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author | Richard Smith <richard-llvm@metafoo.co.uk> | 2012-08-21 20:48:36 +0000 |
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committer | Richard Smith <richard-llvm@metafoo.co.uk> | 2012-08-21 20:48:36 +0000 |
commit | fca01b5e2b509f2e9aeeb1cc51aea89c3722cb2e (patch) | |
tree | 7657019bfa9a90709f430d7f1f02d2f429cccdda /lib/Target/X86/X86JITInfo.cpp | |
parent | 79b59a2766c42180f08fd49c3ea1c5b66682d487 (diff) | |
download | llvm-fca01b5e2b509f2e9aeeb1cc51aea89c3722cb2e.tar.gz llvm-fca01b5e2b509f2e9aeeb1cc51aea89c3722cb2e.tar.bz2 llvm-fca01b5e2b509f2e9aeeb1cc51aea89c3722cb2e.tar.xz |
Fix unaligned memory accesses when performing relocations in X86 JIT. There's
no cost to using memcpy here: the fixed code is optimized by LLVM to perfect
machine code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162311 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Target/X86/X86JITInfo.cpp')
-rw-r--r-- | lib/Target/X86/X86JITInfo.cpp | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/lib/Target/X86/X86JITInfo.cpp b/lib/Target/X86/X86JITInfo.cpp index 0168d12231..7ac4cec867 100644 --- a/lib/Target/X86/X86JITInfo.cpp +++ b/lib/Target/X86/X86JITInfo.cpp @@ -532,6 +532,15 @@ uintptr_t X86JITInfo::getPICJumpTableEntry(uintptr_t BB, uintptr_t Entry) { #endif } +template<typename T> void addUnaligned(void *Pos, T Delta) { + T Value; + std::memcpy(reinterpret_cast<char*>(&Value), reinterpret_cast<char*>(Pos), + sizeof(T)); + Value += Delta; + std::memcpy(reinterpret_cast<char*>(Pos), reinterpret_cast<char*>(&Value), + sizeof(T)); +} + /// relocate - Before the JIT can run a block of code that has been emitted, /// it must rewrite the code to contain the actual addresses of any /// referenced global symbols. @@ -545,24 +554,24 @@ void X86JITInfo::relocate(void *Function, MachineRelocation *MR, // PC relative relocation, add the relocated value to the value already in // memory, after we adjust it for where the PC is. ResultPtr = ResultPtr -(intptr_t)RelocPos - 4 - MR->getConstantVal(); - *((unsigned*)RelocPos) += (unsigned)ResultPtr; + addUnaligned<unsigned>(RelocPos, ResultPtr); break; } case X86::reloc_picrel_word: { // PIC base relative relocation, add the relocated value to the value // already in memory, after we adjust it for where the PIC base is. ResultPtr = ResultPtr - ((intptr_t)Function + MR->getConstantVal()); - *((unsigned*)RelocPos) += (unsigned)ResultPtr; + addUnaligned<unsigned>(RelocPos, ResultPtr); break; } case X86::reloc_absolute_word: case X86::reloc_absolute_word_sext: // Absolute relocation, just add the relocated value to the value already // in memory. - *((unsigned*)RelocPos) += (unsigned)ResultPtr; + addUnaligned<unsigned>(RelocPos, ResultPtr); break; case X86::reloc_absolute_dword: - *((intptr_t*)RelocPos) += ResultPtr; + addUnaligned<intptr_t>(RelocPos, ResultPtr); break; } } |