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Fix wide select expansion and substitution (#6341) (#6345)

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This commit is contained in:
Geza Lore
2025-08-30 10:34:39 -04:00
committed by GitHub
parent 14ec6258d9
commit c33f2b42aa
3 changed files with 204 additions and 80 deletions
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src/V3Subst.cpp
+24 -12
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@@ -118,15 +118,21 @@ public:
}
// ACCESSORS
AstNodeExpr* substWhole(AstNode* errp) {
if (!m_varp->isWide() && !m_whole.m_complex && m_whole.m_assignp && !m_wordAssign) {
const AstNodeAssign* const assp = m_whole.m_assignp;
UASSERT_OBJ(assp, errp, "Reading whole that was never assigned");
// AstCvtPackedToArray can't be anywhere else than on the RHS of assignment
if (VN_IS(assp->rhsp(), CvtPackedToArray)) return nullptr;
return assp->rhsp();
} else {
return nullptr;
}
if (m_varp->isWide()) return nullptr;
if (m_whole.m_complex) return nullptr;
if (!m_whole.m_assignp) return nullptr;
if (m_wordAssign) return nullptr;
const AstNodeAssign* const assp = m_whole.m_assignp;
UASSERT_OBJ(assp, errp, "Reading whole that was never assigned");
AstNodeExpr* const rhsp = assp->rhsp();
// AstCvtPackedToArray can't be anywhere else than on the RHS of assignment
if (VN_IS(rhsp, CvtPackedToArray)) return nullptr;
// Check if only substitute if constant
if (m_varp->substConstOnly() && !VN_IS(rhsp, Const)) return nullptr;
// Substitute it
return rhsp;
}
// Return what to substitute given word number for
AstNodeExpr* substWord(AstNode* errp, int word) {
@@ -227,7 +233,7 @@ class SubstVisitor final : public VNVisitor {
int m_ops = 0; // Number of operators on assign rhs
int m_assignStep = 0; // Assignment number to determine var lifetime
const AstCFunc* m_funcp = nullptr; // Current function we are under
VDouble0 m_statSubsts; // Statistic tracking
size_t m_nSubst = 0; // Number of substitutions performed
enum {
SUBST_MAX_OPS_SUBST = 30, // Maximum number of ops to substitute in
@@ -251,7 +257,10 @@ class SubstVisitor final : public VNVisitor {
VL_RESTORER(m_ops);
m_ops = 0;
m_assignStep++;
const size_t nSubstBefore = m_nSubst;
iterateAndNextNull(nodep->rhsp());
if (nSubstBefore != m_nSubst) V3Const::constifyEditCpp(nodep->rhsp());
if (VN_IS(nodep->rhsp(), Const)) m_ops = 0;
bool hit = false;
if (AstVarRef* const varrefp = VN_CAST(nodep->lhsp(), VarRef)) {
if (isSubstVar(varrefp->varp())) {
@@ -292,11 +301,14 @@ class SubstVisitor final : public VNVisitor {
UINFOTREE(6, newp, "", "w_new");
nodep->replaceWith(newp);
VL_DO_DANGLING(nodep->deleteTree(), nodep);
++m_statSubsts;
++m_nSubst;
}
void visit(AstWordSel* nodep) override {
if (!m_funcp) return;
const size_t nSubstBefore = m_nSubst;
iterate(nodep->bitp());
// Simplify in case it was substituted and became constant
if (nSubstBefore != m_nSubst) V3Const::constifyEditCpp(nodep->bitp());
AstVarRef* const varrefp = VN_CAST(nodep->fromp(), VarRef);
const AstConst* const constp = VN_CAST(nodep->bitp(), Const);
if (varrefp && isSubstVar(varrefp->varp()) && varrefp->access().isReadOnly() && constp) {
@@ -380,7 +392,7 @@ public:
// CONSTRUCTORS
explicit SubstVisitor(AstNode* nodep) { iterate(nodep); }
~SubstVisitor() override {
V3Stats::addStat("Optimizations, Substituted temps", m_statSubsts);
V3Stats::addStat("Optimizations, Substituted temps", m_nSubst);
UASSERT(m_entries.empty(), "References outside functions");
}
};