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[CIR] Const member expr for struct type #164172

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Merged
merged 1 commit into from
Oct 21, 2025
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[CIR] Const member expr for struct type #164172

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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 @@ -280,6 +280,7 @@ class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
void VisitUnaryDeref(UnaryOperator *e) { emitAggLoadOfLValue(e); }
void VisitStringLiteral(StringLiteral *e) { emitAggLoadOfLValue(e); }
void VisitCompoundLiteralExpr(CompoundLiteralExpr *e);

void VisitPredefinedExpr(const PredefinedExpr *e) {
cgf.cgm.errorNYI(e->getSourceRange(),
"AggExprEmitter: VisitPredefinedExpr");
Expand Down Expand Up @@ -670,7 +671,7 @@ void AggExprEmitter::emitNullInitializationToLValue(mlir::Location loc,
return;
}

cgf.cgm.errorNYI("emitStoreThroughBitfieldLValue");
cgf.emitStoreThroughBitfieldLValue(RValue::get(null), lv);
return;
}

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5 changes: 3 additions & 2 deletions clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
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Expand Up @@ -2041,8 +2041,9 @@ mlir::Value ScalarExprEmitter::VisitMemberExpr(MemberExpr *e) {
assert(!cir::MissingFeatures::tryEmitAsConstant());
Expr::EvalResult result;
if (e->EvaluateAsInt(result, cgf.getContext(), Expr::SE_AllowSideEffects)) {
cgf.cgm.errorNYI(e->getSourceRange(), "Constant interger member expr");
// Fall through to emit this as a non-constant access.
llvm::APSInt value = result.Val.getInt();
cgf.emitIgnoredExpr(e->getBase());
return builder.getConstInt(cgf.getLoc(e->getExprLoc()), value);
}
return emitLoadOfLValue(e);
}
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64 changes: 64 additions & 0 deletions clang/test/CIR/CodeGen/struct.cpp
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Expand Up @@ -280,3 +280,67 @@ void bin_comma() {
// 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)

void compound_literal_expr() { CompleteS a = (CompleteS){}; }

// CIR: %[[A_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["a", init]
// CIR: %[[A_ELEM_0_PTR:.*]] = cir.get_member %[[A_ADDR]][0] {name = "a"} : !cir.ptr<!rec_CompleteS> -> !cir.ptr<!s32i>
// CIR: %[[CONST_0:.*]] = cir.const #cir.int<0> : !s32i
// CIR: cir.store{{.*}} %[[CONST_0]], %[[A_ELEM_0_PTR]] : !s32i, !cir.ptr<!s32i>
// CIR: %[[A_ELEM_1_PTR:.*]] = cir.get_member %[[A_ADDR]][1] {name = "b"} : !cir.ptr<!rec_CompleteS> -> !cir.ptr<!s8i>
// CIR: %[[CONST_0:.*]] = cir.const #cir.int<0> : !s8i
// CIR: cir.store{{.*}} %[[CONST_0]], %[[A_ELEM_1_PTR]] : !s8i, !cir.ptr<!s8i>

// TODO(cir): zero-initialize the padding

// LLVM: %[[A_ADDR:.*]] = alloca %struct.CompleteS, i64 1, align 4
// LLVM: %[[A_ELEM_0_PTR:.*]] = getelementptr %struct.CompleteS, ptr %[[A_ADDR]], i32 0, i32 0
// LLVM: store i32 0, ptr %[[A_ELEM_0_PTR]], align 4
// LLVM: %[[A_ELEM_1_PTR:.*]] = getelementptr %struct.CompleteS, ptr %[[A_ADDR]], i32 0, i32 1
// LLVM: store i8 0, ptr %[[A_ELEM_1_PTR]], align 4
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Unlike OGCG, this doesn't zero-initialize the padding. Is that OK? Does the fact that we're setting each member prevent the optimizer from turning this into a memset?

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I added a TODO for now, and later we can revisit it


// 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)

struct StructWithConstMember {
int a : 1;
};

void struct_with_const_member_expr() {
int a = (StructWithConstMember){}.a;
}

// CIR: %[[A_ADDR:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["a", init]
// CIR: %[[RESULT:.*]] = cir.scope {
// CIR: %[[REF_ADDR:.*]] = cir.alloca !rec_StructWithConstMember, !cir.ptr<!rec_StructWithConstMember>, ["ref.tmp0"]
// CIR: %[[ELEM_0_PTR:.*]] = cir.get_member %[[REF_ADDR]][0] {name = "a"} : !cir.ptr<!rec_StructWithConstMember> -> !cir.ptr<!u8i>
// CIR: %[[CONST_0:.*]] = cir.const #cir.int<0> : !s32i
// CIR: %[[SET_BF:.*]] = cir.set_bitfield{{.*}} (#bfi_a, %[[ELEM_0_PTR]] : !cir.ptr<!u8i>, %[[CONST_0]] : !s32i) -> !s32i
// CIR: %[[CONST_0:.*]] = cir.const #cir.int<0> : !s32i
// CIR: cir.yield %[[CONST_0]] : !s32i
// CIR: } : !s32i
// CIR: cir.store{{.*}} %[[RESULT]], %[[A_ADDR]] : !s32i, !cir.ptr<!s32i>

// TODO(cir): zero-initialize the padding

// LLVM: %[[REF_ADDR:.*]] = alloca %struct.StructWithConstMember, i64 1, align 4
// LLVM: %[[A_ADDR:.*]] = alloca i32, i64 1, align 4
// LLVM: br label %[[BF_LABEL:.*]]
// LLVM: [[BF_LABEL]]:
// LLVM: %[[ELEM_0_PTR:.*]] = getelementptr %struct.StructWithConstMember, ptr %[[REF_ADDR]], i32 0, i32 0
// LLVM: %[[TMP_REF:.*]] = load i8, ptr %[[ELEM_0_PTR]], align 4
// LLVM: %[[BF_CLEAR:.*]] = and i8 %[[TMP_REF]], -2
// LLVM: %[[BF_SET:.*]] = or i8 %[[BF_CLEAR]], 0
// LLVM: store i8 %[[BF_SET]], ptr %[[ELEM_0_PTR]], align 4
// LLVM: br label %[[RESULT_LABEL:.*]]
// LLVM: [[RESULT_LABEL]]:
// LLVM: %[[RESULT:.*]] = phi i32 [ 0, %[[BF_LABEL]] ]
// LLVM: store i32 %[[RESULT]], ptr %[[A_ADDR]], align 4

// OGCG: %[[A_ADDR:.*]] = alloca i32, align 4
// OGCG: %[[REF_ADDR:.*]] = alloca %struct.StructWithConstMember, align 4
// OGCG: %[[TMP_REF:.*]] = load i8, ptr %[[REF_ADDR]], align 4
// OGCG: %[[BF_CLEAR:.*]] = and i8 %[[TMP_REF]], -2
// OGCG: %[[BF_SET:.*]] = or i8 %[[BF_CLEAR]], 0
// OGCG: store i8 %[[BF_SET]], ptr %[[REF_ADDR]], align 4
// OGCG: store i32 0, ptr %[[A_ADDR]], align 4
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