lib/LTO/ThinLTOCodeGenerator.cpp

   1 //===-ThinLTOCodeGenerator.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 Thin 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/ThinLTOCodeGenerator.h"
  15
  16 #include "llvm/ADT/Statistic.h"
  17 #include "llvm/ADT/StringExtras.h"
  18 #include "llvm/Analysis/ModuleSummaryAnalysis.h"
  19 #include "llvm/Analysis/ProfileSummaryInfo.h"
  20 #include "llvm/Analysis/TargetLibraryInfo.h"
  21 #include "llvm/Analysis/TargetTransformInfo.h"
  22 #include "llvm/Bitcode/BitcodeReader.h"
  23 #include "llvm/Bitcode/BitcodeWriter.h"
  24 #include "llvm/Bitcode/BitcodeWriterPass.h"
  25 #include "llvm/Config/llvm-config.h"
  26 #include "llvm/IR/DebugInfo.h"
  27 #include "llvm/IR/DiagnosticPrinter.h"
  28 #include "llvm/IR/LLVMContext.h"
  29 #include "llvm/IR/LegacyPassManager.h"
  30 #include "llvm/IR/Mangler.h"
  31 #include "llvm/IR/PassTimingInfo.h"
  32 #include "llvm/IR/Verifier.h"
  33 #include "llvm/IRReader/IRReader.h"
  34 #include "llvm/LTO/LTO.h"
  35 #include "llvm/LTO/SummaryBasedOptimizations.h"
  36 #include "llvm/MC/SubtargetFeature.h"
  37 #include "llvm/Object/IRObjectFile.h"
  38 #include "llvm/Support/CachePruning.h"
  39 #include "llvm/Support/Debug.h"
  40 #include "llvm/Support/Error.h"
  41 #include "llvm/Support/Path.h"
  42 #include "llvm/Support/SHA1.h"
  43 #include "llvm/Support/SmallVectorMemoryBuffer.h"
  44 #include "llvm/Support/TargetRegistry.h"
  45 #include "llvm/Support/ThreadPool.h"
  46 #include "llvm/Support/Threading.h"
  47 #include "llvm/Support/ToolOutputFile.h"
  48 #include "llvm/Support/VCSRevision.h"
  49 #include "llvm/Target/TargetMachine.h"
  50 #include "llvm/Transforms/IPO.h"
  51 #include "llvm/Transforms/IPO/FunctionImport.h"
  52 #include "llvm/Transforms/IPO/Internalize.h"
  53 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
  54 #include "llvm/Transforms/ObjCARC.h"
  55 #include "llvm/Transforms/Utils/FunctionImportUtils.h"
  56
  57 #include <numeric>
  58
  59 #if !defined(_MSC_VER) && !defined(__MINGW32__)
  60 #include <unistd.h>
  61 #else
  62 #include <io.h>
  63 #endif
  64
  65 using namespace llvm;
  66
  67 #define DEBUG_TYPE "thinlto"
  68
  69 namespace llvm {
  70 // Flags -discard-value-names, defined in LTOCodeGenerator.cpp
  71 extern cl::opt<bool> LTODiscardValueNames;
  72 extern cl::opt<std::string> LTORemarksFilename;
  73 extern cl::opt<bool> LTOPassRemarksWithHotness;
  74 }
  75
  76 namespace {
  77
  78 static cl::opt<int>
  79     ThreadCount("threads", cl::init(llvm::heavyweight_hardware_concurrency()));
  80
  81 // Simple helper to save temporary files for debug.
  82 static void saveTempBitcode(const Module &TheModule, StringRef TempDir,
  83                             unsigned count, StringRef Suffix) {
  84   if (TempDir.empty())
  85     return;
  86   // User asked to save temps, let dump the bitcode file after import.
  87   std::string SaveTempPath = (TempDir + llvm::Twine(count) + Suffix).str();
  88   std::error_code EC;
  89   raw_fd_ostream OS(SaveTempPath, EC, sys::fs::F_None);
  90   if (EC)
  91     report_fatal_error(Twine("Failed to open ") + SaveTempPath +
  92                        " to save optimized bitcode\n");
  93   WriteBitcodeToFile(TheModule, OS, /* ShouldPreserveUseListOrder */ true);
  94 }
  95
  96 static const GlobalValueSummary *
  97 getFirstDefinitionForLinker(const GlobalValueSummaryList &GVSummaryList) {
  98   // If there is any strong definition anywhere, get it.
  99   auto StrongDefForLinker = llvm::find_if(
 100       GVSummaryList, [](const std::unique_ptr<GlobalValueSummary> &Summary) {
 101         auto Linkage = Summary->linkage();
 102         return !GlobalValue::isAvailableExternallyLinkage(Linkage) &&
 103                !GlobalValue::isWeakForLinker(Linkage);
 104       });
 105   if (StrongDefForLinker != GVSummaryList.end())
 106     return StrongDefForLinker->get();
 107   // Get the first *linker visible* definition for this global in the summary
 108   // list.
 109   auto FirstDefForLinker = llvm::find_if(
 110       GVSummaryList, [](const std::unique_ptr<GlobalValueSummary> &Summary) {
 111         auto Linkage = Summary->linkage();
 112         return !GlobalValue::isAvailableExternallyLinkage(Linkage);
 113       });
 114   // Extern templates can be emitted as available_externally.
 115   if (FirstDefForLinker == GVSummaryList.end())
 116     return nullptr;
 117   return FirstDefForLinker->get();
 118 }
 119
 120 // Populate map of GUID to the prevailing copy for any multiply defined
 121 // symbols. Currently assume first copy is prevailing, or any strong
 122 // definition. Can be refined with Linker information in the future.
 123 static void computePrevailingCopies(
 124     const ModuleSummaryIndex &Index,
 125     DenseMap<GlobalValue::GUID, const GlobalValueSummary *> &PrevailingCopy) {
 126   auto HasMultipleCopies = [&](const GlobalValueSummaryList &GVSummaryList) {
 127     return GVSummaryList.size() > 1;
 128   };
 129
 130   for (auto &I : Index) {
 131     if (HasMultipleCopies(I.second.SummaryList))
 132       PrevailingCopy[I.first] =
 133           getFirstDefinitionForLinker(I.second.SummaryList);
 134   }
 135 }
 136
 137 static StringMap<MemoryBufferRef>
 138 generateModuleMap(const std::vector<ThinLTOBuffer> &Modules) {
 139   StringMap<MemoryBufferRef> ModuleMap;
 140   for (auto &ModuleBuffer : Modules) {
 141     assert(ModuleMap.find(ModuleBuffer.getBufferIdentifier()) ==
 142                ModuleMap.end() &&
 143            "Expect unique Buffer Identifier");
 144     ModuleMap[ModuleBuffer.getBufferIdentifier()] = ModuleBuffer.getMemBuffer();
 145   }
 146   return ModuleMap;
 147 }
 148
 149 static void promoteModule(Module &TheModule, const ModuleSummaryIndex &Index) {
 150   if (renameModuleForThinLTO(TheModule, Index))
 151     report_fatal_error("renameModuleForThinLTO failed");
 152 }
 153
 154 namespace {
 155 class ThinLTODiagnosticInfo : public DiagnosticInfo {
 156   const Twine &Msg;
 157 public:
 158   ThinLTODiagnosticInfo(const Twine &DiagMsg,
 159                         DiagnosticSeverity Severity = DS_Error)
 160       : DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
 161   void print(DiagnosticPrinter &DP) const override { DP << Msg; }
 162 };
 163 }
 164
 165 /// Verify the module and strip broken debug info.
 166 static void verifyLoadedModule(Module &TheModule) {
 167   bool BrokenDebugInfo = false;
 168   if (verifyModule(TheModule, &dbgs(), &BrokenDebugInfo))
 169     report_fatal_error("Broken module found, compilation aborted!");
 170   if (BrokenDebugInfo) {
 171     TheModule.getContext().diagnose(ThinLTODiagnosticInfo(
 172         "Invalid debug info found, debug info will be stripped", DS_Warning));
 173     StripDebugInfo(TheModule);
 174   }
 175 }
 176
 177 static std::unique_ptr<Module>
 178 loadModuleFromBuffer(const MemoryBufferRef &Buffer, LLVMContext &Context,
 179                      bool Lazy, bool IsImporting) {
 180   SMDiagnostic Err;
 181   Expected<std::unique_ptr<Module>> ModuleOrErr =
 182       Lazy
 183           ? getLazyBitcodeModule(Buffer, Context,
 184                                  /* ShouldLazyLoadMetadata */ true, IsImporting)
 185           : parseBitcodeFile(Buffer, Context);
 186   if (!ModuleOrErr) {
 187     handleAllErrors(ModuleOrErr.takeError(), [&](ErrorInfoBase &EIB) {
 188       SMDiagnostic Err = SMDiagnostic(Buffer.getBufferIdentifier(),
 189                                       SourceMgr::DK_Error, EIB.message());
 190       Err.print("ThinLTO", errs());
 191     });
 192     report_fatal_error("Can't load module, abort.");
 193   }
 194   if (!Lazy)
 195     verifyLoadedModule(*ModuleOrErr.get());
 196   return std::move(ModuleOrErr.get());
 197 }
 198
 199 static void
 200 crossImportIntoModule(Module &TheModule, const ModuleSummaryIndex &Index,
 201                       StringMap<MemoryBufferRef> &ModuleMap,
 202                       const FunctionImporter::ImportMapTy &ImportList) {
 203   auto Loader = [&](StringRef Identifier) {
 204     return loadModuleFromBuffer(ModuleMap[Identifier], TheModule.getContext(),
 205                                 /*Lazy=*/true, /*IsImporting*/ true);
 206   };
 207
 208   FunctionImporter Importer(Index, Loader);
 209   Expected<bool> Result = Importer.importFunctions(TheModule, ImportList);
 210   if (!Result) {
 211     handleAllErrors(Result.takeError(), [&](ErrorInfoBase &EIB) {
 212       SMDiagnostic Err = SMDiagnostic(TheModule.getModuleIdentifier(),
 213                                       SourceMgr::DK_Error, EIB.message());
 214       Err.print("ThinLTO", errs());
 215     });
 216     report_fatal_error("importFunctions failed");
 217   }
 218   // Verify again after cross-importing.
 219   verifyLoadedModule(TheModule);
 220 }
 221
 222 static void optimizeModule(Module &TheModule, TargetMachine &TM,
 223                            unsigned OptLevel, bool Freestanding) {
 224   // Populate the PassManager
 225   PassManagerBuilder PMB;
 226   PMB.LibraryInfo = new TargetLibraryInfoImpl(TM.getTargetTriple());
 227   if (Freestanding)
 228     PMB.LibraryInfo->disableAllFunctions();
 229   PMB.Inliner = createFunctionInliningPass();
 230   // FIXME: should get it from the bitcode?
 231   PMB.OptLevel = OptLevel;
 232   PMB.LoopVectorize = true;
 233   PMB.SLPVectorize = true;
 234   // Already did this in verifyLoadedModule().
 235   PMB.VerifyInput = false;
 236   PMB.VerifyOutput = false;
 237
 238   legacy::PassManager PM;
 239
 240   // Add the TTI (required to inform the vectorizer about register size for
 241   // instance)
 242   PM.add(createTargetTransformInfoWrapperPass(TM.getTargetIRAnalysis()));
 243
 244   // Add optimizations
 245   PMB.populateThinLTOPassManager(PM);
 246
 247   PM.run(TheModule);
 248 }
 249
 250 // Convert the PreservedSymbols map from "Name" based to "GUID" based.
 251 static DenseSet<GlobalValue::GUID>
 252 computeGUIDPreservedSymbols(const StringSet<> &PreservedSymbols,
 253                             const Triple &TheTriple) {
 254   DenseSet<GlobalValue::GUID> GUIDPreservedSymbols(PreservedSymbols.size());
 255   for (auto &Entry : PreservedSymbols) {
 256     StringRef Name = Entry.first();
 257     if (TheTriple.isOSBinFormatMachO() && Name.size() > 0 && Name[0] == '_')
 258       Name = Name.drop_front();
 259     GUIDPreservedSymbols.insert(GlobalValue::getGUID(Name));
 260   }
 261   return GUIDPreservedSymbols;
 262 }
 263
 264 std::unique_ptr<MemoryBuffer> codegenModule(Module &TheModule,
 265                                             TargetMachine &TM) {
 266   SmallVector<char, 128> OutputBuffer;
 267
 268   // CodeGen
 269   {
 270     raw_svector_ostream OS(OutputBuffer);
 271     legacy::PassManager PM;
 272
 273     // If the bitcode files contain ARC code and were compiled with optimization,
 274     // the ObjCARCContractPass must be run, so do it unconditionally here.
 275     PM.add(createObjCARCContractPass());
 276
 277     // Setup the codegen now.
 278     if (TM.addPassesToEmitFile(PM, OS, nullptr, TargetMachine::CGFT_ObjectFile,
 279                                /* DisableVerify */ true))
 280       report_fatal_error("Failed to setup codegen");
 281
 282     // Run codegen now. resulting binary is in OutputBuffer.
 283     PM.run(TheModule);
 284   }
 285   return make_unique<SmallVectorMemoryBuffer>(std::move(OutputBuffer));
 286 }
 287
 288 /// Manage caching for a single Module.
 289 class ModuleCacheEntry {
 290   SmallString<128> EntryPath;
 291
 292 public:
 293   // Create a cache entry. This compute a unique hash for the Module considering
 294   // the current list of export/import, and offer an interface to query to
 295   // access the content in the cache.
 296   ModuleCacheEntry(
 297       StringRef CachePath, const ModuleSummaryIndex &Index, StringRef ModuleID,
 298       const FunctionImporter::ImportMapTy &ImportList,
 299       const FunctionImporter::ExportSetTy &ExportList,
 300       const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
 301       const GVSummaryMapTy &DefinedGVSummaries, unsigned OptLevel,
 302       bool Freestanding, const TargetMachineBuilder &TMBuilder) {
 303     if (CachePath.empty())
 304       return;
 305
 306     if (!Index.modulePaths().count(ModuleID))
 307       // The module does not have an entry, it can't have a hash at all
 308       return;
 309
 310     if (all_of(Index.getModuleHash(ModuleID),
 311                [](uint32_t V) { return V == 0; }))
 312       // No hash entry, no caching!
 313       return;
 314
 315     llvm::lto::Config Conf;
 316     Conf.OptLevel = OptLevel;
 317     Conf.Options = TMBuilder.Options;
 318     Conf.CPU = TMBuilder.MCpu;
 319     Conf.MAttrs.push_back(TMBuilder.MAttr);
 320     Conf.RelocModel = TMBuilder.RelocModel;
 321     Conf.CGOptLevel = TMBuilder.CGOptLevel;
 322     Conf.Freestanding = Freestanding;
 323     SmallString<40> Key;
 324     computeLTOCacheKey(Key, Conf, Index, ModuleID, ImportList, ExportList,
 325                        ResolvedODR, DefinedGVSummaries);
 326
 327     // This choice of file name allows the cache to be pruned (see pruneCache()
 328     // in include/llvm/Support/CachePruning.h).
 329     sys::path::append(EntryPath, CachePath, "llvmcache-" + Key);
 330   }
 331
 332   // Access the path to this entry in the cache.
 333   StringRef getEntryPath() { return EntryPath; }
 334
 335   // Try loading the buffer for this cache entry.
 336   ErrorOr<std::unique_ptr<MemoryBuffer>> tryLoadingBuffer() {
 337     if (EntryPath.empty())
 338       return std::error_code();
 339     int FD;
 340     SmallString<64> ResultPath;
 341     std::error_code EC = sys::fs::openFileForRead(
 342         Twine(EntryPath), FD, sys::fs::OF_UpdateAtime, &ResultPath);
 343     if (EC)
 344       return EC;
 345     ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
 346         MemoryBuffer::getOpenFile(FD, EntryPath,
 347                                   /*FileSize*/ -1,
 348                                   /*RequiresNullTerminator*/ false);
 349     close(FD);
 350     return MBOrErr;
 351   }
 352
 353   // Cache the Produced object file
 354   void write(const MemoryBuffer &OutputBuffer) {
 355     if (EntryPath.empty())
 356       return;
 357
 358     // Write to a temporary to avoid race condition
 359     SmallString<128> TempFilename;
 360     SmallString<128> CachePath(EntryPath);
 361     int TempFD;
 362     llvm::sys::path::remove_filename(CachePath);
 363     sys::path::append(TempFilename, CachePath, "Thin-%%%%%%.tmp.o");
 364     std::error_code EC =
 365       sys::fs::createUniqueFile(TempFilename, TempFD, TempFilename);
 366     if (EC) {
 367       errs() << "Error: " << EC.message() << "\n";
 368       report_fatal_error("ThinLTO: Can't get a temporary file");
 369     }
 370     {
 371       raw_fd_ostream OS(TempFD, /* ShouldClose */ true);
 372       OS << OutputBuffer.getBuffer();
 373     }
 374     // Rename temp file to final destination; rename is atomic
 375     EC = sys::fs::rename(TempFilename, EntryPath);
 376     if (EC)
 377       sys::fs::remove(TempFilename);
 378   }
 379 };
 380
 381 static std::unique_ptr<MemoryBuffer>
 382 ProcessThinLTOModule(Module &TheModule, ModuleSummaryIndex &Index,
 383                      StringMap<MemoryBufferRef> &ModuleMap, TargetMachine &TM,
 384                      const FunctionImporter::ImportMapTy &ImportList,
 385                      const FunctionImporter::ExportSetTy &ExportList,
 386                      const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols,
 387                      const GVSummaryMapTy &DefinedGlobals,
 388                      const ThinLTOCodeGenerator::CachingOptions &CacheOptions,
 389                      bool DisableCodeGen, StringRef SaveTempsDir,
 390                      bool Freestanding, unsigned OptLevel, unsigned count) {
 391
 392   // "Benchmark"-like optimization: single-source case
 393   bool SingleModule = (ModuleMap.size() == 1);
 394
 395   if (!SingleModule) {
 396     promoteModule(TheModule, Index);
 397
 398     // Apply summary-based prevailing-symbol resolution decisions.
 399     thinLTOResolvePrevailingInModule(TheModule, DefinedGlobals);
 400
 401     // Save temps: after promotion.
 402     saveTempBitcode(TheModule, SaveTempsDir, count, ".1.promoted.bc");
 403   }
 404
 405   // Be friendly and don't nuke totally the module when the client didn't
 406   // supply anything to preserve.
 407   if (!ExportList.empty() || !GUIDPreservedSymbols.empty()) {
 408     // Apply summary-based internalization decisions.
 409     thinLTOInternalizeModule(TheModule, DefinedGlobals);
 410   }
 411
 412   // Save internalized bitcode
 413   saveTempBitcode(TheModule, SaveTempsDir, count, ".2.internalized.bc");
 414
 415   if (!SingleModule) {
 416     crossImportIntoModule(TheModule, Index, ModuleMap, ImportList);
 417
 418     // Save temps: after cross-module import.
 419     saveTempBitcode(TheModule, SaveTempsDir, count, ".3.imported.bc");
 420   }
 421
 422   optimizeModule(TheModule, TM, OptLevel, Freestanding);
 423
 424   saveTempBitcode(TheModule, SaveTempsDir, count, ".4.opt.bc");
 425
 426   if (DisableCodeGen) {
 427     // Configured to stop before CodeGen, serialize the bitcode and return.
 428     SmallVector<char, 128> OutputBuffer;
 429     {
 430       raw_svector_ostream OS(OutputBuffer);
 431       ProfileSummaryInfo PSI(TheModule);
 432       auto Index = buildModuleSummaryIndex(TheModule, nullptr, &PSI);
 433       WriteBitcodeToFile(TheModule, OS, true, &Index);
 434     }
 435     return make_unique<SmallVectorMemoryBuffer>(std::move(OutputBuffer));
 436   }
 437
 438   return codegenModule(TheModule, TM);
 439 }
 440
 441 /// Resolve prevailing symbols. Record resolutions in the \p ResolvedODR map
 442 /// for caching, and in the \p Index for application during the ThinLTO
 443 /// backends. This is needed for correctness for exported symbols (ensure
 444 /// at least one copy kept) and a compile-time optimization (to drop duplicate
 445 /// copies when possible).
 446 static void resolvePrevailingInIndex(
 447     ModuleSummaryIndex &Index,
 448     StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>>
 449         &ResolvedODR) {
 450
 451   DenseMap<GlobalValue::GUID, const GlobalValueSummary *> PrevailingCopy;
 452   computePrevailingCopies(Index, PrevailingCopy);
 453
 454   auto isPrevailing = [&](GlobalValue::GUID GUID, const GlobalValueSummary *S) {
 455     const auto &Prevailing = PrevailingCopy.find(GUID);
 456     // Not in map means that there was only one copy, which must be prevailing.
 457     if (Prevailing == PrevailingCopy.end())
 458       return true;
 459     return Prevailing->second == S;
 460   };
 461
 462   auto recordNewLinkage = [&](StringRef ModuleIdentifier,
 463                               GlobalValue::GUID GUID,
 464                               GlobalValue::LinkageTypes NewLinkage) {
 465     ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
 466   };
 467
 468   thinLTOResolvePrevailingInIndex(Index, isPrevailing, recordNewLinkage);
 469 }
 470
 471 // Initialize the TargetMachine builder for a given Triple
 472 static void initTMBuilder(TargetMachineBuilder &TMBuilder,
 473                           const Triple &TheTriple) {
 474   // Set a default CPU for Darwin triples (copied from LTOCodeGenerator).
 475   // FIXME this looks pretty terrible...
 476   if (TMBuilder.MCpu.empty() && TheTriple.isOSDarwin()) {
 477     if (TheTriple.getArch() == llvm::Triple::x86_64)
 478       TMBuilder.MCpu = "core2";
 479     else if (TheTriple.getArch() == llvm::Triple::x86)
 480       TMBuilder.MCpu = "yonah";
 481     else if (TheTriple.getArch() == llvm::Triple::aarch64)
 482       TMBuilder.MCpu = "cyclone";
 483   }
 484   TMBuilder.TheTriple = std::move(TheTriple);
 485 }
 486
 487 } // end anonymous namespace
 488
 489 void ThinLTOCodeGenerator::addModule(StringRef Identifier, StringRef Data) {
 490   ThinLTOBuffer Buffer(Data, Identifier);
 491   LLVMContext Context;
 492   StringRef TripleStr;
 493   ErrorOr<std::string> TripleOrErr = expectedToErrorOrAndEmitErrors(
 494       Context, getBitcodeTargetTriple(Buffer.getMemBuffer()));
 495
 496   if (TripleOrErr)
 497     TripleStr = *TripleOrErr;
 498
 499   Triple TheTriple(TripleStr);
 500
 501   if (Modules.empty())
 502     initTMBuilder(TMBuilder, Triple(TheTriple));
 503   else if (TMBuilder.TheTriple != TheTriple) {
 504     if (!TMBuilder.TheTriple.isCompatibleWith(TheTriple))
 505       report_fatal_error("ThinLTO modules with incompatible triples not "
 506                          "supported");
 507     initTMBuilder(TMBuilder, Triple(TMBuilder.TheTriple.merge(TheTriple)));
 508   }
 509
 510   Modules.push_back(Buffer);
 511 }
 512
 513 void ThinLTOCodeGenerator::preserveSymbol(StringRef Name) {
 514   PreservedSymbols.insert(Name);
 515 }
 516
 517 void ThinLTOCodeGenerator::crossReferenceSymbol(StringRef Name) {
 518   // FIXME: At the moment, we don't take advantage of this extra information,
 519   // we're conservatively considering cross-references as preserved.
 520   //  CrossReferencedSymbols.insert(Name);
 521   PreservedSymbols.insert(Name);
 522 }
 523
 524 // TargetMachine factory
 525 std::unique_ptr<TargetMachine> TargetMachineBuilder::create() const {
 526   std::string ErrMsg;
 527   const Target *TheTarget =
 528       TargetRegistry::lookupTarget(TheTriple.str(), ErrMsg);
 529   if (!TheTarget) {
 530     report_fatal_error("Can't load target for this Triple: " + ErrMsg);
 531   }
 532
 533   // Use MAttr as the default set of features.
 534   SubtargetFeatures Features(MAttr);
 535   Features.getDefaultSubtargetFeatures(TheTriple);
 536   std::string FeatureStr = Features.getString();
 537
 538   return std::unique_ptr<TargetMachine>(
 539       TheTarget->createTargetMachine(TheTriple.str(), MCpu, FeatureStr, Options,
 540                                      RelocModel, None, CGOptLevel));
 541 }
 542
 543 /**
 544  * Produce the combined summary index from all the bitcode files:
 545  * "thin-link".
 546  */
 547 std::unique_ptr<ModuleSummaryIndex> ThinLTOCodeGenerator::linkCombinedIndex() {
 548   std::unique_ptr<ModuleSummaryIndex> CombinedIndex =
 549       llvm::make_unique<ModuleSummaryIndex>(/*HaveGVs=*/false);
 550   uint64_t NextModuleId = 0;
 551   for (auto &ModuleBuffer : Modules) {
 552     if (Error Err = readModuleSummaryIndex(ModuleBuffer.getMemBuffer(),
 553                                            *CombinedIndex, NextModuleId++)) {
 554       // FIXME diagnose
 555       logAllUnhandledErrors(
 556           std::move(Err), errs(),
 557           "error: can't create module summary index for buffer: ");
 558       return nullptr;
 559     }
 560   }
 561   return CombinedIndex;
 562 }
 563
 564 static void internalizeAndPromoteInIndex(
 565     const StringMap<FunctionImporter::ExportSetTy> &ExportLists,
 566     const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols,
 567     ModuleSummaryIndex &Index) {
 568   auto isExported = [&](StringRef ModuleIdentifier, GlobalValue::GUID GUID) {
 569     const auto &ExportList = ExportLists.find(ModuleIdentifier);
 570     return (ExportList != ExportLists.end() &&
 571             ExportList->second.count(GUID)) ||
 572            GUIDPreservedSymbols.count(GUID);
 573   };
 574
 575   thinLTOInternalizeAndPromoteInIndex(Index, isExported);
 576 }
 577
 578 static void computeDeadSymbolsInIndex(
 579     ModuleSummaryIndex &Index,
 580     const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) {
 581   // We have no symbols resolution available. And can't do any better now in the
 582   // case where the prevailing symbol is in a native object. It can be refined
 583   // with linker information in the future.
 584   auto isPrevailing = [&](GlobalValue::GUID G) {
 585     return PrevailingType::Unknown;
 586   };
 587   computeDeadSymbolsWithConstProp(Index, GUIDPreservedSymbols, isPrevailing,
 588                                   /* ImportEnabled = */ true);
 589 }
 590
 591 /**
 592  * Perform promotion and renaming of exported internal functions.
 593  * Index is updated to reflect linkage changes from weak resolution.
 594  */
 595 void ThinLTOCodeGenerator::promote(Module &TheModule,
 596                                    ModuleSummaryIndex &Index) {
 597   auto ModuleCount = Index.modulePaths().size();
 598   auto ModuleIdentifier = TheModule.getModuleIdentifier();
 599
 600   // Collect for each module the list of function it defines (GUID -> Summary).
 601   StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries;
 602   Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
 603
 604   // Convert the preserved symbols set from string to GUID
 605   auto GUIDPreservedSymbols = computeGUIDPreservedSymbols(
 606       PreservedSymbols, Triple(TheModule.getTargetTriple()));
 607
 608   // Compute "dead" symbols, we don't want to import/export these!
 609   computeDeadSymbolsInIndex(Index, GUIDPreservedSymbols);
 610
 611   // Generate import/export list
 612   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
 613   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
 614   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
 615                            ExportLists);
 616
 617   // Resolve prevailing symbols
 618   StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>> ResolvedODR;
 619   resolvePrevailingInIndex(Index, ResolvedODR);
 620
 621   thinLTOResolvePrevailingInModule(
 622       TheModule, ModuleToDefinedGVSummaries[ModuleIdentifier]);
 623
 624   // Promote the exported values in the index, so that they are promoted
 625   // in the module.
 626   internalizeAndPromoteInIndex(ExportLists, GUIDPreservedSymbols, Index);
 627
 628   promoteModule(TheModule, Index);
 629 }
 630
 631 /**
 632  * Perform cross-module importing for the module identified by ModuleIdentifier.
 633  */
 634 void ThinLTOCodeGenerator::crossModuleImport(Module &TheModule,
 635                                              ModuleSummaryIndex &Index) {
 636   auto ModuleMap = generateModuleMap(Modules);
 637   auto ModuleCount = Index.modulePaths().size();
 638
 639   // Collect for each module the list of function it defines (GUID -> Summary).
 640   StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries(ModuleCount);
 641   Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
 642
 643   // Convert the preserved symbols set from string to GUID
 644   auto GUIDPreservedSymbols = computeGUIDPreservedSymbols(
 645       PreservedSymbols, Triple(TheModule.getTargetTriple()));
 646
 647   // Compute "dead" symbols, we don't want to import/export these!
 648   computeDeadSymbolsInIndex(Index, GUIDPreservedSymbols);
 649
 650   // Generate import/export list
 651   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
 652   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
 653   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
 654                            ExportLists);
 655   auto &ImportList = ImportLists[TheModule.getModuleIdentifier()];
 656
 657   crossImportIntoModule(TheModule, Index, ModuleMap, ImportList);
 658 }
 659
 660 /**
 661  * Compute the list of summaries needed for importing into module.
 662  */
 663 void ThinLTOCodeGenerator::gatherImportedSummariesForModule(
 664     Module &TheModule, ModuleSummaryIndex &Index,
 665     std::map<std::string, GVSummaryMapTy> &ModuleToSummariesForIndex) {
 666   auto ModuleCount = Index.modulePaths().size();
 667   auto ModuleIdentifier = TheModule.getModuleIdentifier();
 668
 669   // Collect for each module the list of function it defines (GUID -> Summary).
 670   StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries(ModuleCount);
 671   Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
 672
 673   // Convert the preserved symbols set from string to GUID
 674   auto GUIDPreservedSymbols = computeGUIDPreservedSymbols(
 675       PreservedSymbols, Triple(TheModule.getTargetTriple()));
 676
 677   // Compute "dead" symbols, we don't want to import/export these!
 678   computeDeadSymbolsInIndex(Index, GUIDPreservedSymbols);
 679
 680   // Generate import/export list
 681   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
 682   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
 683   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
 684                            ExportLists);
 685
 686   llvm::gatherImportedSummariesForModule(
 687       ModuleIdentifier, ModuleToDefinedGVSummaries,
 688       ImportLists[ModuleIdentifier], ModuleToSummariesForIndex);
 689 }
 690
 691 /**
 692  * Emit the list of files needed for importing into module.
 693  */
 694 void ThinLTOCodeGenerator::emitImports(Module &TheModule, StringRef OutputName,
 695                                        ModuleSummaryIndex &Index) {
 696   auto ModuleCount = Index.modulePaths().size();
 697   auto ModuleIdentifier = TheModule.getModuleIdentifier();
 698
 699   // Collect for each module the list of function it defines (GUID -> Summary).
 700   StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries(ModuleCount);
 701   Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
 702
 703   // Convert the preserved symbols set from string to GUID
 704   auto GUIDPreservedSymbols = computeGUIDPreservedSymbols(
 705       PreservedSymbols, Triple(TheModule.getTargetTriple()));
 706
 707   // Compute "dead" symbols, we don't want to import/export these!
 708   computeDeadSymbolsInIndex(Index, GUIDPreservedSymbols);
 709
 710   // Generate import/export list
 711   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
 712   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
 713   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
 714                            ExportLists);
 715
 716   std::map<std::string, GVSummaryMapTy> ModuleToSummariesForIndex;
 717   llvm::gatherImportedSummariesForModule(
 718       ModuleIdentifier, ModuleToDefinedGVSummaries,
 719       ImportLists[ModuleIdentifier], ModuleToSummariesForIndex);
 720
 721   std::error_code EC;
 722   if ((EC = EmitImportsFiles(ModuleIdentifier, OutputName,
 723                              ModuleToSummariesForIndex)))
 724     report_fatal_error(Twine("Failed to open ") + OutputName +
 725                        " to save imports lists\n");
 726 }
 727
 728 /**
 729  * Perform internalization. Index is updated to reflect linkage changes.
 730  */
 731 void ThinLTOCodeGenerator::internalize(Module &TheModule,
 732                                        ModuleSummaryIndex &Index) {
 733   initTMBuilder(TMBuilder, Triple(TheModule.getTargetTriple()));
 734   auto ModuleCount = Index.modulePaths().size();
 735   auto ModuleIdentifier = TheModule.getModuleIdentifier();
 736
 737   // Convert the preserved symbols set from string to GUID
 738   auto GUIDPreservedSymbols =
 739       computeGUIDPreservedSymbols(PreservedSymbols, TMBuilder.TheTriple);
 740
 741   // Collect for each module the list of function it defines (GUID -> Summary).
 742   StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries(ModuleCount);
 743   Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
 744
 745   // Compute "dead" symbols, we don't want to import/export these!
 746   computeDeadSymbolsInIndex(Index, GUIDPreservedSymbols);
 747
 748   // Generate import/export list
 749   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
 750   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
 751   ComputeCrossModuleImport(Index, ModuleToDefinedGVSummaries, ImportLists,
 752                            ExportLists);
 753   auto &ExportList = ExportLists[ModuleIdentifier];
 754
 755   // Be friendly and don't nuke totally the module when the client didn't
 756   // supply anything to preserve.
 757   if (ExportList.empty() && GUIDPreservedSymbols.empty())
 758     return;
 759
 760   // Internalization
 761   internalizeAndPromoteInIndex(ExportLists, GUIDPreservedSymbols, Index);
 762   thinLTOInternalizeModule(TheModule,
 763                            ModuleToDefinedGVSummaries[ModuleIdentifier]);
 764 }
 765
 766 /**
 767  * Perform post-importing ThinLTO optimizations.
 768  */
 769 void ThinLTOCodeGenerator::optimize(Module &TheModule) {
 770   initTMBuilder(TMBuilder, Triple(TheModule.getTargetTriple()));
 771
 772   // Optimize now
 773   optimizeModule(TheModule, *TMBuilder.create(), OptLevel, Freestanding);
 774 }
 775
 776 /// Write out the generated object file, either from CacheEntryPath or from
 777 /// OutputBuffer, preferring hard-link when possible.
 778 /// Returns the path to the generated file in SavedObjectsDirectoryPath.
 779 static std::string writeGeneratedObject(int count, StringRef CacheEntryPath,
 780                                         StringRef SavedObjectsDirectoryPath,
 781                                         const MemoryBuffer &OutputBuffer) {
 782   SmallString<128> OutputPath(SavedObjectsDirectoryPath);
 783   llvm::sys::path::append(OutputPath, Twine(count) + ".thinlto.o");
 784   OutputPath.c_str(); // Ensure the string is null terminated.
 785   if (sys::fs::exists(OutputPath))
 786     sys::fs::remove(OutputPath);
 787
 788   // We don't return a memory buffer to the linker, just a list of files.
 789   if (!CacheEntryPath.empty()) {
 790     // Cache is enabled, hard-link the entry (or copy if hard-link fails).
 791     auto Err = sys::fs::create_hard_link(CacheEntryPath, OutputPath);
 792     if (!Err)
 793       return OutputPath.str();
 794     // Hard linking failed, try to copy.
 795     Err = sys::fs::copy_file(CacheEntryPath, OutputPath);
 796     if (!Err)
 797       return OutputPath.str();
 798     // Copy failed (could be because the CacheEntry was removed from the cache
 799     // in the meantime by another process), fall back and try to write down the
 800     // buffer to the output.
 801     errs() << "error: can't link or copy from cached entry '" << CacheEntryPath
 802            << "' to '" << OutputPath << "'\n";
 803   }
 804   // No cache entry, just write out the buffer.
 805   std::error_code Err;
 806   raw_fd_ostream OS(OutputPath, Err, sys::fs::F_None);
 807   if (Err)
 808     report_fatal_error("Can't open output '" + OutputPath + "'\n");
 809   OS << OutputBuffer.getBuffer();
 810   return OutputPath.str();
 811 }
 812
 813 // Main entry point for the ThinLTO processing
 814 void ThinLTOCodeGenerator::run() {
 815   // Prepare the resulting object vector
 816   assert(ProducedBinaries.empty() && "The generator should not be reused");
 817   if (SavedObjectsDirectoryPath.empty())
 818     ProducedBinaries.resize(Modules.size());
 819   else {
 820     sys::fs::create_directories(SavedObjectsDirectoryPath);
 821     bool IsDir;
 822     sys::fs::is_directory(SavedObjectsDirectoryPath, IsDir);
 823     if (!IsDir)
 824       report_fatal_error("Unexistent dir: '" + SavedObjectsDirectoryPath + "'");
 825     ProducedBinaryFiles.resize(Modules.size());
 826   }
 827
 828   if (CodeGenOnly) {
 829     // Perform only parallel codegen and return.
 830     ThreadPool Pool;
 831     int count = 0;
 832     for (auto &ModuleBuffer : Modules) {
 833       Pool.async([&](int count) {
 834         LLVMContext Context;
 835         Context.setDiscardValueNames(LTODiscardValueNames);
 836
 837         // Parse module now
 838         auto TheModule =
 839             loadModuleFromBuffer(ModuleBuffer.getMemBuffer(), Context, false,
 840                                  /*IsImporting*/ false);
 841
 842         // CodeGen
 843         auto OutputBuffer = codegenModule(*TheModule, *TMBuilder.create());
 844         if (SavedObjectsDirectoryPath.empty())
 845           ProducedBinaries[count] = std::move(OutputBuffer);
 846         else
 847           ProducedBinaryFiles[count] = writeGeneratedObject(
 848               count, "", SavedObjectsDirectoryPath, *OutputBuffer);
 849       }, count++);
 850     }
 851
 852     return;
 853   }
 854
 855   // Sequential linking phase
 856   auto Index = linkCombinedIndex();
 857
 858   // Save temps: index.
 859   if (!SaveTempsDir.empty()) {
 860     auto SaveTempPath = SaveTempsDir + "index.bc";
 861     std::error_code EC;
 862     raw_fd_ostream OS(SaveTempPath, EC, sys::fs::F_None);
 863     if (EC)
 864       report_fatal_error(Twine("Failed to open ") + SaveTempPath +
 865                          " to save optimized bitcode\n");
 866     WriteIndexToFile(*Index, OS);
 867   }
 868
 869
 870   // Prepare the module map.
 871   auto ModuleMap = generateModuleMap(Modules);
 872   auto ModuleCount = Modules.size();
 873
 874   // Collect for each module the list of function it defines (GUID -> Summary).
 875   StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries(ModuleCount);
 876   Index->collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
 877
 878   // Convert the preserved symbols set from string to GUID, this is needed for
 879   // computing the caching hash and the internalization.
 880   auto GUIDPreservedSymbols =
 881       computeGUIDPreservedSymbols(PreservedSymbols, TMBuilder.TheTriple);
 882
 883   // Compute "dead" symbols, we don't want to import/export these!
 884   computeDeadSymbolsInIndex(*Index, GUIDPreservedSymbols);
 885
 886   // Synthesize entry counts for functions in the combined index.
 887   computeSyntheticCounts(*Index);
 888
 889   // Collect the import/export lists for all modules from the call-graph in the
 890   // combined index.
 891   StringMap<FunctionImporter::ImportMapTy> ImportLists(ModuleCount);
 892   StringMap<FunctionImporter::ExportSetTy> ExportLists(ModuleCount);
 893   ComputeCrossModuleImport(*Index, ModuleToDefinedGVSummaries, ImportLists,
 894                            ExportLists);
 895
 896   // We use a std::map here to be able to have a defined ordering when
 897   // producing a hash for the cache entry.
 898   // FIXME: we should be able to compute the caching hash for the entry based
 899   // on the index, and nuke this map.
 900   StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>> ResolvedODR;
 901
 902   // Resolve prevailing symbols, this has to be computed early because it
 903   // impacts the caching.
 904   resolvePrevailingInIndex(*Index, ResolvedODR);
 905
 906   // Use global summary-based analysis to identify symbols that can be
 907   // internalized (because they aren't exported or preserved as per callback).
 908   // Changes are made in the index, consumed in the ThinLTO backends.
 909   internalizeAndPromoteInIndex(ExportLists, GUIDPreservedSymbols, *Index);
 910
 911   // Make sure that every module has an entry in the ExportLists, ImportList,
 912   // GVSummary and ResolvedODR maps to enable threaded access to these maps
 913   // below.
 914   for (auto &Module : Modules) {
 915     auto ModuleIdentifier = Module.getBufferIdentifier();
 916     ExportLists[ModuleIdentifier];
 917     ImportLists[ModuleIdentifier];
 918     ResolvedODR[ModuleIdentifier];
 919     ModuleToDefinedGVSummaries[ModuleIdentifier];
 920   }
 921
 922   // Compute the ordering we will process the inputs: the rough heuristic here
 923   // is to sort them per size so that the largest module get schedule as soon as
 924   // possible. This is purely a compile-time optimization.
 925   std::vector<int> ModulesOrdering;
 926   ModulesOrdering.resize(Modules.size());
 927   std::iota(ModulesOrdering.begin(), ModulesOrdering.end(), 0);
 928   llvm::sort(ModulesOrdering, [&](int LeftIndex, int RightIndex) {
 929     auto LSize = Modules[LeftIndex].getBuffer().size();
 930     auto RSize = Modules[RightIndex].getBuffer().size();
 931     return LSize > RSize;
 932   });
 933
 934   // Parallel optimizer + codegen
 935   {
 936     ThreadPool Pool(ThreadCount);
 937     for (auto IndexCount : ModulesOrdering) {
 938       auto &ModuleBuffer = Modules[IndexCount];
 939       Pool.async([&](int count) {
 940         auto ModuleIdentifier = ModuleBuffer.getBufferIdentifier();
 941         auto &ExportList = ExportLists[ModuleIdentifier];
 942
 943         auto &DefinedGVSummaries = ModuleToDefinedGVSummaries[ModuleIdentifier];
 944
 945         // The module may be cached, this helps handling it.
 946         ModuleCacheEntry CacheEntry(CacheOptions.Path, *Index, ModuleIdentifier,
 947                                     ImportLists[ModuleIdentifier], ExportList,
 948                                     ResolvedODR[ModuleIdentifier],
 949                                     DefinedGVSummaries, OptLevel, Freestanding,
 950                                     TMBuilder);
 951         auto CacheEntryPath = CacheEntry.getEntryPath();
 952
 953         {
 954           auto ErrOrBuffer = CacheEntry.tryLoadingBuffer();
 955           LLVM_DEBUG(dbgs() << "Cache " << (ErrOrBuffer ? "hit" : "miss")
 956                             << " '" << CacheEntryPath << "' for buffer "
 957                             << count << " " << ModuleIdentifier << "\n");
 958
 959           if (ErrOrBuffer) {
 960             // Cache Hit!
 961             if (SavedObjectsDirectoryPath.empty())
 962               ProducedBinaries[count] = std::move(ErrOrBuffer.get());
 963             else
 964               ProducedBinaryFiles[count] = writeGeneratedObject(
 965                   count, CacheEntryPath, SavedObjectsDirectoryPath,
 966                   *ErrOrBuffer.get());
 967             return;
 968           }
 969         }
 970
 971         LLVMContext Context;
 972         Context.setDiscardValueNames(LTODiscardValueNames);
 973         Context.enableDebugTypeODRUniquing();
 974         auto DiagFileOrErr = lto::setupOptimizationRemarks(
 975             Context, LTORemarksFilename, LTOPassRemarksWithHotness, count);
 976         if (!DiagFileOrErr) {
 977           errs() << "Error: " << toString(DiagFileOrErr.takeError()) << "\n";
 978           report_fatal_error("ThinLTO: Can't get an output file for the "
 979                              "remarks");
 980         }
 981
 982         // Parse module now
 983         auto TheModule =
 984             loadModuleFromBuffer(ModuleBuffer.getMemBuffer(), Context, false,
 985                                  /*IsImporting*/ false);
 986
 987         // Save temps: original file.
 988         saveTempBitcode(*TheModule, SaveTempsDir, count, ".0.original.bc");
 989
 990         auto &ImportList = ImportLists[ModuleIdentifier];
 991         // Run the main process now, and generates a binary
 992         auto OutputBuffer = ProcessThinLTOModule(
 993             *TheModule, *Index, ModuleMap, *TMBuilder.create(), ImportList,
 994             ExportList, GUIDPreservedSymbols,
 995             ModuleToDefinedGVSummaries[ModuleIdentifier], CacheOptions,
 996             DisableCodeGen, SaveTempsDir, Freestanding, OptLevel, count);
 997
 998         // Commit to the cache (if enabled)
 999         CacheEntry.write(*OutputBuffer);
1000
1001         if (SavedObjectsDirectoryPath.empty()) {
1002           // We need to generated a memory buffer for the linker.
1003           if (!CacheEntryPath.empty()) {
1004             // When cache is enabled, reload from the cache if possible.
1005             // Releasing the buffer from the heap and reloading it from the
1006             // cache file with mmap helps us to lower memory pressure.
1007             // The freed memory can be used for the next input file.
1008             // The final binary link will read from the VFS cache (hopefully!)
1009             // or from disk (if the memory pressure was too high).
1010             auto ReloadedBufferOrErr = CacheEntry.tryLoadingBuffer();
1011             if (auto EC = ReloadedBufferOrErr.getError()) {
1012               // On error, keep the preexisting buffer and print a diagnostic.
1013               errs() << "error: can't reload cached file '" << CacheEntryPath
1014                      << "': " << EC.message() << "\n";
1015             } else {
1016               OutputBuffer = std::move(*ReloadedBufferOrErr);
1017             }
1018           }
1019           ProducedBinaries[count] = std::move(OutputBuffer);
1020           return;
1021         }
1022         ProducedBinaryFiles[count] = writeGeneratedObject(
1023             count, CacheEntryPath, SavedObjectsDirectoryPath, *OutputBuffer);
1024       }, IndexCount);
1025     }
1026   }
1027
1028   pruneCache(CacheOptions.Path, CacheOptions.Policy);
1029
1030   // If statistics were requested, print them out now.
1031   if (llvm::AreStatisticsEnabled())
1032     llvm::PrintStatistics();
1033   reportAndResetTimings();
1034 }