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| author | Michael J. Spencer <bigcheesegs@gmail.com> | 2013-02-03 10:48:31 +0000 |
|---|---|---|
| committer | Michael J. Spencer <bigcheesegs@gmail.com> | 2013-02-03 10:48:31 +0000 |
| commit | d9d2f187759d0154574657c195068d367c338473 (patch) | |
| tree | 5b467a7f84e18ccf93fceccc6ed4ef210ea3de94 | |
| parent | fa987f08fb237e61e4f542572535546d92838b4f (diff) | |
| download | llvm-d9d2f187759d0154574657c195068d367c338473.tar.gz llvm-d9d2f187759d0154574657c195068d367c338473.tar.bz2 llvm-d9d2f187759d0154574657c195068d367c338473.tar.xz | |
[Support] Add LLVM_IS_UNALIGNED_ACCESS_FAST.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174271 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | include/llvm/Support/Compiler.h | 13 | ||||
| -rw-r--r-- | lib/Object/ELFObjectFile.cpp | 20 |
2 files changed, 29 insertions, 4 deletions
diff --git a/include/llvm/Support/Compiler.h b/include/llvm/Support/Compiler.h index 36539f6d34..6ca86bdd50 100644 --- a/include/llvm/Support/Compiler.h +++ b/include/llvm/Support/Compiler.h @@ -311,4 +311,17 @@ # define LLVM_MEMORY_SANITIZER_BUILD 0 #endif +/// \macro LLVM_IS_UNALIGNED_ACCESS_FAST +/// \brief Is unaligned memory access fast on the host machine. +/// +/// Don't specialize on alignment for platforms where unaligned memory accesses +/// generates the same code as aligned memory accesses for common types. +#if defined(_M_AMD64) || defined(_M_IX86) || defined(__amd64) || \ + defined(__amd64__) || defined(__x86_64) || defined(__x86_64__) || \ + defined(_X86_) || defined(__i386) || defined(__i386__) +# define LLVM_IS_UNALIGNED_ACCESS_FAST 1 +#else +# define LLVM_IS_UNALIGNED_ACCESS_FAST 0 +#endif + #endif diff --git a/lib/Object/ELFObjectFile.cpp b/lib/Object/ELFObjectFile.cpp index 160053dabd..cfe0eb467e 100644 --- a/lib/Object/ELFObjectFile.cpp +++ b/lib/Object/ELFObjectFile.cpp @@ -27,30 +27,42 @@ ObjectFile *ObjectFile::createELFObjectFile(MemoryBuffer *Object) { 1ULL << CountTrailingZeros_64(uintptr_t(Object->getBufferStart())); if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB) +#if !LLVM_IS_UNALIGNED_ACCESS_FAST if (MaxAlignment >= 4) return new ELFObjectFile<ELFType<support::little, 4, false> >(Object, ec); - else if (MaxAlignment >= 2) + else +#endif + if (MaxAlignment >= 2) return new ELFObjectFile<ELFType<support::little, 2, false> >(Object, ec); else llvm_unreachable("Invalid alignment for ELF file!"); else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB) +#if !LLVM_IS_UNALIGNED_ACCESS_FAST if (MaxAlignment >= 4) return new ELFObjectFile<ELFType<support::big, 4, false> >(Object, ec); - else if (MaxAlignment >= 2) + else +#endif + if (MaxAlignment >= 2) return new ELFObjectFile<ELFType<support::big, 2, false> >(Object, ec); else llvm_unreachable("Invalid alignment for ELF file!"); else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB) +#if !LLVM_IS_UNALIGNED_ACCESS_FAST if (MaxAlignment >= 8) return new ELFObjectFile<ELFType<support::big, 8, true> >(Object, ec); - else if (MaxAlignment >= 2) + else +#endif + if (MaxAlignment >= 2) return new ELFObjectFile<ELFType<support::big, 2, true> >(Object, ec); else llvm_unreachable("Invalid alignment for ELF file!"); else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) { +#if !LLVM_IS_UNALIGNED_ACCESS_FAST if (MaxAlignment >= 8) return new ELFObjectFile<ELFType<support::little, 8, true> >(Object, ec); - else if (MaxAlignment >= 2) + else +#endif + if (MaxAlignment >= 2) return new ELFObjectFile<ELFType<support::little, 2, true> >(Object, ec); else llvm_unreachable("Invalid alignment for ELF file!"); |