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/TargetRegistry.h"
  47 #include "llvm/Remarks/HotnessThresholdParser.h"
  48 #include "llvm/Support/CommandLine.h"
  49 #include "llvm/Support/FileSystem.h"
  50 #include "llvm/Support/MemoryBuffer.h"
  51 #include "llvm/Support/Process.h"
  52 #include "llvm/Support/Signals.h"
  53 #include "llvm/Support/TargetSelect.h"
  54 #include "llvm/Support/ToolOutputFile.h"
  55 #include "llvm/Support/YAMLTraits.h"
  56 #include "llvm/Support/raw_ostream.h"
  57 #include "llvm/Target/TargetOptions.h"
  58 #include "llvm/TargetParser/Host.h"
  59 #include "llvm/TargetParser/SubtargetFeature.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<CodeGenOptLevel> 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() && Config.Options.DisableIntegratedAS;
 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(CodeGenFileType::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(
 318         Config.CGFileType == CodeGenFileType::AssemblyFile ? "s" : "o");
 319
 320     int FD;
 321     std::error_code EC =
 322         sys::fs::createTemporaryFile("lto-llvm", Extension, FD, Filename);
 323     if (EC)
 324       emitError(EC.message());
 325
 326     return std::make_unique<CachedFileStream>(
 327         std::make_unique<llvm::raw_fd_ostream>(FD, true));
 328   };
 329
 330   bool genResult = compileOptimized(AddStream, 1);
 331
 332   if (!genResult) {
 333     sys::fs::remove(Twine(Filename));
 334     return false;
 335   }
 336
 337   // If statistics were requested, save them to the specified file or
 338   // print them out after codegen.
 339   if (StatsFile)
 340     PrintStatisticsJSON(StatsFile->os());
 341   else if (AreStatisticsEnabled())
 342     PrintStatistics();
 343
 344   if (useAIXSystemAssembler())
 345     if (!runAIXSystemAssembler(Filename))
 346       return false;
 347
 348   NativeObjectPath = Filename.c_str();
 349   *Name = NativeObjectPath.c_str();
 350   return true;
 351 }
 352
 353 std::unique_ptr<MemoryBuffer>
 354 LTOCodeGenerator::compileOptimized() {
 355   const char *name;
 356   if (!compileOptimizedToFile(&name))
 357     return nullptr;
 358
 359   // read .o file into memory buffer
 360   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr = MemoryBuffer::getFile(
 361       name, /*IsText=*/false, /*RequiresNullTerminator=*/false);
 362   if (std::error_code EC = BufferOrErr.getError()) {
 363     emitError(EC.message());
 364     sys::fs::remove(NativeObjectPath);
 365     return nullptr;
 366   }
 367
 368   // remove temp files
 369   sys::fs::remove(NativeObjectPath);
 370
 371   return std::move(*BufferOrErr);
 372 }
 373
 374 bool LTOCodeGenerator::compile_to_file(const char **Name) {
 375   if (!optimize())
 376     return false;
 377
 378   return compileOptimizedToFile(Name);
 379 }
 380
 381 std::unique_ptr<MemoryBuffer> LTOCodeGenerator::compile() {
 382   if (!optimize())
 383     return nullptr;
 384
 385   return compileOptimized();
 386 }
 387
 388 bool LTOCodeGenerator::determineTarget() {
 389   if (TargetMach)
 390     return true;
 391
 392   TripleStr = MergedModule->getTargetTriple();
 393   if (TripleStr.empty()) {
 394     TripleStr = sys::getDefaultTargetTriple();
 395     MergedModule->setTargetTriple(TripleStr);
 396   }
 397   llvm::Triple Triple(TripleStr);
 398
 399   // create target machine from info for merged modules
 400   std::string ErrMsg;
 401   MArch = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
 402   if (!MArch) {
 403     emitError(ErrMsg);
 404     return false;
 405   }
 406
 407   // Construct LTOModule, hand over ownership of module and target. Use MAttr as
 408   // the default set of features.
 409   SubtargetFeatures Features(join(Config.MAttrs, ""));
 410   Features.getDefaultSubtargetFeatures(Triple);
 411   FeatureStr = Features.getString();
 412   // Set a default CPU for Darwin triples.
 413   if (Config.CPU.empty() && Triple.isOSDarwin()) {
 414     if (Triple.getArch() == llvm::Triple::x86_64)
 415       Config.CPU = "core2";
 416     else if (Triple.getArch() == llvm::Triple::x86)
 417       Config.CPU = "yonah";
 418     else if (Triple.isArm64e())
 419       Config.CPU = "apple-a12";
 420     else if (Triple.getArch() == llvm::Triple::aarch64 ||
 421              Triple.getArch() == llvm::Triple::aarch64_32)
 422       Config.CPU = "cyclone";
 423   }
 424
 425   // If data-sections is not explicitly set or unset, set data-sections by
 426   // default to match the behaviour of lld and gold plugin.
 427   if (!codegen::getExplicitDataSections())
 428     Config.Options.DataSections = true;
 429
 430   TargetMach = createTargetMachine();
 431   assert(TargetMach && "Unable to create target machine");
 432
 433   return true;
 434 }
 435
 436 std::unique_ptr<TargetMachine> LTOCodeGenerator::createTargetMachine() {
 437   assert(MArch && "MArch is not set!");
 438   return std::unique_ptr<TargetMachine>(MArch->createTargetMachine(
 439       TripleStr, Config.CPU, FeatureStr, Config.Options, Config.RelocModel,
 440       std::nullopt, Config.CGOptLevel));
 441 }
 442
 443 // If a linkonce global is present in the MustPreserveSymbols, we need to make
 444 // sure we honor this. To force the compiler to not drop it, we add it to the
 445 // "llvm.compiler.used" global.
 446 void LTOCodeGenerator::preserveDiscardableGVs(
 447     Module &TheModule,
 448     llvm::function_ref<bool(const GlobalValue &)> mustPreserveGV) {
 449   std::vector<GlobalValue *> Used;
 450   auto mayPreserveGlobal = [&](GlobalValue &GV) {
 451     if (!GV.isDiscardableIfUnused() || GV.isDeclaration() ||
 452         !mustPreserveGV(GV))
 453       return;
 454     if (GV.hasAvailableExternallyLinkage())
 455       return emitWarning(
 456           (Twine("Linker asked to preserve available_externally global: '") +
 457            GV.getName() + "'").str());
 458     if (GV.hasInternalLinkage())
 459       return emitWarning((Twine("Linker asked to preserve internal global: '") +
 460                    GV.getName() + "'").str());
 461     Used.push_back(&GV);
 462   };
 463   for (auto &GV : TheModule)
 464     mayPreserveGlobal(GV);
 465   for (auto &GV : TheModule.globals())
 466     mayPreserveGlobal(GV);
 467   for (auto &GV : TheModule.aliases())
 468     mayPreserveGlobal(GV);
 469
 470   if (Used.empty())
 471     return;
 472
 473   appendToCompilerUsed(TheModule, Used);
 474 }
 475
 476 void LTOCodeGenerator::applyScopeRestrictions() {
 477   if (ScopeRestrictionsDone)
 478     return;
 479
 480   // Declare a callback for the internalize pass that will ask for every
 481   // candidate GlobalValue if it can be internalized or not.
 482   Mangler Mang;
 483   SmallString<64> MangledName;
 484   auto mustPreserveGV = [&](const GlobalValue &GV) -> bool {
 485     // Unnamed globals can't be mangled, but they can't be preserved either.
 486     if (!GV.hasName())
 487       return false;
 488
 489     // Need to mangle the GV as the "MustPreserveSymbols" StringSet is filled
 490     // with the linker supplied name, which on Darwin includes a leading
 491     // underscore.
 492     MangledName.clear();
 493     MangledName.reserve(GV.getName().size() + 1);
 494     Mang.getNameWithPrefix(MangledName, &GV, /*CannotUsePrivateLabel=*/false);
 495     return MustPreserveSymbols.count(MangledName);
 496   };
 497
 498   // Preserve linkonce value on linker request
 499   preserveDiscardableGVs(*MergedModule, mustPreserveGV);
 500
 501   if (!ShouldInternalize)
 502     return;
 503
 504   if (ShouldRestoreGlobalsLinkage) {
 505     // Record the linkage type of non-local symbols so they can be restored
 506     // prior
 507     // to module splitting.
 508     auto RecordLinkage = [&](const GlobalValue &GV) {
 509       if (!GV.hasAvailableExternallyLinkage() && !GV.hasLocalLinkage() &&
 510           GV.hasName())
 511         ExternalSymbols.insert(std::make_pair(GV.getName(), GV.getLinkage()));
 512     };
 513     for (auto &GV : *MergedModule)
 514       RecordLinkage(GV);
 515     for (auto &GV : MergedModule->globals())
 516       RecordLinkage(GV);
 517     for (auto &GV : MergedModule->aliases())
 518       RecordLinkage(GV);
 519   }
 520
 521   // Update the llvm.compiler_used globals to force preserving libcalls and
 522   // symbols referenced from asm
 523   updateCompilerUsed(*MergedModule, *TargetMach, AsmUndefinedRefs);
 524
 525   internalizeModule(*MergedModule, mustPreserveGV);
 526
 527   ScopeRestrictionsDone = true;
 528 }
 529
 530 /// Restore original linkage for symbols that may have been internalized
 531 void LTOCodeGenerator::restoreLinkageForExternals() {
 532   if (!ShouldInternalize || !ShouldRestoreGlobalsLinkage)
 533     return;
 534
 535   assert(ScopeRestrictionsDone &&
 536          "Cannot externalize without internalization!");
 537
 538   if (ExternalSymbols.empty())
 539     return;
 540
 541   auto externalize = [this](GlobalValue &GV) {
 542     if (!GV.hasLocalLinkage() || !GV.hasName())
 543       return;
 544
 545     auto I = ExternalSymbols.find(GV.getName());
 546     if (I == ExternalSymbols.end())
 547       return;
 548
 549     GV.setLinkage(I->second);
 550   };
 551
 552   llvm::for_each(MergedModule->functions(), externalize);
 553   llvm::for_each(MergedModule->globals(), externalize);
 554   llvm::for_each(MergedModule->aliases(), externalize);
 555 }
 556
 557 void LTOCodeGenerator::verifyMergedModuleOnce() {
 558   // Only run on the first call.
 559   if (HasVerifiedInput)
 560     return;
 561   HasVerifiedInput = true;
 562
 563   bool BrokenDebugInfo = false;
 564   if (verifyModule(*MergedModule, &dbgs(), &BrokenDebugInfo))
 565     report_fatal_error("Broken module found, compilation aborted!");
 566   if (BrokenDebugInfo) {
 567     emitWarning("Invalid debug info found, debug info will be stripped");
 568     StripDebugInfo(*MergedModule);
 569   }
 570 }
 571
 572 void LTOCodeGenerator::finishOptimizationRemarks() {
 573   if (DiagnosticOutputFile) {
 574     DiagnosticOutputFile->keep();
 575     // FIXME: LTOCodeGenerator dtor is not invoked on Darwin
 576     DiagnosticOutputFile->os().flush();
 577   }
 578 }
 579
 580 /// Optimize merged modules using various IPO passes
 581 bool LTOCodeGenerator::optimize() {
 582   if (!this->determineTarget())
 583     return false;
 584
 585   auto DiagFileOrErr = lto::setupLLVMOptimizationRemarks(
 586       Context, RemarksFilename, RemarksPasses, RemarksFormat,
 587       RemarksWithHotness, RemarksHotnessThreshold);
 588   if (!DiagFileOrErr) {
 589     errs() << "Error: " << toString(DiagFileOrErr.takeError()) << "\n";
 590     report_fatal_error("Can't get an output file for the remarks");
 591   }
 592   DiagnosticOutputFile = std::move(*DiagFileOrErr);
 593
 594   // Setup output file to emit statistics.
 595   auto StatsFileOrErr = lto::setupStatsFile(LTOStatsFile);
 596   if (!StatsFileOrErr) {
 597     errs() << "Error: " << toString(StatsFileOrErr.takeError()) << "\n";
 598     report_fatal_error("Can't get an output file for the statistics");
 599   }
 600   StatsFile = std::move(StatsFileOrErr.get());
 601
 602   // Currently there is no support for enabling whole program visibility via a
 603   // linker option in the old LTO API, but this call allows it to be specified
 604   // via the internal option. Must be done before WPD invoked via the optimizer
 605   // pipeline run below.
 606   updatePublicTypeTestCalls(*MergedModule,
 607                             /* WholeProgramVisibilityEnabledInLTO */ false);
 608   updateVCallVisibilityInModule(
 609       *MergedModule,
 610       /* WholeProgramVisibilityEnabledInLTO */ false,
 611       // FIXME: These need linker information via a
 612       // TBD new interface.
 613       /*DynamicExportSymbols=*/{},
 614       /*ValidateAllVtablesHaveTypeInfos=*/false,
 615       /*IsVisibleToRegularObj=*/[](StringRef) { return true; });
 616
 617   // We always run the verifier once on the merged module, the `DisableVerify`
 618   // parameter only applies to subsequent verify.
 619   verifyMergedModuleOnce();
 620
 621   // Mark which symbols can not be internalized
 622   this->applyScopeRestrictions();
 623
 624   // Add an appropriate DataLayout instance for this module...
 625   MergedModule->setDataLayout(TargetMach->createDataLayout());
 626
 627   if (!SaveIRBeforeOptPath.empty()) {
 628     std::error_code EC;
 629     raw_fd_ostream OS(SaveIRBeforeOptPath, EC, sys::fs::OF_None);
 630     if (EC)
 631       report_fatal_error(Twine("Failed to open ") + SaveIRBeforeOptPath +
 632                          " to save optimized bitcode\n");
 633     WriteBitcodeToFile(*MergedModule, OS,
 634                        /* ShouldPreserveUseListOrder */ true);
 635   }
 636
 637   ModuleSummaryIndex CombinedIndex(false);
 638   TargetMach = createTargetMachine();
 639   if (!opt(Config, TargetMach.get(), 0, *MergedModule, /*IsThinLTO=*/false,
 640            /*ExportSummary=*/&CombinedIndex, /*ImportSummary=*/nullptr,
 641            /*CmdArgs*/ std::vector<uint8_t>())) {
 642     emitError("LTO middle-end optimizations failed");
 643     return false;
 644   }
 645
 646   return true;
 647 }
 648
 649 bool LTOCodeGenerator::compileOptimized(AddStreamFn AddStream,
 650                                         unsigned ParallelismLevel) {
 651   if (!this->determineTarget())
 652     return false;
 653
 654   // We always run the verifier once on the merged module.  If it has already
 655   // been called in optimize(), this call will return early.
 656   verifyMergedModuleOnce();
 657
 658   // Re-externalize globals that may have been internalized to increase scope
 659   // for splitting
 660   restoreLinkageForExternals();
 661
 662   ModuleSummaryIndex CombinedIndex(false);
 663
 664   Config.CodeGenOnly = true;
 665   Error Err = backend(Config, AddStream, ParallelismLevel, *MergedModule,
 666                       CombinedIndex);
 667   assert(!Err && "unexpected code-generation failure");
 668   (void)Err;
 669
 670   // If statistics were requested, save them to the specified file or
 671   // print them out after codegen.
 672   if (StatsFile)
 673     PrintStatisticsJSON(StatsFile->os());
 674   else if (AreStatisticsEnabled())
 675     PrintStatistics();
 676
 677   reportAndResetTimings();
 678
 679   finishOptimizationRemarks();
 680
 681   return true;
 682 }
 683
 684 void LTOCodeGenerator::setCodeGenDebugOptions(ArrayRef<StringRef> Options) {
 685   for (StringRef Option : Options)
 686     CodegenOptions.push_back(Option.str());
 687 }
 688
 689 void LTOCodeGenerator::parseCodeGenDebugOptions() {
 690   if (!CodegenOptions.empty())
 691     llvm::parseCommandLineOptions(CodegenOptions);
 692 }
 693
 694 void llvm::parseCommandLineOptions(std::vector<std::string> &Options) {
 695   if (!Options.empty()) {
 696     // ParseCommandLineOptions() expects argv[0] to be program name.
 697     std::vector<const char *> CodegenArgv(1, "libLLVMLTO");
 698     for (std::string &Arg : Options)
 699       CodegenArgv.push_back(Arg.c_str());
 700     cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
 701   }
 702 }
 703
 704 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI) {
 705   // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
 706   lto_codegen_diagnostic_severity_t Severity;
 707   switch (DI.getSeverity()) {
 708   case DS_Error:
 709     Severity = LTO_DS_ERROR;
 710     break;
 711   case DS_Warning:
 712     Severity = LTO_DS_WARNING;
 713     break;
 714   case DS_Remark:
 715     Severity = LTO_DS_REMARK;
 716     break;
 717   case DS_Note:
 718     Severity = LTO_DS_NOTE;
 719     break;
 720   }
 721   // Create the string that will be reported to the external diagnostic handler.
 722   std::string MsgStorage;
 723   raw_string_ostream Stream(MsgStorage);
 724   DiagnosticPrinterRawOStream DP(Stream);
 725   DI.print(DP);
 726   Stream.flush();
 727
 728   // If this method has been called it means someone has set up an external
 729   // diagnostic handler. Assert on that.
 730   assert(DiagHandler && "Invalid diagnostic handler");
 731   (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
 732 }
 733
 734 namespace {
 735 struct LTODiagnosticHandler : public DiagnosticHandler {
 736   LTOCodeGenerator *CodeGenerator;
 737   LTODiagnosticHandler(LTOCodeGenerator *CodeGenPtr)
 738       : CodeGenerator(CodeGenPtr) {}
 739   bool handleDiagnostics(const DiagnosticInfo &DI) override {
 740     CodeGenerator->DiagnosticHandler(DI);
 741     return true;
 742   }
 743 };
 744 }
 745
 746 void
 747 LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
 748                                        void *Ctxt) {
 749   this->DiagHandler = DiagHandler;
 750   this->DiagContext = Ctxt;
 751   if (!DiagHandler)
 752     return Context.setDiagnosticHandler(nullptr);
 753   // Register the LTOCodeGenerator stub in the LLVMContext to forward the
 754   // diagnostic to the external DiagHandler.
 755   Context.setDiagnosticHandler(std::make_unique<LTODiagnosticHandler>(this),
 756                                true);
 757 }
 758
 759 namespace {
 760 class LTODiagnosticInfo : public DiagnosticInfo {
 761   const Twine &Msg;
 762 public:
 763   LTODiagnosticInfo(const Twine &DiagMsg, DiagnosticSeverity Severity=DS_Error)
 764       : DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
 765   void print(DiagnosticPrinter &DP) const override { DP << Msg; }
 766 };
 767 }
 768
 769 void LTOCodeGenerator::emitError(const std::string &ErrMsg) {
 770   if (DiagHandler)
 771     (*DiagHandler)(LTO_DS_ERROR, ErrMsg.c_str(), DiagContext);
 772   else
 773     Context.diagnose(LTODiagnosticInfo(ErrMsg));
 774 }
 775
 776 void LTOCodeGenerator::emitWarning(const std::string &ErrMsg) {
 777   if (DiagHandler)
 778     (*DiagHandler)(LTO_DS_WARNING, ErrMsg.c_str(), DiagContext);
 779   else
 780     Context.diagnose(LTODiagnosticInfo(ErrMsg, DS_Warning));
 781 }