llvm/tools/gold/gold-plugin.cpp

   1 //===-- gold-plugin.cpp - Plugin to gold for Link Time Optimization  ------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This is a gold plugin for LLVM. It provides an LLVM implementation of the
  10 // interface described in http://gcc.gnu.org/wiki/whopr/driver .
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/ADT/Statistic.h"
  15 #include "llvm/Bitcode/BitcodeReader.h"
  16 #include "llvm/Bitcode/BitcodeWriter.h"
  17 #include "llvm/CodeGen/CommandFlags.h"
  18 #include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
  19 #include "llvm/Config/llvm-config.h"
  20 #include "llvm/IR/Constants.h"
  21 #include "llvm/IR/DiagnosticPrinter.h"
  22 #include "llvm/LTO/LTO.h"
  23 #include "llvm/Object/Error.h"
  24 #include "llvm/Remarks/HotnessThresholdParser.h"
  25 #include "llvm/Support/CachePruning.h"
  26 #include "llvm/Support/Caching.h"
  27 #include "llvm/Support/CommandLine.h"
  28 #include "llvm/Support/FileSystem.h"
  29 #include "llvm/Support/Host.h"
  30 #include "llvm/Support/ManagedStatic.h"
  31 #include "llvm/Support/MemoryBuffer.h"
  32 #include "llvm/Support/Path.h"
  33 #include "llvm/Support/TargetSelect.h"
  34 #include "llvm/Support/Threading.h"
  35 #include "llvm/Support/raw_ostream.h"
  36 #include <list>
  37 #include <map>
  38 #include <plugin-api.h>
  39 #include <string>
  40 #include <system_error>
  41 #include <utility>
  42 #include <vector>
  43
  44 // FIXME: remove this declaration when we stop maintaining Ubuntu Quantal and
  45 // Precise and Debian Wheezy (binutils 2.23 is required)
  46 #define LDPO_PIE 3
  47
  48 #define LDPT_GET_SYMBOLS_V3 28
  49
  50 // FIXME: Remove when binutils 2.31 (containing gold 1.16) is the minimum
  51 // required version.
  52 #define LDPT_GET_WRAP_SYMBOLS 32
  53
  54 using namespace llvm;
  55 using namespace lto;
  56
  57 static codegen::RegisterCodeGenFlags CodeGenFlags;
  58
  59 // FIXME: Remove when binutils 2.31 (containing gold 1.16) is the minimum
  60 // required version.
  61 typedef enum ld_plugin_status (*ld_plugin_get_wrap_symbols)(
  62     uint64_t *num_symbols, const char ***wrap_symbol_list);
  63
  64 static ld_plugin_status discard_message(int level, const char *format, ...) {
  65   // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
  66   // callback in the transfer vector. This should never be called.
  67   abort();
  68 }
  69
  70 static ld_plugin_release_input_file release_input_file = nullptr;
  71 static ld_plugin_get_input_file get_input_file = nullptr;
  72 static ld_plugin_message message = discard_message;
  73 static ld_plugin_get_wrap_symbols get_wrap_symbols = nullptr;
  74
  75 namespace {
  76 struct claimed_file {
  77   void *handle;
  78   void *leader_handle;
  79   std::vector<ld_plugin_symbol> syms;
  80   off_t filesize;
  81   std::string name;
  82 };
  83
  84 /// RAII wrapper to manage opening and releasing of a ld_plugin_input_file.
  85 struct PluginInputFile {
  86   void *Handle;
  87   std::unique_ptr<ld_plugin_input_file> File;
  88
  89   PluginInputFile(void *Handle) : Handle(Handle) {
  90     File = std::make_unique<ld_plugin_input_file>();
  91     if (get_input_file(Handle, File.get()) != LDPS_OK)
  92       message(LDPL_FATAL, "Failed to get file information");
  93   }
  94   ~PluginInputFile() {
  95     // File would have been reset to nullptr if we moved this object
  96     // to a new owner.
  97     if (File)
  98       if (release_input_file(Handle) != LDPS_OK)
  99         message(LDPL_FATAL, "Failed to release file information");
 100   }
 101
 102   ld_plugin_input_file &file() { return *File; }
 103
 104   PluginInputFile(PluginInputFile &&RHS) = default;
 105   PluginInputFile &operator=(PluginInputFile &&RHS) = default;
 106 };
 107
 108 struct ResolutionInfo {
 109   bool CanOmitFromDynSym = true;
 110   bool DefaultVisibility = true;
 111   bool CanInline = true;
 112   bool IsUsedInRegularObj = false;
 113 };
 114
 115 }
 116
 117 static ld_plugin_add_symbols add_symbols = nullptr;
 118 static ld_plugin_get_symbols get_symbols = nullptr;
 119 static ld_plugin_add_input_file add_input_file = nullptr;
 120 static ld_plugin_set_extra_library_path set_extra_library_path = nullptr;
 121 static ld_plugin_get_view get_view = nullptr;
 122 static bool IsExecutable = false;
 123 static bool SplitSections = true;
 124 static Optional<Reloc::Model> RelocationModel = None;
 125 static std::string output_name = "";
 126 static std::list<claimed_file> Modules;
 127 static DenseMap<int, void *> FDToLeaderHandle;
 128 static StringMap<ResolutionInfo> ResInfo;
 129 static std::vector<std::string> Cleanup;
 130
 131 namespace options {
 132   enum OutputType {
 133     OT_NORMAL,
 134     OT_DISABLE,
 135     OT_BC_ONLY,
 136     OT_ASM_ONLY,
 137     OT_SAVE_TEMPS
 138   };
 139   static OutputType TheOutputType = OT_NORMAL;
 140   static unsigned OptLevel = 2;
 141   // Currently only affects ThinLTO, where the default is the max cores in the
 142   // system. See llvm::get_threadpool_strategy() for acceptable values.
 143   static std::string Parallelism;
 144   // Default regular LTO codegen parallelism (number of partitions).
 145   static unsigned ParallelCodeGenParallelismLevel = 1;
 146 #ifdef NDEBUG
 147   static bool DisableVerify = true;
 148 #else
 149   static bool DisableVerify = false;
 150 #endif
 151   static std::string obj_path;
 152   static std::string extra_library_path;
 153   static std::string triple;
 154   static std::string mcpu;
 155   // When the thinlto plugin option is specified, only read the function
 156   // the information from intermediate files and write a combined
 157   // global index for the ThinLTO backends.
 158   static bool thinlto = false;
 159   // If false, all ThinLTO backend compilations through code gen are performed
 160   // using multiple threads in the gold-plugin, before handing control back to
 161   // gold. If true, write individual backend index files which reflect
 162   // the import decisions, and exit afterwards. The assumption is
 163   // that the build system will launch the backend processes.
 164   static bool thinlto_index_only = false;
 165   // If non-empty, holds the name of a file in which to write the list of
 166   // oject files gold selected for inclusion in the link after symbol
 167   // resolution (i.e. they had selected symbols). This will only be non-empty
 168   // in the thinlto_index_only case. It is used to identify files, which may
 169   // have originally been within archive libraries specified via
 170   // --start-lib/--end-lib pairs, that should be included in the final
 171   // native link process (since intervening function importing and inlining
 172   // may change the symbol resolution detected in the final link and which
 173   // files to include out of --start-lib/--end-lib libraries as a result).
 174   static std::string thinlto_linked_objects_file;
 175   // If true, when generating individual index files for distributed backends,
 176   // also generate a "${bitcodefile}.imports" file at the same location for each
 177   // bitcode file, listing the files it imports from in plain text. This is to
 178   // support distributed build file staging.
 179   static bool thinlto_emit_imports_files = false;
 180   // Option to control where files for a distributed backend (the individual
 181   // index files and optional imports files) are created.
 182   // If specified, expects a string of the form "oldprefix:newprefix", and
 183   // instead of generating these files in the same directory path as the
 184   // corresponding bitcode file, will use a path formed by replacing the
 185   // bitcode file's path prefix matching oldprefix with newprefix.
 186   static std::string thinlto_prefix_replace;
 187   // Option to control the name of modules encoded in the individual index
 188   // files for a distributed backend. This enables the use of minimized
 189   // bitcode files for the thin link, assuming the name of the full bitcode
 190   // file used in the backend differs just in some part of the file suffix.
 191   // If specified, expects a string of the form "oldsuffix:newsuffix".
 192   static std::string thinlto_object_suffix_replace;
 193   // Optional path to a directory for caching ThinLTO objects.
 194   static std::string cache_dir;
 195   // Optional pruning policy for ThinLTO caches.
 196   static std::string cache_policy;
 197   // Additional options to pass into the code generator.
 198   // Note: This array will contain all plugin options which are not claimed
 199   // as plugin exclusive to pass to the code generator.
 200   static std::vector<const char *> extra;
 201   // Sample profile file path
 202   static std::string sample_profile;
 203   // Debug new pass manager
 204   static bool debug_pass_manager = false;
 205   // Directory to store the .dwo files.
 206   static std::string dwo_dir;
 207   /// Statistics output filename.
 208   static std::string stats_file;
 209   // Asserts that LTO link has whole program visibility
 210   static bool whole_program_visibility = false;
 211   // Use opaque pointer types.
 212   static bool opaque_pointers = true;
 213
 214   // Optimization remarks filename, accepted passes and hotness options
 215   static std::string RemarksFilename;
 216   static std::string RemarksPasses;
 217   static bool RemarksWithHotness = false;
 218   static Optional<uint64_t> RemarksHotnessThreshold = 0;
 219   static std::string RemarksFormat;
 220
 221   // Context sensitive PGO options.
 222   static std::string cs_profile_path;
 223   static bool cs_pgo_gen = false;
 224
 225   static void process_plugin_option(const char *opt_)
 226   {
 227     if (opt_ == nullptr)
 228       return;
 229     llvm::StringRef opt = opt_;
 230
 231     if (opt.consume_front("mcpu=")) {
 232       mcpu = std::string(opt);
 233     } else if (opt.consume_front("extra-library-path=")) {
 234       extra_library_path = std::string(opt);
 235     } else if (opt.consume_front("mtriple=")) {
 236       triple = std::string(opt);
 237     } else if (opt.consume_front("obj-path=")) {
 238       obj_path = std::string(opt);
 239     } else if (opt == "emit-llvm") {
 240       TheOutputType = OT_BC_ONLY;
 241     } else if (opt == "save-temps") {
 242       TheOutputType = OT_SAVE_TEMPS;
 243     } else if (opt == "disable-output") {
 244       TheOutputType = OT_DISABLE;
 245     } else if (opt == "emit-asm") {
 246       TheOutputType = OT_ASM_ONLY;
 247     } else if (opt == "thinlto") {
 248       thinlto = true;
 249     } else if (opt == "thinlto-index-only") {
 250       thinlto_index_only = true;
 251     } else if (opt.consume_front("thinlto-index-only=")) {
 252       thinlto_index_only = true;
 253       thinlto_linked_objects_file = std::string(opt);
 254     } else if (opt == "thinlto-emit-imports-files") {
 255       thinlto_emit_imports_files = true;
 256     } else if (opt.consume_front("thinlto-prefix-replace=")) {
 257       thinlto_prefix_replace = std::string(opt);
 258       if (thinlto_prefix_replace.find(';') == std::string::npos)
 259         message(LDPL_FATAL, "thinlto-prefix-replace expects 'old;new' format");
 260     } else if (opt.consume_front("thinlto-object-suffix-replace=")) {
 261       thinlto_object_suffix_replace = std::string(opt);
 262       if (thinlto_object_suffix_replace.find(';') == std::string::npos)
 263         message(LDPL_FATAL,
 264                 "thinlto-object-suffix-replace expects 'old;new' format");
 265     } else if (opt.consume_front("cache-dir=")) {
 266       cache_dir = std::string(opt);
 267     } else if (opt.consume_front("cache-policy=")) {
 268       cache_policy = std::string(opt);
 269     } else if (opt.size() == 2 && opt[0] == 'O') {
 270       if (opt[1] < '0' || opt[1] > '3')
 271         message(LDPL_FATAL, "Optimization level must be between 0 and 3");
 272       OptLevel = opt[1] - '0';
 273     } else if (opt.consume_front("jobs=")) {
 274       Parallelism = std::string(opt);
 275       if (!get_threadpool_strategy(opt))
 276         message(LDPL_FATAL, "Invalid parallelism level: %s",
 277                 Parallelism.c_str());
 278     } else if (opt.consume_front("lto-partitions=")) {
 279       if (opt.getAsInteger(10, ParallelCodeGenParallelismLevel))
 280         message(LDPL_FATAL, "Invalid codegen partition level: %s", opt_ + 5);
 281     } else if (opt == "disable-verify") {
 282       DisableVerify = true;
 283     } else if (opt.consume_front("sample-profile=")) {
 284       sample_profile = std::string(opt);
 285     } else if (opt == "cs-profile-generate") {
 286       cs_pgo_gen = true;
 287     } else if (opt.consume_front("cs-profile-path=")) {
 288       cs_profile_path = std::string(opt);
 289     } else if (opt == "new-pass-manager") {
 290       // We always use the new pass manager.
 291     } else if (opt == "debug-pass-manager") {
 292       debug_pass_manager = true;
 293     } else if (opt == "whole-program-visibility") {
 294       whole_program_visibility = true;
 295     } else if (opt.consume_front("dwo_dir=")) {
 296       dwo_dir = std::string(opt);
 297     } else if (opt.consume_front("opt-remarks-filename=")) {
 298       RemarksFilename = std::string(opt);
 299     } else if (opt.consume_front("opt-remarks-passes=")) {
 300       RemarksPasses = std::string(opt);
 301     } else if (opt == "opt-remarks-with-hotness") {
 302       RemarksWithHotness = true;
 303     } else if (opt.consume_front("opt-remarks-hotness-threshold=")) {
 304       auto ResultOrErr = remarks::parseHotnessThresholdOption(opt);
 305       if (!ResultOrErr)
 306         message(LDPL_FATAL, "Invalid remarks hotness threshold: %s", opt);
 307       else
 308         RemarksHotnessThreshold = *ResultOrErr;
 309     } else if (opt.consume_front("opt-remarks-format=")) {
 310       RemarksFormat = std::string(opt);
 311     } else if (opt.consume_front("stats-file=")) {
 312       stats_file = std::string(opt);
 313     } else if (opt == "opaque-pointers") {
 314       opaque_pointers = true;
 315     } else if (opt == "no-opaque-pointers") {
 316       opaque_pointers = false;
 317     } else {
 318       // Save this option to pass to the code generator.
 319       // ParseCommandLineOptions() expects argv[0] to be program name. Lazily
 320       // add that.
 321       if (extra.empty())
 322         extra.push_back("LLVMgold");
 323
 324       extra.push_back(opt_);
 325     }
 326   }
 327 }
 328
 329 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
 330                                         int *claimed);
 331 static ld_plugin_status all_symbols_read_hook(void);
 332 static ld_plugin_status cleanup_hook(void);
 333
 334 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
 335 ld_plugin_status onload(ld_plugin_tv *tv) {
 336   InitializeAllTargetInfos();
 337   InitializeAllTargets();
 338   InitializeAllTargetMCs();
 339   InitializeAllAsmParsers();
 340   InitializeAllAsmPrinters();
 341
 342   // We're given a pointer to the first transfer vector. We read through them
 343   // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
 344   // contain pointers to functions that we need to call to register our own
 345   // hooks. The others are addresses of functions we can use to call into gold
 346   // for services.
 347
 348   bool registeredClaimFile = false;
 349   bool RegisteredAllSymbolsRead = false;
 350
 351   for (; tv->tv_tag != LDPT_NULL; ++tv) {
 352     // Cast tv_tag to int to allow values not in "enum ld_plugin_tag", like, for
 353     // example, LDPT_GET_SYMBOLS_V3 when building against an older plugin-api.h
 354     // header.
 355     switch (static_cast<int>(tv->tv_tag)) {
 356     case LDPT_OUTPUT_NAME:
 357       output_name = tv->tv_u.tv_string;
 358       break;
 359     case LDPT_LINKER_OUTPUT:
 360       switch (tv->tv_u.tv_val) {
 361       case LDPO_REL: // .o
 362         IsExecutable = false;
 363         SplitSections = false;
 364         break;
 365       case LDPO_DYN: // .so
 366         IsExecutable = false;
 367         RelocationModel = Reloc::PIC_;
 368         break;
 369       case LDPO_PIE: // position independent executable
 370         IsExecutable = true;
 371         RelocationModel = Reloc::PIC_;
 372         break;
 373       case LDPO_EXEC: // .exe
 374         IsExecutable = true;
 375         RelocationModel = Reloc::Static;
 376         break;
 377       default:
 378         message(LDPL_ERROR, "Unknown output file type %d", tv->tv_u.tv_val);
 379         return LDPS_ERR;
 380       }
 381       break;
 382     case LDPT_OPTION:
 383       options::process_plugin_option(tv->tv_u.tv_string);
 384       break;
 385     case LDPT_REGISTER_CLAIM_FILE_HOOK: {
 386       ld_plugin_register_claim_file callback;
 387       callback = tv->tv_u.tv_register_claim_file;
 388
 389       if (callback(claim_file_hook) != LDPS_OK)
 390         return LDPS_ERR;
 391
 392       registeredClaimFile = true;
 393     } break;
 394     case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
 395       ld_plugin_register_all_symbols_read callback;
 396       callback = tv->tv_u.tv_register_all_symbols_read;
 397
 398       if (callback(all_symbols_read_hook) != LDPS_OK)
 399         return LDPS_ERR;
 400
 401       RegisteredAllSymbolsRead = true;
 402     } break;
 403     case LDPT_REGISTER_CLEANUP_HOOK: {
 404       ld_plugin_register_cleanup callback;
 405       callback = tv->tv_u.tv_register_cleanup;
 406
 407       if (callback(cleanup_hook) != LDPS_OK)
 408         return LDPS_ERR;
 409     } break;
 410     case LDPT_GET_INPUT_FILE:
 411       get_input_file = tv->tv_u.tv_get_input_file;
 412       break;
 413     case LDPT_RELEASE_INPUT_FILE:
 414       release_input_file = tv->tv_u.tv_release_input_file;
 415       break;
 416     case LDPT_ADD_SYMBOLS:
 417       add_symbols = tv->tv_u.tv_add_symbols;
 418       break;
 419     case LDPT_GET_SYMBOLS_V2:
 420       // Do not override get_symbols_v3 with get_symbols_v2.
 421       if (!get_symbols)
 422         get_symbols = tv->tv_u.tv_get_symbols;
 423       break;
 424     case LDPT_GET_SYMBOLS_V3:
 425       get_symbols = tv->tv_u.tv_get_symbols;
 426       break;
 427     case LDPT_ADD_INPUT_FILE:
 428       add_input_file = tv->tv_u.tv_add_input_file;
 429       break;
 430     case LDPT_SET_EXTRA_LIBRARY_PATH:
 431       set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
 432       break;
 433     case LDPT_GET_VIEW:
 434       get_view = tv->tv_u.tv_get_view;
 435       break;
 436     case LDPT_MESSAGE:
 437       message = tv->tv_u.tv_message;
 438       break;
 439     case LDPT_GET_WRAP_SYMBOLS:
 440       // FIXME: When binutils 2.31 (containing gold 1.16) is the minimum
 441       // required version, this should be changed to:
 442       // get_wrap_symbols = tv->tv_u.tv_get_wrap_symbols;
 443       get_wrap_symbols =
 444           (ld_plugin_get_wrap_symbols)tv->tv_u.tv_message;
 445       break;
 446     default:
 447       break;
 448     }
 449   }
 450
 451   if (!registeredClaimFile) {
 452     message(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
 453     return LDPS_ERR;
 454   }
 455   if (!add_symbols) {
 456     message(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
 457     return LDPS_ERR;
 458   }
 459
 460   if (!RegisteredAllSymbolsRead)
 461     return LDPS_OK;
 462
 463   if (!get_input_file) {
 464     message(LDPL_ERROR, "get_input_file not passed to LLVMgold.");
 465     return LDPS_ERR;
 466   }
 467   if (!release_input_file) {
 468     message(LDPL_ERROR, "release_input_file not passed to LLVMgold.");
 469     return LDPS_ERR;
 470   }
 471
 472   return LDPS_OK;
 473 }
 474
 475 static void diagnosticHandler(const DiagnosticInfo &DI) {
 476   std::string ErrStorage;
 477   {
 478     raw_string_ostream OS(ErrStorage);
 479     DiagnosticPrinterRawOStream DP(OS);
 480     DI.print(DP);
 481   }
 482   ld_plugin_level Level;
 483   switch (DI.getSeverity()) {
 484   case DS_Error:
 485     Level = LDPL_FATAL;
 486     break;
 487   case DS_Warning:
 488     Level = LDPL_WARNING;
 489     break;
 490   case DS_Note:
 491   case DS_Remark:
 492     Level = LDPL_INFO;
 493     break;
 494   }
 495   message(Level, "LLVM gold plugin: %s",  ErrStorage.c_str());
 496 }
 497
 498 static void check(Error E, std::string Msg = "LLVM gold plugin") {
 499   handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) -> Error {
 500     message(LDPL_FATAL, "%s: %s", Msg.c_str(), EIB.message().c_str());
 501     return Error::success();
 502   });
 503 }
 504
 505 template <typename T> static T check(Expected<T> E) {
 506   if (E)
 507     return std::move(*E);
 508   check(E.takeError());
 509   return T();
 510 }
 511
 512 /// Called by gold to see whether this file is one that our plugin can handle.
 513 /// We'll try to open it and register all the symbols with add_symbol if
 514 /// possible.
 515 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
 516                                         int *claimed) {
 517   MemoryBufferRef BufferRef;
 518   std::unique_ptr<MemoryBuffer> Buffer;
 519   if (get_view) {
 520     const void *view;
 521     if (get_view(file->handle, &view) != LDPS_OK) {
 522       message(LDPL_ERROR, "Failed to get a view of %s", file->name);
 523       return LDPS_ERR;
 524     }
 525     BufferRef =
 526         MemoryBufferRef(StringRef((const char *)view, file->filesize), "");
 527   } else {
 528     int64_t offset = 0;
 529     // Gold has found what might be IR part-way inside of a file, such as
 530     // an .a archive.
 531     if (file->offset) {
 532       offset = file->offset;
 533     }
 534     ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
 535         MemoryBuffer::getOpenFileSlice(sys::fs::convertFDToNativeFile(file->fd),
 536                                        file->name, file->filesize, offset);
 537     if (std::error_code EC = BufferOrErr.getError()) {
 538       message(LDPL_ERROR, EC.message().c_str());
 539       return LDPS_ERR;
 540     }
 541     Buffer = std::move(BufferOrErr.get());
 542     BufferRef = Buffer->getMemBufferRef();
 543   }
 544
 545   // Only use bitcode files for LTO.  InputFile::create() will load bitcode
 546   // from the .llvmbc section within a binary object, this bitcode is typically
 547   // generated by -fembed-bitcode and is not to be used by LLVMgold.so for LTO.
 548   if (identify_magic(BufferRef.getBuffer()) != file_magic::bitcode) {
 549     *claimed = 0;
 550     return LDPS_OK;
 551   }
 552
 553   *claimed = 1;
 554
 555   Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
 556   if (!ObjOrErr) {
 557     handleAllErrors(ObjOrErr.takeError(), [&](const ErrorInfoBase &EI) {
 558       std::error_code EC = EI.convertToErrorCode();
 559       if (EC == object::object_error::invalid_file_type ||
 560           EC == object::object_error::bitcode_section_not_found)
 561         *claimed = 0;
 562       else
 563         message(LDPL_FATAL,
 564                 "LLVM gold plugin has failed to create LTO module: %s",
 565                 EI.message().c_str());
 566     });
 567
 568     return *claimed ? LDPS_ERR : LDPS_OK;
 569   }
 570
 571   std::unique_ptr<InputFile> Obj = std::move(*ObjOrErr);
 572
 573   Modules.emplace_back();
 574   claimed_file &cf = Modules.back();
 575
 576   cf.handle = file->handle;
 577   // Keep track of the first handle for each file descriptor, since there are
 578   // multiple in the case of an archive. This is used later in the case of
 579   // ThinLTO parallel backends to ensure that each file is only opened and
 580   // released once.
 581   auto LeaderHandle =
 582       FDToLeaderHandle.insert(std::make_pair(file->fd, file->handle)).first;
 583   cf.leader_handle = LeaderHandle->second;
 584   // Save the filesize since for parallel ThinLTO backends we can only
 585   // invoke get_input_file once per archive (only for the leader handle).
 586   cf.filesize = file->filesize;
 587   // In the case of an archive library, all but the first member must have a
 588   // non-zero offset, which we can append to the file name to obtain a
 589   // unique name.
 590   cf.name = file->name;
 591   if (file->offset)
 592     cf.name += ".llvm." + std::to_string(file->offset) + "." +
 593                sys::path::filename(Obj->getSourceFileName()).str();
 594
 595   for (auto &Sym : Obj->symbols()) {
 596     cf.syms.push_back(ld_plugin_symbol());
 597     ld_plugin_symbol &sym = cf.syms.back();
 598     sym.version = nullptr;
 599     StringRef Name = Sym.getName();
 600     sym.name = strdup(Name.str().c_str());
 601
 602     ResolutionInfo &Res = ResInfo[Name];
 603
 604     Res.CanOmitFromDynSym &= Sym.canBeOmittedFromSymbolTable();
 605
 606     sym.visibility = LDPV_DEFAULT;
 607     GlobalValue::VisibilityTypes Vis = Sym.getVisibility();
 608     if (Vis != GlobalValue::DefaultVisibility)
 609       Res.DefaultVisibility = false;
 610     switch (Vis) {
 611     case GlobalValue::DefaultVisibility:
 612       break;
 613     case GlobalValue::HiddenVisibility:
 614       sym.visibility = LDPV_HIDDEN;
 615       break;
 616     case GlobalValue::ProtectedVisibility:
 617       sym.visibility = LDPV_PROTECTED;
 618       break;
 619     }
 620
 621     if (Sym.isUndefined()) {
 622       sym.def = LDPK_UNDEF;
 623       if (Sym.isWeak())
 624         sym.def = LDPK_WEAKUNDEF;
 625     } else if (Sym.isCommon())
 626       sym.def = LDPK_COMMON;
 627     else if (Sym.isWeak())
 628       sym.def = LDPK_WEAKDEF;
 629     else
 630       sym.def = LDPK_DEF;
 631
 632     sym.size = 0;
 633     sym.comdat_key = nullptr;
 634     int CI = Sym.getComdatIndex();
 635     if (CI != -1) {
 636       // Not setting comdat_key for nodeduplicate ensuress we don't deduplicate.
 637       std::pair<StringRef, Comdat::SelectionKind> C = Obj->getComdatTable()[CI];
 638       if (C.second != Comdat::NoDeduplicate)
 639         sym.comdat_key = strdup(C.first.str().c_str());
 640     }
 641
 642     sym.resolution = LDPR_UNKNOWN;
 643   }
 644
 645   if (!cf.syms.empty()) {
 646     if (add_symbols(cf.handle, cf.syms.size(), cf.syms.data()) != LDPS_OK) {
 647       message(LDPL_ERROR, "Unable to add symbols!");
 648       return LDPS_ERR;
 649     }
 650   }
 651
 652   // Handle any --wrap options passed to gold, which are than passed
 653   // along to the plugin.
 654   if (get_wrap_symbols) {
 655     const char **wrap_symbols;
 656     uint64_t count = 0;
 657     if (get_wrap_symbols(&count, &wrap_symbols) != LDPS_OK) {
 658       message(LDPL_ERROR, "Unable to get wrap symbols!");
 659       return LDPS_ERR;
 660     }
 661     for (uint64_t i = 0; i < count; i++) {
 662       StringRef Name = wrap_symbols[i];
 663       ResolutionInfo &Res = ResInfo[Name];
 664       ResolutionInfo &WrapRes = ResInfo["__wrap_" + Name.str()];
 665       ResolutionInfo &RealRes = ResInfo["__real_" + Name.str()];
 666       // Tell LTO not to inline symbols that will be overwritten.
 667       Res.CanInline = false;
 668       RealRes.CanInline = false;
 669       // Tell LTO not to eliminate symbols that will be used after renaming.
 670       Res.IsUsedInRegularObj = true;
 671       WrapRes.IsUsedInRegularObj = true;
 672     }
 673   }
 674
 675   return LDPS_OK;
 676 }
 677
 678 static void freeSymName(ld_plugin_symbol &Sym) {
 679   free(Sym.name);
 680   free(Sym.comdat_key);
 681   Sym.name = nullptr;
 682   Sym.comdat_key = nullptr;
 683 }
 684
 685 /// Helper to get a file's symbols and a view into it via gold callbacks.
 686 static const void *getSymbolsAndView(claimed_file &F) {
 687   ld_plugin_status status = get_symbols(F.handle, F.syms.size(), F.syms.data());
 688   if (status == LDPS_NO_SYMS)
 689     return nullptr;
 690
 691   if (status != LDPS_OK)
 692     message(LDPL_FATAL, "Failed to get symbol information");
 693
 694   const void *View;
 695   if (get_view(F.handle, &View) != LDPS_OK)
 696     message(LDPL_FATAL, "Failed to get a view of file");
 697
 698   return View;
 699 }
 700
 701 /// Parse the thinlto-object-suffix-replace option into the \p OldSuffix and
 702 /// \p NewSuffix strings, if it was specified.
 703 static void getThinLTOOldAndNewSuffix(std::string &OldSuffix,
 704                                       std::string &NewSuffix) {
 705   assert(options::thinlto_object_suffix_replace.empty() ||
 706          options::thinlto_object_suffix_replace.find(';') != StringRef::npos);
 707   StringRef SuffixReplace = options::thinlto_object_suffix_replace;
 708   auto Split = SuffixReplace.split(';');
 709   OldSuffix = std::string(Split.first);
 710   NewSuffix = std::string(Split.second);
 711 }
 712
 713 /// Given the original \p Path to an output file, replace any filename
 714 /// suffix matching \p OldSuffix with \p NewSuffix.
 715 static std::string getThinLTOObjectFileName(StringRef Path, StringRef OldSuffix,
 716                                             StringRef NewSuffix) {
 717   if (Path.consume_back(OldSuffix))
 718     return (Path + NewSuffix).str();
 719   return std::string(Path);
 720 }
 721
 722 // Returns true if S is valid as a C language identifier.
 723 static bool isValidCIdentifier(StringRef S) {
 724   return !S.empty() && (isAlpha(S[0]) || S[0] == '_') &&
 725          llvm::all_of(llvm::drop_begin(S),
 726                       [](char C) { return C == '_' || isAlnum(C); });
 727 }
 728
 729 static bool isUndefined(ld_plugin_symbol &Sym) {
 730   return Sym.def == LDPK_UNDEF || Sym.def == LDPK_WEAKUNDEF;
 731 }
 732
 733 static void addModule(LTO &Lto, claimed_file &F, const void *View,
 734                       StringRef Filename) {
 735   MemoryBufferRef BufferRef(StringRef((const char *)View, F.filesize),
 736                             Filename);
 737   Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
 738
 739   if (!ObjOrErr)
 740     message(LDPL_FATAL, "Could not read bitcode from file : %s",
 741             toString(ObjOrErr.takeError()).c_str());
 742
 743   unsigned SymNum = 0;
 744   std::unique_ptr<InputFile> Input = std::move(ObjOrErr.get());
 745   auto InputFileSyms = Input->symbols();
 746   assert(InputFileSyms.size() == F.syms.size());
 747   std::vector<SymbolResolution> Resols(F.syms.size());
 748   for (ld_plugin_symbol &Sym : F.syms) {
 749     const InputFile::Symbol &InpSym = InputFileSyms[SymNum];
 750     SymbolResolution &R = Resols[SymNum++];
 751
 752     ld_plugin_symbol_resolution Resolution =
 753         (ld_plugin_symbol_resolution)Sym.resolution;
 754
 755     ResolutionInfo &Res = ResInfo[Sym.name];
 756
 757     switch (Resolution) {
 758     case LDPR_UNKNOWN:
 759       llvm_unreachable("Unexpected resolution");
 760
 761     case LDPR_RESOLVED_IR:
 762     case LDPR_RESOLVED_EXEC:
 763     case LDPR_PREEMPTED_IR:
 764     case LDPR_PREEMPTED_REG:
 765     case LDPR_UNDEF:
 766       break;
 767
 768     case LDPR_RESOLVED_DYN:
 769       R.ExportDynamic = true;
 770       break;
 771
 772     case LDPR_PREVAILING_DEF_IRONLY:
 773       R.Prevailing = !isUndefined(Sym);
 774       break;
 775
 776     case LDPR_PREVAILING_DEF:
 777       R.Prevailing = !isUndefined(Sym);
 778       R.VisibleToRegularObj = true;
 779       break;
 780
 781     case LDPR_PREVAILING_DEF_IRONLY_EXP:
 782       R.Prevailing = !isUndefined(Sym);
 783       // Identify symbols exported dynamically, and that therefore could be
 784       // referenced by a shared library not visible to the linker.
 785       R.ExportDynamic = true;
 786       if (!Res.CanOmitFromDynSym)
 787         R.VisibleToRegularObj = true;
 788       break;
 789     }
 790
 791     // If the symbol has a C identifier section name, we need to mark
 792     // it as visible to a regular object so that LTO will keep it around
 793     // to ensure the linker generates special __start_<secname> and
 794     // __stop_<secname> symbols which may be used elsewhere.
 795     if (isValidCIdentifier(InpSym.getSectionName()))
 796       R.VisibleToRegularObj = true;
 797
 798     if (Resolution != LDPR_RESOLVED_DYN && Resolution != LDPR_UNDEF &&
 799         (IsExecutable || !Res.DefaultVisibility))
 800       R.FinalDefinitionInLinkageUnit = true;
 801
 802     if (!Res.CanInline)
 803       R.LinkerRedefined = true;
 804
 805     if (Res.IsUsedInRegularObj)
 806       R.VisibleToRegularObj = true;
 807
 808     freeSymName(Sym);
 809   }
 810
 811   check(Lto.add(std::move(Input), Resols),
 812         std::string("Failed to link module ") + F.name);
 813 }
 814
 815 static void recordFile(const std::string &Filename, bool TempOutFile) {
 816   if (add_input_file(Filename.c_str()) != LDPS_OK)
 817     message(LDPL_FATAL,
 818             "Unable to add .o file to the link. File left behind in: %s",
 819             Filename.c_str());
 820   if (TempOutFile)
 821     Cleanup.push_back(Filename);
 822 }
 823
 824 /// Return the desired output filename given a base input name, a flag
 825 /// indicating whether a temp file should be generated, and an optional task id.
 826 /// The new filename generated is returned in \p NewFilename.
 827 static int getOutputFileName(StringRef InFilename, bool TempOutFile,
 828                              SmallString<128> &NewFilename, int TaskID) {
 829   int FD = -1;
 830   if (TempOutFile) {
 831     std::error_code EC =
 832         sys::fs::createTemporaryFile("lto-llvm", "o", FD, NewFilename);
 833     if (EC)
 834       message(LDPL_FATAL, "Could not create temporary file: %s",
 835               EC.message().c_str());
 836   } else {
 837     NewFilename = InFilename;
 838     if (TaskID > 0)
 839       NewFilename += utostr(TaskID);
 840     std::error_code EC =
 841         sys::fs::openFileForWrite(NewFilename, FD, sys::fs::CD_CreateAlways);
 842     if (EC)
 843       message(LDPL_FATAL, "Could not open file %s: %s", NewFilename.c_str(),
 844               EC.message().c_str());
 845   }
 846   return FD;
 847 }
 848
 849 static CodeGenOpt::Level getCGOptLevel() {
 850   switch (options::OptLevel) {
 851   case 0:
 852     return CodeGenOpt::None;
 853   case 1:
 854     return CodeGenOpt::Less;
 855   case 2:
 856     return CodeGenOpt::Default;
 857   case 3:
 858     return CodeGenOpt::Aggressive;
 859   }
 860   llvm_unreachable("Invalid optimization level");
 861 }
 862
 863 /// Parse the thinlto_prefix_replace option into the \p OldPrefix and
 864 /// \p NewPrefix strings, if it was specified.
 865 static void getThinLTOOldAndNewPrefix(std::string &OldPrefix,
 866                                       std::string &NewPrefix) {
 867   StringRef PrefixReplace = options::thinlto_prefix_replace;
 868   assert(PrefixReplace.empty() || PrefixReplace.find(';') != StringRef::npos);
 869   auto Split = PrefixReplace.split(';');
 870   OldPrefix = std::string(Split.first);
 871   NewPrefix = std::string(Split.second);
 872 }
 873
 874 /// Creates instance of LTO.
 875 /// OnIndexWrite is callback to let caller know when LTO writes index files.
 876 /// LinkedObjectsFile is an output stream to write the list of object files for
 877 /// the final ThinLTO linking. Can be nullptr.
 878 static std::unique_ptr<LTO> createLTO(IndexWriteCallback OnIndexWrite,
 879                                       raw_fd_ostream *LinkedObjectsFile) {
 880   Config Conf;
 881   ThinBackend Backend;
 882
 883   Conf.CPU = options::mcpu;
 884   Conf.Options = codegen::InitTargetOptionsFromCodeGenFlags(Triple());
 885
 886   // Disable the new X86 relax relocations since gold might not support them.
 887   // FIXME: Check the gold version or add a new option to enable them.
 888   Conf.Options.RelaxELFRelocations = false;
 889
 890   // Toggle function/data sections.
 891   if (!codegen::getExplicitFunctionSections())
 892     Conf.Options.FunctionSections = SplitSections;
 893   if (!codegen::getExplicitDataSections())
 894     Conf.Options.DataSections = SplitSections;
 895
 896   Conf.MAttrs = codegen::getMAttrs();
 897   Conf.RelocModel = RelocationModel;
 898   Conf.CodeModel = codegen::getExplicitCodeModel();
 899   Conf.CGOptLevel = getCGOptLevel();
 900   Conf.DisableVerify = options::DisableVerify;
 901   Conf.OptLevel = options::OptLevel;
 902   Conf.PTO.LoopVectorization = options::OptLevel > 1;
 903   Conf.PTO.SLPVectorization = options::OptLevel > 1;
 904   Conf.AlwaysEmitRegularLTOObj = !options::obj_path.empty();
 905
 906   if (options::thinlto_index_only) {
 907     std::string OldPrefix, NewPrefix;
 908     getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
 909     Backend = createWriteIndexesThinBackend(OldPrefix, NewPrefix,
 910                                             options::thinlto_emit_imports_files,
 911                                             LinkedObjectsFile, OnIndexWrite);
 912   } else {
 913     Backend = createInProcessThinBackend(
 914         llvm::heavyweight_hardware_concurrency(options::Parallelism));
 915   }
 916
 917   Conf.OverrideTriple = options::triple;
 918   Conf.DefaultTriple = sys::getDefaultTargetTriple();
 919
 920   Conf.DiagHandler = diagnosticHandler;
 921
 922   switch (options::TheOutputType) {
 923   case options::OT_NORMAL:
 924     break;
 925
 926   case options::OT_DISABLE:
 927     Conf.PreOptModuleHook = [](size_t Task, const Module &M) { return false; };
 928     break;
 929
 930   case options::OT_BC_ONLY:
 931     Conf.PostInternalizeModuleHook = [](size_t Task, const Module &M) {
 932       std::error_code EC;
 933       SmallString<128> TaskFilename;
 934       getOutputFileName(output_name, /* TempOutFile */ false, TaskFilename,
 935                         Task);
 936       raw_fd_ostream OS(TaskFilename, EC, sys::fs::OpenFlags::OF_None);
 937       if (EC)
 938         message(LDPL_FATAL, "Failed to write the output file.");
 939       WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ false);
 940       return false;
 941     };
 942     break;
 943
 944   case options::OT_SAVE_TEMPS:
 945     check(Conf.addSaveTemps(output_name + ".",
 946                             /* UseInputModulePath */ true));
 947     break;
 948   case options::OT_ASM_ONLY:
 949     Conf.CGFileType = CGFT_AssemblyFile;
 950     break;
 951   }
 952
 953   if (!options::sample_profile.empty())
 954     Conf.SampleProfile = options::sample_profile;
 955
 956   if (!options::cs_profile_path.empty())
 957     Conf.CSIRProfile = options::cs_profile_path;
 958   Conf.RunCSIRInstr = options::cs_pgo_gen;
 959
 960   Conf.DwoDir = options::dwo_dir;
 961
 962   // Set up optimization remarks handling.
 963   Conf.RemarksFilename = options::RemarksFilename;
 964   Conf.RemarksPasses = options::RemarksPasses;
 965   Conf.RemarksWithHotness = options::RemarksWithHotness;
 966   Conf.RemarksHotnessThreshold = options::RemarksHotnessThreshold;
 967   Conf.RemarksFormat = options::RemarksFormat;
 968
 969   // Debug new pass manager if requested
 970   Conf.DebugPassManager = options::debug_pass_manager;
 971
 972   Conf.HasWholeProgramVisibility = options::whole_program_visibility;
 973
 974   Conf.OpaquePointers = options::opaque_pointers;
 975
 976   Conf.StatsFile = options::stats_file;
 977   return std::make_unique<LTO>(std::move(Conf), Backend,
 978                                 options::ParallelCodeGenParallelismLevel);
 979 }
 980
 981 // Write empty files that may be expected by a distributed build
 982 // system when invoked with thinlto_index_only. This is invoked when
 983 // the linker has decided not to include the given module in the
 984 // final link. Frequently the distributed build system will want to
 985 // confirm that all expected outputs are created based on all of the
 986 // modules provided to the linker.
 987 // If SkipModule is true then .thinlto.bc should contain just
 988 // SkipModuleByDistributedBackend flag which requests distributed backend
 989 // to skip the compilation of the corresponding module and produce an empty
 990 // object file.
 991 static void writeEmptyDistributedBuildOutputs(const std::string &ModulePath,
 992                                               const std::string &OldPrefix,
 993                                               const std::string &NewPrefix,
 994                                               bool SkipModule) {
 995   std::string NewModulePath =
 996       getThinLTOOutputFile(ModulePath, OldPrefix, NewPrefix);
 997   std::error_code EC;
 998   {
 999     raw_fd_ostream OS(NewModulePath + ".thinlto.bc", EC,
1000                       sys::fs::OpenFlags::OF_None);
1001     if (EC)
1002       message(LDPL_FATAL, "Failed to write '%s': %s",
1003               (NewModulePath + ".thinlto.bc").c_str(), EC.message().c_str());
1004
1005     if (SkipModule) {
1006       ModuleSummaryIndex Index(/*HaveGVs*/ false);
1007       Index.setSkipModuleByDistributedBackend();
1008       writeIndexToFile(Index, OS, nullptr);
1009     }
1010   }
1011   if (options::thinlto_emit_imports_files) {
1012     raw_fd_ostream OS(NewModulePath + ".imports", EC,
1013                       sys::fs::OpenFlags::OF_None);
1014     if (EC)
1015       message(LDPL_FATAL, "Failed to write '%s': %s",
1016               (NewModulePath + ".imports").c_str(), EC.message().c_str());
1017   }
1018 }
1019
1020 // Creates and returns output stream with a list of object files for final
1021 // linking of distributed ThinLTO.
1022 static std::unique_ptr<raw_fd_ostream> CreateLinkedObjectsFile() {
1023   if (options::thinlto_linked_objects_file.empty())
1024     return nullptr;
1025   assert(options::thinlto_index_only);
1026   std::error_code EC;
1027   auto LinkedObjectsFile = std::make_unique<raw_fd_ostream>(
1028       options::thinlto_linked_objects_file, EC, sys::fs::OpenFlags::OF_None);
1029   if (EC)
1030     message(LDPL_FATAL, "Failed to create '%s': %s",
1031             options::thinlto_linked_objects_file.c_str(), EC.message().c_str());
1032   return LinkedObjectsFile;
1033 }
1034
1035 /// Runs LTO and return a list of pairs <FileName, IsTemporary>.
1036 static std::vector<std::pair<SmallString<128>, bool>> runLTO() {
1037   // Map to own RAII objects that manage the file opening and releasing
1038   // interfaces with gold. This is needed only for ThinLTO mode, since
1039   // unlike regular LTO, where addModule will result in the opened file
1040   // being merged into a new combined module, we need to keep these files open
1041   // through Lto->run().
1042   DenseMap<void *, std::unique_ptr<PluginInputFile>> HandleToInputFile;
1043
1044   // Owns string objects and tells if index file was already created.
1045   StringMap<bool> ObjectToIndexFileState;
1046
1047   std::unique_ptr<raw_fd_ostream> LinkedObjects = CreateLinkedObjectsFile();
1048   std::unique_ptr<LTO> Lto = createLTO(
1049       [&ObjectToIndexFileState](const std::string &Identifier) {
1050         ObjectToIndexFileState[Identifier] = true;
1051       },
1052       LinkedObjects.get());
1053
1054   std::string OldPrefix, NewPrefix;
1055   if (options::thinlto_index_only)
1056     getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
1057
1058   std::string OldSuffix, NewSuffix;
1059   getThinLTOOldAndNewSuffix(OldSuffix, NewSuffix);
1060
1061   for (claimed_file &F : Modules) {
1062     if (options::thinlto && !HandleToInputFile.count(F.leader_handle))
1063       HandleToInputFile.insert(std::make_pair(
1064           F.leader_handle, std::make_unique<PluginInputFile>(F.handle)));
1065     // In case we are thin linking with a minimized bitcode file, ensure
1066     // the module paths encoded in the index reflect where the backends
1067     // will locate the full bitcode files for compiling/importing.
1068     std::string Identifier =
1069         getThinLTOObjectFileName(F.name, OldSuffix, NewSuffix);
1070     auto ObjFilename = ObjectToIndexFileState.insert({Identifier, false});
1071     assert(ObjFilename.second);
1072     if (const void *View = getSymbolsAndView(F))
1073       addModule(*Lto, F, View, ObjFilename.first->first());
1074     else if (options::thinlto_index_only) {
1075       ObjFilename.first->second = true;
1076       writeEmptyDistributedBuildOutputs(Identifier, OldPrefix, NewPrefix,
1077                                         /* SkipModule */ true);
1078     }
1079   }
1080
1081   SmallString<128> Filename;
1082   // Note that getOutputFileName will append a unique ID for each task
1083   if (!options::obj_path.empty())
1084     Filename = options::obj_path;
1085   else if (options::TheOutputType == options::OT_SAVE_TEMPS)
1086     Filename = output_name + ".lto.o";
1087   else if (options::TheOutputType == options::OT_ASM_ONLY)
1088     Filename = output_name;
1089   bool SaveTemps = !Filename.empty();
1090
1091   size_t MaxTasks = Lto->getMaxTasks();
1092   std::vector<std::pair<SmallString<128>, bool>> Files(MaxTasks);
1093
1094   auto AddStream = [&](size_t Task) -> std::unique_ptr<CachedFileStream> {
1095     Files[Task].second = !SaveTemps;
1096     int FD = getOutputFileName(Filename, /* TempOutFile */ !SaveTemps,
1097                                Files[Task].first, Task);
1098     return std::make_unique<CachedFileStream>(
1099         std::make_unique<llvm::raw_fd_ostream>(FD, true));
1100   };
1101
1102   auto AddBuffer = [&](size_t Task, std::unique_ptr<MemoryBuffer> MB) {
1103     *AddStream(Task)->OS << MB->getBuffer();
1104   };
1105
1106   FileCache Cache;
1107   if (!options::cache_dir.empty())
1108     Cache = check(localCache("ThinLTO", "Thin", options::cache_dir, AddBuffer));
1109
1110   check(Lto->run(AddStream, Cache));
1111
1112   // Write empty output files that may be expected by the distributed build
1113   // system.
1114   if (options::thinlto_index_only)
1115     for (auto &Identifier : ObjectToIndexFileState)
1116       if (!Identifier.getValue())
1117         writeEmptyDistributedBuildOutputs(std::string(Identifier.getKey()),
1118                                           OldPrefix, NewPrefix,
1119                                           /* SkipModule */ false);
1120
1121   return Files;
1122 }
1123
1124 /// gold informs us that all symbols have been read. At this point, we use
1125 /// get_symbols to see if any of our definitions have been overridden by a
1126 /// native object file. Then, perform optimization and codegen.
1127 static ld_plugin_status allSymbolsReadHook() {
1128   if (Modules.empty())
1129     return LDPS_OK;
1130
1131   if (unsigned NumOpts = options::extra.size())
1132     cl::ParseCommandLineOptions(NumOpts, &options::extra[0]);
1133
1134   std::vector<std::pair<SmallString<128>, bool>> Files = runLTO();
1135
1136   if (options::TheOutputType == options::OT_DISABLE ||
1137       options::TheOutputType == options::OT_BC_ONLY ||
1138       options::TheOutputType == options::OT_ASM_ONLY)
1139     return LDPS_OK;
1140
1141   if (options::thinlto_index_only) {
1142     llvm_shutdown();
1143     cleanup_hook();
1144     exit(0);
1145   }
1146
1147   for (const auto &F : Files)
1148     if (!F.first.empty())
1149       recordFile(std::string(F.first.str()), F.second);
1150
1151   if (!options::extra_library_path.empty() &&
1152       set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK)
1153     message(LDPL_FATAL, "Unable to set the extra library path.");
1154
1155   return LDPS_OK;
1156 }
1157
1158 static ld_plugin_status all_symbols_read_hook(void) {
1159   ld_plugin_status Ret = allSymbolsReadHook();
1160   llvm_shutdown();
1161
1162   if (options::TheOutputType == options::OT_BC_ONLY ||
1163       options::TheOutputType == options::OT_ASM_ONLY ||
1164       options::TheOutputType == options::OT_DISABLE) {
1165     if (options::TheOutputType == options::OT_DISABLE) {
1166       // Remove the output file here since ld.bfd creates the output file
1167       // early.
1168       std::error_code EC = sys::fs::remove(output_name);
1169       if (EC)
1170         message(LDPL_ERROR, "Failed to delete '%s': %s", output_name.c_str(),
1171                 EC.message().c_str());
1172     }
1173     exit(0);
1174   }
1175
1176   return Ret;
1177 }
1178
1179 static ld_plugin_status cleanup_hook(void) {
1180   for (std::string &Name : Cleanup) {
1181     std::error_code EC = sys::fs::remove(Name);
1182     if (EC)
1183       message(LDPL_ERROR, "Failed to delete '%s': %s", Name.c_str(),
1184               EC.message().c_str());
1185   }
1186
1187   // Prune cache
1188   if (!options::cache_dir.empty()) {
1189     CachePruningPolicy policy = check(parseCachePruningPolicy(options::cache_policy));
1190     pruneCache(options::cache_dir, policy);
1191   }
1192
1193   return LDPS_OK;
1194 }