//===- lib/Driver/DarwinLdDriver.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 darwin's ld.
///
//===----------------------------------------------------------------------===//

#include "lld/Core/File.h"
#include "lld/Core/ArchiveLibraryFile.h"
#include "lld/Core/SharedLibraryFile.h"
#include "lld/Driver/Driver.h"
#include "lld/ReaderWriter/MachOLinkingContext.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/Option.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/MachO.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/PrettyStackTrace.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>

using namespace lld;

namespace {

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

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

// Create table mapping all options defined in DarwinLdOptions.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 "DarwinLdOptions.inc"
#undef OPTION
};

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

std::vector<std::unique_ptr<File>>
loadFile(MachOLinkingContext &ctx, StringRef path,
         raw_ostream &diag, bool wholeArchive, bool upwardDylib) {
  if (ctx.logInputFiles())
    diag << path << "\n";

  ErrorOr<std::unique_ptr<MemoryBuffer>> mbOrErr = ctx.getMemoryBuffer(path);
  if (std::error_code ec = mbOrErr.getError())
    return makeErrorFile(path, ec);
  std::vector<std::unique_ptr<File>> files;
  if (std::error_code ec = ctx.registry().loadFile(std::move(mbOrErr.get()), files))
    return makeErrorFile(path, ec);
  for (std::unique_ptr<File> &pf : files) {
    // If file is a dylib, inform LinkingContext about it.
    if (SharedLibraryFile *shl = dyn_cast<SharedLibraryFile>(pf.get())) {
      if (std::error_code ec = shl->parse())
        return makeErrorFile(path, ec);
      ctx.registerDylib(reinterpret_cast<mach_o::MachODylibFile*>(shl),
                        upwardDylib);
    }
  }
  if (wholeArchive)
    return parseMemberFiles(files);
  return files;
}

} // anonymous namespace

// Test may be running on Windows. Canonicalize the path
// separator to '/' to get consistent outputs for tests.
static std::string canonicalizePath(StringRef path) {
  char sep = llvm::sys::path::get_separator().front();
  if (sep != '/') {
    std::string fixedPath = path;
    std::replace(fixedPath.begin(), fixedPath.end(), sep, '/');
    return fixedPath;
  } else {
    return path;
  }
}

static void addFile(StringRef path, MachOLinkingContext &ctx,
                    bool loadWholeArchive,
                    bool upwardDylib, raw_ostream &diag) {
  std::vector<std::unique_ptr<File>> files =
      loadFile(ctx, path, diag, loadWholeArchive, upwardDylib);
  for (std::unique_ptr<File> &file : files)
    ctx.getNodes().push_back(llvm::make_unique<FileNode>(std::move(file)));
}

// Export lists are one symbol per line.  Blank lines are ignored.
// Trailing comments start with #.
static std::error_code parseExportsList(StringRef exportFilePath,
                                        MachOLinkingContext &ctx,
                                        raw_ostream &diagnostics) {
  // Map in export list file.
  ErrorOr<std::unique_ptr<MemoryBuffer>> mb =
                                   MemoryBuffer::getFileOrSTDIN(exportFilePath);
  if (std::error_code ec = mb.getError())
    return ec;
  ctx.addInputFileDependency(exportFilePath);
  StringRef buffer = mb->get()->getBuffer();
  while (!buffer.empty()) {
    // Split off each line in the file.
    std::pair<StringRef, StringRef> lineAndRest = buffer.split('\n');
    StringRef line = lineAndRest.first;
    // Ignore trailing # comments.
    std::pair<StringRef, StringRef> symAndComment = line.split('#');
    StringRef sym = symAndComment.first.trim();
    if (!sym.empty())
      ctx.addExportSymbol(sym);
    buffer = lineAndRest.second;
  }
  return std::error_code();
}



/// Order files are one symbol per line. Blank lines are ignored.
/// Trailing comments start with #. Symbol names can be prefixed with an
/// architecture name and/or .o leaf name.  Examples:
///     _foo
///     bar.o:_bar
///     libfrob.a(bar.o):_bar
///     x86_64:_foo64
static std::error_code parseOrderFile(StringRef orderFilePath,
                                      MachOLinkingContext &ctx,
                                      raw_ostream &diagnostics) {
  // Map in order file.
  ErrorOr<std::unique_ptr<MemoryBuffer>> mb =
                                   MemoryBuffer::getFileOrSTDIN(orderFilePath);
  if (std::error_code ec = mb.getError())
    return ec;
  ctx.addInputFileDependency(orderFilePath);
  StringRef buffer = mb->get()->getBuffer();
  while (!buffer.empty()) {
    // Split off each line in the file.
    std::pair<StringRef, StringRef> lineAndRest = buffer.split('\n');
    StringRef line = lineAndRest.first;
    buffer = lineAndRest.second;
    // Ignore trailing # comments.
    std::pair<StringRef, StringRef> symAndComment = line.split('#');
    if (symAndComment.first.empty())
      continue;
    StringRef sym = symAndComment.first.trim();
    if (sym.empty())
      continue;
    // Check for prefix.
    StringRef prefix;
    std::pair<StringRef, StringRef> prefixAndSym = sym.split(':');
    if (!prefixAndSym.second.empty()) {
      sym = prefixAndSym.second;
      prefix = prefixAndSym.first;
      if (!prefix.endswith(".o") && !prefix.endswith(".o)")) {
        // If arch name prefix does not match arch being linked, ignore symbol.
        if (!ctx.archName().equals(prefix))
          continue;
        prefix = "";
      }
    } else
     sym = prefixAndSym.first;
    if (!sym.empty()) {
      ctx.appendOrderedSymbol(sym, prefix);
      //llvm::errs() << sym << ", prefix=" << prefix << "\n";
    }
  }
  return std::error_code();
}

//
// There are two variants of the  -filelist option:
//
//   -filelist <path>
// In this variant, the path is to a text file which contains one file path
// per line.  There are no comments or trimming of whitespace.
//
//   -fileList <path>,<dir>
// In this variant, the path is to a text file which contains a partial path
// per line. The <dir> prefix is prepended to each partial path.
//
static std::error_code loadFileList(StringRef fileListPath,
                                    MachOLinkingContext &ctx, bool forceLoad,
                                    raw_ostream &diagnostics) {
  // If there is a comma, split off <dir>.
  std::pair<StringRef, StringRef> opt = fileListPath.split(',');
  StringRef filePath = opt.first;
  StringRef dirName = opt.second;
  ctx.addInputFileDependency(filePath);
  // Map in file list file.
  ErrorOr<std::unique_ptr<MemoryBuffer>> mb =
                                        MemoryBuffer::getFileOrSTDIN(filePath);
  if (std::error_code ec = mb.getError())
    return ec;
  StringRef buffer = mb->get()->getBuffer();
  while (!buffer.empty()) {
    // Split off each line in the file.
    std::pair<StringRef, StringRef> lineAndRest = buffer.split('\n');
    StringRef line = lineAndRest.first;
    StringRef path;
    if (!dirName.empty()) {
      // If there is a <dir> then prepend dir to each line.
      SmallString<256> fullPath;
      fullPath.assign(dirName);
      llvm::sys::path::append(fullPath, Twine(line));
      path = ctx.copy(fullPath.str());
    } else {
      // No <dir> use whole line as input file path.
      path = ctx.copy(line);
    }
    if (!ctx.pathExists(path)) {
      return make_dynamic_error_code(Twine("File not found '")
                                     + path
                                     + "'");
    }
    if (ctx.testingFileUsage()) {
      diagnostics << "Found filelist entry " << canonicalizePath(path) << '\n';
    }
    addFile(path, ctx, forceLoad, false, diagnostics);
    buffer = lineAndRest.second;
  }
  return std::error_code();
}

/// Parse number assuming it is base 16, but allow 0x prefix.
static bool parseNumberBase16(StringRef numStr, uint64_t &baseAddress) {
  if (numStr.startswith_lower("0x"))
    numStr = numStr.drop_front(2);
  return numStr.getAsInteger(16, baseAddress);
}

namespace lld {

bool DarwinLdDriver::linkMachO(int argc, const char *argv[],
                               raw_ostream &diagnostics) {
  MachOLinkingContext ctx;
  if (!parse(argc, argv, ctx, diagnostics))
    return false;
  if (ctx.doNothing())
    return true;
  return link(ctx, diagnostics);
}

bool DarwinLdDriver::parse(int argc, const char *argv[],
                           MachOLinkingContext &ctx, raw_ostream &diagnostics) {
  // Parse command line options using DarwinLdOptions.td
  std::unique_ptr<llvm::opt::InputArgList> parsedArgs;
  DarwinLdOptTable table;
  unsigned missingIndex;
  unsigned missingCount;
  bool globalWholeArchive = false;
  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 false;
  }

  for (auto unknownArg : parsedArgs->filtered(OPT_UNKNOWN)) {
    diagnostics  << "warning: ignoring unknown argument: "
                 << unknownArg->getAsString(*parsedArgs) << "\n";
  }

  // Figure out output kind ( -dylib, -r, -bundle, -preload, or -static )
  llvm::MachO::HeaderFileType fileType = llvm::MachO::MH_EXECUTE;
  if ( llvm::opt::Arg *kind = parsedArgs->getLastArg(OPT_dylib, OPT_relocatable,
                                      OPT_bundle, OPT_static, OPT_preload)) {
    switch (kind->getOption().getID()) {
    case OPT_dylib:
      fileType = llvm::MachO::MH_DYLIB;
      break;
    case OPT_relocatable:
      fileType = llvm::MachO::MH_OBJECT;
      break;
    case OPT_bundle:
      fileType = llvm::MachO::MH_BUNDLE;
      break;
    case OPT_static:
      fileType = llvm::MachO::MH_EXECUTE;
      break;
    case OPT_preload:
      fileType = llvm::MachO::MH_PRELOAD;
      break;
    }
  }

  // Handle -arch xxx
  MachOLinkingContext::Arch arch = MachOLinkingContext::arch_unknown;
  if (llvm::opt::Arg *archStr = parsedArgs->getLastArg(OPT_arch)) {
    arch = MachOLinkingContext::archFromName(archStr->getValue());
    if (arch == MachOLinkingContext::arch_unknown) {
      diagnostics << "error: unknown arch named '" << archStr->getValue()
                  << "'\n";
      return false;
    }
  }
  // If no -arch specified, scan input files to find first non-fat .o file.
  if (arch == MachOLinkingContext::arch_unknown) {
    for (auto &inFile: parsedArgs->filtered(OPT_INPUT)) {
      // This is expensive because it opens and maps the file.  But that is
      // ok because no -arch is rare.
      if (MachOLinkingContext::isThinObjectFile(inFile->getValue(), arch))
        break;
    }
    if (arch == MachOLinkingContext::arch_unknown
        && !parsedArgs->getLastArg(OPT_test_file_usage)) {
      // If no -arch and no options at all, print usage message.
      if (parsedArgs->size() == 0)
        table.PrintHelp(llvm::outs(), argv[0], "LLVM Linker", false);
      else
        diagnostics << "error: -arch not specified and could not be inferred\n";
      return false;
    }
  }

  // Handle -macosx_version_min or -ios_version_min
  MachOLinkingContext::OS os = MachOLinkingContext::OS::macOSX;
  uint32_t minOSVersion = 0;
  if (llvm::opt::Arg *minOS =
          parsedArgs->getLastArg(OPT_macosx_version_min, OPT_ios_version_min,
                                 OPT_ios_simulator_version_min)) {
    switch (minOS->getOption().getID()) {
    case OPT_macosx_version_min:
      os = MachOLinkingContext::OS::macOSX;
      if (MachOLinkingContext::parsePackedVersion(minOS->getValue(),
                                                  minOSVersion)) {
        diagnostics << "error: malformed macosx_version_min value\n";
        return false;
      }
      break;
    case OPT_ios_version_min:
      os = MachOLinkingContext::OS::iOS;
      if (MachOLinkingContext::parsePackedVersion(minOS->getValue(),
                                                  minOSVersion)) {
        diagnostics << "error: malformed ios_version_min value\n";
        return false;
      }
      break;
    case OPT_ios_simulator_version_min:
      os = MachOLinkingContext::OS::iOS_simulator;
      if (MachOLinkingContext::parsePackedVersion(minOS->getValue(),
                                                  minOSVersion)) {
        diagnostics << "error: malformed ios_simulator_version_min value\n";
        return false;
      }
      break;
    }
  } else {
    // No min-os version on command line, check environment variables
  }

  // Now that there's enough information parsed in, let the linking context
  // set up default values.
  ctx.configure(fileType, arch, os, minOSVersion);

  // Handle -e xxx
  if (llvm::opt::Arg *entry = parsedArgs->getLastArg(OPT_entry))
    ctx.setEntrySymbolName(entry->getValue());

  // Handle -o xxx
  if (llvm::opt::Arg *outpath = parsedArgs->getLastArg(OPT_output))
    ctx.setOutputPath(outpath->getValue());
  else
    ctx.setOutputPath("a.out");

  // Handle -image_base XXX and -seg1addr XXXX
  if (llvm::opt::Arg *imageBase = parsedArgs->getLastArg(OPT_image_base)) {
    uint64_t baseAddress;
    if (parseNumberBase16(imageBase->getValue(), baseAddress)) {
      diagnostics << "error: image_base expects a hex number\n";
      return false;
    } else if (baseAddress < ctx.pageZeroSize()) {
      diagnostics << "error: image_base overlaps with __PAGEZERO\n";
      return false;
    } else if (baseAddress % ctx.pageSize()) {
      diagnostics << "error: image_base must be a multiple of page size ("
                  << llvm::format("0x%" PRIx64, ctx.pageSize()) << ")\n";
      return false;
    }

    ctx.setBaseAddress(baseAddress);
  }

  // Handle -dead_strip
  if (parsedArgs->getLastArg(OPT_dead_strip))
    ctx.setDeadStripping(true);

  // Handle -all_load
  if (parsedArgs->getLastArg(OPT_all_load))
    globalWholeArchive = true;

  // Handle -install_name
  if (llvm::opt::Arg *installName = parsedArgs->getLastArg(OPT_install_name))
    ctx.setInstallName(installName->getValue());
  else
    ctx.setInstallName(ctx.outputPath());

  // Handle -mark_dead_strippable_dylib
  if (parsedArgs->getLastArg(OPT_mark_dead_strippable_dylib))
    ctx.setDeadStrippableDylib(true);

  // Handle -compatibility_version and -current_version
  if (llvm::opt::Arg *vers =
          parsedArgs->getLastArg(OPT_compatibility_version)) {
    if (ctx.outputMachOType() != llvm::MachO::MH_DYLIB) {
      diagnostics
          << "error: -compatibility_version can only be used with -dylib\n";
      return false;
    }
    uint32_t parsedVers;
    if (MachOLinkingContext::parsePackedVersion(vers->getValue(), parsedVers)) {
      diagnostics << "error: -compatibility_version value is malformed\n";
      return false;
    }
    ctx.setCompatibilityVersion(parsedVers);
  }

  if (llvm::opt::Arg *vers = parsedArgs->getLastArg(OPT_current_version)) {
    if (ctx.outputMachOType() != llvm::MachO::MH_DYLIB) {
      diagnostics << "-current_version can only be used with -dylib\n";
      return false;
    }
    uint32_t parsedVers;
    if (MachOLinkingContext::parsePackedVersion(vers->getValue(), parsedVers)) {
      diagnostics << "error: -current_version value is malformed\n";
      return false;
    }
    ctx.setCurrentVersion(parsedVers);
  }

  // Handle -bundle_loader
  if (llvm::opt::Arg *loader = parsedArgs->getLastArg(OPT_bundle_loader))
    ctx.setBundleLoader(loader->getValue());

  // Handle -sectalign segname sectname align
  for (auto &alignArg : parsedArgs->filtered(OPT_sectalign)) {
    const char* segName   = alignArg->getValue(0);
    const char* sectName  = alignArg->getValue(1);
    const char* alignStr  = alignArg->getValue(2);
    if ((alignStr[0] == '0') && (alignStr[1] == 'x'))
      alignStr += 2;
    unsigned long long alignValue;
    if (llvm::getAsUnsignedInteger(alignStr, 16, alignValue)) {
      diagnostics << "error: -sectalign alignment value '"
                  << alignStr << "' not a valid number\n";
      return false;
    }
    uint8_t align2 = llvm::countTrailingZeros(alignValue);
    if ( (unsigned long)(1 << align2) != alignValue ) {
      diagnostics << "warning: alignment for '-sectalign "
                  << segName << " " << sectName
                  << llvm::format(" 0x%llX", alignValue)
                  << "' is not a power of two, using "
                  << llvm::format("0x%08X", (1 << align2)) << "\n";
    }
    ctx.addSectionAlignment(segName, sectName, align2);
  }

  // Handle -mllvm
  for (auto &llvmArg : parsedArgs->filtered(OPT_mllvm)) {
    ctx.appendLLVMOption(llvmArg->getValue());
  }

  // Handle -print_atoms
  if (parsedArgs->getLastArg(OPT_print_atoms))
    ctx.setPrintAtoms();

  // Handle -t (trace) option.
  if (parsedArgs->getLastArg(OPT_t))
    ctx.setLogInputFiles(true);

  // Handle -demangle option.
  if (parsedArgs->getLastArg(OPT_demangle))
    ctx.setDemangleSymbols(true);

  // Handle -keep_private_externs
  if (parsedArgs->getLastArg(OPT_keep_private_externs)) {
    ctx.setKeepPrivateExterns(true);
    if (ctx.outputMachOType() != llvm::MachO::MH_OBJECT)
      diagnostics << "warning: -keep_private_externs only used in -r mode\n";
  }

  // Handle -dependency_info <path> used by Xcode.
  if (llvm::opt::Arg *depInfo = parsedArgs->getLastArg(OPT_dependency_info)) {
    if (std::error_code ec = ctx.createDependencyFile(depInfo->getValue())) {
      diagnostics << "warning: " << ec.message()
                  << ", processing '-dependency_info "
                  << depInfo->getValue()
                  << "'\n";
    }
  }

  // In -test_file_usage mode, we'll be given an explicit list of paths that
  // exist. We'll also be expected to print out information about how we located
  // libraries and so on that the user specified, but not to actually do any
  // linking.
  if (parsedArgs->getLastArg(OPT_test_file_usage)) {
    ctx.setTestingFileUsage();

    // With paths existing by fiat, linking is not going to end well.
    ctx.setDoNothing(true);

    // Only bother looking for an existence override if we're going to use it.
    for (auto existingPath : parsedArgs->filtered(OPT_path_exists)) {
      ctx.addExistingPathForDebug(existingPath->getValue());
    }
  }

  // Register possible input file parsers.
  if (!ctx.doNothing()) {
    ctx.registry().addSupportMachOObjects(ctx);
    ctx.registry().addSupportArchives(ctx.logInputFiles());
    ctx.registry().addSupportNativeObjects();
    ctx.registry().addSupportYamlFiles();
  }

  // Now construct the set of library search directories, following ld64's
  // baroque set of accumulated hacks. Mostly, the algorithm constructs
  //     { syslibroots } x { libpaths }
  //
  // Unfortunately, there are numerous exceptions:
  //   1. Only absolute paths get modified by syslibroot options.
  //   2. If there is just 1 -syslibroot, system paths not found in it are
  //      skipped.
  //   3. If the last -syslibroot is "/", all of them are ignored entirely.
  //   4. If { syslibroots } x path ==  {}, the original path is kept.
  std::vector<StringRef> sysLibRoots;
  for (auto syslibRoot : parsedArgs->filtered(OPT_syslibroot)) {
    sysLibRoots.push_back(syslibRoot->getValue());
  }
  if (!sysLibRoots.empty()) {
    // Ignore all if last -syslibroot is "/".
    if (sysLibRoots.back() != "/")
      ctx.setSysLibRoots(sysLibRoots);
  }

  // Paths specified with -L come first, and are not considered system paths for
  // the case where there is precisely 1 -syslibroot.
  for (auto libPath : parsedArgs->filtered(OPT_L)) {
    ctx.addModifiedSearchDir(libPath->getValue());
  }

  // Process -F directories (where to look for frameworks).
  for (auto fwPath : parsedArgs->filtered(OPT_F)) {
    ctx.addFrameworkSearchDir(fwPath->getValue());
  }

  // -Z suppresses the standard search paths.
  if (!parsedArgs->hasArg(OPT_Z)) {
    ctx.addModifiedSearchDir("/usr/lib", true);
    ctx.addModifiedSearchDir("/usr/local/lib", true);
    ctx.addFrameworkSearchDir("/Library/Frameworks", true);
    ctx.addFrameworkSearchDir("/System/Library/Frameworks", true);
  }

  // Now that we've constructed the final set of search paths, print out those
  // search paths in verbose mode.
  if (parsedArgs->getLastArg(OPT_v)) {
    diagnostics << "Library search paths:\n";
    for (auto path : ctx.searchDirs()) {
      diagnostics << "    " << path << '\n';
    }
    diagnostics << "Framework search paths:\n";
    for (auto path : ctx.frameworkDirs()) {
      diagnostics << "    " << path << '\n';
    }
  }

  // Handle -exported_symbols_list <file>
  for (auto expFile : parsedArgs->filtered(OPT_exported_symbols_list)) {
    if (ctx.exportMode() == MachOLinkingContext::ExportMode::blackList) {
      diagnostics << "error: -exported_symbols_list cannot be combined "
                  << "with -unexported_symbol[s_list]\n";
       return false;
    }
    ctx.setExportMode(MachOLinkingContext::ExportMode::whiteList);
    if (std::error_code ec = parseExportsList(expFile->getValue(), ctx,
                                              diagnostics)) {
      diagnostics << "error: " << ec.message()
                  << ", processing '-exported_symbols_list "
                  << expFile->getValue()
                  << "'\n";
      return false;
    }
  }

  // Handle -exported_symbol <symbol>
  for (auto symbol : parsedArgs->filtered(OPT_exported_symbol)) {
    if (ctx.exportMode() == MachOLinkingContext::ExportMode::blackList) {
      diagnostics << "error: -exported_symbol cannot be combined "
                  << "with -unexported_symbol[s_list]\n";
       return false;
    }
    ctx.setExportMode(MachOLinkingContext::ExportMode::whiteList);
    ctx.addExportSymbol(symbol->getValue());
  }

  // Handle -unexported_symbols_list <file>
  for (auto expFile : parsedArgs->filtered(OPT_unexported_symbols_list)) {
    if (ctx.exportMode() == MachOLinkingContext::ExportMode::whiteList) {
      diagnostics << "error: -unexported_symbols_list cannot be combined "
                  << "with -exported_symbol[s_list]\n";
       return false;
    }
    ctx.setExportMode(MachOLinkingContext::ExportMode::blackList);
    if (std::error_code ec = parseExportsList(expFile->getValue(), ctx,
                                              diagnostics)) {
      diagnostics << "error: " << ec.message()
                  << ", processing '-unexported_symbols_list "
                  << expFile->getValue()
                  << "'\n";
      return false;
    }
  }

  // Handle -unexported_symbol <symbol>
  for (auto symbol : parsedArgs->filtered(OPT_unexported_symbol)) {
    if (ctx.exportMode() == MachOLinkingContext::ExportMode::whiteList) {
      diagnostics << "error: -unexported_symbol cannot be combined "
                  << "with -exported_symbol[s_list]\n";
       return false;
    }
    ctx.setExportMode(MachOLinkingContext::ExportMode::blackList);
    ctx.addExportSymbol(symbol->getValue());
  }

  // Handle obosolete -multi_module and -single_module
  if (llvm::opt::Arg *mod = parsedArgs->getLastArg(OPT_multi_module,
                                                   OPT_single_module)) {
    if (mod->getOption().getID() == OPT_multi_module) {
      diagnostics << "warning: -multi_module is obsolete and being ignored\n";
    }
    else {
      if (ctx.outputMachOType() != llvm::MachO::MH_DYLIB) {
        diagnostics << "warning: -single_module being ignored. "
                       "It is only for use when producing a dylib\n";
      }
    }
  }

  // Handle -pie or -no_pie
  if (llvm::opt::Arg *pie = parsedArgs->getLastArg(OPT_pie, OPT_no_pie)) {
    switch (ctx.outputMachOType()) {
    case llvm::MachO::MH_EXECUTE:
      switch (ctx.os()) {
      case MachOLinkingContext::OS::macOSX:
        if ((minOSVersion < 0x000A0500) &&
            (pie->getOption().getID() == OPT_pie)) {
          diagnostics << "-pie can only be used when targeting "
                         "Mac OS X 10.5 or later\n";
          return false;
        }
        break;
      case MachOLinkingContext::OS::iOS:
        if ((minOSVersion < 0x00040200) &&
            (pie->getOption().getID() == OPT_pie)) {
          diagnostics << "-pie can only be used when targeting "
                         "iOS 4.2 or later\n";
          return false;
        }
        break;
      case MachOLinkingContext::OS::iOS_simulator:
        if (pie->getOption().getID() == OPT_no_pie)
          diagnostics << "iOS simulator programs must be built PIE\n";
          return false;
        break;
      case MachOLinkingContext::OS::unknown:
        break;
      }
      ctx.setPIE(pie->getOption().getID() == OPT_pie);
      break;
    case llvm::MachO::MH_PRELOAD:
      break;
    case llvm::MachO::MH_DYLIB:
    case llvm::MachO::MH_BUNDLE:
      diagnostics << "warning: " << pie->getSpelling() << " being ignored. "
                  << "It is only used when linking main executables\n";
      break;
    default:
      diagnostics << pie->getSpelling()
                  << " can only used when linking main executables\n";
      return false;
      break;
    }
  }

  // Handle debug info handling options: -S
  if (parsedArgs->hasArg(OPT_S))
    ctx.setDebugInfoMode(MachOLinkingContext::DebugInfoMode::noDebugMap);

  // Handle -order_file <file>
  for (auto orderFile : parsedArgs->filtered(OPT_order_file)) {
    if (std::error_code ec = parseOrderFile(orderFile->getValue(), ctx,
                                              diagnostics)) {
      diagnostics << "error: " << ec.message()
                  << ", processing '-order_file "
                  << orderFile->getValue()
                  << "'\n";
      return false;
    }
  }

  // Handle -rpath <path>
  if (parsedArgs->hasArg(OPT_rpath)) {
    switch (ctx.outputMachOType()) {
      case llvm::MachO::MH_EXECUTE:
      case llvm::MachO::MH_DYLIB:
      case llvm::MachO::MH_BUNDLE:
        if (!ctx.minOS("10.5", "2.0")) {
          if (ctx.os() == MachOLinkingContext::OS::macOSX) {
            diagnostics << "error: -rpath can only be used when targeting "
                           "OS X 10.5 or later\n";
          } else {
            diagnostics << "error: -rpath can only be used when targeting "
                           "iOS 2.0 or later\n";
          }
          return false;
        }
        break;
      default:
        diagnostics << "error: -rpath can only be used when creating "
                       "a dynamic final linked image\n";
        return false;
    }

    for (auto rPath : parsedArgs->filtered(OPT_rpath)) {
      ctx.addRpath(rPath->getValue());
    }
  }

  // Handle input files
  for (auto &arg : *parsedArgs) {
    bool upward;
    ErrorOr<StringRef> resolvedPath = StringRef();
    switch (arg->getOption().getID()) {
    default:
      continue;
    case OPT_INPUT:
      addFile(arg->getValue(), ctx, globalWholeArchive, false, diagnostics);
      break;
    case OPT_upward_library:
      addFile(arg->getValue(), ctx, false, true, diagnostics);
      break;
    case OPT_force_load:
      addFile(arg->getValue(), ctx, true, false, diagnostics);
      break;
    case OPT_l:
    case OPT_upward_l:
      upward = (arg->getOption().getID() == OPT_upward_l);
      resolvedPath = ctx.searchLibrary(arg->getValue());
      if (!resolvedPath) {
        diagnostics << "Unable to find library for " << arg->getSpelling()
                    << arg->getValue() << "\n";
        return false;
      } else if (ctx.testingFileUsage()) {
        diagnostics << "Found " << (upward ? "upward " : " ") << "library "
                   << canonicalizePath(resolvedPath.get()) << '\n';
      }
      addFile(resolvedPath.get(), ctx, globalWholeArchive, upward, diagnostics);
      break;
    case OPT_framework:
    case OPT_upward_framework:
      upward = (arg->getOption().getID() == OPT_upward_framework);
      resolvedPath = ctx.findPathForFramework(arg->getValue());
      if (!resolvedPath) {
        diagnostics << "Unable to find framework for "
                    << arg->getSpelling() << " " << arg->getValue() << "\n";
        return false;
      } else if (ctx.testingFileUsage()) {
        diagnostics << "Found " << (upward ? "upward " : " ") << "framework "
                    << canonicalizePath(resolvedPath.get()) << '\n';
      }
      addFile(resolvedPath.get(), ctx, globalWholeArchive, upward, diagnostics);
      break;
    case OPT_filelist:
      if (std::error_code ec = loadFileList(arg->getValue(),
                                            ctx, globalWholeArchive,
                                            diagnostics)) {
        diagnostics << "error: " << ec.message()
                    << ", processing '-filelist " << arg->getValue()
                    << "'\n";
        return false;
      }
      break;
    }
  }

  if (ctx.getNodes().empty()) {
    diagnostics << "No input files\n";
    return false;
  }

  // Validate the combination of options used.
  return ctx.validate(diagnostics);
}


} // namespace lld