[SYCL] Fix host-to-host copy during copyback#1692
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Copyback is performed unconditionally during buffer destruction, so it's possible for it to perform a copy from and to the same host pointer. This patch adds a check for this scenario so that we don't rely on undefined behaviour of std::memcpy. Signed-off-by: Sergey Semenov <sergey.semenov@intel.com>
Signed-off-by: Sergey Semenov <sergey.semenov@intel.com>
s-kanaev
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May 15, 2020
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| DstOffset[0] *= DstElemSize; | ||
| SrcOffset[0] *= SrcElemSize; | ||
| SrcMem += SrcOffset[0] * SrcElemSize; |
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Just curious.
Why only SrcOffset[0] is involved? Is multidimensional offset "merged" into singledimensional?
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I think the checks at lines 353-355 in this file make this line 361 correct. If Dim > 1, then the statement is SrcMem += 0;
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Honestly speaking it is hard to believe that std::memcpy() does not check src==dst case and does something wrong in such case.
Why did you decide fixing this, did you really noticed unexpected behavior when src==dst?
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@v-klochkov I have indeed encountered such behaviour when linking with Intel's implementation of memcpy (_intel_fast_memcpy).
v-klochkov
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May 15, 2020
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…_docs * origin/sycl: (1867 commits) [SYCL] Implement USM vars and placeholder accessors passed to reduction (intel#1657) [SYCL] Fix post-commit testing (intel#1705) [SYCL][NFC] Remove multi_ptr<const void, Space>::operator multi_ptr<const void, Space> (intel#1702) [Doc] Readme update. (intel#1701) Support function pointers in cast instructions Adjust FPGA IVDep translation for embedded loops [SYCL] Fix host-to-host copy during copyback (intel#1692) [SYCL] Add information about dependencies used in CI [SYCL] Add runtime support for fsycl-id-queries-fit-in-int (intel#1685) Revert "Revert "[llvm][NFC] Cleanup uses of std::function in Inlining-related APIs"" StoreInst should store Align, not MaybeAlign [clang][slh] Add test for SLH feature checking macro [NFC] Deduplicate comment in PromoteMemoryToRegister.cpp [WebAssembly] Optimize splats of bitcasted vectors [LLD][ELF] Use offset in thin archives to disambiguate thinLTO members [AArch64][SVE] Implement AArch64ISD::SETCC_PRED [SVE] Restore broken LLVM-C ABI compatability IR: Remove extra name mangling from llvm.ptrmask [NFC] Whitespace fix inside OptParserEmitter [compiler-rt][CMAKE] Only add cmake link flags in standalone build ...
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Copyback is performed unconditionally during buffer destruction, so
it's possible for it to perform a copy from and to the same host
pointer. This patch adds a check for this scenario so that we don't rely
on undefined behaviour of std::memcpy.
Signed-off-by: Sergey Semenov sergey.semenov@intel.com