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Support constraint with item.index array reduction (#7198)

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This commit is contained in:
Rahul Behl
2026-03-06 05:14:55 -05:00
committed by GitHub
parent cedec65c39
commit efa53189ea
7 changed files with 728 additions and 68 deletions
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src/V3Randomize.cpp
+55 -32
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@@ -878,6 +878,26 @@ class ConstraintExprVisitor final : public VNVisitor {
return selp;
}
// Convert expression to target width using extend or truncate as needed
AstNodeExpr* adjustWidth(FileLine* fl, AstNodeExpr* exprp, int targetWidth,
VSigning targetSigning) {
const int exprWidth = exprp->width();
if (targetWidth > exprWidth) {
// Extend to match target width
AstNodeExpr* const result = new AstExtend{fl, exprp, targetWidth};
result->dtypeSetLogicSized(targetWidth, targetSigning);
return result;
} else if (targetWidth < exprWidth) {
// Truncate to match target width
AstNodeExpr* const result = new AstSel{fl, exprp, 0, targetWidth};
result->dtypeSetLogicSized(targetWidth, targetSigning);
return result;
} else {
// Width already matches
return exprp;
}
}
// Extract return expression from a simple function body, or nullptr if too complex.
// Uses foreach to walk all assigns regardless of body organization (JumpBlock nesting etc.).
// Takes the last assignment to the return variable -- the first is the initializer.
@@ -1284,13 +1304,8 @@ class ConstraintExprVisitor final : public VNVisitor {
FileLine* const fl = nodep->fileline();
AstNodeExpr* const argp = nodep->lhsp()->unlinkFrBack();
AstNodeExpr* sump = buildCountOnesExpansion(fl, argp, nodep);
if (nodep->width() > sump->width()) {
sump = new AstExtend{fl, sump, nodep->width()};
sump->user1(true);
} else if (nodep->width() < sump->width()) {
sump = new AstSel{fl, sump, 0, nodep->width()};
sump->user1(true);
}
sump = adjustWidth(fl, sump, nodep->width(), nodep->dtypep()->numeric());
sump->user1(true);
nodep->replaceWith(sump);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
iterate(sump);
@@ -1407,13 +1422,8 @@ class ConstraintExprVisitor final : public VNVisitor {
VL_DO_DANGLING(argp->deleteTree(), argp);
}
if (nodep->width() > sump->width()) {
sump = new AstExtend{fl, sump, nodep->width()};
sump->user1(true);
} else if (nodep->width() < sump->width()) {
sump = new AstSel{fl, sump, 0, nodep->width()};
sump->user1(true);
}
sump = adjustWidth(fl, sump, nodep->width(), nodep->dtypep()->numeric());
sump->user1(true);
nodep->replaceWith(sump);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
@@ -2114,20 +2124,6 @@ class ConstraintExprVisitor final : public VNVisitor {
return;
}
}
bool hasItemIndex = false;
withp->exprp()->foreach([&](AstLambdaArgRef* refp) {
if (refp->index()) hasItemIndex = true;
});
if (hasItemIndex) {
nodep->v3warn(CONSTRAINTIGN,
"Unsupported: item.index in array reduction constraint 'with' "
"clause; treating as state");
nodep->user1(false);
if (editFormat(nodep)) return;
nodep->v3fatalSrc("Method not handled in constraints? " << nodep);
return;
}
}
// For without 'with' clause: need random array for variable registration
@@ -2210,20 +2206,47 @@ class ConstraintExprVisitor final : public VNVisitor {
AstNodeExpr* const elemSelp = newSel(fl, nodep->fromp(), idxRefp);
elemSelp->user1(randArr);
// Get the result width for the reduction
const int resultWidth = nodep->dtypep()->width();
const VSigning resultSigning = nodep->dtypep()->numeric();
AstNode* perElemExprp = withp->exprp()->cloneTreePure(false);
if (AstLambdaArgRef* const rootRefp = VN_CAST(perElemExprp, LambdaArgRef)) {
perElemExprp = elemSelp->cloneTreePure(false);
if (rootRefp->index()) {
// item.index at root -> replace with loop variable, adjust width
AstVarRef* const loopRef = new AstVarRef{fl, loopVarp, VAccess::READ};
perElemExprp = adjustWidth(fl, loopRef, resultWidth, resultSigning);
} else {
// item at root -> replace with array element
perElemExprp = elemSelp->cloneTreePure(false);
}
VL_DO_DANGLING(rootRefp->deleteTree(), rootRefp);
} else {
perElemExprp->foreach([&](AstLambdaArgRef* refp) {
refp->replaceWith(elemSelp->cloneTreePure(false));
if (refp->index()) {
// item.index -> replace with loop variable, adjust width
AstVarRef* loopRef = new AstVarRef{fl, loopVarp, VAccess::READ};
AstNode* const replacement
= adjustWidth(fl, loopRef, resultWidth, resultSigning);
refp->replaceWith(replacement);
} else {
// item -> replace with array element
refp->replaceWith(elemSelp->cloneTreePure(false));
}
VL_DO_DANGLING(pushDeletep(refp), refp);
});
}
VL_DO_DANGLING(elemSelp->deleteTree(), elemSelp);
perElemExprp->foreach([](AstNode* nodep) {
if (!VN_IS(nodep, Const)) nodep->user1(true);
perElemExprp->foreach([&](AstNode* nodep) {
// Don't mark loop variable references as randomizable
if (!VN_IS(nodep, Const)) {
if (AstNodeVarRef* const vrefp = VN_CAST(nodep, NodeVarRef)) {
if (vrefp->varp() != loopVarp) nodep->user1(true);
} else {
nodep->user1(true);
}
}
});
cstmtp->add("ret = \"(" + std::string(smtOp) + " \" + ret + \" \";\n");