ELFObjectFile.cpp revision 263508 
1//===- ELFObjectFile.cpp - ELF object file implementation -------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Part of the ELFObjectFile class implementation.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Object/ELFObjectFile.h"
15#include "llvm/Support/MathExtras.h"
16
17namespace llvm {
18using namespace object;
19
20// Creates an in-memory object-file by default: createELFObjectFile(Buffer)
21ObjectFile *ObjectFile::createELFObjectFile(MemoryBuffer *Object) {
22  std::pair<unsigned char, unsigned char> Ident = getElfArchType(Object);
23  error_code ec;
24
25  std::size_t MaxAlignment =
26    1ULL << countTrailingZeros(uintptr_t(Object->getBufferStart()));
27
28  if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB)
29#if !LLVM_IS_UNALIGNED_ACCESS_FAST
30    if (MaxAlignment >= 4)
31      return new ELFObjectFile<ELFType<support::little, 4, false> >(Object, ec);
32    else
33#endif
34    if (MaxAlignment >= 2)
35      return new ELFObjectFile<ELFType<support::little, 2, false> >(Object, ec);
36    else
37      llvm_unreachable("Invalid alignment for ELF file!");
38  else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB)
39#if !LLVM_IS_UNALIGNED_ACCESS_FAST
40    if (MaxAlignment >= 4)
41      return new ELFObjectFile<ELFType<support::big, 4, false> >(Object, ec);
42    else
43#endif
44    if (MaxAlignment >= 2)
45      return new ELFObjectFile<ELFType<support::big, 2, false> >(Object, ec);
46    else
47      llvm_unreachable("Invalid alignment for ELF file!");
48  else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB)
49#if !LLVM_IS_UNALIGNED_ACCESS_FAST
50    if (MaxAlignment >= 8)
51      return new ELFObjectFile<ELFType<support::big, 8, true> >(Object, ec);
52    else
53#endif
54    if (MaxAlignment >= 2)
55      return new ELFObjectFile<ELFType<support::big, 2, true> >(Object, ec);
56    else
57      llvm_unreachable("Invalid alignment for ELF file!");
58  else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
59#if !LLVM_IS_UNALIGNED_ACCESS_FAST
60    if (MaxAlignment >= 8)
61      return new ELFObjectFile<ELFType<support::little, 8, true> >(Object, ec);
62    else
63#endif
64    if (MaxAlignment >= 2)
65      return new ELFObjectFile<ELFType<support::little, 2, true> >(Object, ec);
66    else
67      llvm_unreachable("Invalid alignment for ELF file!");
68  }
69
70  report_fatal_error("Buffer is not an ELF object file!");
71}
72
73} // end namespace llvm
74