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/ScopeExit.h"
  15 #include "llvm/ADT/Statistic.h"
  16 #include "llvm/Bitcode/BitcodeReader.h"
  17 #include "llvm/Bitcode/BitcodeWriter.h"
  18 #include "llvm/CodeGen/CommandFlags.h"
  19 #include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
  20 #include "llvm/Config/llvm-config.h"
  21 #include "llvm/IR/Constants.h"
  22 #include "llvm/IR/DiagnosticPrinter.h"
  23 #include "llvm/LTO/LTO.h"
  24 #include "llvm/Object/Error.h"
  25 #include "llvm/Remarks/HotnessThresholdParser.h"
  26 #include "llvm/Support/CachePruning.h"
  27 #include "llvm/Support/Caching.h"
  28 #include "llvm/Support/CommandLine.h"
  29 #include "llvm/Support/FileSystem.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/TimeProfiler.h"
  36 #include "llvm/Support/raw_ostream.h"
  37 #include "llvm/TargetParser/Host.h"
  38 #include <list>
  39 #include <map>
  40 #include <plugin-api.h>
  41 #include <string>
  42 #include <system_error>
  43 #include <utility>
  44 #include <vector>
  45
  46 // FIXME: remove this declaration when we stop maintaining Ubuntu Quantal and
  47 // Precise and Debian Wheezy (binutils 2.23 is required)
  48 #define LDPO_PIE 3
  49
  50 #define LDPT_GET_SYMBOLS_V3 28
  51
  52 // FIXME: Remove when binutils 2.31 (containing gold 1.16) is the minimum
  53 // required version.
  54 #define LDPT_GET_WRAP_SYMBOLS 32
  55
  56 using namespace llvm;
  57 using namespace lto;
  58
  59 static codegen::RegisterCodeGenFlags CodeGenFlags;
  60
  61 // FIXME: Remove when binutils 2.31 (containing gold 1.16) is the minimum
  62 // required version.
  63 typedef enum ld_plugin_status (*ld_plugin_get_wrap_symbols)(
  64     uint64_t *num_symbols, const char ***wrap_symbol_list);
  65
  66 static ld_plugin_status discard_message(int level, const char *format, ...) {
  67   // Die loudly. Recent versions of Gold pass ld_plugin_message as the first
  68   // callback in the transfer vector. This should never be called.
  69   abort();
  70 }
  71
  72 static ld_plugin_release_input_file release_input_file = nullptr;
  73 static ld_plugin_get_input_file get_input_file = nullptr;
  74 static ld_plugin_message message = discard_message;
  75 static ld_plugin_get_wrap_symbols get_wrap_symbols = nullptr;
  76
  77 namespace {
  78 struct claimed_file {
  79   void *handle;
  80   void *leader_handle;
  81   std::vector<ld_plugin_symbol> syms;
  82   off_t filesize;
  83   std::string name;
  84 };
  85
  86 /// RAII wrapper to manage opening and releasing of a ld_plugin_input_file.
  87 struct PluginInputFile {
  88   void *Handle;
  89   std::unique_ptr<ld_plugin_input_file> File;
  90
  91   PluginInputFile(void *Handle) : Handle(Handle) {
  92     File = std::make_unique<ld_plugin_input_file>();
  93     if (get_input_file(Handle, File.get()) != LDPS_OK)
  94       message(LDPL_FATAL, "Failed to get file information");
  95   }
  96   ~PluginInputFile() {
  97     // File would have been reset to nullptr if we moved this object
  98     // to a new owner.
  99     if (File)
 100       if (release_input_file(Handle) != LDPS_OK)
 101         message(LDPL_FATAL, "Failed to release file information");
 102   }
 103
 104   ld_plugin_input_file &file() { return *File; }
 105
 106   PluginInputFile(PluginInputFile &&RHS) = default;
 107   PluginInputFile &operator=(PluginInputFile &&RHS) = default;
 108 };
 109
 110 struct ResolutionInfo {
 111   bool CanOmitFromDynSym = true;
 112   bool DefaultVisibility = true;
 113   bool CanInline = true;
 114   bool IsUsedInRegularObj = false;
 115 };
 116
 117 }
 118
 119 static ld_plugin_add_symbols add_symbols = nullptr;
 120 static ld_plugin_get_symbols get_symbols = nullptr;
 121 static ld_plugin_add_input_file add_input_file = nullptr;
 122 static ld_plugin_set_extra_library_path set_extra_library_path = nullptr;
 123 static ld_plugin_get_view get_view = nullptr;
 124 static bool IsExecutable = false;
 125 static bool SplitSections = true;
 126 static std::optional<Reloc::Model> RelocationModel;
 127 static std::string output_name = "";
 128 static std::list<claimed_file> Modules;
 129 static DenseMap<int, void *> FDToLeaderHandle;
 130 static StringMap<ResolutionInfo> ResInfo;
 131 static std::vector<std::string> Cleanup;
 132
 133 namespace options {
 134   enum OutputType {
 135     OT_NORMAL,
 136     OT_DISABLE,
 137     OT_BC_ONLY,
 138     OT_ASM_ONLY,
 139     OT_SAVE_TEMPS
 140   };
 141   static OutputType TheOutputType = OT_NORMAL;
 142   static unsigned OptLevel = 2;
 143   // Currently only affects ThinLTO, where the default is the max cores in the
 144   // system. See llvm::get_threadpool_strategy() for acceptable values.
 145   static std::string Parallelism;
 146   // Default regular LTO codegen parallelism (number of partitions).
 147   static unsigned ParallelCodeGenParallelismLevel = 1;
 148 #ifdef NDEBUG
 149   static bool DisableVerify = true;
 150 #else
 151   static bool DisableVerify = false;
 152 #endif
 153   static std::string obj_path;
 154   static std::string extra_library_path;
 155   static std::string triple;
 156   static std::string mcpu;
 157   // When the thinlto plugin option is specified, only read the function
 158   // the information from intermediate files and write a combined
 159   // global index for the ThinLTO backends.
 160   static bool thinlto = false;
 161   // If false, all ThinLTO backend compilations through code gen are performed
 162   // using multiple threads in the gold-plugin, before handing control back to
 163   // gold. If true, write individual backend index files which reflect
 164   // the import decisions, and exit afterwards. The assumption is
 165   // that the build system will launch the backend processes.
 166   static bool thinlto_index_only = false;
 167   // If non-empty, holds the name of a file in which to write the list of
 168   // oject files gold selected for inclusion in the link after symbol
 169   // resolution (i.e. they had selected symbols). This will only be non-empty
 170   // in the thinlto_index_only case. It is used to identify files, which may
 171   // have originally been within archive libraries specified via
 172   // --start-lib/--end-lib pairs, that should be included in the final
 173   // native link process (since intervening function importing and inlining
 174   // may change the symbol resolution detected in the final link and which
 175   // files to include out of --start-lib/--end-lib libraries as a result).
 176   static std::string thinlto_linked_objects_file;
 177   // If true, when generating individual index files for distributed backends,
 178   // also generate a "${bitcodefile}.imports" file at the same location for each
 179   // bitcode file, listing the files it imports from in plain text. This is to
 180   // support distributed build file staging.
 181   static bool thinlto_emit_imports_files = false;
 182   // Option to control where files for a distributed backend (the individual
 183   // index files and optional imports files) are created.
 184   // If specified, expects a string of the form "oldprefix:newprefix", and
 185   // instead of generating these files in the same directory path as the
 186   // corresponding bitcode file, will use a path formed by replacing the
 187   // bitcode file's path prefix matching oldprefix with newprefix.
 188   static std::string thinlto_prefix_replace;
 189   // Option to control the name of modules encoded in the individual index
 190   // files for a distributed backend. This enables the use of minimized
 191   // bitcode files for the thin link, assuming the name of the full bitcode
 192   // file used in the backend differs just in some part of the file suffix.
 193   // If specified, expects a string of the form "oldsuffix:newsuffix".
 194   static std::string thinlto_object_suffix_replace;
 195   // Optional path to a directory for caching ThinLTO objects.
 196   static std::string cache_dir;
 197   // Optional pruning policy for ThinLTO caches.
 198   static std::string cache_policy;
 199   // Additional options to pass into the code generator.
 200   // Note: This array will contain all plugin options which are not claimed
 201   // as plugin exclusive to pass to the code generator.
 202   static std::vector<const char *> extra;
 203   // Sample profile file path
 204   static std::string sample_profile;
 205   // Debug new pass manager
 206   static bool debug_pass_manager = false;
 207   // Directory to store the .dwo files.
 208   static std::string dwo_dir;
 209   /// Statistics output filename.
 210   static std::string stats_file;
 211   // Asserts that LTO link has whole program visibility
 212   static bool whole_program_visibility = false;
 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 std::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   // Time trace options.
 226   static std::string time_trace_file;
 227   static unsigned time_trace_granularity = 500;
 228
 229   static void process_plugin_option(const char *opt_)
 230   {
 231     if (opt_ == nullptr)
 232       return;
 233     llvm::StringRef opt = opt_;
 234
 235     if (opt.consume_front("mcpu=")) {
 236       mcpu = std::string(opt);
 237     } else if (opt.consume_front("extra-library-path=")) {
 238       extra_library_path = std::string(opt);
 239     } else if (opt.consume_front("mtriple=")) {
 240       triple = std::string(opt);
 241     } else if (opt.consume_front("obj-path=")) {
 242       obj_path = std::string(opt);
 243     } else if (opt == "emit-llvm") {
 244       TheOutputType = OT_BC_ONLY;
 245     } else if (opt == "save-temps") {
 246       TheOutputType = OT_SAVE_TEMPS;
 247     } else if (opt == "disable-output") {
 248       TheOutputType = OT_DISABLE;
 249     } else if (opt == "emit-asm") {
 250       TheOutputType = OT_ASM_ONLY;
 251     } else if (opt == "thinlto") {
 252       thinlto = true;
 253     } else if (opt == "thinlto-index-only") {
 254       thinlto_index_only = true;
 255     } else if (opt.consume_front("thinlto-index-only=")) {
 256       thinlto_index_only = true;
 257       thinlto_linked_objects_file = std::string(opt);
 258     } else if (opt == "thinlto-emit-imports-files") {
 259       thinlto_emit_imports_files = true;
 260     } else if (opt.consume_front("thinlto-prefix-replace=")) {
 261       thinlto_prefix_replace = std::string(opt);
 262       if (thinlto_prefix_replace.find(';') == std::string::npos)
 263         message(LDPL_FATAL, "thinlto-prefix-replace expects 'old;new' format");
 264     } else if (opt.consume_front("thinlto-object-suffix-replace=")) {
 265       thinlto_object_suffix_replace = std::string(opt);
 266       if (thinlto_object_suffix_replace.find(';') == std::string::npos)
 267         message(LDPL_FATAL,
 268                 "thinlto-object-suffix-replace expects 'old;new' format");
 269     } else if (opt.consume_front("cache-dir=")) {
 270       cache_dir = std::string(opt);
 271     } else if (opt.consume_front("cache-policy=")) {
 272       cache_policy = std::string(opt);
 273     } else if (opt.size() == 2 && opt[0] == 'O') {
 274       if (opt[1] < '0' || opt[1] > '3')
 275         message(LDPL_FATAL, "Optimization level must be between 0 and 3");
 276       OptLevel = opt[1] - '0';
 277     } else if (opt.consume_front("jobs=")) {
 278       Parallelism = std::string(opt);
 279       if (!get_threadpool_strategy(opt))
 280         message(LDPL_FATAL, "Invalid parallelism level: %s",
 281                 Parallelism.c_str());
 282     } else if (opt.consume_front("lto-partitions=")) {
 283       if (opt.getAsInteger(10, ParallelCodeGenParallelismLevel))
 284         message(LDPL_FATAL, "Invalid codegen partition level: %s", opt_ + 5);
 285     } else if (opt == "disable-verify") {
 286       DisableVerify = true;
 287     } else if (opt.consume_front("sample-profile=")) {
 288       sample_profile = std::string(opt);
 289     } else if (opt == "cs-profile-generate") {
 290       cs_pgo_gen = true;
 291     } else if (opt.consume_front("cs-profile-path=")) {
 292       cs_profile_path = std::string(opt);
 293     } else if (opt == "new-pass-manager") {
 294       // We always use the new pass manager.
 295     } else if (opt == "debug-pass-manager") {
 296       debug_pass_manager = true;
 297     } else if (opt == "whole-program-visibility") {
 298       whole_program_visibility = true;
 299     } else if (opt.consume_front("dwo_dir=")) {
 300       dwo_dir = std::string(opt);
 301     } else if (opt.consume_front("opt-remarks-filename=")) {
 302       RemarksFilename = std::string(opt);
 303     } else if (opt.consume_front("opt-remarks-passes=")) {
 304       RemarksPasses = std::string(opt);
 305     } else if (opt == "opt-remarks-with-hotness") {
 306       RemarksWithHotness = true;
 307     } else if (opt.consume_front("opt-remarks-hotness-threshold=")) {
 308       auto ResultOrErr = remarks::parseHotnessThresholdOption(opt);
 309       if (!ResultOrErr)
 310         message(LDPL_FATAL, "Invalid remarks hotness threshold: %s",
 311                 opt.data());
 312       else
 313         RemarksHotnessThreshold = *ResultOrErr;
 314     } else if (opt.consume_front("opt-remarks-format=")) {
 315       RemarksFormat = std::string(opt);
 316     } else if (opt.consume_front("stats-file=")) {
 317       stats_file = std::string(opt);
 318     } else if (opt.consume_front("time-trace=")) {
 319       time_trace_file = std::string(opt);
 320     } else if (opt.consume_front("time-trace-granularity=")) {
 321       unsigned Granularity;
 322       if (opt.getAsInteger(10, Granularity))
 323         message(LDPL_FATAL, "Invalid time trace granularity: %s", opt.data());
 324       else
 325         time_trace_granularity = Granularity;
 326     } else {
 327       // Save this option to pass to the code generator.
 328       // ParseCommandLineOptions() expects argv[0] to be program name. Lazily
 329       // add that.
 330       if (extra.empty())
 331         extra.push_back("LLVMgold");
 332
 333       extra.push_back(opt_);
 334     }
 335   }
 336 }
 337
 338 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
 339                                         int *claimed);
 340 static ld_plugin_status all_symbols_read_hook(void);
 341 static ld_plugin_status cleanup_hook(void);
 342
 343 extern "C" ld_plugin_status onload(ld_plugin_tv *tv);
 344 ld_plugin_status onload(ld_plugin_tv *tv) {
 345   InitializeAllTargetInfos();
 346   InitializeAllTargets();
 347   InitializeAllTargetMCs();
 348   InitializeAllAsmParsers();
 349   InitializeAllAsmPrinters();
 350
 351   // We're given a pointer to the first transfer vector. We read through them
 352   // until we find one where tv_tag == LDPT_NULL. The REGISTER_* tagged values
 353   // contain pointers to functions that we need to call to register our own
 354   // hooks. The others are addresses of functions we can use to call into gold
 355   // for services.
 356
 357   bool registeredClaimFile = false;
 358   bool RegisteredAllSymbolsRead = false;
 359
 360   for (; tv->tv_tag != LDPT_NULL; ++tv) {
 361     // Cast tv_tag to int to allow values not in "enum ld_plugin_tag", like, for
 362     // example, LDPT_GET_SYMBOLS_V3 when building against an older plugin-api.h
 363     // header.
 364     switch (static_cast<int>(tv->tv_tag)) {
 365     case LDPT_OUTPUT_NAME:
 366       output_name = tv->tv_u.tv_string;
 367       break;
 368     case LDPT_LINKER_OUTPUT:
 369       switch (tv->tv_u.tv_val) {
 370       case LDPO_REL: // .o
 371         IsExecutable = false;
 372         SplitSections = false;
 373         break;
 374       case LDPO_DYN: // .so
 375         IsExecutable = false;
 376         RelocationModel = Reloc::PIC_;
 377         break;
 378       case LDPO_PIE: // position independent executable
 379         IsExecutable = true;
 380         RelocationModel = Reloc::PIC_;
 381         break;
 382       case LDPO_EXEC: // .exe
 383         IsExecutable = true;
 384         RelocationModel = Reloc::Static;
 385         break;
 386       default:
 387         message(LDPL_ERROR, "Unknown output file type %d", tv->tv_u.tv_val);
 388         return LDPS_ERR;
 389       }
 390       break;
 391     case LDPT_OPTION:
 392       options::process_plugin_option(tv->tv_u.tv_string);
 393       break;
 394     case LDPT_REGISTER_CLAIM_FILE_HOOK: {
 395       ld_plugin_register_claim_file callback;
 396       callback = tv->tv_u.tv_register_claim_file;
 397
 398       if (callback(claim_file_hook) != LDPS_OK)
 399         return LDPS_ERR;
 400
 401       registeredClaimFile = true;
 402     } break;
 403     case LDPT_REGISTER_ALL_SYMBOLS_READ_HOOK: {
 404       ld_plugin_register_all_symbols_read callback;
 405       callback = tv->tv_u.tv_register_all_symbols_read;
 406
 407       if (callback(all_symbols_read_hook) != LDPS_OK)
 408         return LDPS_ERR;
 409
 410       RegisteredAllSymbolsRead = true;
 411     } break;
 412     case LDPT_REGISTER_CLEANUP_HOOK: {
 413       ld_plugin_register_cleanup callback;
 414       callback = tv->tv_u.tv_register_cleanup;
 415
 416       if (callback(cleanup_hook) != LDPS_OK)
 417         return LDPS_ERR;
 418     } break;
 419     case LDPT_GET_INPUT_FILE:
 420       get_input_file = tv->tv_u.tv_get_input_file;
 421       break;
 422     case LDPT_RELEASE_INPUT_FILE:
 423       release_input_file = tv->tv_u.tv_release_input_file;
 424       break;
 425     case LDPT_ADD_SYMBOLS:
 426       add_symbols = tv->tv_u.tv_add_symbols;
 427       break;
 428     case LDPT_GET_SYMBOLS_V2:
 429       // Do not override get_symbols_v3 with get_symbols_v2.
 430       if (!get_symbols)
 431         get_symbols = tv->tv_u.tv_get_symbols;
 432       break;
 433     case LDPT_GET_SYMBOLS_V3:
 434       get_symbols = tv->tv_u.tv_get_symbols;
 435       break;
 436     case LDPT_ADD_INPUT_FILE:
 437       add_input_file = tv->tv_u.tv_add_input_file;
 438       break;
 439     case LDPT_SET_EXTRA_LIBRARY_PATH:
 440       set_extra_library_path = tv->tv_u.tv_set_extra_library_path;
 441       break;
 442     case LDPT_GET_VIEW:
 443       get_view = tv->tv_u.tv_get_view;
 444       break;
 445     case LDPT_MESSAGE:
 446       message = tv->tv_u.tv_message;
 447       break;
 448     case LDPT_GET_WRAP_SYMBOLS:
 449       // FIXME: When binutils 2.31 (containing gold 1.16) is the minimum
 450       // required version, this should be changed to:
 451       // get_wrap_symbols = tv->tv_u.tv_get_wrap_symbols;
 452 #pragma GCC diagnostic push
 453 #pragma GCC diagnostic ignored "-Wcast-function-type"
 454       get_wrap_symbols = (ld_plugin_get_wrap_symbols)tv->tv_u.tv_message;
 455 #pragma GCC diagnostic pop
 456       break;
 457     default:
 458       break;
 459     }
 460   }
 461
 462   if (!registeredClaimFile) {
 463     message(LDPL_ERROR, "register_claim_file not passed to LLVMgold.");
 464     return LDPS_ERR;
 465   }
 466   if (!add_symbols) {
 467     message(LDPL_ERROR, "add_symbols not passed to LLVMgold.");
 468     return LDPS_ERR;
 469   }
 470
 471   if (!RegisteredAllSymbolsRead)
 472     return LDPS_OK;
 473
 474   if (!get_input_file) {
 475     message(LDPL_ERROR, "get_input_file not passed to LLVMgold.");
 476     return LDPS_ERR;
 477   }
 478   if (!release_input_file) {
 479     message(LDPL_ERROR, "release_input_file not passed to LLVMgold.");
 480     return LDPS_ERR;
 481   }
 482
 483   return LDPS_OK;
 484 }
 485
 486 static void diagnosticHandler(const DiagnosticInfo &DI) {
 487   std::string ErrStorage;
 488   {
 489     raw_string_ostream OS(ErrStorage);
 490     DiagnosticPrinterRawOStream DP(OS);
 491     DI.print(DP);
 492   }
 493   ld_plugin_level Level;
 494   switch (DI.getSeverity()) {
 495   case DS_Error:
 496     Level = LDPL_FATAL;
 497     break;
 498   case DS_Warning:
 499     Level = LDPL_WARNING;
 500     break;
 501   case DS_Note:
 502   case DS_Remark:
 503     Level = LDPL_INFO;
 504     break;
 505   }
 506   message(Level, "LLVM gold plugin: %s",  ErrStorage.c_str());
 507 }
 508
 509 static void check(Error E, std::string Msg = "LLVM gold plugin") {
 510   handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) -> Error {
 511     message(LDPL_FATAL, "%s: %s", Msg.c_str(), EIB.message().c_str());
 512     return Error::success();
 513   });
 514 }
 515
 516 template <typename T> static T check(Expected<T> E) {
 517   if (E)
 518     return std::move(*E);
 519   check(E.takeError());
 520   return T();
 521 }
 522
 523 /// Called by gold to see whether this file is one that our plugin can handle.
 524 /// We'll try to open it and register all the symbols with add_symbol if
 525 /// possible.
 526 static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
 527                                         int *claimed) {
 528   MemoryBufferRef BufferRef;
 529   std::unique_ptr<MemoryBuffer> Buffer;
 530   if (get_view) {
 531     const void *view;
 532     if (get_view(file->handle, &view) != LDPS_OK) {
 533       message(LDPL_ERROR, "Failed to get a view of %s", file->name);
 534       return LDPS_ERR;
 535     }
 536     BufferRef =
 537         MemoryBufferRef(StringRef((const char *)view, file->filesize), "");
 538   } else {
 539     int64_t offset = 0;
 540     // Gold has found what might be IR part-way inside of a file, such as
 541     // an .a archive.
 542     if (file->offset) {
 543       offset = file->offset;
 544     }
 545     ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
 546         MemoryBuffer::getOpenFileSlice(sys::fs::convertFDToNativeFile(file->fd),
 547                                        file->name, file->filesize, offset);
 548     if (std::error_code EC = BufferOrErr.getError()) {
 549       message(LDPL_ERROR, EC.message().c_str());
 550       return LDPS_ERR;
 551     }
 552     Buffer = std::move(BufferOrErr.get());
 553     BufferRef = Buffer->getMemBufferRef();
 554   }
 555
 556   *claimed = 1;
 557
 558   Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
 559   if (!ObjOrErr) {
 560     handleAllErrors(ObjOrErr.takeError(), [&](const ErrorInfoBase &EI) {
 561       std::error_code EC = EI.convertToErrorCode();
 562       if (EC == object::object_error::invalid_file_type ||
 563           EC == object::object_error::bitcode_section_not_found)
 564         *claimed = 0;
 565       else
 566         message(LDPL_FATAL,
 567                 "LLVM gold plugin has failed to create LTO module: %s",
 568                 EI.message().c_str());
 569     });
 570
 571     return *claimed ? LDPS_ERR : LDPS_OK;
 572   }
 573
 574   std::unique_ptr<InputFile> Obj = std::move(*ObjOrErr);
 575
 576   Modules.emplace_back();
 577   claimed_file &cf = Modules.back();
 578
 579   cf.handle = file->handle;
 580   // Keep track of the first handle for each file descriptor, since there are
 581   // multiple in the case of an archive. This is used later in the case of
 582   // ThinLTO parallel backends to ensure that each file is only opened and
 583   // released once.
 584   auto LeaderHandle =
 585       FDToLeaderHandle.insert(std::make_pair(file->fd, file->handle)).first;
 586   cf.leader_handle = LeaderHandle->second;
 587   // Save the filesize since for parallel ThinLTO backends we can only
 588   // invoke get_input_file once per archive (only for the leader handle).
 589   cf.filesize = file->filesize;
 590   // In the case of an archive library, all but the first member must have a
 591   // non-zero offset, which we can append to the file name to obtain a
 592   // unique name.
 593   cf.name = file->name;
 594   if (file->offset)
 595     cf.name += ".llvm." + std::to_string(file->offset) + "." +
 596                sys::path::filename(Obj->getSourceFileName()).str();
 597
 598   for (auto &Sym : Obj->symbols()) {
 599     cf.syms.push_back(ld_plugin_symbol());
 600     ld_plugin_symbol &sym = cf.syms.back();
 601     sym.version = nullptr;
 602     StringRef Name = Sym.getName();
 603     sym.name = strdup(Name.str().c_str());
 604
 605     ResolutionInfo &Res = ResInfo[Name];
 606
 607     Res.CanOmitFromDynSym &= Sym.canBeOmittedFromSymbolTable();
 608
 609     sym.visibility = LDPV_DEFAULT;
 610     GlobalValue::VisibilityTypes Vis = Sym.getVisibility();
 611     if (Vis != GlobalValue::DefaultVisibility)
 612       Res.DefaultVisibility = false;
 613     switch (Vis) {
 614     case GlobalValue::DefaultVisibility:
 615       break;
 616     case GlobalValue::HiddenVisibility:
 617       sym.visibility = LDPV_HIDDEN;
 618       break;
 619     case GlobalValue::ProtectedVisibility:
 620       sym.visibility = LDPV_PROTECTED;
 621       break;
 622     }
 623
 624     if (Sym.isUndefined()) {
 625       sym.def = LDPK_UNDEF;
 626       if (Sym.isWeak())
 627         sym.def = LDPK_WEAKUNDEF;
 628     } else if (Sym.isCommon())
 629       sym.def = LDPK_COMMON;
 630     else if (Sym.isWeak())
 631       sym.def = LDPK_WEAKDEF;
 632     else
 633       sym.def = LDPK_DEF;
 634
 635     sym.size = 0;
 636     sym.comdat_key = nullptr;
 637     int CI = Sym.getComdatIndex();
 638     if (CI != -1) {
 639       // Not setting comdat_key for nodeduplicate ensuress we don't deduplicate.
 640       std::pair<StringRef, Comdat::SelectionKind> C = Obj->getComdatTable()[CI];
 641       if (C.second != Comdat::NoDeduplicate)
 642         sym.comdat_key = strdup(C.first.str().c_str());
 643     }
 644
 645     sym.resolution = LDPR_UNKNOWN;
 646   }
 647
 648   if (!cf.syms.empty()) {
 649     if (add_symbols(cf.handle, cf.syms.size(), cf.syms.data()) != LDPS_OK) {
 650       message(LDPL_ERROR, "Unable to add symbols!");
 651       return LDPS_ERR;
 652     }
 653   }
 654
 655   // Handle any --wrap options passed to gold, which are than passed
 656   // along to the plugin.
 657   if (get_wrap_symbols) {
 658     const char **wrap_symbols;
 659     uint64_t count = 0;
 660     if (get_wrap_symbols(&count, &wrap_symbols) != LDPS_OK) {
 661       message(LDPL_ERROR, "Unable to get wrap symbols!");
 662       return LDPS_ERR;
 663     }
 664     for (uint64_t i = 0; i < count; i++) {
 665       StringRef Name = wrap_symbols[i];
 666       ResolutionInfo &Res = ResInfo[Name];
 667       ResolutionInfo &WrapRes = ResInfo["__wrap_" + Name.str()];
 668       ResolutionInfo &RealRes = ResInfo["__real_" + Name.str()];
 669       // Tell LTO not to inline symbols that will be overwritten.
 670       Res.CanInline = false;
 671       RealRes.CanInline = false;
 672       // Tell LTO not to eliminate symbols that will be used after renaming.
 673       Res.IsUsedInRegularObj = true;
 674       WrapRes.IsUsedInRegularObj = true;
 675     }
 676   }
 677
 678   return LDPS_OK;
 679 }
 680
 681 static void freeSymName(ld_plugin_symbol &Sym) {
 682   free(Sym.name);
 683   free(Sym.comdat_key);
 684   Sym.name = nullptr;
 685   Sym.comdat_key = nullptr;
 686 }
 687
 688 /// Helper to get a file's symbols and a view into it via gold callbacks.
 689 static const void *getSymbolsAndView(claimed_file &F) {
 690   ld_plugin_status status = get_symbols(F.handle, F.syms.size(), F.syms.data());
 691   if (status == LDPS_NO_SYMS)
 692     return nullptr;
 693
 694   if (status != LDPS_OK)
 695     message(LDPL_FATAL, "Failed to get symbol information");
 696
 697   const void *View;
 698   if (get_view(F.handle, &View) != LDPS_OK)
 699     message(LDPL_FATAL, "Failed to get a view of file");
 700
 701   return View;
 702 }
 703
 704 /// Parse the thinlto-object-suffix-replace option into the \p OldSuffix and
 705 /// \p NewSuffix strings, if it was specified.
 706 static void getThinLTOOldAndNewSuffix(std::string &OldSuffix,
 707                                       std::string &NewSuffix) {
 708   assert(options::thinlto_object_suffix_replace.empty() ||
 709          options::thinlto_object_suffix_replace.find(';') != StringRef::npos);
 710   StringRef SuffixReplace = options::thinlto_object_suffix_replace;
 711   auto Split = SuffixReplace.split(';');
 712   OldSuffix = std::string(Split.first);
 713   NewSuffix = std::string(Split.second);
 714 }
 715
 716 /// Given the original \p Path to an output file, replace any filename
 717 /// suffix matching \p OldSuffix with \p NewSuffix.
 718 static std::string getThinLTOObjectFileName(StringRef Path, StringRef OldSuffix,
 719                                             StringRef NewSuffix) {
 720   if (Path.consume_back(OldSuffix))
 721     return (Path + NewSuffix).str();
 722   return std::string(Path);
 723 }
 724
 725 // Returns true if S is valid as a C language identifier.
 726 static bool isValidCIdentifier(StringRef S) {
 727   return !S.empty() && (isAlpha(S[0]) || S[0] == '_') &&
 728          llvm::all_of(llvm::drop_begin(S),
 729                       [](char C) { return C == '_' || isAlnum(C); });
 730 }
 731
 732 static bool isUndefined(ld_plugin_symbol &Sym) {
 733   return Sym.def == LDPK_UNDEF || Sym.def == LDPK_WEAKUNDEF;
 734 }
 735
 736 static void addModule(LTO &Lto, claimed_file &F, const void *View,
 737                       StringRef Filename) {
 738   MemoryBufferRef BufferRef(StringRef((const char *)View, F.filesize),
 739                             Filename);
 740   Expected<std::unique_ptr<InputFile>> ObjOrErr = InputFile::create(BufferRef);
 741
 742   if (!ObjOrErr)
 743     message(LDPL_FATAL, "Could not read bitcode from file : %s",
 744             toString(ObjOrErr.takeError()).c_str());
 745
 746   unsigned SymNum = 0;
 747   std::unique_ptr<InputFile> Input = std::move(ObjOrErr.get());
 748   auto InputFileSyms = Input->symbols();
 749   assert(InputFileSyms.size() == F.syms.size());
 750   std::vector<SymbolResolution> Resols(F.syms.size());
 751   for (ld_plugin_symbol &Sym : F.syms) {
 752     const InputFile::Symbol &InpSym = InputFileSyms[SymNum];
 753     SymbolResolution &R = Resols[SymNum++];
 754
 755     ld_plugin_symbol_resolution Resolution =
 756         (ld_plugin_symbol_resolution)Sym.resolution;
 757
 758     ResolutionInfo &Res = ResInfo[Sym.name];
 759
 760     switch (Resolution) {
 761     case LDPR_UNKNOWN:
 762       llvm_unreachable("Unexpected resolution");
 763
 764     case LDPR_RESOLVED_IR:
 765     case LDPR_RESOLVED_EXEC:
 766     case LDPR_PREEMPTED_IR:
 767     case LDPR_PREEMPTED_REG:
 768     case LDPR_UNDEF:
 769       break;
 770
 771     case LDPR_RESOLVED_DYN:
 772       R.ExportDynamic = true;
 773       break;
 774
 775     case LDPR_PREVAILING_DEF_IRONLY:
 776       R.Prevailing = !isUndefined(Sym);
 777       break;
 778
 779     case LDPR_PREVAILING_DEF:
 780       R.Prevailing = !isUndefined(Sym);
 781       R.VisibleToRegularObj = true;
 782       break;
 783
 784     case LDPR_PREVAILING_DEF_IRONLY_EXP:
 785       R.Prevailing = !isUndefined(Sym);
 786       // Identify symbols exported dynamically, and that therefore could be
 787       // referenced by a shared library not visible to the linker.
 788       R.ExportDynamic = true;
 789       if (!Res.CanOmitFromDynSym)
 790         R.VisibleToRegularObj = true;
 791       break;
 792     }
 793
 794     // If the symbol has a C identifier section name, we need to mark
 795     // it as visible to a regular object so that LTO will keep it around
 796     // to ensure the linker generates special __start_<secname> and
 797     // __stop_<secname> symbols which may be used elsewhere.
 798     if (isValidCIdentifier(InpSym.getSectionName()))
 799       R.VisibleToRegularObj = true;
 800
 801     if (Resolution != LDPR_RESOLVED_DYN && Resolution != LDPR_UNDEF &&
 802         (IsExecutable || !Res.DefaultVisibility))
 803       R.FinalDefinitionInLinkageUnit = true;
 804
 805     if (!Res.CanInline)
 806       R.LinkerRedefined = true;
 807
 808     if (Res.IsUsedInRegularObj)
 809       R.VisibleToRegularObj = true;
 810
 811     freeSymName(Sym);
 812   }
 813
 814   check(Lto.add(std::move(Input), Resols),
 815         std::string("Failed to link module ") + F.name);
 816 }
 817
 818 static void recordFile(const std::string &Filename, bool TempOutFile) {
 819   if (add_input_file(Filename.c_str()) != LDPS_OK)
 820     message(LDPL_FATAL,
 821             "Unable to add .o file to the link. File left behind in: %s",
 822             Filename.c_str());
 823   if (TempOutFile)
 824     Cleanup.push_back(Filename);
 825 }
 826
 827 /// Return the desired output filename given a base input name, a flag
 828 /// indicating whether a temp file should be generated, and an optional task id.
 829 /// The new filename generated is returned in \p NewFilename.
 830 static int getOutputFileName(StringRef InFilename, bool TempOutFile,
 831                              SmallString<128> &NewFilename, int TaskID) {
 832   int FD = -1;
 833   if (TempOutFile) {
 834     std::error_code EC =
 835         sys::fs::createTemporaryFile("lto-llvm", "o", FD, NewFilename);
 836     if (EC)
 837       message(LDPL_FATAL, "Could not create temporary file: %s",
 838               EC.message().c_str());
 839   } else {
 840     NewFilename = InFilename;
 841     if (TaskID > 0)
 842       NewFilename += utostr(TaskID);
 843     std::error_code EC =
 844         sys::fs::openFileForWrite(NewFilename, FD, sys::fs::CD_CreateAlways);
 845     if (EC)
 846       message(LDPL_FATAL, "Could not open file %s: %s", NewFilename.c_str(),
 847               EC.message().c_str());
 848   }
 849   return FD;
 850 }
 851
 852 /// Parse the thinlto_prefix_replace option into the \p OldPrefix and
 853 /// \p NewPrefix strings, if it was specified.
 854 static void getThinLTOOldAndNewPrefix(std::string &OldPrefix,
 855                                       std::string &NewPrefix) {
 856   StringRef PrefixReplace = options::thinlto_prefix_replace;
 857   assert(PrefixReplace.empty() || PrefixReplace.find(';') != StringRef::npos);
 858   auto Split = PrefixReplace.split(';');
 859   OldPrefix = std::string(Split.first);
 860   NewPrefix = std::string(Split.second);
 861 }
 862
 863 /// Creates instance of LTO.
 864 /// OnIndexWrite is callback to let caller know when LTO writes index files.
 865 /// LinkedObjectsFile is an output stream to write the list of object files for
 866 /// the final ThinLTO linking. Can be nullptr.
 867 static std::unique_ptr<LTO> createLTO(IndexWriteCallback OnIndexWrite,
 868                                       raw_fd_ostream *LinkedObjectsFile) {
 869   Config Conf;
 870   ThinBackend Backend;
 871
 872   Conf.CPU = options::mcpu;
 873   Conf.Options = codegen::InitTargetOptionsFromCodeGenFlags(Triple());
 874
 875   // Disable the new X86 relax relocations since gold might not support them.
 876   // FIXME: Check the gold version or add a new option to enable them.
 877   Conf.Options.MCOptions.X86RelaxRelocations = false;
 878
 879   // Toggle function/data sections.
 880   if (!codegen::getExplicitFunctionSections())
 881     Conf.Options.FunctionSections = SplitSections;
 882   if (!codegen::getExplicitDataSections())
 883     Conf.Options.DataSections = SplitSections;
 884
 885   Conf.MAttrs = codegen::getMAttrs();
 886   Conf.RelocModel = RelocationModel;
 887   Conf.CodeModel = codegen::getExplicitCodeModel();
 888   std::optional<CodeGenOptLevel> CGOptLevelOrNone =
 889       CodeGenOpt::getLevel(options::OptLevel);
 890   assert(CGOptLevelOrNone && "Invalid optimization level");
 891   Conf.CGOptLevel = *CGOptLevelOrNone;
 892   Conf.DisableVerify = options::DisableVerify;
 893   Conf.OptLevel = options::OptLevel;
 894   Conf.PTO.LoopVectorization = options::OptLevel > 1;
 895   Conf.PTO.SLPVectorization = options::OptLevel > 1;
 896   Conf.AlwaysEmitRegularLTOObj = !options::obj_path.empty();
 897
 898   if (options::thinlto_index_only) {
 899     std::string OldPrefix, NewPrefix;
 900     getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
 901     Backend = createWriteIndexesThinBackend(
 902         llvm::hardware_concurrency(options::Parallelism), OldPrefix, NewPrefix,
 903         // TODO: Add support for optional native object path in
 904         // thinlto_prefix_replace option to match lld.
 905         /*NativeObjectPrefix=*/"", options::thinlto_emit_imports_files,
 906         LinkedObjectsFile, OnIndexWrite);
 907   } else {
 908     Backend = createInProcessThinBackend(
 909         llvm::heavyweight_hardware_concurrency(options::Parallelism));
 910   }
 911
 912   Conf.OverrideTriple = options::triple;
 913   Conf.DefaultTriple = sys::getDefaultTargetTriple();
 914
 915   Conf.DiagHandler = diagnosticHandler;
 916
 917   switch (options::TheOutputType) {
 918   case options::OT_NORMAL:
 919     break;
 920
 921   case options::OT_DISABLE:
 922     Conf.PreOptModuleHook = [](size_t Task, const Module &M) { return false; };
 923     break;
 924
 925   case options::OT_BC_ONLY:
 926     Conf.PostInternalizeModuleHook = [](size_t Task, const Module &M) {
 927       std::error_code EC;
 928       SmallString<128> TaskFilename;
 929       getOutputFileName(output_name, /* TempOutFile */ false, TaskFilename,
 930                         Task);
 931       raw_fd_ostream OS(TaskFilename, EC, sys::fs::OpenFlags::OF_None);
 932       if (EC)
 933         message(LDPL_FATAL, "Failed to write the output file.");
 934       WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ false);
 935       return false;
 936     };
 937     break;
 938
 939   case options::OT_SAVE_TEMPS:
 940     check(Conf.addSaveTemps(output_name + ".",
 941                             /* UseInputModulePath */ true));
 942     break;
 943   case options::OT_ASM_ONLY:
 944     Conf.CGFileType = CodeGenFileType::AssemblyFile;
 945     Conf.Options.MCOptions.AsmVerbose = true;
 946     break;
 947   }
 948
 949   if (!options::sample_profile.empty())
 950     Conf.SampleProfile = options::sample_profile;
 951
 952   if (!options::cs_profile_path.empty())
 953     Conf.CSIRProfile = options::cs_profile_path;
 954   Conf.RunCSIRInstr = options::cs_pgo_gen;
 955
 956   Conf.DwoDir = options::dwo_dir;
 957
 958   // Set up optimization remarks handling.
 959   Conf.RemarksFilename = options::RemarksFilename;
 960   Conf.RemarksPasses = options::RemarksPasses;
 961   Conf.RemarksWithHotness = options::RemarksWithHotness;
 962   Conf.RemarksHotnessThreshold = options::RemarksHotnessThreshold;
 963   Conf.RemarksFormat = options::RemarksFormat;
 964
 965   // Debug new pass manager if requested
 966   Conf.DebugPassManager = options::debug_pass_manager;
 967
 968   Conf.HasWholeProgramVisibility = options::whole_program_visibility;
 969
 970   Conf.StatsFile = options::stats_file;
 971
 972   Conf.TimeTraceEnabled = !options::time_trace_file.empty();
 973   Conf.TimeTraceGranularity = options::time_trace_granularity;
 974
 975   return std::make_unique<LTO>(std::move(Conf), Backend,
 976                                 options::ParallelCodeGenParallelismLevel);
 977 }
 978
 979 // Write empty files that may be expected by a distributed build
 980 // system when invoked with thinlto_index_only. This is invoked when
 981 // the linker has decided not to include the given module in the
 982 // final link. Frequently the distributed build system will want to
 983 // confirm that all expected outputs are created based on all of the
 984 // modules provided to the linker.
 985 // If SkipModule is true then .thinlto.bc should contain just
 986 // SkipModuleByDistributedBackend flag which requests distributed backend
 987 // to skip the compilation of the corresponding module and produce an empty
 988 // object file.
 989 static void writeEmptyDistributedBuildOutputs(const std::string &ModulePath,
 990                                               const std::string &OldPrefix,
 991                                               const std::string &NewPrefix,
 992                                               bool SkipModule) {
 993   std::string NewModulePath =
 994       getThinLTOOutputFile(ModulePath, OldPrefix, NewPrefix);
 995   std::error_code EC;
 996   {
 997     raw_fd_ostream OS(NewModulePath + ".thinlto.bc", EC,
 998                       sys::fs::OpenFlags::OF_None);
 999     if (EC)
1000       message(LDPL_FATAL, "Failed to write '%s': %s",
1001               (NewModulePath + ".thinlto.bc").c_str(), EC.message().c_str());
1002
1003     if (SkipModule) {
1004       ModuleSummaryIndex Index(/*HaveGVs*/ false);
1005       Index.setSkipModuleByDistributedBackend();
1006       writeIndexToFile(Index, OS, nullptr);
1007     }
1008   }
1009   if (options::thinlto_emit_imports_files) {
1010     raw_fd_ostream OS(NewModulePath + ".imports", EC,
1011                       sys::fs::OpenFlags::OF_None);
1012     if (EC)
1013       message(LDPL_FATAL, "Failed to write '%s': %s",
1014               (NewModulePath + ".imports").c_str(), EC.message().c_str());
1015   }
1016 }
1017
1018 // Creates and returns output stream with a list of object files for final
1019 // linking of distributed ThinLTO.
1020 static std::unique_ptr<raw_fd_ostream> CreateLinkedObjectsFile() {
1021   if (options::thinlto_linked_objects_file.empty())
1022     return nullptr;
1023   assert(options::thinlto_index_only);
1024   std::error_code EC;
1025   auto LinkedObjectsFile = std::make_unique<raw_fd_ostream>(
1026       options::thinlto_linked_objects_file, EC, sys::fs::OpenFlags::OF_None);
1027   if (EC)
1028     message(LDPL_FATAL, "Failed to create '%s': %s",
1029             options::thinlto_linked_objects_file.c_str(), EC.message().c_str());
1030   return LinkedObjectsFile;
1031 }
1032
1033 /// Runs LTO and return a list of pairs <FileName, IsTemporary>.
1034 static std::vector<std::pair<SmallString<128>, bool>> runLTO() {
1035   // Map to own RAII objects that manage the file opening and releasing
1036   // interfaces with gold. This is needed only for ThinLTO mode, since
1037   // unlike regular LTO, where addModule will result in the opened file
1038   // being merged into a new combined module, we need to keep these files open
1039   // through Lto->run().
1040   DenseMap<void *, std::unique_ptr<PluginInputFile>> HandleToInputFile;
1041
1042   // Owns string objects and tells if index file was already created.
1043   StringMap<bool> ObjectToIndexFileState;
1044
1045   std::unique_ptr<raw_fd_ostream> LinkedObjects = CreateLinkedObjectsFile();
1046   std::unique_ptr<LTO> Lto = createLTO(
1047       [&ObjectToIndexFileState](const std::string &Identifier) {
1048         ObjectToIndexFileState[Identifier] = true;
1049       },
1050       LinkedObjects.get());
1051
1052   std::string OldPrefix, NewPrefix;
1053   if (options::thinlto_index_only)
1054     getThinLTOOldAndNewPrefix(OldPrefix, NewPrefix);
1055
1056   std::string OldSuffix, NewSuffix;
1057   getThinLTOOldAndNewSuffix(OldSuffix, NewSuffix);
1058
1059   for (claimed_file &F : Modules) {
1060     if (options::thinlto) {
1061       auto [It, Inserted] = HandleToInputFile.try_emplace(F.leader_handle);
1062       if (Inserted)
1063         It->second = std::make_unique<PluginInputFile>(F.handle);
1064     }
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 =
1095       [&](size_t Task,
1096           const Twine &ModuleName) -> std::unique_ptr<CachedFileStream> {
1097     Files[Task].second = !SaveTemps;
1098     int FD = getOutputFileName(Filename, /* TempOutFile */ !SaveTemps,
1099                                Files[Task].first, Task);
1100     return std::make_unique<CachedFileStream>(
1101         std::make_unique<llvm::raw_fd_ostream>(FD, true));
1102   };
1103
1104   auto AddBuffer = [&](size_t Task, const Twine &moduleName,
1105                        std::unique_ptr<MemoryBuffer> MB) {
1106     *AddStream(Task, moduleName)->OS << MB->getBuffer();
1107   };
1108
1109   FileCache Cache;
1110   if (!options::cache_dir.empty())
1111     Cache = check(localCache("ThinLTO", "Thin", options::cache_dir, AddBuffer));
1112
1113   check(Lto->run(AddStream, Cache));
1114
1115   // Write empty output files that may be expected by the distributed build
1116   // system.
1117   if (options::thinlto_index_only)
1118     for (auto &Identifier : ObjectToIndexFileState)
1119       if (!Identifier.getValue())
1120         writeEmptyDistributedBuildOutputs(std::string(Identifier.getKey()),
1121                                           OldPrefix, NewPrefix,
1122                                           /* SkipModule */ false);
1123
1124   return Files;
1125 }
1126
1127 /// gold informs us that all symbols have been read. At this point, we use
1128 /// get_symbols to see if any of our definitions have been overridden by a
1129 /// native object file. Then, perform optimization and codegen.
1130 static ld_plugin_status allSymbolsReadHook() {
1131   if (Modules.empty())
1132     return LDPS_OK;
1133
1134   if (unsigned NumOpts = options::extra.size())
1135     cl::ParseCommandLineOptions(NumOpts, &options::extra[0]);
1136
1137   // Initialize time trace profiler
1138   if (!options::time_trace_file.empty())
1139     llvm::timeTraceProfilerInitialize(options::time_trace_granularity,
1140                                       options::extra.size() ? options::extra[0]
1141                                                             : "LLVMgold");
1142   auto FinalizeTimeTrace = llvm::make_scope_exit([&]() {
1143     if (!llvm::timeTraceProfilerEnabled())
1144       return;
1145     assert(!options::time_trace_file.empty());
1146     check(llvm::timeTraceProfilerWrite(options::time_trace_file, output_name));
1147     llvm::timeTraceProfilerCleanup();
1148   });
1149
1150   std::vector<std::pair<SmallString<128>, bool>> Files = runLTO();
1151
1152   if (options::TheOutputType == options::OT_DISABLE ||
1153       options::TheOutputType == options::OT_BC_ONLY ||
1154       options::TheOutputType == options::OT_ASM_ONLY)
1155     return LDPS_OK;
1156
1157   if (options::thinlto_index_only) {
1158     llvm_shutdown();
1159     cleanup_hook();
1160     exit(0);
1161   }
1162
1163   for (const auto &F : Files)
1164     if (!F.first.empty())
1165       recordFile(std::string(F.first.str()), F.second);
1166
1167   if (!options::extra_library_path.empty() &&
1168       set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK)
1169     message(LDPL_FATAL, "Unable to set the extra library path.");
1170
1171   return LDPS_OK;
1172 }
1173
1174 static ld_plugin_status all_symbols_read_hook(void) {
1175   ld_plugin_status Ret = allSymbolsReadHook();
1176   llvm_shutdown();
1177
1178   if (options::TheOutputType == options::OT_BC_ONLY ||
1179       options::TheOutputType == options::OT_ASM_ONLY ||
1180       options::TheOutputType == options::OT_DISABLE) {
1181     if (options::TheOutputType == options::OT_DISABLE) {
1182       // Remove the output file here since ld.bfd creates the output file
1183       // early.
1184       std::error_code EC = sys::fs::remove(output_name);
1185       if (EC)
1186         message(LDPL_ERROR, "Failed to delete '%s': %s", output_name.c_str(),
1187                 EC.message().c_str());
1188     }
1189     exit(0);
1190   }
1191
1192   return Ret;
1193 }
1194
1195 static ld_plugin_status cleanup_hook(void) {
1196   for (std::string &Name : Cleanup) {
1197     std::error_code EC = sys::fs::remove(Name);
1198     if (EC)
1199       message(LDPL_ERROR, "Failed to delete '%s': %s", Name.c_str(),
1200               EC.message().c_str());
1201   }
1202
1203   // Prune cache
1204   if (!options::cache_dir.empty()) {
1205     CachePruningPolicy policy = check(parseCachePruningPolicy(options::cache_policy));
1206     pruneCache(options::cache_dir, policy);
1207   }
1208
1209   return LDPS_OK;
1210 }