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Support power expressions with constant exponent in constraints (#7073)

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This commit is contained in:
Kamil Danecki
2026-02-16 06:01:24 -05:00
committed by GitHub
parent 7c1b348b41
commit 821eacebea
8 changed files with 115 additions and 5 deletions
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src/V3Randomize.cpp
+43
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@@ -1354,6 +1354,49 @@ class ConstraintExprVisitor final : public VNVisitor {
VL_DO_DANGLING(nodep->deleteTree(), nodep);
iterate(resultp);
}
void handlePow(AstNodeBiop* nodep) {
if (AstConst* const exponentp = VN_CAST(nodep->rhsp(), Const)) {
FileLine* const fl = nodep->fileline();
AstNodeExpr* const basep = nodep->lhsp();
V3Number numOne{nodep, basep->width(), 1};
AstNodeExpr* powerp = new AstConst{fl, numOne};
const bool baseSigned = VN_IS(nodep, PowSS) || VN_IS(nodep, PowSU);
const int32_t exponent = baseSigned ? exponentp->toSInt() : exponentp->toUInt();
if (exponent > 0) {
for (int32_t i = 0; i < exponent; i++) {
if (baseSigned) {
powerp = new AstMulS{fl, powerp, basep->cloneTreePure(false)};
} else {
powerp = new AstMul{fl, powerp, basep->cloneTreePure(false)};
}
powerp->user1(true);
}
} else if (exponent < 0) {
// Limit chain of divisions to max 2, because operations are on integers.
// Two divisions are needed to preserve the sign.
if (baseSigned) {
powerp = new AstDivS{fl, powerp, basep->cloneTreePure(false)};
powerp->user1(true);
powerp = new AstDivS{fl, powerp, basep->cloneTreePure(false)};
powerp->user1(true);
} else {
powerp = new AstDiv{fl, powerp, basep->cloneTreePure(false)};
powerp->user1(true);
}
}
nodep->replaceWith(powerp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
iterate(powerp);
} else {
nodep->v3warn(
CONSTRAINTIGN,
"Unsupported: Power (**) expression with non-constant exponent in constraint");
}
}
void visit(AstPow* nodep) override { handlePow(nodep); }
void visit(AstPowSS* nodep) override { handlePow(nodep); }
void visit(AstPowSU* nodep) override { handlePow(nodep); }
void visit(AstPowUS* nodep) override { handlePow(nodep); }
void visit(AstNodeBiop* nodep) override {
if (editFormat(nodep)) return;
editSMT(nodep, nodep->lhsp(), nodep->rhsp());