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