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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, llvmorg-16.0.6, llvmorg-16.0.5, llvmorg-16.0.4, llvmorg-16.0.3, llvmorg-16.0.2, llvmorg-16.0.1, llvmorg-16.0.0, llvmorg-16.0.0-rc4 |
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401f7680 |
| 23-Feb-2023 |
Qiongsi Wu <qwu@ibm.com> |
[PGO] Setting ValueProfNode Array's Alignment
`instrprof` currently does not set `__llvm_prf_vnds`'s alignment after creating it. The consequence is that the alignment is set to 16 later (https://gi
[PGO] Setting ValueProfNode Array's Alignment
`instrprof` currently does not set `__llvm_prf_vnds`'s alignment after creating it. The consequence is that the alignment is set to 16 later (https://github.com/llvm/llvm-project/blob/c0f3ac1d0015fd051144a987ff500b888a32be86/llvm/lib/IR/DataLayout.cpp#L1019). This can lead to undefined behaviour when we calculate `NumVNodes` in `lprofGetLoadModuleSignature` (https://github.com/llvm/llvm-project/blob/c0f3ac1d0015fd051144a987ff500b888a32be86/compiler-rt/lib/profile/InstrProfilingMerge.c#L32). The reason is that when the `__llvm_prf_vnds` array is 16 byte aligned, `__llvm_profile_end_vnodes() - __llvm_profile_begin_vnodes()` may not be a multiple of the size of ValueProfNode (which is 24, 20 on 32 bit targets).
This patch sets `__llvm_prf_vnds`'s alignment to its ABI alignment, which always divides its size. Then `__llvm_profile_end_vnodes() - __llvm_profile_begin_vnodes()` will be a multiple of `sizeof(ValueProfNode)`.
Reviewed By: w2yehia, MaskRay
Differential Revision: https://reviews.llvm.org/D144302
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