lib/Object/ELFObjectFile.cpp

   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
  17 namespace llvm {
  18 using namespace object;
  19
  20 ErrorOr<ObjectFile *>
  21 ObjectFile::createELFObjectFile(std::unique_ptr<MemoryBuffer> &Obj) {
  22   std::pair<unsigned char, unsigned char> Ident =
  23       getElfArchType(Obj->getBuffer());
  24   std::size_t MaxAlignment =
  25     1ULL << countTrailingZeros(uintptr_t(Obj->getBufferStart()));
  26
  27   std::error_code EC;
  28   std::unique_ptr<ObjectFile> R;
  29   if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2LSB)
  30 #if !LLVM_IS_UNALIGNED_ACCESS_FAST
  31     if (MaxAlignment >= 4)
  32       R.reset(new ELFObjectFile<ELFType<support::little, 4, false>>(
  33           std::move(Obj), EC));
  34     else
  35 #endif
  36     if (MaxAlignment >= 2)
  37       R.reset(new ELFObjectFile<ELFType<support::little, 2, false>>(
  38           std::move(Obj), EC));
  39     else
  40       return object_error::parse_failed;
  41   else if (Ident.first == ELF::ELFCLASS32 && Ident.second == ELF::ELFDATA2MSB)
  42 #if !LLVM_IS_UNALIGNED_ACCESS_FAST
  43     if (MaxAlignment >= 4)
  44       R.reset(new ELFObjectFile<ELFType<support::big, 4, false>>(std::move(Obj),
  45                                                                  EC));
  46     else
  47 #endif
  48     if (MaxAlignment >= 2)
  49       R.reset(new ELFObjectFile<ELFType<support::big, 2, false>>(std::move(Obj),
  50                                                                  EC));
  51     else
  52       return object_error::parse_failed;
  53   else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2MSB)
  54 #if !LLVM_IS_UNALIGNED_ACCESS_FAST
  55     if (MaxAlignment >= 8)
  56       R.reset(new ELFObjectFile<ELFType<support::big, 8, true>>(std::move(Obj),
  57                                                                 EC));
  58     else
  59 #endif
  60     if (MaxAlignment >= 2)
  61       R.reset(new ELFObjectFile<ELFType<support::big, 2, true>>(std::move(Obj),
  62                                                                 EC));
  63     else
  64       return object_error::parse_failed;
  65   else if (Ident.first == ELF::ELFCLASS64 && Ident.second == ELF::ELFDATA2LSB) {
  66 #if !LLVM_IS_UNALIGNED_ACCESS_FAST
  67     if (MaxAlignment >= 8)
  68       R.reset(new ELFObjectFile<ELFType<support::little, 8, true>>(
  69           std::move(Obj), EC));
  70     else
  71 #endif
  72     if (MaxAlignment >= 2)
  73       R.reset(new ELFObjectFile<ELFType<support::little, 2, true>>(
  74           std::move(Obj), EC));
  75     else
  76       return object_error::parse_failed;
  77   }
  78   else
  79     llvm_unreachable("Buffer is not an ELF object file!");
  80
  81   if (EC)
  82     return EC;
  83   return R.release();
  84 }
  85
  86 } // end namespace llvm