https://github.com/ahatanak created https://github.com/llvm/llvm-project/pull/167344
Evaluate all aggregate compound literals into a temporary and then copy it to the destination if aliasing is possible. This fixes a latent issue exposed by #154490, where evaluating the RHS directly into the destination could ignore potential aliasing. rdar://164094548 >From c381519885ec6c5ca34822488f16632498fa358b Mon Sep 17 00:00:00 2001 From: Akira Hatanaka <[email protected]> Date: Sun, 9 Nov 2025 09:35:45 -0800 Subject: [PATCH] [CodeGen] Remove the check that allowed non-POD compound literals to be directly evaluated into the destination even when it might alias the source Evaluate all aggregate compound literals into a temporary and then copy it to the destination if aliasing is possible. This fixes a latent issue exposed by #154490, where evaluating the RHS directly into the destination could ignore potential aliasing. rdar://164094548 --- clang/lib/CodeGen/CGExprAgg.cpp | 7 +-- clang/test/CodeGenObjC/nontrivial-c-struct.m | 59 ++++++++++++++++++++ 2 files changed, 62 insertions(+), 4 deletions(-) create mode 100644 clang/test/CodeGenObjC/nontrivial-c-struct.m diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp index eee397f1f3d19..4e61a6f61948f 100644 --- a/clang/lib/CodeGen/CGExprAgg.cpp +++ b/clang/lib/CodeGen/CGExprAgg.cpp @@ -755,10 +755,9 @@ void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) { void AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { - if (Dest.isPotentiallyAliased() && - E->getType().isPODType(CGF.getContext())) { - // For a POD type, just emit a load of the lvalue + a copy, because our - // compound literal might alias the destination. + if (Dest.isPotentiallyAliased()) { + // Just emit a load of the lvalue + a copy, because our compound literal + // might alias the destination. EmitAggLoadOfLValue(E); return; } diff --git a/clang/test/CodeGenObjC/nontrivial-c-struct.m b/clang/test/CodeGenObjC/nontrivial-c-struct.m new file mode 100644 index 0000000000000..fa4fa223bc2d9 --- /dev/null +++ b/clang/test/CodeGenObjC/nontrivial-c-struct.m @@ -0,0 +1,59 @@ +// RUN: %clang_cc1 -triple arm64e-apple-ios18 -fptrauth-calls -fptrauth-intrinsics -fobjc-arc -emit-llvm -o - %s | FileCheck %s + +// CHECK: %[[STRUCT_S0:.*]] = type { i32, i32, ptr } +// CHECK: %[[STRUCT_S1:.*]] = type { ptr, ptr } + +// This struct isn't POD because it has an address-discriminated ptrauth +// field. +typedef struct { + int f0, f1; + int * __ptrauth(1,1,50) f2; +} S0; + +// This struct isn't POD because it has an address-discriminated ptrauth +// field and an ARC ObjC pointer field. +typedef struct { + id f0; + int * __ptrauth(1,1,50) f1; +} S1; + +// CHECK: define void @compound_literal_assignment0(ptr noundef %[[P:.*]]) +// CHECK: %[[P_ADDR:.*]] = alloca ptr, align 8 +// CHECK-NEXT: %[[_COMPOUNDLITERAL:.*]] = alloca %[[STRUCT_S0]], align 8 +// CHECK-NEXT: store ptr %[[P]], ptr %[[P_ADDR]], align 8 +// CHECK-NEXT: %[[V0:.*]] = load ptr, ptr %[[P_ADDR]], align 8 +// CHECK-NEXT: %[[F0:.*]] = getelementptr inbounds nuw %[[STRUCT_S0]], ptr %[[_COMPOUNDLITERAL]], i32 0, i32 0 +// CHECK-NEXT: %[[V1:.*]] = load ptr, ptr %[[P_ADDR]], align 8 +// CHECK-NEXT: %[[F1:.*]] = getelementptr inbounds nuw %[[STRUCT_S0]], ptr %[[V1]], i32 0, i32 1 +// CHECK-NEXT: %[[V2:.*]] = load i32, ptr %[[F1]], align 4 +// CHECK-NEXT: store i32 %[[V2]], ptr %[[F0]], align 8 +// CHECK-NEXT: %[[F11:.*]] = getelementptr inbounds nuw %[[STRUCT_S0]], ptr %[[_COMPOUNDLITERAL]], i32 0, i32 1 +// CHECK-NEXT: %[[V3:.*]] = load ptr, ptr %[[P_ADDR]], align 8 +// CHECK-NEXT: %[[F02:.*]] = getelementptr inbounds nuw %[[STRUCT_S0]], ptr %[[V3]], i32 0, i32 0 +// CHECK-NEXT: %[[V4:.*]] = load i32, ptr %[[F02]], align 8 +// CHECK-NEXT: store i32 %[[V4]], ptr %[[F11]], align 4 +// CHECK-NEXT: %[[F2:.*]] = getelementptr inbounds nuw %[[STRUCT_S0]], ptr %[[_COMPOUNDLITERAL]], i32 0, i32 2 +// CHECK-NEXT: store ptr null, ptr %[[F2]], align 8 +// CHECK-NEXT: call void @__copy_assignment_8_8_t0w8_pa1_50_8(ptr %[[V0]], ptr %[[_COMPOUNDLITERAL]]) +// CHECK-NEXT: ret void + +void compound_literal_assignment0(S0 *p) { + *p = (S0){.f0 = p->f1, .f1 = p->f0}; +} + +// CHECK: define void @compound_literal_assignment1(ptr noundef %[[P:.*]]) +// CHECK: %[[P_ADDR:.*]] = alloca ptr, align 8 +// CHECK-NEXT: %[[_COMPOUNDLITERAL:.*]] = alloca %[[STRUCT_S1]], align 8 +// CHECK-NEXT: store ptr %[[P]], ptr %[[P_ADDR]], align 8 +// CHECK-NEXT: %[[V0:.*]] = load ptr, ptr %[[P_ADDR]], align 8 +// CHECK-NEXT: %[[F0:.*]] = getelementptr inbounds nuw %[[STRUCT_S1]], ptr %[[_COMPOUNDLITERAL]], i32 0, i32 0 +// CHECK-NEXT: store ptr null, ptr %[[F0]], align 8 +// CHECK-NEXT: %[[F1:.*]] = getelementptr inbounds nuw %[[STRUCT_S1]], ptr %[[_COMPOUNDLITERAL]], i32 0, i32 1 +// CHECK-NEXT: store ptr null, ptr %[[F1]], align 8 +// CHECK-NEXT: call void @__copy_assignment_8_8_s0_pa1_50_8(ptr %[[V0]], ptr %[[_COMPOUNDLITERAL]]) +// CHECK-NEXT: call void @__destructor_8_s0(ptr %[[_COMPOUNDLITERAL]]) +// CHECK-NEXT: ret void + +void compound_literal_assignment1(S1 *p) { + *p = (S1){}; +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
