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