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[Object][ELF] Add a maximum alignment. This is used by createELFObjectFile to create a properly aligned reader.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171520 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael J. Spencer
2013-01-04 20:36:28 +00:00
parent e13f441e00
commit 4d9c5397b4
5 changed files with 465 additions and 385 deletions
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34
lib/Object/ELFObjectFile.cpp
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@@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/Object/ELF.h"
#include "llvm/Support/MathExtras.h"
namespace llvm {
@@ -22,16 +23,37 @@ ObjectFile *ObjectFile::createELFObjectFile(MemoryBuffer *Object) {
std::pair<unsigned char, unsigned char> Ident = getElfArchType(Object);
error_code ec;
std::size_t MaxAlignment =
1ULL << CountTrailingZeros_64(uintptr_t(Object->getBufferStart()));
if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB)
return new ELFObjectFile<support::little, false>(Object, ec);
if (MaxAlignment >= 4)
return new ELFObjectFile<support::little, 4, false>(Object, ec);
else if (MaxAlignment >= 2)
return new ELFObjectFile<support::little, 2, false>(Object, ec);
else
llvm_unreachable("Invalid alignment for ELF file!");
else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB)
return new ELFObjectFile<support::big, false>(Object, ec);
if (MaxAlignment >= 4)
return new ELFObjectFile<support::big, 4, false>(Object, ec);
else if (MaxAlignment >= 2)
return new ELFObjectFile<support::big, 2, false>(Object, ec);
else
llvm_unreachable("Invalid alignment for ELF file!");
else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB)
return new ELFObjectFile<support::big, true>(Object, ec);
if (MaxAlignment >= 8)
return new ELFObjectFile<support::big, 8, true>(Object, ec);
else if (MaxAlignment >= 2)
return new ELFObjectFile<support::big, 2, true>(Object, ec);
else
llvm_unreachable("Invalid alignment for ELF file!");
else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
ELFObjectFile<support::little, true> *result =
new ELFObjectFile<support::little, true>(Object, ec);
return result;
if (MaxAlignment >= 8)
return new ELFObjectFile<support::little, 8, true>(Object, ec);
else if (MaxAlignment >= 2)
return new ELFObjectFile<support::little, 2, true>(Object, ec);
else
llvm_unreachable("Invalid alignment for ELF file!");
}
report_fatal_error("Buffer is not an ELF object file!");