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Support solve..before constraints (#5647) (#7123)

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This commit is contained in:
Yilou Wang
2026-02-22 11:33:18 -05:00
committed by GitHub
parent 350966de6b
commit 1717df0261
10 changed files with 450 additions and 5 deletions
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src/V3Randomize.cpp
+46 -1
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@@ -753,6 +753,17 @@ class ConstraintExprVisitor final : public VNVisitor {
return "";
}
// Extract SMT variable name from a solve-before expression.
// Returns empty string if the expression is not a simple variable reference.
std::string extractSolveBeforeVarName(AstNodeExpr* exprp) {
if (const AstMemberSel* const memberSelp = VN_CAST(exprp, MemberSel)) {
return buildMemberPath(memberSelp);
} else if (const AstVarRef* const varrefp = VN_CAST(exprp, VarRef)) {
return varrefp->name();
}
return "";
}
AstSFormatF* getConstFormat(AstNodeExpr* nodep) {
return new AstSFormatF{nodep->fileline(), (nodep->width() & 3) ? "#b%b" : "#x%x", false,
nodep};
@@ -1754,7 +1765,41 @@ class ConstraintExprVisitor final : public VNVisitor {
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
void visit(AstConstraintBefore* nodep) override {
nodep->v3warn(CONSTRAINTIGN, "Constraint expression ignored (imperfect distribution)");
// Generate solveBefore() calls for each (lhs, rhs) variable pair.
// Do NOT iterate children -- these are variable references, not constraint expressions.
FileLine* const fl = nodep->fileline();
AstNodeModule* const genModp = VN_AS(m_genp->user2p(), NodeModule);
for (AstNodeExpr* lhsp = nodep->lhssp(); lhsp; lhsp = VN_CAST(lhsp->nextp(), NodeExpr)) {
const std::string lhsName = extractSolveBeforeVarName(lhsp);
if (lhsName.empty()) {
lhsp->v3warn(CONSTRAINTIGN,
"Unsupported: non-variable expression in solve...before");
continue;
}
for (AstNodeExpr* rhsp = nodep->rhssp(); rhsp;
rhsp = VN_CAST(rhsp->nextp(), NodeExpr)) {
const std::string rhsName = extractSolveBeforeVarName(rhsp);
if (rhsName.empty()) {
rhsp->v3warn(CONSTRAINTIGN,
"Unsupported: non-variable expression in solve...before");
continue;
}
AstCMethodHard* const callp = new AstCMethodHard{
fl, new AstVarRef{fl, genModp, m_genp, VAccess::READWRITE},
VCMethod::RANDOMIZER_SOLVE_BEFORE};
callp->dtypeSetVoid();
AstNodeExpr* const beforeNamep
= new AstCExpr{fl, AstCExpr::Pure{}, "\"" + lhsName + "\""};
beforeNamep->dtypeSetUInt32();
AstNodeExpr* const afterNamep
= new AstCExpr{fl, AstCExpr::Pure{}, "\"" + rhsName + "\""};
afterNamep->dtypeSetUInt32();
callp->addPinsp(beforeNamep);
callp->addPinsp(afterNamep);
nodep->addHereThisAsNext(callp->makeStmt());
}
}
VL_DO_DANGLING(nodep->unlinkFrBack()->deleteTree(), nodep);
}
void visit(AstConstraintUnique* nodep) override {