llvm/lib/LTO/LTOCodeGenerator.cpp

   1 //===-LTOCodeGenerator.cpp - LLVM Link Time Optimizer ---------------------===//
   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 file implements the Link Time Optimization library. This library is
  10 // intended to be used by linker to optimize code at link time.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/LTO/legacy/LTOCodeGenerator.h"
  15
  16 #include "llvm/ADT/Statistic.h"
  17 #include "llvm/ADT/StringExtras.h"
  18 #include "llvm/Analysis/Passes.h"
  19 #include "llvm/Analysis/TargetLibraryInfo.h"
  20 #include "llvm/Analysis/TargetTransformInfo.h"
  21 #include "llvm/Bitcode/BitcodeWriter.h"
  22 #include "llvm/CodeGen/ParallelCG.h"
  23 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  24 #include "llvm/Config/config.h"
  25 #include "llvm/IR/Constants.h"
  26 #include "llvm/IR/DataLayout.h"
  27 #include "llvm/IR/DebugInfo.h"
  28 #include "llvm/IR/DerivedTypes.h"
  29 #include "llvm/IR/DiagnosticInfo.h"
  30 #include "llvm/IR/DiagnosticPrinter.h"
  31 #include "llvm/IR/LLVMContext.h"
  32 #include "llvm/IR/LLVMRemarkStreamer.h"
  33 #include "llvm/IR/LegacyPassManager.h"
  34 #include "llvm/IR/Mangler.h"
  35 #include "llvm/IR/Module.h"
  36 #include "llvm/IR/PassTimingInfo.h"
  37 #include "llvm/IR/Verifier.h"
  38 #include "llvm/InitializePasses.h"
  39 #include "llvm/LTO/LTO.h"
  40 #include "llvm/LTO/LTOBackend.h"
  41 #include "llvm/LTO/legacy/LTOModule.h"
  42 #include "llvm/LTO/legacy/UpdateCompilerUsed.h"
  43 #include "llvm/Linker/Linker.h"
  44 #include "llvm/MC/MCAsmInfo.h"
  45 #include "llvm/MC/MCContext.h"
  46 #include "llvm/MC/SubtargetFeature.h"
  47 #include "llvm/MC/TargetRegistry.h"
  48 #include "llvm/Remarks/HotnessThresholdParser.h"
  49 #include "llvm/Support/CommandLine.h"
  50 #include "llvm/Support/FileSystem.h"
  51 #include "llvm/Support/Host.h"
  52 #include "llvm/Support/MemoryBuffer.h"
  53 #include "llvm/Support/Signals.h"
  54 #include "llvm/Support/TargetSelect.h"
  55 #include "llvm/Support/ToolOutputFile.h"
  56 #include "llvm/Support/YAMLTraits.h"
  57 #include "llvm/Support/raw_ostream.h"
  58 #include "llvm/Target/TargetOptions.h"
  59 #include "llvm/Transforms/IPO.h"
  60 #include "llvm/Transforms/IPO/Internalize.h"
  61 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
  62 #include "llvm/Transforms/IPO/WholeProgramDevirt.h"
  63 #include "llvm/Transforms/ObjCARC.h"
  64 #include "llvm/Transforms/Utils/ModuleUtils.h"
  65 #include <system_error>
  66 using namespace llvm;
  67
  68 const char* LTOCodeGenerator::getVersionString() {
  69 #ifdef LLVM_VERSION_INFO
  70   return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
  71 #else
  72   return PACKAGE_NAME " version " PACKAGE_VERSION;
  73 #endif
  74 }
  75
  76 namespace llvm {
  77 cl::opt<bool> LTODiscardValueNames(
  78     "lto-discard-value-names",
  79     cl::desc("Strip names from Value during LTO (other than GlobalValue)."),
  80 #ifdef NDEBUG
  81     cl::init(true),
  82 #else
  83     cl::init(false),
  84 #endif
  85     cl::Hidden);
  86
  87 cl::opt<bool> RemarksWithHotness(
  88     "lto-pass-remarks-with-hotness",
  89     cl::desc("With PGO, include profile count in optimization remarks"),
  90     cl::Hidden);
  91
  92 cl::opt<Optional<uint64_t>, false, remarks::HotnessThresholdParser>
  93     RemarksHotnessThreshold(
  94         "lto-pass-remarks-hotness-threshold",
  95         cl::desc("Minimum profile count required for an "
  96                  "optimization remark to be output."
  97                  " Use 'auto' to apply the threshold from profile summary."),
  98         cl::value_desc("uint or 'auto'"), cl::init(0), cl::Hidden);
  99
 100 cl::opt<std::string>
 101     RemarksFilename("lto-pass-remarks-output",
 102                     cl::desc("Output filename for pass remarks"),
 103                     cl::value_desc("filename"));
 104
 105 cl::opt<std::string>
 106     RemarksPasses("lto-pass-remarks-filter",
 107                   cl::desc("Only record optimization remarks from passes whose "
 108                            "names match the given regular expression"),
 109                   cl::value_desc("regex"));
 110
 111 cl::opt<std::string> RemarksFormat(
 112     "lto-pass-remarks-format",
 113     cl::desc("The format used for serializing remarks (default: YAML)"),
 114     cl::value_desc("format"), cl::init("yaml"));
 115
 116 cl::opt<std::string> LTOStatsFile(
 117     "lto-stats-file",
 118     cl::desc("Save statistics to the specified file"),
 119     cl::Hidden);
 120 }
 121
 122 LTOCodeGenerator::LTOCodeGenerator(LLVMContext &Context)
 123     : Context(Context), MergedModule(new Module("ld-temp.o", Context)),
 124       TheLinker(new Linker(*MergedModule)) {
 125   Context.setDiscardValueNames(LTODiscardValueNames);
 126   Context.enableDebugTypeODRUniquing();
 127
 128   Config.CodeModel = None;
 129   Config.StatsFile = LTOStatsFile;
 130   Config.PreCodeGenPassesHook = [](legacy::PassManager &PM) {
 131     PM.add(createObjCARCContractPass());
 132   };
 133 }
 134
 135 LTOCodeGenerator::~LTOCodeGenerator() {}
 136
 137 void LTOCodeGenerator::setAsmUndefinedRefs(LTOModule *Mod) {
 138   for (const StringRef &Undef : Mod->getAsmUndefinedRefs())
 139     AsmUndefinedRefs.insert(Undef);
 140 }
 141
 142 bool LTOCodeGenerator::addModule(LTOModule *Mod) {
 143   assert(&Mod->getModule().getContext() == &Context &&
 144          "Expected module in same context");
 145
 146   bool ret = TheLinker->linkInModule(Mod->takeModule());
 147   setAsmUndefinedRefs(Mod);
 148
 149   // We've just changed the input, so let's make sure we verify it.
 150   HasVerifiedInput = false;
 151
 152   return !ret;
 153 }
 154
 155 void LTOCodeGenerator::setModule(std::unique_ptr<LTOModule> Mod) {
 156   assert(&Mod->getModule().getContext() == &Context &&
 157          "Expected module in same context");
 158
 159   AsmUndefinedRefs.clear();
 160
 161   MergedModule = Mod->takeModule();
 162   TheLinker = std::make_unique<Linker>(*MergedModule);
 163   setAsmUndefinedRefs(&*Mod);
 164
 165   // We've just changed the input, so let's make sure we verify it.
 166   HasVerifiedInput = false;
 167 }
 168
 169 void LTOCodeGenerator::setTargetOptions(const TargetOptions &Options) {
 170   Config.Options = Options;
 171 }
 172
 173 void LTOCodeGenerator::setDebugInfo(lto_debug_model Debug) {
 174   switch (Debug) {
 175   case LTO_DEBUG_MODEL_NONE:
 176     EmitDwarfDebugInfo = false;
 177     return;
 178
 179   case LTO_DEBUG_MODEL_DWARF:
 180     EmitDwarfDebugInfo = true;
 181     return;
 182   }
 183   llvm_unreachable("Unknown debug format!");
 184 }
 185
 186 void LTOCodeGenerator::setOptLevel(unsigned Level) {
 187   Config.OptLevel = Level;
 188   Config.PTO.LoopVectorization = Config.OptLevel > 1;
 189   Config.PTO.SLPVectorization = Config.OptLevel > 1;
 190   switch (Config.OptLevel) {
 191   case 0:
 192     Config.CGOptLevel = CodeGenOpt::None;
 193     return;
 194   case 1:
 195     Config.CGOptLevel = CodeGenOpt::Less;
 196     return;
 197   case 2:
 198     Config.CGOptLevel = CodeGenOpt::Default;
 199     return;
 200   case 3:
 201     Config.CGOptLevel = CodeGenOpt::Aggressive;
 202     return;
 203   }
 204   llvm_unreachable("Unknown optimization level!");
 205 }
 206
 207 bool LTOCodeGenerator::writeMergedModules(StringRef Path) {
 208   if (!determineTarget())
 209     return false;
 210
 211   // We always run the verifier once on the merged module.
 212   verifyMergedModuleOnce();
 213
 214   // mark which symbols can not be internalized
 215   applyScopeRestrictions();
 216
 217   // create output file
 218   std::error_code EC;
 219   ToolOutputFile Out(Path, EC, sys::fs::OF_None);
 220   if (EC) {
 221     std::string ErrMsg = "could not open bitcode file for writing: ";
 222     ErrMsg += Path.str() + ": " + EC.message();
 223     emitError(ErrMsg);
 224     return false;
 225   }
 226
 227   // write bitcode to it
 228   WriteBitcodeToFile(*MergedModule, Out.os(), ShouldEmbedUselists);
 229   Out.os().close();
 230
 231   if (Out.os().has_error()) {
 232     std::string ErrMsg = "could not write bitcode file: ";
 233     ErrMsg += Path.str() + ": " + Out.os().error().message();
 234     emitError(ErrMsg);
 235     Out.os().clear_error();
 236     return false;
 237   }
 238
 239   Out.keep();
 240   return true;
 241 }
 242
 243 bool LTOCodeGenerator::compileOptimizedToFile(const char **Name) {
 244   // make unique temp output file to put generated code
 245   SmallString<128> Filename;
 246
 247   auto AddStream = [&](size_t Task) -> std::unique_ptr<CachedFileStream> {
 248     StringRef Extension(Config.CGFileType == CGFT_AssemblyFile ? "s" : "o");
 249
 250     int FD;
 251     std::error_code EC =
 252         sys::fs::createTemporaryFile("lto-llvm", Extension, FD, Filename);
 253     if (EC)
 254       emitError(EC.message());
 255
 256     return std::make_unique<CachedFileStream>(
 257         std::make_unique<llvm::raw_fd_ostream>(FD, true));
 258   };
 259
 260   bool genResult = compileOptimized(AddStream, 1);
 261
 262   if (!genResult) {
 263     sys::fs::remove(Twine(Filename));
 264     return false;
 265   }
 266
 267   // If statistics were requested, save them to the specified file or
 268   // print them out after codegen.
 269   if (StatsFile)
 270     PrintStatisticsJSON(StatsFile->os());
 271   else if (AreStatisticsEnabled())
 272     PrintStatistics();
 273
 274   NativeObjectPath = Filename.c_str();
 275   *Name = NativeObjectPath.c_str();
 276   return true;
 277 }
 278
 279 std::unique_ptr<MemoryBuffer>
 280 LTOCodeGenerator::compileOptimized() {
 281   const char *name;
 282   if (!compileOptimizedToFile(&name))
 283     return nullptr;
 284
 285   // read .o file into memory buffer
 286   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr = MemoryBuffer::getFile(
 287       name, /*IsText=*/false, /*RequiresNullTerminator=*/false);
 288   if (std::error_code EC = BufferOrErr.getError()) {
 289     emitError(EC.message());
 290     sys::fs::remove(NativeObjectPath);
 291     return nullptr;
 292   }
 293
 294   // remove temp files
 295   sys::fs::remove(NativeObjectPath);
 296
 297   return std::move(*BufferOrErr);
 298 }
 299
 300 bool LTOCodeGenerator::compile_to_file(const char **Name) {
 301   if (!optimize())
 302     return false;
 303
 304   return compileOptimizedToFile(Name);
 305 }
 306
 307 std::unique_ptr<MemoryBuffer> LTOCodeGenerator::compile() {
 308   if (!optimize())
 309     return nullptr;
 310
 311   return compileOptimized();
 312 }
 313
 314 bool LTOCodeGenerator::determineTarget() {
 315   if (TargetMach)
 316     return true;
 317
 318   TripleStr = MergedModule->getTargetTriple();
 319   if (TripleStr.empty()) {
 320     TripleStr = sys::getDefaultTargetTriple();
 321     MergedModule->setTargetTriple(TripleStr);
 322   }
 323   llvm::Triple Triple(TripleStr);
 324
 325   // create target machine from info for merged modules
 326   std::string ErrMsg;
 327   MArch = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
 328   if (!MArch) {
 329     emitError(ErrMsg);
 330     return false;
 331   }
 332
 333   // Construct LTOModule, hand over ownership of module and target. Use MAttr as
 334   // the default set of features.
 335   SubtargetFeatures Features(join(Config.MAttrs, ""));
 336   Features.getDefaultSubtargetFeatures(Triple);
 337   FeatureStr = Features.getString();
 338   // Set a default CPU for Darwin triples.
 339   if (Config.CPU.empty() && Triple.isOSDarwin()) {
 340     if (Triple.getArch() == llvm::Triple::x86_64)
 341       Config.CPU = "core2";
 342     else if (Triple.getArch() == llvm::Triple::x86)
 343       Config.CPU = "yonah";
 344     else if (Triple.isArm64e())
 345       Config.CPU = "apple-a12";
 346     else if (Triple.getArch() == llvm::Triple::aarch64 ||
 347              Triple.getArch() == llvm::Triple::aarch64_32)
 348       Config.CPU = "cyclone";
 349   }
 350
 351   TargetMach = createTargetMachine();
 352   assert(TargetMach && "Unable to create target machine");
 353
 354   return true;
 355 }
 356
 357 std::unique_ptr<TargetMachine> LTOCodeGenerator::createTargetMachine() {
 358   assert(MArch && "MArch is not set!");
 359   return std::unique_ptr<TargetMachine>(MArch->createTargetMachine(
 360       TripleStr, Config.CPU, FeatureStr, Config.Options, Config.RelocModel,
 361       None, Config.CGOptLevel));
 362 }
 363
 364 // If a linkonce global is present in the MustPreserveSymbols, we need to make
 365 // sure we honor this. To force the compiler to not drop it, we add it to the
 366 // "llvm.compiler.used" global.
 367 void LTOCodeGenerator::preserveDiscardableGVs(
 368     Module &TheModule,
 369     llvm::function_ref<bool(const GlobalValue &)> mustPreserveGV) {
 370   std::vector<GlobalValue *> Used;
 371   auto mayPreserveGlobal = [&](GlobalValue &GV) {
 372     if (!GV.isDiscardableIfUnused() || GV.isDeclaration() ||
 373         !mustPreserveGV(GV))
 374       return;
 375     if (GV.hasAvailableExternallyLinkage())
 376       return emitWarning(
 377           (Twine("Linker asked to preserve available_externally global: '") +
 378            GV.getName() + "'").str());
 379     if (GV.hasInternalLinkage())
 380       return emitWarning((Twine("Linker asked to preserve internal global: '") +
 381                    GV.getName() + "'").str());
 382     Used.push_back(&GV);
 383   };
 384   for (auto &GV : TheModule)
 385     mayPreserveGlobal(GV);
 386   for (auto &GV : TheModule.globals())
 387     mayPreserveGlobal(GV);
 388   for (auto &GV : TheModule.aliases())
 389     mayPreserveGlobal(GV);
 390
 391   if (Used.empty())
 392     return;
 393
 394   appendToCompilerUsed(TheModule, Used);
 395 }
 396
 397 void LTOCodeGenerator::applyScopeRestrictions() {
 398   if (ScopeRestrictionsDone)
 399     return;
 400
 401   // Declare a callback for the internalize pass that will ask for every
 402   // candidate GlobalValue if it can be internalized or not.
 403   Mangler Mang;
 404   SmallString<64> MangledName;
 405   auto mustPreserveGV = [&](const GlobalValue &GV) -> bool {
 406     // Unnamed globals can't be mangled, but they can't be preserved either.
 407     if (!GV.hasName())
 408       return false;
 409
 410     // Need to mangle the GV as the "MustPreserveSymbols" StringSet is filled
 411     // with the linker supplied name, which on Darwin includes a leading
 412     // underscore.
 413     MangledName.clear();
 414     MangledName.reserve(GV.getName().size() + 1);
 415     Mang.getNameWithPrefix(MangledName, &GV, /*CannotUsePrivateLabel=*/false);
 416     return MustPreserveSymbols.count(MangledName);
 417   };
 418
 419   // Preserve linkonce value on linker request
 420   preserveDiscardableGVs(*MergedModule, mustPreserveGV);
 421
 422   if (!ShouldInternalize)
 423     return;
 424
 425   if (ShouldRestoreGlobalsLinkage) {
 426     // Record the linkage type of non-local symbols so they can be restored
 427     // prior
 428     // to module splitting.
 429     auto RecordLinkage = [&](const GlobalValue &GV) {
 430       if (!GV.hasAvailableExternallyLinkage() && !GV.hasLocalLinkage() &&
 431           GV.hasName())
 432         ExternalSymbols.insert(std::make_pair(GV.getName(), GV.getLinkage()));
 433     };
 434     for (auto &GV : *MergedModule)
 435       RecordLinkage(GV);
 436     for (auto &GV : MergedModule->globals())
 437       RecordLinkage(GV);
 438     for (auto &GV : MergedModule->aliases())
 439       RecordLinkage(GV);
 440   }
 441
 442   // Update the llvm.compiler_used globals to force preserving libcalls and
 443   // symbols referenced from asm
 444   updateCompilerUsed(*MergedModule, *TargetMach, AsmUndefinedRefs);
 445
 446   internalizeModule(*MergedModule, mustPreserveGV);
 447
 448   ScopeRestrictionsDone = true;
 449 }
 450
 451 /// Restore original linkage for symbols that may have been internalized
 452 void LTOCodeGenerator::restoreLinkageForExternals() {
 453   if (!ShouldInternalize || !ShouldRestoreGlobalsLinkage)
 454     return;
 455
 456   assert(ScopeRestrictionsDone &&
 457          "Cannot externalize without internalization!");
 458
 459   if (ExternalSymbols.empty())
 460     return;
 461
 462   auto externalize = [this](GlobalValue &GV) {
 463     if (!GV.hasLocalLinkage() || !GV.hasName())
 464       return;
 465
 466     auto I = ExternalSymbols.find(GV.getName());
 467     if (I == ExternalSymbols.end())
 468       return;
 469
 470     GV.setLinkage(I->second);
 471   };
 472
 473   llvm::for_each(MergedModule->functions(), externalize);
 474   llvm::for_each(MergedModule->globals(), externalize);
 475   llvm::for_each(MergedModule->aliases(), externalize);
 476 }
 477
 478 void LTOCodeGenerator::verifyMergedModuleOnce() {
 479   // Only run on the first call.
 480   if (HasVerifiedInput)
 481     return;
 482   HasVerifiedInput = true;
 483
 484   bool BrokenDebugInfo = false;
 485   if (verifyModule(*MergedModule, &dbgs(), &BrokenDebugInfo))
 486     report_fatal_error("Broken module found, compilation aborted!");
 487   if (BrokenDebugInfo) {
 488     emitWarning("Invalid debug info found, debug info will be stripped");
 489     StripDebugInfo(*MergedModule);
 490   }
 491 }
 492
 493 void LTOCodeGenerator::finishOptimizationRemarks() {
 494   if (DiagnosticOutputFile) {
 495     DiagnosticOutputFile->keep();
 496     // FIXME: LTOCodeGenerator dtor is not invoked on Darwin
 497     DiagnosticOutputFile->os().flush();
 498   }
 499 }
 500
 501 /// Optimize merged modules using various IPO passes
 502 bool LTOCodeGenerator::optimize() {
 503   if (!this->determineTarget())
 504     return false;
 505
 506   auto DiagFileOrErr = lto::setupLLVMOptimizationRemarks(
 507       Context, RemarksFilename, RemarksPasses, RemarksFormat,
 508       RemarksWithHotness, RemarksHotnessThreshold);
 509   if (!DiagFileOrErr) {
 510     errs() << "Error: " << toString(DiagFileOrErr.takeError()) << "\n";
 511     report_fatal_error("Can't get an output file for the remarks");
 512   }
 513   DiagnosticOutputFile = std::move(*DiagFileOrErr);
 514
 515   // Setup output file to emit statistics.
 516   auto StatsFileOrErr = lto::setupStatsFile(LTOStatsFile);
 517   if (!StatsFileOrErr) {
 518     errs() << "Error: " << toString(StatsFileOrErr.takeError()) << "\n";
 519     report_fatal_error("Can't get an output file for the statistics");
 520   }
 521   StatsFile = std::move(StatsFileOrErr.get());
 522
 523   // Currently there is no support for enabling whole program visibility via a
 524   // linker option in the old LTO API, but this call allows it to be specified
 525   // via the internal option. Must be done before WPD invoked via the optimizer
 526   // pipeline run below.
 527   updateVCallVisibilityInModule(*MergedModule,
 528                                 /* WholeProgramVisibilityEnabledInLTO */ false,
 529                                 // FIXME: This needs linker information via a
 530                                 // TBD new interface.
 531                                 /* DynamicExportSymbols */ {});
 532
 533   // We always run the verifier once on the merged module, the `DisableVerify`
 534   // parameter only applies to subsequent verify.
 535   verifyMergedModuleOnce();
 536
 537   // Mark which symbols can not be internalized
 538   this->applyScopeRestrictions();
 539
 540   // Write LTOPostLink flag for passes that require all the modules.
 541   MergedModule->addModuleFlag(Module::Error, "LTOPostLink", 1);
 542
 543   // Add an appropriate DataLayout instance for this module...
 544   MergedModule->setDataLayout(TargetMach->createDataLayout());
 545
 546   ModuleSummaryIndex CombinedIndex(false);
 547   TargetMach = createTargetMachine();
 548   if (!opt(Config, TargetMach.get(), 0, *MergedModule, /*IsThinLTO=*/false,
 549            /*ExportSummary=*/&CombinedIndex, /*ImportSummary=*/nullptr,
 550            /*CmdArgs*/ std::vector<uint8_t>())) {
 551     emitError("LTO middle-end optimizations failed");
 552     return false;
 553   }
 554
 555   return true;
 556 }
 557
 558 bool LTOCodeGenerator::compileOptimized(AddStreamFn AddStream,
 559                                         unsigned ParallelismLevel) {
 560   if (!this->determineTarget())
 561     return false;
 562
 563   // We always run the verifier once on the merged module.  If it has already
 564   // been called in optimize(), this call will return early.
 565   verifyMergedModuleOnce();
 566
 567   // Re-externalize globals that may have been internalized to increase scope
 568   // for splitting
 569   restoreLinkageForExternals();
 570
 571   ModuleSummaryIndex CombinedIndex(false);
 572
 573   Config.CodeGenOnly = true;
 574   Error Err = backend(Config, AddStream, ParallelismLevel, *MergedModule,
 575                       CombinedIndex);
 576   assert(!Err && "unexpected code-generation failure");
 577   (void)Err;
 578
 579   // If statistics were requested, save them to the specified file or
 580   // print them out after codegen.
 581   if (StatsFile)
 582     PrintStatisticsJSON(StatsFile->os());
 583   else if (AreStatisticsEnabled())
 584     PrintStatistics();
 585
 586   reportAndResetTimings();
 587
 588   finishOptimizationRemarks();
 589
 590   return true;
 591 }
 592
 593 void LTOCodeGenerator::setCodeGenDebugOptions(ArrayRef<StringRef> Options) {
 594   for (StringRef Option : Options)
 595     CodegenOptions.push_back(Option.str());
 596 }
 597
 598 void LTOCodeGenerator::parseCodeGenDebugOptions() {
 599   if (!CodegenOptions.empty())
 600     llvm::parseCommandLineOptions(CodegenOptions);
 601 }
 602
 603 void llvm::parseCommandLineOptions(std::vector<std::string> &Options) {
 604   if (!Options.empty()) {
 605     // ParseCommandLineOptions() expects argv[0] to be program name.
 606     std::vector<const char *> CodegenArgv(1, "libLLVMLTO");
 607     for (std::string &Arg : Options)
 608       CodegenArgv.push_back(Arg.c_str());
 609     cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
 610   }
 611 }
 612
 613 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI) {
 614   // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
 615   lto_codegen_diagnostic_severity_t Severity;
 616   switch (DI.getSeverity()) {
 617   case DS_Error:
 618     Severity = LTO_DS_ERROR;
 619     break;
 620   case DS_Warning:
 621     Severity = LTO_DS_WARNING;
 622     break;
 623   case DS_Remark:
 624     Severity = LTO_DS_REMARK;
 625     break;
 626   case DS_Note:
 627     Severity = LTO_DS_NOTE;
 628     break;
 629   }
 630   // Create the string that will be reported to the external diagnostic handler.
 631   std::string MsgStorage;
 632   raw_string_ostream Stream(MsgStorage);
 633   DiagnosticPrinterRawOStream DP(Stream);
 634   DI.print(DP);
 635   Stream.flush();
 636
 637   // If this method has been called it means someone has set up an external
 638   // diagnostic handler. Assert on that.
 639   assert(DiagHandler && "Invalid diagnostic handler");
 640   (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
 641 }
 642
 643 namespace {
 644 struct LTODiagnosticHandler : public DiagnosticHandler {
 645   LTOCodeGenerator *CodeGenerator;
 646   LTODiagnosticHandler(LTOCodeGenerator *CodeGenPtr)
 647       : CodeGenerator(CodeGenPtr) {}
 648   bool handleDiagnostics(const DiagnosticInfo &DI) override {
 649     CodeGenerator->DiagnosticHandler(DI);
 650     return true;
 651   }
 652 };
 653 }
 654
 655 void
 656 LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
 657                                        void *Ctxt) {
 658   this->DiagHandler = DiagHandler;
 659   this->DiagContext = Ctxt;
 660   if (!DiagHandler)
 661     return Context.setDiagnosticHandler(nullptr);
 662   // Register the LTOCodeGenerator stub in the LLVMContext to forward the
 663   // diagnostic to the external DiagHandler.
 664   Context.setDiagnosticHandler(std::make_unique<LTODiagnosticHandler>(this),
 665                                true);
 666 }
 667
 668 namespace {
 669 class LTODiagnosticInfo : public DiagnosticInfo {
 670   const Twine &Msg;
 671 public:
 672   LTODiagnosticInfo(const Twine &DiagMsg, DiagnosticSeverity Severity=DS_Error)
 673       : DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
 674   void print(DiagnosticPrinter &DP) const override { DP << Msg; }
 675 };
 676 }
 677
 678 void LTOCodeGenerator::emitError(const std::string &ErrMsg) {
 679   if (DiagHandler)
 680     (*DiagHandler)(LTO_DS_ERROR, ErrMsg.c_str(), DiagContext);
 681   else
 682     Context.diagnose(LTODiagnosticInfo(ErrMsg));
 683 }
 684
 685 void LTOCodeGenerator::emitWarning(const std::string &ErrMsg) {
 686   if (DiagHandler)
 687     (*DiagHandler)(LTO_DS_WARNING, ErrMsg.c_str(), DiagContext);
 688   else
 689     Context.diagnose(LTODiagnosticInfo(ErrMsg, DS_Warning));
 690 }