llvm-project/lld/lib/ReaderWriter/ELF/ELFTargetInfo.cpp

//===- lib/ReaderWriter/ELF/ELFTargetInfo.cpp -----------------------------===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "lld/ReaderWriter/ELFTargetInfo.h"

#include "TargetHandler.h"
#include "Targets.h"

#include "lld/Passes/LayoutPass.h"
#include "lld/ReaderWriter/ReaderLinkerScript.h"

#include "llvm/ADT/Triple.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"

namespace lld {
ELFTargetInfo::ELFTargetInfo(llvm::Triple triple)
 : _outputFileType(elf::ET_EXEC)
 , _triple(triple)
 , _baseAddress(0)
 , _isStaticExecutable(false)
 , _outputYAML(false)
 , _noInhibitExec(false)
 , _mergeCommonStrings(false)
 , _runLayoutPass(true) {
}

bool ELFTargetInfo::is64Bits() const {
  return getTriple().isArch64Bit();
}

bool ELFTargetInfo::isLittleEndian() const {
  // TODO: Do this properly. It is not defined purely by arch.
  return true;
}

void ELFTargetInfo::addPasses(PassManager &pm) const {
  if (_runLayoutPass)
    pm.add(std::unique_ptr<Pass>(new LayoutPass()));
}

uint16_t ELFTargetInfo::getOutputMachine() const {
  switch (getTriple().getArch()) {
  case llvm::Triple::x86:
    return llvm::ELF::EM_386;
  case llvm::Triple::x86_64:
    return llvm::ELF::EM_X86_64;
  case llvm::Triple::hexagon:
    return llvm::ELF::EM_HEXAGON;
  case llvm::Triple::ppc:
    return llvm::ELF::EM_PPC;
  default:
    llvm_unreachable("Unhandled arch");
  }
}

bool ELFTargetInfo::validate(raw_ostream &diagnostics) {
  if (_outputFileType == elf::ET_EXEC) {
    if (_entrySymbolName.empty()) {
      _entrySymbolName = "_start";
    }
  }

  if (_inputFiles.empty()) {
    diagnostics << "No input files\n";
    return true;
  }


  return false;
}


bool ELFTargetInfo::isDynamic() const {
  switch (_outputFileType) {
  case llvm::ELF::ET_EXEC:
    if (_isStaticExecutable)
      return false;
    else
      return true;
  case llvm::ELF::ET_DYN:
    return true;
  }
  return false;
}

error_code ELFTargetInfo::parseFile(std::unique_ptr<MemoryBuffer> &mb,
                          std::vector<std::unique_ptr<File>> &result) const {
  if (!_elfReader)
    _elfReader = createReaderELF(*this);
  error_code ec = _elfReader->parseFile(mb, result);
  if (ec) {
    // Not an ELF file, check file extension to see if it might be yaml
    StringRef path = mb->getBufferIdentifier();
    if ( path.endswith(".objtxt") ) {
      if (!_yamlReader)
          _yamlReader = createReaderYAML(*this);
      ec = _yamlReader->parseFile(mb, result);
    }
    if (ec) {
      // Not a yaml file, assume it is a linkerscript
      if (!_linkerScriptReader)
        _linkerScriptReader.reset(new ReaderLinkerScript(*this));
      ec = _linkerScriptReader->parseFile(mb, result);
    }
  }
  return ec;
}

Writer &ELFTargetInfo::writer() const {
  if (!_writer) {
    if (_outputYAML)
      _writer = createWriterYAML(*this);
    else
      _writer = createWriterELF(*this);
  }
  return *_writer;
}


std::unique_ptr<ELFTargetInfo> ELFTargetInfo::create(llvm::Triple triple) {
  switch (triple.getArch()) {
  case llvm::Triple::x86:
    return std::unique_ptr<ELFTargetInfo>(new lld::elf::X86TargetInfo(triple));
  case llvm::Triple::x86_64:
    return std::unique_ptr<
        ELFTargetInfo>(new lld::elf::X86_64TargetInfo(triple));
  case llvm::Triple::hexagon:
    return std::unique_ptr<
        ELFTargetInfo>(new lld::elf::HexagonTargetInfo(triple));
  case llvm::Triple::ppc:
    return std::unique_ptr<ELFTargetInfo>(new lld::elf::PPCTargetInfo(triple));
  default:
    return std::unique_ptr<ELFTargetInfo>();
  }
}

bool ELFTargetInfo::appendLibrary(StringRef libName) {
  bool foundFile = false;
  StringRef pathref;
  for (StringRef dir : _inputSearchPaths) {
    // Search for dynamic library
    if (!_isStaticExecutable) {
      SmallString<128> dynlibPath;
      dynlibPath.assign(dir);
      llvm::sys::path::append(dynlibPath, Twine("lib") + libName + ".so");
      pathref = dynlibPath.str();
      if (llvm::sys::fs::exists(pathref)) {
        foundFile = true;
      }
    }
    // Search for static libraries too
    if (!foundFile) {
      SmallString<128> archivefullPath;
      archivefullPath.assign(dir);
      llvm::sys::path::append(archivefullPath, Twine("lib") + libName + ".a");
      pathref = archivefullPath.str();
      if (llvm::sys::fs::exists(pathref)) {
        foundFile = true;
      }
    }
    if (foundFile) {
      unsigned pathlen = pathref.size();
      char *x = _extraStrings.Allocate<char>(pathlen);
      memcpy(x, pathref.data(), pathlen);
      appendInputFile(StringRef(x,pathlen));
      return false;
    }
  }
  return true;
}

} // end namespace lld