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[CIR] Implement BinComma Expr for AggregateExpr #161823

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Merged
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Oct 4, 2025
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[CIR] Implement BinComma Expr for AggregateExpr #161823

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3 changes: 2 additions & 1 deletion clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -184,7 +184,8 @@ class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
cgf.cgm.errorNYI(e->getSourceRange(), "AggExprEmitter: VisitBinAssign");
}
void VisitBinComma(const BinaryOperator *e) {
cgf.cgm.errorNYI(e->getSourceRange(), "AggExprEmitter: VisitBinComma");
cgf.emitIgnoredExpr(e->getLHS());
Visit(e->getRHS());
}
void VisitBinCmp(const BinaryOperator *e) {
cgf.cgm.errorNYI(e->getSourceRange(), "AggExprEmitter: VisitBinCmp");
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22 changes: 22 additions & 0 deletions clang/test/CIR/CodeGen/struct.cpp
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Expand Up @@ -183,3 +183,25 @@ void generic_selection() {
// OGCG: %[[C_ADDR:.*]] = alloca i32, align 4
// OGCG: %[[D_ADDR:.*]] = alloca %struct.CompleteS, align 4
// OGCG: call void @llvm.memcpy.p0.p0.i64(ptr align 4 %[[D_ADDR]], ptr align 4 %[[A_ADDR]], i64 8, i1 false)

void bin_comma() {
CompleteS a = (CompleteS(), CompleteS());
}

// CIR: cir.func{{.*}} @_Z9bin_commav()
// CIR: %[[A_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["a", init]
// CIR: %[[TMP_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["agg.tmp0"]
// CIR: %[[ZERO:.*]] = cir.const #cir.zero : !rec_CompleteS
// CIR: cir.store{{.*}} %[[ZERO]], %[[TMP_ADDR]] : !rec_CompleteS, !cir.ptr<!rec_CompleteS>
// CIR: %[[ZERO:.*]] = cir.const #cir.zero : !rec_CompleteS
// CIR: cir.store{{.*}} %[[ZERO]], %[[A_ADDR]] : !rec_CompleteS, !cir.ptr<!rec_CompleteS>

// LLVM: define{{.*}} void @_Z9bin_commav()
// LLVM: %[[A_ADDR:.*]] = alloca %struct.CompleteS, i64 1, align 4
// LLVM: %[[TMP_ADDR:.*]] = alloca %struct.CompleteS, i64 1, align 4
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Do you know why OGCG doesn't emit the temporary? Is it checking somewhere for a trivial constructor and not emitting unused temporaries, or does it get deleted somewhere?

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Not yet, I will check what and where the OGCG do that because in the emitter it just similar to CIR

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The difference is from CodeGenFunction::EmitAnyExpr there is extra param ignoreResult and the temporary is emitted only if ignoreResult is false which is false by default

OGCG:

llvm-project/clang/lib/CodeGen/CGExpr.cpp

Line 273 in eabfed8

if (!ignoreResult && aggSlot.isIgnored())

llvm-project/clang/lib/CIR/CodeGen/CIRGenExpr.cpp

Line 1630 in eabfed8

if (aggSlot.isIgnored())

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Actually, we have this parameter in the incubator, but it's not upstreamed yet. I will handle it in a follow-up PR to check other pleases also

// LLVM: store %struct.CompleteS zeroinitializer, ptr %[[TMP_ADDR]], align 4
// LLVM: store %struct.CompleteS zeroinitializer, ptr %[[A_ADDR]], align 4

// OGCG: define{{.*}} void @_Z9bin_commav()
// OGCG: %[[A_ADDR:.*]] = alloca %struct.CompleteS, align 4
// OGCG: call void @llvm.memset.p0.i64(ptr align 4 %[[A_ADDR]], i8 0, i64 8, i1 false)
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