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efriedma-quic opened this issue Mar 21, 2025 · 1 comment · Fixed by #134269
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-fwrapv-pointer doesn't affect member accesses #132449

efriedma-quic opened this issue Mar 21, 2025 · 1 comment · Fixed by #134269
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@dtcxzyw
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clang:codegen IR generation bugs: mangling, exceptions, etc.

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@efriedma-quic
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Compile the following with -fwrapv-pointer:

struct S { int x,y; };
int *a(struct S *x) { return &x->y; }

Produces getelementptr inbounds nuw %struct.S, ptr %0, i32 0, i32 1... which seems counter to the premise of -fwrapv-pointer. And seems like it might be a problem with #130742 .

CC @dtcxzyw @nikic
@dtcxzyw dtcxzyw added clang:codegen IR generation bugs: mangling, exceptions, etc. and removed new issue labels Mar 22, 2025
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llvmbot commented Mar 22, 2025

@llvm/issue-subscribers-clang-codegen

Author: Eli Friedman (efriedma-quic)

Compile the following with -fwrapv-pointer: 
struct S { int x,y; };
int *a(struct S *x) { return &x->y; }

Produces getelementptr inbounds nuw %struct.S, ptr %0, i32 0, i32 1... which seems counter to the premise of -fwrapv-pointer. And seems like it might be a problem with #130742 .

CC @dtcxzyw @nikic

@dtcxzyw dtcxzyw mentioned this issue Apr 3, 2025
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@dtcxzyw dtcxzyw self-assigned this Apr 3, 2025
@dtcxzyw dtcxzyw mentioned this issue Apr 3, 2025
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@dtcxzyw dtcxzyw closed this as completed in c048073 Apr 9, 2025
llvm-sync bot pushed a commit to arm/arm-toolchain that referenced this issue Apr 9, 2025
@dtcxzyw @github-actions
Automerge: [Clang][CodeGen] Respect -fwrapv-pointer when emitting str…
eb51213 
…uct GEPs (#134269)

This patch turns off inbounds/nuw flags for member accesses when
`-fwrapv-pointer` is set.

Closes llvm/llvm-project#132449.

It is required by llvm/llvm-project#130734.
AllinLeeYL pushed a commit to AllinLeeYL/llvm-project that referenced this issue Apr 10, 2025
@dtcxzyw
[Clang][CodeGen] Respect -fwrapv-pointer when emitting struct GEPs (l…
62f54b1 
…lvm#134269)

This patch turns off inbounds/nuw flags for member accesses when
`-fwrapv-pointer` is set.

Closes llvm#132449.

It is required by llvm#130734.
var-const pushed a commit to ldionne/llvm-project that referenced this issue Apr 17, 2025
@dtcxzyw @var-const
[Clang][CodeGen] Respect -fwrapv-pointer when emitting struct GEPs (l…
270141c 
…lvm#134269)

This patch turns off inbounds/nuw flags for member accesses when
`-fwrapv-pointer` is set.

Closes llvm#132449.

It is required by llvm#130734.
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[Clang][CodeGen] Respect -fwrapv-pointer when emitting struct GEPs dtcxzyw/llvm-project
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@dtcxzyw @efriedma-quic @llvmbot