
new AstVarRef{varp->fileline(), VN_AS(m_genp->user2p(), NodeModule),
m_genp, VAccess::READWRITE},
VCMethod::RANDOMIZER_SET_VAR_DISABLED};
disablep->dtypeSetVoid();
AstNodeExpr* const disnp
= new AstCExpr{varp->fileline(), AstCExpr::Pure{},
"\"" + smtName + "\"", varp->width()};
disnp->dtypep(varp->dtypep());
disablep->addPinsp(disnp);
AstIf* const ifp = new AstIf{varp->fileline(), atp, enablep->makeStmt(),
disablep->makeStmt()};
initTaskp->addStmtsp(ifp);
}
}
// If randc, also emit markRandc() for cyclic tracking
if (varp->isRandC()) {
AstCMethodHard* const markp = new AstCMethodHard{
@@ -3087,6 +3131,29 @@ class RandomizeVisitor final : public VNVisitor {
}
}
});
// Also account for rand_mode indices from globalConstrained sub-objects.
// When constraints from sub-objects are flattened into this class's constraint
// setup functions, the generated code references this->__Vrandmode.at(index).
// We must ensure this class's __Vrandmode is initialized to cover those indices.
{
std::function<void(AstClass*)> findSubObjRandModes = [&](AstClass* subClassp) {
subClassp->foreachMember([&](AstClass*, AstNode* subMemberp) {
if (AstVar* const subVarp = VN_CAST(subMemberp, Var)) {
const RandomizeMode rm = {.asInt = subVarp->user1()};
if (!rm.usesMode) return;
const uint32_t needed = rm.index + 1;
if (needed > randModeCount) randModeCount = needed;
}
});
};
classp->foreachMember([&](AstClass*, AstVar* memberVarp) {
if (!memberVarp->globalConstrained()) return;
const AstNodeDType* const dtypep = memberVarp->dtypep()->skipRefp();
const AstClassRefDType* const classRefp = VN_CAST(dtypep, ClassRefDType);
if (!classRefp) return;
findSubObjRandModes(classRefp->classp());
});
}
if (hasConstraints) createRandomGenerator(classp);
if (randModeCount > 0) {
AstVar* const randModeVarp = getCreateRandModeVar(classp);