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Internals: Make V3LiftExpr non optional (#8369)

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This commit is contained in:
Geza Lore
2026-09-16 12:29:56 -04:00
committed by GitHub
parent 282b898b21
commit 573c2e61a6
13 changed files with 141 additions and 24 deletions
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src/V3LiftExpr.cpp
+25 -4
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@@ -49,9 +49,8 @@
// __VleLogAnd_0 = __VleCall_0;
// }
// z = __VleLogAnd_1;
// Similar patterns are used for AstLogOr and AstCond to preserve the
// short-circuiting semantics and side effects. All AstLogIf should have
// been converted to AstLogOr earlier by V3Const.
// Similar patterns are used for AstLogOr, AstLogIf and AstCond to preserve
// the short-circuiting semantics and side effects.
//
// Care must be taken for impure LValues as well. While, all LValue expressions
// permitted by IEEE-1800 are themselves pure (except possibly for the non-lvalue
@@ -108,6 +107,7 @@ class LiftExprVisitor final : public VNVisitor {
VDouble0 m_statLiftedConds;
VDouble0 m_statLiftedLogAnds;
VDouble0 m_statLiftedLogOrs;
VDouble0 m_statLiftedLogIfs;
VDouble0 m_statLiftedExprStmts;
VDouble0 m_statTemporariesCreated;
VDouble0 m_statTemporariesReused;
@@ -432,7 +432,27 @@ class LiftExprVisitor final : public VNVisitor {
}
void visit(AstLogIf* nodep) override {
if (!m_lift) return;
nodep->v3fatalSrc("AstLogIf should have been folded by V3Const");
// Lift from LHS
iterate(nodep->lhsp());
// Lift from RHS, if nothing lifted, then nothing to do
AstNode* const rhsStmtps = lift(nodep->rhsp());
if (!rhsStmtps) return;
// Otherwise convert to an AstIf with a temporary variable
++m_statLiftedLogIfs;
FileLine* const flp = nodep->fileline();
AstVar* varp = getExistingVar(nodep->rhsp());
if (!varp) varp = newVar("LogIf", nodep);
addStmtps(new AstAssign{flp, new AstVarRef{flp, varp, VAccess::WRITE},
new AstLogNot{flp, nodep->lhsp()->unlinkFrBack()}});
AstIf* const ifp = new AstIf{flp, new AstVarRef{flp, varp, VAccess::READ}};
addStmtps(ifp);
ifp->addElsesp(rhsStmtps);
ifp->addElsesp(assignIfDifferent(flp, varp, nodep->rhsp()));
nodep->replaceWith(new AstVarRef{flp, varp, VAccess::READ});
VL_DO_DANGLING(nodep->deleteTree(), nodep);
}
void visit(AstExprStmt* nodep) override {
if (!m_lift) return;
@@ -476,6 +496,7 @@ public:
V3Stats::addStat("LiftExpr, lifted Cond", m_statLiftedConds);
V3Stats::addStat("LiftExpr, lifted LogAnd", m_statLiftedLogAnds);
V3Stats::addStat("LiftExpr, lifted LogOr", m_statLiftedLogOrs);
V3Stats::addStat("LiftExpr, lifted LogIf", m_statLiftedLogIfs);
V3Stats::addStat("LiftExpr, lifted ExprStmt", m_statLiftedExprStmts);
V3Stats::addStat("LiftExpr, temporaries created", m_statTemporariesCreated);
V3Stats::addStat("LiftExpr, temporaries reused", m_statTemporariesReused);