llvm/lib/Object/ELFObjectFile.cpp

//===- ELFObjectFile.cpp - ELF object file implementation -------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Part of the ELFObjectFile class implementation.
//
//===----------------------------------------------------------------------===//

#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Support/MathExtras.h"

namespace llvm {
using namespace object;

ELFObjectFileBase::ELFObjectFileBase(unsigned int Type, MemoryBufferRef Source)
    : ObjectFile(Type, Source) {}

ErrorOr<std::unique_ptr<ObjectFile>>
ObjectFile::createELFObjectFile(MemoryBufferRef Obj) {
  std::pair<unsigned char, unsigned char> Ident =
      getElfArchType(Obj.getBuffer());
  std::size_t MaxAlignment =
      1ULL << countTrailingZeros(uintptr_t(Obj.getBufferStart()));

  if (MaxAlignment < 2)
    return object_error::parse_failed;

  std::error_code EC;
  std::unique_ptr<ObjectFile> R;
  if (Ident.first == ELF::ELFCLASS32) {
    if (Ident.second == ELF::ELFDATA2LSB)
      R.reset(new ELFObjectFile<ELFType<support::little, false>>(Obj, EC));
    else if (Ident.second == ELF::ELFDATA2MSB)
      R.reset(new ELFObjectFile<ELFType<support::big, false>>(Obj, EC));
    else
      return object_error::parse_failed;
  } else if (Ident.first == ELF::ELFCLASS64) {
    if (Ident.second == ELF::ELFDATA2LSB)
      R.reset(new ELFObjectFile<ELFType<support::little, true>>(Obj, EC));
    else if (Ident.second == ELF::ELFDATA2MSB)
      R.reset(new ELFObjectFile<ELFType<support::big, true>>(Obj, EC));
    else
      return object_error::parse_failed;
  } else {
    return object_error::parse_failed;
  }

  if (EC)
    return EC;
  return std::move(R);
}

SubtargetFeatures ELFObjectFileBase::getFeatures() const {
  switch (getEMachine()) {
  case ELF::EM_MIPS: {
    SubtargetFeatures Features;
    unsigned PlatformFlags;
    getPlatformFlags(PlatformFlags);

    switch (PlatformFlags & ELF::EF_MIPS_ARCH) {
    case ELF::EF_MIPS_ARCH_1:
      break;
    case ELF::EF_MIPS_ARCH_2:
      Features.AddFeature("mips2");
      break;
    case ELF::EF_MIPS_ARCH_3:
      Features.AddFeature("mips3");
      break;
    case ELF::EF_MIPS_ARCH_4:
      Features.AddFeature("mips4");
      break;
    case ELF::EF_MIPS_ARCH_5:
      Features.AddFeature("mips5");
      break;
    case ELF::EF_MIPS_ARCH_32:
      Features.AddFeature("mips32");
      break;
    case ELF::EF_MIPS_ARCH_64:
      Features.AddFeature("mips64");
      break;
    case ELF::EF_MIPS_ARCH_32R2:
      Features.AddFeature("mips32r2");
      break;
    case ELF::EF_MIPS_ARCH_64R2:
      Features.AddFeature("mips64r2");
      break;
    case ELF::EF_MIPS_ARCH_32R6:
      Features.AddFeature("mips32r6");
      break;
    case ELF::EF_MIPS_ARCH_64R6:
      Features.AddFeature("mips64r6");
      break;
    default:
      llvm_unreachable("Unknown EF_MIPS_ARCH value");
    }

    switch (PlatformFlags & ELF::EF_MIPS_MACH) {
    case ELF::EF_MIPS_MACH_NONE:
      // No feature associated with this value.
      break;
    case ELF::EF_MIPS_MACH_OCTEON:
      Features.AddFeature("cnmips");
      break;
    default:
      llvm_unreachable("Unknown EF_MIPS_ARCH value");
    }

    if (PlatformFlags & ELF::EF_MIPS_ARCH_ASE_M16)
      Features.AddFeature("mips16");
    if (PlatformFlags & ELF::EF_MIPS_MICROMIPS)
      Features.AddFeature("micromips");

    return Features;
  }
  default:
    return SubtargetFeatures();
  }
}

// FIXME Encode from a tablegen description or target parser.
void ELFObjectFileBase::setARMSubArch(Triple &TheTriple) const {
  if (TheTriple.getSubArch() != Triple::NoSubArch)
    return;

  ARMAttributeParser Attributes;
  std::error_code EC = getBuildAttributes(Attributes);
  if (EC)
    return;

  std::string Triple;
  // Default to ARM, but use the triple if it's been set.
  if (TheTriple.getArch() == Triple::thumb ||
      TheTriple.getArch() == Triple::thumbeb)
    Triple = "thumb";
  else
    Triple = "arm";

  if (Attributes.hasAttribute(ARMBuildAttrs::CPU_arch)) {
    switch(Attributes.getAttributeValue(ARMBuildAttrs::CPU_arch)) {
    case ARMBuildAttrs::v4:
      Triple += "v4";
      break;
    case ARMBuildAttrs::v4T:
      Triple += "v4t";
      break;
    case ARMBuildAttrs::v5T:
      Triple += "v5t";
      break;
    case ARMBuildAttrs::v5TE:
      Triple += "v5te";
      break;
    case ARMBuildAttrs::v5TEJ:
      Triple += "v5tej";
      break;
    case ARMBuildAttrs::v6:
      Triple += "v6";
      break;
    case ARMBuildAttrs::v6KZ:
      Triple += "v6kz";
      break;
    case ARMBuildAttrs::v6T2:
      Triple += "v6t2";
      break;
    case ARMBuildAttrs::v6K:
      Triple += "v6k";
      break;
    case ARMBuildAttrs::v7:
      Triple += "v7";
      break;
    case ARMBuildAttrs::v6_M:
      Triple += "v6m";
      break;
    case ARMBuildAttrs::v6S_M:
      Triple += "v6sm";
      break;
    case ARMBuildAttrs::v7E_M:
      Triple += "v7em";
      break;
    }
  }
  if (!isLittleEndian())
    Triple += "eb";

  TheTriple.setArchName(Triple);
}

} // end namespace llvm