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Revision tags: llvmorg-18.1.8, llvmorg-18.1.7, llvmorg-18.1.6, llvmorg-18.1.5, llvmorg-18.1.4, llvmorg-18.1.3, llvmorg-18.1.2, llvmorg-18.1.1, llvmorg-18.1.0, llvmorg-18.1.0-rc4, llvmorg-18.1.0-rc3, llvmorg-18.1.0-rc2, llvmorg-18.1.0-rc1, llvmorg-19-init, llvmorg-17.0.6, llvmorg-17.0.5, llvmorg-17.0.4, llvmorg-17.0.3, llvmorg-17.0.2, llvmorg-17.0.1, llvmorg-17.0.0, llvmorg-17.0.0-rc4, llvmorg-17.0.0-rc3, llvmorg-17.0.0-rc2, llvmorg-17.0.0-rc1, llvmorg-18-init |
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| #
afd20587 |
| 30-Jun-2023 |
Fangrui Song <i@maskray.me> |
MachineFunction: -fsanitize={function,kcfi}: ensure 4-byte alignment
Fix https://github.com/llvm/llvm-project/issues/63579
```
% cat a.c
void foo() {}
% clang --target=arm-none-eabi -mthumb -mno-una
MachineFunction: -fsanitize={function,kcfi}: ensure 4-byte alignment
Fix https://github.com/llvm/llvm-project/issues/63579
```
% cat a.c
void foo() {}
% clang --target=arm-none-eabi -mthumb -mno-unaligned-access -fsanitize=kcfi a.c -S -o - | grep p2align
.p2align 1
% clang --target=armv6m-none-eabi -fsanitize=function a.c -S -o - | grep p2align
.p2align 1
```
Ensure that -fsanitize={function,kcfi} instrumented functions are aligned by at
least 4, so that loading the type hash before the function label will not cause
a misaligned access. This is especially important for -mno-unaligned-access
configurations that don't set `setMinFunctionAlignment` to 4 or greater.
With this patch, the generated assembly for the examples above will contain `.p2align 2`
before the type hash.
If `__attribute__((aligned(N)))` or `-falign-functions=N` is specified, the
larger alignment will be used.
Reviewed By: simon_tatham, samitolvanen
Differential Revision: https://reviews.llvm.org/D154125
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