path: root/lld/lib/Driver/GnuLdDriver.cpp

//===- lib/Driver/GnuLdDriver.cpp -----------------------------------------===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
///
/// Concrete instance of the Driver for GNU's ld.
///
//===----------------------------------------------------------------------===//

#include "lld/Driver/Driver.h"
#include "lld/Driver/GnuLDInputGraph.h"

#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/Option.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/PrettyStackTrace.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Signals.h"

using namespace lld;


namespace {

// Create enum with OPT_xxx values for each option in LDOptions.td
enum LDOpt {
  OPT_INVALID = 0,
#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM, \
               HELP, META) \
          OPT_##ID,
#include "LDOptions.inc"
  LastOption
#undef OPTION
};

// Create prefix string literals used in LDOptions.td
#define PREFIX(NAME, VALUE) const char *const NAME[] = VALUE;
#include "LDOptions.inc"
#undef PREFIX

// Create table mapping all options defined in LDOptions.td
static const llvm::opt::OptTable::Info infoTable[] = {
#define OPTION(PREFIX, NAME, ID, KIND, GROUP, ALIAS, ALIASARGS, FLAGS, PARAM, \
               HELPTEXT, METAVAR)   \
  { PREFIX, NAME, HELPTEXT, METAVAR, OPT_##ID, llvm::opt::Option::KIND##Class, \
    PARAM, FLAGS, OPT_##GROUP, OPT_##ALIAS, ALIASARGS },
#include "LDOptions.inc"
#undef OPTION
};


// Create OptTable class for parsing actual command line arguments
class GnuLdOptTable : public llvm::opt::OptTable {
public:
  GnuLdOptTable() : OptTable(infoTable, llvm::array_lengthof(infoTable)){}
};

} // namespace

std::unique_ptr<lld::LinkerInput>
ELFFileNode::createLinkerInput(const LinkingContext &ctx) {
  std::unique_ptr<LinkerInput> inputFile(new LinkerInput(path(ctx)));
  inputFile->setAsNeeded(_asNeeded);
  inputFile->setForceLoad(_isWholeArchive);
  return std::move(inputFile);
}

StringRef ELFFileNode::path(const LinkingContext &) const {
  return _elfLinkingContext.searchLibrary(_path, _libraryPaths);
}

bool GnuLdDriver::linkELF(int argc, const char *argv[],
                          raw_ostream &diagnostics) {
  std::unique_ptr<ELFLinkingContext> options;
  bool error = parse(argc, argv, options, diagnostics);
  if (error)
    return true;
  if (!options)
    return false;

  return link(*options, diagnostics);
}

bool GnuLdDriver::parse(int argc, const char *argv[],
                        std::unique_ptr<ELFLinkingContext> &context,
                        raw_ostream &diagnostics) {
  // Parse command line options using LDOptions.td
  std::unique_ptr<llvm::opt::InputArgList> parsedArgs;
  GnuLdOptTable table;
  unsigned missingIndex;
  unsigned missingCount;

  parsedArgs.reset(
      table.ParseArgs(&argv[1], &argv[argc], missingIndex, missingCount));
  if (missingCount) {
    diagnostics << "error: missing arg value for '"
                << parsedArgs->getArgString(missingIndex) << "' expected "
                << missingCount << " argument(s).\n";
    return true;
  }

  // Handle --help
  if (parsedArgs->getLastArg(OPT_help)) {
    table.PrintHelp(llvm::outs(), argv[0], "LLVM Linker", false);
    return false;
  }

  // Use -target or use default target triple to instantiate LinkingContext
  llvm::Triple triple;
  if (llvm::opt::Arg *trip = parsedArgs->getLastArg(OPT_target))
    triple = llvm::Triple(trip->getValue());
  else
    triple = getDefaultTarget(argv[0]);
  std::unique_ptr<ELFLinkingContext> ctx(ELFLinkingContext::create(triple));

  if (!ctx) {
    diagnostics << "unknown target triple\n";
    return true;
  }

  std::unique_ptr<InputGraph> inputGraph(new InputGraph());
  std::stack<InputElement *> controlNodeStack;

  // Positional options for an Input File
  std::vector<StringRef> searchPath;
  bool isWholeArchive = false;
  bool asNeeded = false;
  bool _outputOptionSet = false;

  // Create a dynamic executable by default
  ctx->setOutputFileType(llvm::ELF::ET_EXEC);
  ctx->setIsStaticExecutable(false);
  ctx->setAllowShlibUndefines(false);
  ctx->setUseShlibUndefines(true);

  // Set the output file to be a.out
  ctx->setOutputPath("a.out");

  // Process all the arguments and create Input Elements
  for (auto inputArg : *parsedArgs) {
    switch (inputArg->getOption().getID()) {
    case OPT_mllvm:
      ctx->appendLLVMOption(inputArg->getValue());
      break;
    case OPT_relocatable:
      ctx->setOutputFileType(llvm::ELF::ET_REL);
      ctx->setPrintRemainingUndefines(false);
      ctx->setAllowRemainingUndefines(true);
      break;
    case OPT_static:
      ctx->setOutputFileType(llvm::ELF::ET_EXEC);
      ctx->setIsStaticExecutable(true);
      break;
    case OPT_shared:
      ctx->setOutputFileType(llvm::ELF::ET_DYN);
      ctx->setAllowShlibUndefines(true);
      ctx->setUseShlibUndefines(false);
      break;
    case OPT_e:
      ctx->setEntrySymbolName(inputArg->getValue());
      break;

    case OPT_output:
      _outputOptionSet = true;
      ctx->setOutputPath(inputArg->getValue());
      break;

    case OPT_noinhibit_exec:
      ctx->setAllowRemainingUndefines(true);
      break;

    case OPT_merge_strings:
      ctx->setMergeCommonStrings(true);
      break;

    case OPT_all_load:
      ctx->setForceLoadAllArchives(true);
      break;

    case OPT_t:
      ctx->setLogInputFiles(true);
      break;

    case OPT_no_allow_shlib_undefs:
      ctx->setAllowShlibUndefines(false);
      break;

    case OPT_allow_shlib_undefs:
      ctx->setAllowShlibUndefines(true);
      break;

    case OPT_use_shlib_undefs:
      ctx->setUseShlibUndefines(true);
      break;

    case OPT_dynamic_linker:
      ctx->setInterpreter(inputArg->getValue());
      break;

    case OPT_nmagic:
      ctx->setOutputMagic(ELFLinkingContext::OutputMagic::NMAGIC);
      ctx->setIsStaticExecutable(true);
      break;

    case OPT_omagic:
      ctx->setOutputMagic(ELFLinkingContext::OutputMagic::OMAGIC);
      ctx->setIsStaticExecutable(true);
      break;

    case OPT_no_omagic:
      ctx->setOutputMagic(ELFLinkingContext::OutputMagic::DEFAULT);
      ctx->setNoAllowDynamicLibraries();
      break;

    case OPT_u:
      ctx->addInitialUndefinedSymbol(inputArg->getValue());
      break;

    case OPT_emit_yaml:
      if (!_outputOptionSet)
        ctx->setOutputPath("-");
      ctx->setOutputYAML(true);
      break;

    case OPT_no_whole_archive:
      isWholeArchive = false;
      break;
    case OPT_whole_archive:
      isWholeArchive = true;
      break;
    case OPT_as_needed:
      asNeeded = true;
      break;
    case OPT_no_as_needed:
      asNeeded = false;
      break;
    case OPT_L:
      searchPath.push_back(inputArg->getValue());
      break;

    case OPT_start_group: {
      std::unique_ptr<InputElement> controlStart(new ELFGroup(*ctx));
      controlNodeStack.push(controlStart.get());
      (llvm::dyn_cast<ControlNode>)(controlNodeStack.top())
          ->processControlEnter();
      inputGraph->addInputElement(std::move(controlStart));
    } break;

    case OPT_end_group:
      (llvm::dyn_cast<ControlNode>)(controlNodeStack.top())
          ->processControlExit();
      controlNodeStack.pop();
      return false;

    case OPT_INPUT:
    case OPT_l: {
      std::unique_ptr<InputElement> inputFile =
          std::move(std::unique_ptr<InputElement>(
              new ELFFileNode(*ctx, inputArg->getValue(), searchPath,
                              isWholeArchive, asNeeded)));
      if (controlNodeStack.empty())
        inputGraph->addInputElement(std::move(inputFile));
      else
        (llvm::dyn_cast<ControlNode>)(controlNodeStack.top())
            ->processInputElement(std::move(inputFile));
    } break;

    default:
      break;
    } // end switch on option ID
  }   // end for

  if (!inputGraph->numFiles()) {
    diagnostics << "No input files\n";
    return true;
  }

  inputGraph->addInternalFile(ctx->createInternalFiles());

  if (ctx->outputYAML())
    inputGraph->dump(diagnostics);

  // Validate the combination of options used.
  if (ctx->validate(diagnostics))
    return true;

  ctx->setInputGraph(std::move(inputGraph));

  context.swap(ctx);

  return false;
}

/// Get the default target triple based on either the program name
/// (e.g. "x86-ibm-linux-lld") or the primary target llvm was configured for.
llvm::Triple GnuLdDriver::getDefaultTarget(const char *progName) {
  SmallVector<StringRef, 4> components;
  llvm::SplitString(llvm::sys::path::stem(progName), components, "-");
  // If has enough parts to be start with a triple.
  if (components.size() >= 4) {
    llvm::Triple triple(components[0], components[1], components[2],
                        components[3]);
    // If first component looks like an arch.
    if (triple.getArch() != llvm::Triple::UnknownArch)
      return triple;
  }

  // Fallback to use whatever default triple llvm was configured for.
  return llvm::Triple(llvm::sys::getDefaultTargetTriple());
}