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Fix undefined behavior. 

Having std:move(mb) and mb->getBuffer() in the same argument list is not safe
because the order of evaluation is not defined.

llvm-svn: 234541
This commit is contained in:
Rui Ueyama 2015-04-09 22:04:45 +00:00
parent 2e8cb722de
commit 0a997cbd3f
1 changed files with 9 additions and 10 deletions
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19
lld/lib/ReaderWriter/ELF/ELFReader.h
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@ -38,28 +38,27 @@ public:
const Elf_Ehdr *hdr = elfHeader(*mb);
if (auto ec = _ctx.mergeHeaderFlags(hdr->getFileClass(), hdr->e_flags))
return ec;
std::size_t maxAlignment =
1ULL << llvm::countTrailingZeros(uintptr_t(mb->getBufferStart()));
result.push_back(createELF(llvm::object::getElfArchType(mb->getBuffer()),
maxAlignment, std::move(mb)));
result.push_back(createELF(std::move(mb)));
return std::error_code();
}
private:
/// Create an object depending on the runtime attributes and alignment
/// of an ELF file.
std::unique_ptr<File> createELF(std::pair<unsigned char, unsigned char> ident,
std::size_t maxAlignment,
std::unique_ptr<MemoryBuffer> mb) const {
std::unique_ptr<File> createELF(std::unique_ptr<MemoryBuffer> mb) const {
using namespace llvm::ELF;
using namespace llvm::support;
using llvm::object::ELFType;
if (maxAlignment < 2)
size_t align =
1ULL << llvm::countTrailingZeros(uintptr_t(mb->getBufferStart()));
if (align < 2)
llvm_unreachable("Invalid alignment for ELF file!");
unsigned char size;
unsigned char endian;
std::tie(size, endian) = llvm::object::getElfArchType(mb->getBuffer());
File *file = nullptr;
unsigned char size = ident.first;
unsigned char endian = ident.second;
if (size == ELFCLASS32 && endian == ELFDATA2LSB) {
file = new FileT<ELFType<little, 2, false>>(std::move(mb), _ctx);
} else if (size == ELFCLASS32 && endian == ELFDATA2MSB) {