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/CommandFlags.h"
  23 #include "llvm/CodeGen/ParallelCG.h"
  24 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  25 #include "llvm/Config/config.h"
  26 #include "llvm/IR/Constants.h"
  27 #include "llvm/IR/DataLayout.h"
  28 #include "llvm/IR/DebugInfo.h"
  29 #include "llvm/IR/DerivedTypes.h"
  30 #include "llvm/IR/DiagnosticInfo.h"
  31 #include "llvm/IR/DiagnosticPrinter.h"
  32 #include "llvm/IR/LLVMContext.h"
  33 #include "llvm/IR/LLVMRemarkStreamer.h"
  34 #include "llvm/IR/LegacyPassManager.h"
  35 #include "llvm/IR/Mangler.h"
  36 #include "llvm/IR/Module.h"
  37 #include "llvm/IR/PassTimingInfo.h"
  38 #include "llvm/IR/Verifier.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/MemoryBuffer.h"
  52 #include "llvm/Support/Process.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/TargetParser/Host.h"
  60 #include "llvm/Transforms/IPO.h"
  61 #include "llvm/Transforms/IPO/Internalize.h"
  62 #include "llvm/Transforms/IPO/WholeProgramDevirt.h"
  63 #include "llvm/Transforms/ObjCARC.h"
  64 #include "llvm/Transforms/Utils/ModuleUtils.h"
  65 #include <optional>
  66 #include <system_error>
  67 using namespace llvm;
  68
  69 const char* LTOCodeGenerator::getVersionString() {
  70   return PACKAGE_NAME " version " PACKAGE_VERSION;
  71 }
  72
  73 namespace llvm {
  74 cl::opt<bool> LTODiscardValueNames(
  75     "lto-discard-value-names",
  76     cl::desc("Strip names from Value during LTO (other than GlobalValue)."),
  77 #ifdef NDEBUG
  78     cl::init(true),
  79 #else
  80     cl::init(false),
  81 #endif
  82     cl::Hidden);
  83
  84 cl::opt<bool> RemarksWithHotness(
  85     "lto-pass-remarks-with-hotness",
  86     cl::desc("With PGO, include profile count in optimization remarks"),
  87     cl::Hidden);
  88
  89 cl::opt<std::optional<uint64_t>, false, remarks::HotnessThresholdParser>
  90     RemarksHotnessThreshold(
  91         "lto-pass-remarks-hotness-threshold",
  92         cl::desc("Minimum profile count required for an "
  93                  "optimization remark to be output."
  94                  " Use 'auto' to apply the threshold from profile summary."),
  95         cl::value_desc("uint or 'auto'"), cl::init(0), cl::Hidden);
  96
  97 cl::opt<std::string>
  98     RemarksFilename("lto-pass-remarks-output",
  99                     cl::desc("Output filename for pass remarks"),
 100                     cl::value_desc("filename"));
 101
 102 cl::opt<std::string>
 103     RemarksPasses("lto-pass-remarks-filter",
 104                   cl::desc("Only record optimization remarks from passes whose "
 105                            "names match the given regular expression"),
 106                   cl::value_desc("regex"));
 107
 108 cl::opt<std::string> RemarksFormat(
 109     "lto-pass-remarks-format",
 110     cl::desc("The format used for serializing remarks (default: YAML)"),
 111     cl::value_desc("format"), cl::init("yaml"));
 112
 113 cl::opt<std::string> LTOStatsFile(
 114     "lto-stats-file",
 115     cl::desc("Save statistics to the specified file"),
 116     cl::Hidden);
 117
 118 cl::opt<std::string> AIXSystemAssemblerPath(
 119     "lto-aix-system-assembler",
 120     cl::desc("Path to a system assembler, picked up on AIX only"),
 121     cl::value_desc("path"));
 122
 123 cl::opt<bool>
 124     LTORunCSIRInstr("cs-profile-generate",
 125                     cl::desc("Perform context sensitive PGO instrumentation"));
 126
 127 cl::opt<std::string>
 128     LTOCSIRProfile("cs-profile-path",
 129                    cl::desc("Context sensitive profile file path"));
 130 } // namespace llvm
 131
 132 LTOCodeGenerator::LTOCodeGenerator(LLVMContext &Context)
 133     : Context(Context), MergedModule(new Module("ld-temp.o", Context)),
 134       TheLinker(new Linker(*MergedModule)) {
 135   Context.setDiscardValueNames(LTODiscardValueNames);
 136   Context.enableDebugTypeODRUniquing();
 137
 138   Config.CodeModel = std::nullopt;
 139   Config.StatsFile = LTOStatsFile;
 140   Config.PreCodeGenPassesHook = [](legacy::PassManager &PM) {
 141     PM.add(createObjCARCContractPass());
 142   };
 143
 144   Config.RunCSIRInstr = LTORunCSIRInstr;
 145   Config.CSIRProfile = LTOCSIRProfile;
 146 }
 147
 148 LTOCodeGenerator::~LTOCodeGenerator() = default;
 149
 150 void LTOCodeGenerator::setAsmUndefinedRefs(LTOModule *Mod) {
 151   for (const StringRef &Undef : Mod->getAsmUndefinedRefs())
 152     AsmUndefinedRefs.insert(Undef);
 153 }
 154
 155 bool LTOCodeGenerator::addModule(LTOModule *Mod) {
 156   assert(&Mod->getModule().getContext() == &Context &&
 157          "Expected module in same context");
 158
 159   bool ret = TheLinker->linkInModule(Mod->takeModule());
 160   setAsmUndefinedRefs(Mod);
 161
 162   // We've just changed the input, so let's make sure we verify it.
 163   HasVerifiedInput = false;
 164
 165   return !ret;
 166 }
 167
 168 void LTOCodeGenerator::setModule(std::unique_ptr<LTOModule> Mod) {
 169   assert(&Mod->getModule().getContext() == &Context &&
 170          "Expected module in same context");
 171
 172   AsmUndefinedRefs.clear();
 173
 174   MergedModule = Mod->takeModule();
 175   TheLinker = std::make_unique<Linker>(*MergedModule);
 176   setAsmUndefinedRefs(&*Mod);
 177
 178   // We've just changed the input, so let's make sure we verify it.
 179   HasVerifiedInput = false;
 180 }
 181
 182 void LTOCodeGenerator::setTargetOptions(const TargetOptions &Options) {
 183   Config.Options = Options;
 184 }
 185
 186 void LTOCodeGenerator::setDebugInfo(lto_debug_model Debug) {
 187   switch (Debug) {
 188   case LTO_DEBUG_MODEL_NONE:
 189     EmitDwarfDebugInfo = false;
 190     return;
 191
 192   case LTO_DEBUG_MODEL_DWARF:
 193     EmitDwarfDebugInfo = true;
 194     return;
 195   }
 196   llvm_unreachable("Unknown debug format!");
 197 }
 198
 199 void LTOCodeGenerator::setOptLevel(unsigned Level) {
 200   Config.OptLevel = Level;
 201   Config.PTO.LoopVectorization = Config.OptLevel > 1;
 202   Config.PTO.SLPVectorization = Config.OptLevel > 1;
 203   std::optional<CodeGenOpt::Level> CGOptLevelOrNone =
 204       CodeGenOpt::getLevel(Config.OptLevel);
 205   assert(CGOptLevelOrNone && "Unknown optimization level!");
 206   Config.CGOptLevel = *CGOptLevelOrNone;
 207 }
 208
 209 bool LTOCodeGenerator::writeMergedModules(StringRef Path) {
 210   if (!determineTarget())
 211     return false;
 212
 213   // We always run the verifier once on the merged module.
 214   verifyMergedModuleOnce();
 215
 216   // mark which symbols can not be internalized
 217   applyScopeRestrictions();
 218
 219   // create output file
 220   std::error_code EC;
 221   ToolOutputFile Out(Path, EC, sys::fs::OF_None);
 222   if (EC) {
 223     std::string ErrMsg = "could not open bitcode file for writing: ";
 224     ErrMsg += Path.str() + ": " + EC.message();
 225     emitError(ErrMsg);
 226     return false;
 227   }
 228
 229   // write bitcode to it
 230   WriteBitcodeToFile(*MergedModule, Out.os(), ShouldEmbedUselists);
 231   Out.os().close();
 232
 233   if (Out.os().has_error()) {
 234     std::string ErrMsg = "could not write bitcode file: ";
 235     ErrMsg += Path.str() + ": " + Out.os().error().message();
 236     emitError(ErrMsg);
 237     Out.os().clear_error();
 238     return false;
 239   }
 240
 241   Out.keep();
 242   return true;
 243 }
 244
 245 bool LTOCodeGenerator::useAIXSystemAssembler() {
 246   const auto &Triple = TargetMach->getTargetTriple();
 247   return Triple.isOSAIX();
 248 }
 249
 250 bool LTOCodeGenerator::runAIXSystemAssembler(SmallString<128> &AssemblyFile) {
 251   assert(useAIXSystemAssembler() &&
 252          "Runing AIX system assembler when integrated assembler is available!");
 253
 254   // Set the system assembler path.
 255   SmallString<256> AssemblerPath("/usr/bin/as");
 256   if (!llvm::AIXSystemAssemblerPath.empty()) {
 257     if (llvm::sys::fs::real_path(llvm::AIXSystemAssemblerPath, AssemblerPath,
 258                                  /* expand_tilde */ true)) {
 259       emitError(
 260           "Cannot find the assembler specified by lto-aix-system-assembler");
 261       return false;
 262     }
 263   }
 264
 265   // Setup the LDR_CNTRL variable
 266   std::string LDR_CNTRL_var = "LDR_CNTRL=MAXDATA32=0xA0000000@DSA";
 267   if (std::optional<std::string> V = sys::Process::GetEnv("LDR_CNTRL"))
 268     LDR_CNTRL_var += ("@" + *V);
 269
 270   // Prepare inputs for the assember.
 271   const auto &Triple = TargetMach->getTargetTriple();
 272   const char *Arch = Triple.isArch64Bit() ? "-a64" : "-a32";
 273   std::string ObjectFileName(AssemblyFile);
 274   ObjectFileName[ObjectFileName.size() - 1] = 'o';
 275   SmallVector<StringRef, 8> Args = {
 276       "/bin/env",     LDR_CNTRL_var,
 277       AssemblerPath,  Arch,
 278       "-many",        "-o",
 279       ObjectFileName, AssemblyFile};
 280
 281   // Invoke the assembler.
 282   int RC = sys::ExecuteAndWait(Args[0], Args);
 283
 284   // Handle errors.
 285   if (RC < -1) {
 286     emitError("LTO assembler exited abnormally");
 287     return false;
 288   }
 289   if (RC < 0) {
 290     emitError("Unable to invoke LTO assembler");
 291     return false;
 292   }
 293   if (RC > 0) {
 294     emitError("LTO assembler invocation returned non-zero");
 295     return false;
 296   }
 297
 298   // Cleanup.
 299   remove(AssemblyFile.c_str());
 300
 301   // Fix the output file name.
 302   AssemblyFile = ObjectFileName;
 303
 304   return true;
 305 }
 306
 307 bool LTOCodeGenerator::compileOptimizedToFile(const char **Name) {
 308   if (useAIXSystemAssembler())
 309     setFileType(CGFT_AssemblyFile);
 310
 311   // make unique temp output file to put generated code
 312   SmallString<128> Filename;
 313
 314   auto AddStream =
 315       [&](size_t Task,
 316           const Twine &ModuleName) -> std::unique_ptr<CachedFileStream> {
 317     StringRef Extension(Config.CGFileType == CGFT_AssemblyFile ? "s" : "o");
 318
 319     int FD;
 320     std::error_code EC =
 321         sys::fs::createTemporaryFile("lto-llvm", Extension, FD, Filename);
 322     if (EC)
 323       emitError(EC.message());
 324
 325     return std::make_unique<CachedFileStream>(
 326         std::make_unique<llvm::raw_fd_ostream>(FD, true));
 327   };
 328
 329   bool genResult = compileOptimized(AddStream, 1);
 330
 331   if (!genResult) {
 332     sys::fs::remove(Twine(Filename));
 333     return false;
 334   }
 335
 336   // If statistics were requested, save them to the specified file or
 337   // print them out after codegen.
 338   if (StatsFile)
 339     PrintStatisticsJSON(StatsFile->os());
 340   else if (AreStatisticsEnabled())
 341     PrintStatistics();
 342
 343   if (useAIXSystemAssembler())
 344     if (!runAIXSystemAssembler(Filename))
 345       return false;
 346
 347   NativeObjectPath = Filename.c_str();
 348   *Name = NativeObjectPath.c_str();
 349   return true;
 350 }
 351
 352 std::unique_ptr<MemoryBuffer>
 353 LTOCodeGenerator::compileOptimized() {
 354   const char *name;
 355   if (!compileOptimizedToFile(&name))
 356     return nullptr;
 357
 358   // read .o file into memory buffer
 359   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr = MemoryBuffer::getFile(
 360       name, /*IsText=*/false, /*RequiresNullTerminator=*/false);
 361   if (std::error_code EC = BufferOrErr.getError()) {
 362     emitError(EC.message());
 363     sys::fs::remove(NativeObjectPath);
 364     return nullptr;
 365   }
 366
 367   // remove temp files
 368   sys::fs::remove(NativeObjectPath);
 369
 370   return std::move(*BufferOrErr);
 371 }
 372
 373 bool LTOCodeGenerator::compile_to_file(const char **Name) {
 374   if (!optimize())
 375     return false;
 376
 377   return compileOptimizedToFile(Name);
 378 }
 379
 380 std::unique_ptr<MemoryBuffer> LTOCodeGenerator::compile() {
 381   if (!optimize())
 382     return nullptr;
 383
 384   return compileOptimized();
 385 }
 386
 387 bool LTOCodeGenerator::determineTarget() {
 388   if (TargetMach)
 389     return true;
 390
 391   TripleStr = MergedModule->getTargetTriple();
 392   if (TripleStr.empty()) {
 393     TripleStr = sys::getDefaultTargetTriple();
 394     MergedModule->setTargetTriple(TripleStr);
 395   }
 396   llvm::Triple Triple(TripleStr);
 397
 398   // create target machine from info for merged modules
 399   std::string ErrMsg;
 400   MArch = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
 401   if (!MArch) {
 402     emitError(ErrMsg);
 403     return false;
 404   }
 405
 406   // Construct LTOModule, hand over ownership of module and target. Use MAttr as
 407   // the default set of features.
 408   SubtargetFeatures Features(join(Config.MAttrs, ""));
 409   Features.getDefaultSubtargetFeatures(Triple);
 410   FeatureStr = Features.getString();
 411   // Set a default CPU for Darwin triples.
 412   if (Config.CPU.empty() && Triple.isOSDarwin()) {
 413     if (Triple.getArch() == llvm::Triple::x86_64)
 414       Config.CPU = "core2";
 415     else if (Triple.getArch() == llvm::Triple::x86)
 416       Config.CPU = "yonah";
 417     else if (Triple.isArm64e())
 418       Config.CPU = "apple-a12";
 419     else if (Triple.getArch() == llvm::Triple::aarch64 ||
 420              Triple.getArch() == llvm::Triple::aarch64_32)
 421       Config.CPU = "cyclone";
 422   }
 423
 424   // If data-sections is not explicitly set or unset, set data-sections by
 425   // default to match the behaviour of lld and gold plugin.
 426   if (!codegen::getExplicitDataSections())
 427     Config.Options.DataSections = true;
 428
 429   TargetMach = createTargetMachine();
 430   assert(TargetMach && "Unable to create target machine");
 431
 432   return true;
 433 }
 434
 435 std::unique_ptr<TargetMachine> LTOCodeGenerator::createTargetMachine() {
 436   assert(MArch && "MArch is not set!");
 437   return std::unique_ptr<TargetMachine>(MArch->createTargetMachine(
 438       TripleStr, Config.CPU, FeatureStr, Config.Options, Config.RelocModel,
 439       std::nullopt, Config.CGOptLevel));
 440 }
 441
 442 // If a linkonce global is present in the MustPreserveSymbols, we need to make
 443 // sure we honor this. To force the compiler to not drop it, we add it to the
 444 // "llvm.compiler.used" global.
 445 void LTOCodeGenerator::preserveDiscardableGVs(
 446     Module &TheModule,
 447     llvm::function_ref<bool(const GlobalValue &)> mustPreserveGV) {
 448   std::vector<GlobalValue *> Used;
 449   auto mayPreserveGlobal = [&](GlobalValue &GV) {
 450     if (!GV.isDiscardableIfUnused() || GV.isDeclaration() ||
 451         !mustPreserveGV(GV))
 452       return;
 453     if (GV.hasAvailableExternallyLinkage())
 454       return emitWarning(
 455           (Twine("Linker asked to preserve available_externally global: '") +
 456            GV.getName() + "'").str());
 457     if (GV.hasInternalLinkage())
 458       return emitWarning((Twine("Linker asked to preserve internal global: '") +
 459                    GV.getName() + "'").str());
 460     Used.push_back(&GV);
 461   };
 462   for (auto &GV : TheModule)
 463     mayPreserveGlobal(GV);
 464   for (auto &GV : TheModule.globals())
 465     mayPreserveGlobal(GV);
 466   for (auto &GV : TheModule.aliases())
 467     mayPreserveGlobal(GV);
 468
 469   if (Used.empty())
 470     return;
 471
 472   appendToCompilerUsed(TheModule, Used);
 473 }
 474
 475 void LTOCodeGenerator::applyScopeRestrictions() {
 476   if (ScopeRestrictionsDone)
 477     return;
 478
 479   // Declare a callback for the internalize pass that will ask for every
 480   // candidate GlobalValue if it can be internalized or not.
 481   Mangler Mang;
 482   SmallString<64> MangledName;
 483   auto mustPreserveGV = [&](const GlobalValue &GV) -> bool {
 484     // Unnamed globals can't be mangled, but they can't be preserved either.
 485     if (!GV.hasName())
 486       return false;
 487
 488     // Need to mangle the GV as the "MustPreserveSymbols" StringSet is filled
 489     // with the linker supplied name, which on Darwin includes a leading
 490     // underscore.
 491     MangledName.clear();
 492     MangledName.reserve(GV.getName().size() + 1);
 493     Mang.getNameWithPrefix(MangledName, &GV, /*CannotUsePrivateLabel=*/false);
 494     return MustPreserveSymbols.count(MangledName);
 495   };
 496
 497   // Preserve linkonce value on linker request
 498   preserveDiscardableGVs(*MergedModule, mustPreserveGV);
 499
 500   if (!ShouldInternalize)
 501     return;
 502
 503   if (ShouldRestoreGlobalsLinkage) {
 504     // Record the linkage type of non-local symbols so they can be restored
 505     // prior
 506     // to module splitting.
 507     auto RecordLinkage = [&](const GlobalValue &GV) {
 508       if (!GV.hasAvailableExternallyLinkage() && !GV.hasLocalLinkage() &&
 509           GV.hasName())
 510         ExternalSymbols.insert(std::make_pair(GV.getName(), GV.getLinkage()));
 511     };
 512     for (auto &GV : *MergedModule)
 513       RecordLinkage(GV);
 514     for (auto &GV : MergedModule->globals())
 515       RecordLinkage(GV);
 516     for (auto &GV : MergedModule->aliases())
 517       RecordLinkage(GV);
 518   }
 519
 520   // Update the llvm.compiler_used globals to force preserving libcalls and
 521   // symbols referenced from asm
 522   updateCompilerUsed(*MergedModule, *TargetMach, AsmUndefinedRefs);
 523
 524   internalizeModule(*MergedModule, mustPreserveGV);
 525
 526   ScopeRestrictionsDone = true;
 527 }
 528
 529 /// Restore original linkage for symbols that may have been internalized
 530 void LTOCodeGenerator::restoreLinkageForExternals() {
 531   if (!ShouldInternalize || !ShouldRestoreGlobalsLinkage)
 532     return;
 533
 534   assert(ScopeRestrictionsDone &&
 535          "Cannot externalize without internalization!");
 536
 537   if (ExternalSymbols.empty())
 538     return;
 539
 540   auto externalize = [this](GlobalValue &GV) {
 541     if (!GV.hasLocalLinkage() || !GV.hasName())
 542       return;
 543
 544     auto I = ExternalSymbols.find(GV.getName());
 545     if (I == ExternalSymbols.end())
 546       return;
 547
 548     GV.setLinkage(I->second);
 549   };
 550
 551   llvm::for_each(MergedModule->functions(), externalize);
 552   llvm::for_each(MergedModule->globals(), externalize);
 553   llvm::for_each(MergedModule->aliases(), externalize);
 554 }
 555
 556 void LTOCodeGenerator::verifyMergedModuleOnce() {
 557   // Only run on the first call.
 558   if (HasVerifiedInput)
 559     return;
 560   HasVerifiedInput = true;
 561
 562   bool BrokenDebugInfo = false;
 563   if (verifyModule(*MergedModule, &dbgs(), &BrokenDebugInfo))
 564     report_fatal_error("Broken module found, compilation aborted!");
 565   if (BrokenDebugInfo) {
 566     emitWarning("Invalid debug info found, debug info will be stripped");
 567     StripDebugInfo(*MergedModule);
 568   }
 569 }
 570
 571 void LTOCodeGenerator::finishOptimizationRemarks() {
 572   if (DiagnosticOutputFile) {
 573     DiagnosticOutputFile->keep();
 574     // FIXME: LTOCodeGenerator dtor is not invoked on Darwin
 575     DiagnosticOutputFile->os().flush();
 576   }
 577 }
 578
 579 /// Optimize merged modules using various IPO passes
 580 bool LTOCodeGenerator::optimize() {
 581   if (!this->determineTarget())
 582     return false;
 583
 584   auto DiagFileOrErr = lto::setupLLVMOptimizationRemarks(
 585       Context, RemarksFilename, RemarksPasses, RemarksFormat,
 586       RemarksWithHotness, RemarksHotnessThreshold);
 587   if (!DiagFileOrErr) {
 588     errs() << "Error: " << toString(DiagFileOrErr.takeError()) << "\n";
 589     report_fatal_error("Can't get an output file for the remarks");
 590   }
 591   DiagnosticOutputFile = std::move(*DiagFileOrErr);
 592
 593   // Setup output file to emit statistics.
 594   auto StatsFileOrErr = lto::setupStatsFile(LTOStatsFile);
 595   if (!StatsFileOrErr) {
 596     errs() << "Error: " << toString(StatsFileOrErr.takeError()) << "\n";
 597     report_fatal_error("Can't get an output file for the statistics");
 598   }
 599   StatsFile = std::move(StatsFileOrErr.get());
 600
 601   // Currently there is no support for enabling whole program visibility via a
 602   // linker option in the old LTO API, but this call allows it to be specified
 603   // via the internal option. Must be done before WPD invoked via the optimizer
 604   // pipeline run below.
 605   updatePublicTypeTestCalls(*MergedModule,
 606                             /* WholeProgramVisibilityEnabledInLTO */ false);
 607   updateVCallVisibilityInModule(*MergedModule,
 608                                 /* WholeProgramVisibilityEnabledInLTO */ false,
 609                                 // FIXME: This needs linker information via a
 610                                 // TBD new interface.
 611                                 /* DynamicExportSymbols */ {});
 612
 613   // We always run the verifier once on the merged module, the `DisableVerify`
 614   // parameter only applies to subsequent verify.
 615   verifyMergedModuleOnce();
 616
 617   // Mark which symbols can not be internalized
 618   this->applyScopeRestrictions();
 619
 620   // Write LTOPostLink flag for passes that require all the modules.
 621   MergedModule->addModuleFlag(Module::Error, "LTOPostLink", 1);
 622
 623   // Add an appropriate DataLayout instance for this module...
 624   MergedModule->setDataLayout(TargetMach->createDataLayout());
 625
 626   if (!SaveIRBeforeOptPath.empty()) {
 627     std::error_code EC;
 628     raw_fd_ostream OS(SaveIRBeforeOptPath, EC, sys::fs::OF_None);
 629     if (EC)
 630       report_fatal_error(Twine("Failed to open ") + SaveIRBeforeOptPath +
 631                          " to save optimized bitcode\n");
 632     WriteBitcodeToFile(*MergedModule, OS,
 633                        /* ShouldPreserveUseListOrder */ true);
 634   }
 635
 636   ModuleSummaryIndex CombinedIndex(false);
 637   TargetMach = createTargetMachine();
 638   if (!opt(Config, TargetMach.get(), 0, *MergedModule, /*IsThinLTO=*/false,
 639            /*ExportSummary=*/&CombinedIndex, /*ImportSummary=*/nullptr,
 640            /*CmdArgs*/ std::vector<uint8_t>())) {
 641     emitError("LTO middle-end optimizations failed");
 642     return false;
 643   }
 644
 645   return true;
 646 }
 647
 648 bool LTOCodeGenerator::compileOptimized(AddStreamFn AddStream,
 649                                         unsigned ParallelismLevel) {
 650   if (!this->determineTarget())
 651     return false;
 652
 653   // We always run the verifier once on the merged module.  If it has already
 654   // been called in optimize(), this call will return early.
 655   verifyMergedModuleOnce();
 656
 657   // Re-externalize globals that may have been internalized to increase scope
 658   // for splitting
 659   restoreLinkageForExternals();
 660
 661   ModuleSummaryIndex CombinedIndex(false);
 662
 663   Config.CodeGenOnly = true;
 664   Error Err = backend(Config, AddStream, ParallelismLevel, *MergedModule,
 665                       CombinedIndex);
 666   assert(!Err && "unexpected code-generation failure");
 667   (void)Err;
 668
 669   // If statistics were requested, save them to the specified file or
 670   // print them out after codegen.
 671   if (StatsFile)
 672     PrintStatisticsJSON(StatsFile->os());
 673   else if (AreStatisticsEnabled())
 674     PrintStatistics();
 675
 676   reportAndResetTimings();
 677
 678   finishOptimizationRemarks();
 679
 680   return true;
 681 }
 682
 683 void LTOCodeGenerator::setCodeGenDebugOptions(ArrayRef<StringRef> Options) {
 684   for (StringRef Option : Options)
 685     CodegenOptions.push_back(Option.str());
 686 }
 687
 688 void LTOCodeGenerator::parseCodeGenDebugOptions() {
 689   if (!CodegenOptions.empty())
 690     llvm::parseCommandLineOptions(CodegenOptions);
 691 }
 692
 693 void llvm::parseCommandLineOptions(std::vector<std::string> &Options) {
 694   if (!Options.empty()) {
 695     // ParseCommandLineOptions() expects argv[0] to be program name.
 696     std::vector<const char *> CodegenArgv(1, "libLLVMLTO");
 697     for (std::string &Arg : Options)
 698       CodegenArgv.push_back(Arg.c_str());
 699     cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
 700   }
 701 }
 702
 703 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI) {
 704   // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
 705   lto_codegen_diagnostic_severity_t Severity;
 706   switch (DI.getSeverity()) {
 707   case DS_Error:
 708     Severity = LTO_DS_ERROR;
 709     break;
 710   case DS_Warning:
 711     Severity = LTO_DS_WARNING;
 712     break;
 713   case DS_Remark:
 714     Severity = LTO_DS_REMARK;
 715     break;
 716   case DS_Note:
 717     Severity = LTO_DS_NOTE;
 718     break;
 719   }
 720   // Create the string that will be reported to the external diagnostic handler.
 721   std::string MsgStorage;
 722   raw_string_ostream Stream(MsgStorage);
 723   DiagnosticPrinterRawOStream DP(Stream);
 724   DI.print(DP);
 725   Stream.flush();
 726
 727   // If this method has been called it means someone has set up an external
 728   // diagnostic handler. Assert on that.
 729   assert(DiagHandler && "Invalid diagnostic handler");
 730   (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
 731 }
 732
 733 namespace {
 734 struct LTODiagnosticHandler : public DiagnosticHandler {
 735   LTOCodeGenerator *CodeGenerator;
 736   LTODiagnosticHandler(LTOCodeGenerator *CodeGenPtr)
 737       : CodeGenerator(CodeGenPtr) {}
 738   bool handleDiagnostics(const DiagnosticInfo &DI) override {
 739     CodeGenerator->DiagnosticHandler(DI);
 740     return true;
 741   }
 742 };
 743 }
 744
 745 void
 746 LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
 747                                        void *Ctxt) {
 748   this->DiagHandler = DiagHandler;
 749   this->DiagContext = Ctxt;
 750   if (!DiagHandler)
 751     return Context.setDiagnosticHandler(nullptr);
 752   // Register the LTOCodeGenerator stub in the LLVMContext to forward the
 753   // diagnostic to the external DiagHandler.
 754   Context.setDiagnosticHandler(std::make_unique<LTODiagnosticHandler>(this),
 755                                true);
 756 }
 757
 758 namespace {
 759 class LTODiagnosticInfo : public DiagnosticInfo {
 760   const Twine &Msg;
 761 public:
 762   LTODiagnosticInfo(const Twine &DiagMsg, DiagnosticSeverity Severity=DS_Error)
 763       : DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
 764   void print(DiagnosticPrinter &DP) const override { DP << Msg; }
 765 };
 766 }
 767
 768 void LTOCodeGenerator::emitError(const std::string &ErrMsg) {
 769   if (DiagHandler)
 770     (*DiagHandler)(LTO_DS_ERROR, ErrMsg.c_str(), DiagContext);
 771   else
 772     Context.diagnose(LTODiagnosticInfo(ErrMsg));
 773 }
 774
 775 void LTOCodeGenerator::emitWarning(const std::string &ErrMsg) {
 776   if (DiagHandler)
 777     (*DiagHandler)(LTO_DS_WARNING, ErrMsg.c_str(), DiagContext);
 778   else
 779     Context.diagnose(LTODiagnosticInfo(ErrMsg, DS_Warning));
 780 }