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      1 //===--- BackendUtil.cpp - LLVM Backend Utilities -------------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #include "clang/CodeGen/BackendUtil.h"
     11 #include "clang/Basic/Diagnostic.h"
     12 #include "clang/Basic/LangOptions.h"
     13 #include "clang/Basic/TargetOptions.h"
     14 #include "clang/Frontend/CodeGenOptions.h"
     15 #include "clang/Frontend/FrontendDiagnostic.h"
     16 #include "clang/Frontend/Utils.h"
     17 #include "llvm/ADT/StringExtras.h"
     18 #include "llvm/ADT/StringSwitch.h"
     19 #include "llvm/ADT/Triple.h"
     20 #include "llvm/Analysis/TargetLibraryInfo.h"
     21 #include "llvm/Analysis/TargetTransformInfo.h"
     22 #include "llvm/Bitcode/BitcodeWriterPass.h"
     23 #include "llvm/Bitcode/ReaderWriter.h"
     24 #include "llvm/CodeGen/RegAllocRegistry.h"
     25 #include "llvm/CodeGen/SchedulerRegistry.h"
     26 #include "llvm/IR/DataLayout.h"
     27 #include "llvm/IR/ModuleSummaryIndex.h"
     28 #include "llvm/IR/IRPrintingPasses.h"
     29 #include "llvm/IR/LegacyPassManager.h"
     30 #include "llvm/IR/Module.h"
     31 #include "llvm/IR/Verifier.h"
     32 #include "llvm/MC/SubtargetFeature.h"
     33 #include "llvm/Object/ModuleSummaryIndexObjectFile.h"
     34 #include "llvm/Support/CommandLine.h"
     35 #include "llvm/Support/PrettyStackTrace.h"
     36 #include "llvm/Support/TargetRegistry.h"
     37 #include "llvm/Support/Timer.h"
     38 #include "llvm/Support/raw_ostream.h"
     39 #include "llvm/Target/TargetMachine.h"
     40 #include "llvm/Target/TargetOptions.h"
     41 #include "llvm/Target/TargetSubtargetInfo.h"
     42 #include "llvm/Transforms/IPO.h"
     43 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
     44 #include "llvm/Transforms/Instrumentation.h"
     45 #include "llvm/Transforms/ObjCARC.h"
     46 #include "llvm/Transforms/Scalar.h"
     47 #include "llvm/Transforms/Scalar/GVN.h"
     48 #include "llvm/Transforms/Utils/SymbolRewriter.h"
     49 #include <memory>
     50 using namespace clang;
     51 using namespace llvm;
     52 
     53 namespace {
     54 
     55 class EmitAssemblyHelper {
     56   DiagnosticsEngine &Diags;
     57   const CodeGenOptions &CodeGenOpts;
     58   const clang::TargetOptions &TargetOpts;
     59   const LangOptions &LangOpts;
     60   Module *TheModule;
     61 
     62   Timer CodeGenerationTime;
     63 
     64   mutable legacy::PassManager *CodeGenPasses;
     65   mutable legacy::PassManager *PerModulePasses;
     66   mutable legacy::FunctionPassManager *PerFunctionPasses;
     67 
     68 private:
     69   TargetIRAnalysis getTargetIRAnalysis() const {
     70     if (TM)
     71       return TM->getTargetIRAnalysis();
     72 
     73     return TargetIRAnalysis();
     74   }
     75 
     76   legacy::PassManager *getCodeGenPasses() const {
     77     if (!CodeGenPasses) {
     78       CodeGenPasses = new legacy::PassManager();
     79       CodeGenPasses->add(
     80           createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
     81     }
     82     return CodeGenPasses;
     83   }
     84 
     85   legacy::PassManager *getPerModulePasses() const {
     86     if (!PerModulePasses) {
     87       PerModulePasses = new legacy::PassManager();
     88       PerModulePasses->add(
     89           createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
     90     }
     91     return PerModulePasses;
     92   }
     93 
     94   legacy::FunctionPassManager *getPerFunctionPasses() const {
     95     if (!PerFunctionPasses) {
     96       PerFunctionPasses = new legacy::FunctionPassManager(TheModule);
     97       PerFunctionPasses->add(
     98           createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
     99     }
    100     return PerFunctionPasses;
    101   }
    102 
    103   /// Set LLVM command line options passed through -backend-option.
    104   void setCommandLineOpts();
    105 
    106   void CreatePasses(ModuleSummaryIndex *ModuleSummary);
    107 
    108   /// Generates the TargetMachine.
    109   /// Returns Null if it is unable to create the target machine.
    110   /// Some of our clang tests specify triples which are not built
    111   /// into clang. This is okay because these tests check the generated
    112   /// IR, and they require DataLayout which depends on the triple.
    113   /// In this case, we allow this method to fail and not report an error.
    114   /// When MustCreateTM is used, we print an error if we are unable to load
    115   /// the requested target.
    116   TargetMachine *CreateTargetMachine(bool MustCreateTM);
    117 
    118   /// Add passes necessary to emit assembly or LLVM IR.
    119   ///
    120   /// \return True on success.
    121   bool AddEmitPasses(BackendAction Action, raw_pwrite_stream &OS);
    122 
    123 public:
    124   EmitAssemblyHelper(DiagnosticsEngine &_Diags, const CodeGenOptions &CGOpts,
    125                      const clang::TargetOptions &TOpts,
    126                      const LangOptions &LOpts, Module *M)
    127       : Diags(_Diags), CodeGenOpts(CGOpts), TargetOpts(TOpts), LangOpts(LOpts),
    128         TheModule(M), CodeGenerationTime("Code Generation Time"),
    129         CodeGenPasses(nullptr), PerModulePasses(nullptr),
    130         PerFunctionPasses(nullptr) {}
    131 
    132   ~EmitAssemblyHelper() {
    133     delete CodeGenPasses;
    134     delete PerModulePasses;
    135     delete PerFunctionPasses;
    136     if (CodeGenOpts.DisableFree)
    137       BuryPointer(std::move(TM));
    138   }
    139 
    140   std::unique_ptr<TargetMachine> TM;
    141 
    142   void EmitAssembly(BackendAction Action, raw_pwrite_stream *OS);
    143 };
    144 
    145 // We need this wrapper to access LangOpts and CGOpts from extension functions
    146 // that we add to the PassManagerBuilder.
    147 class PassManagerBuilderWrapper : public PassManagerBuilder {
    148 public:
    149   PassManagerBuilderWrapper(const CodeGenOptions &CGOpts,
    150                             const LangOptions &LangOpts)
    151       : PassManagerBuilder(), CGOpts(CGOpts), LangOpts(LangOpts) {}
    152   const CodeGenOptions &getCGOpts() const { return CGOpts; }
    153   const LangOptions &getLangOpts() const { return LangOpts; }
    154 private:
    155   const CodeGenOptions &CGOpts;
    156   const LangOptions &LangOpts;
    157 };
    158 
    159 }
    160 
    161 static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
    162   if (Builder.OptLevel > 0)
    163     PM.add(createObjCARCAPElimPass());
    164 }
    165 
    166 static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
    167   if (Builder.OptLevel > 0)
    168     PM.add(createObjCARCExpandPass());
    169 }
    170 
    171 static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
    172   if (Builder.OptLevel > 0)
    173     PM.add(createObjCARCOptPass());
    174 }
    175 
    176 static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
    177                                      legacy::PassManagerBase &PM) {
    178   PM.add(createAddDiscriminatorsPass());
    179 }
    180 
    181 static void addCleanupPassesForSampleProfiler(
    182     const PassManagerBuilder &Builder, legacy::PassManagerBase &PM) {
    183   // instcombine is needed before sample profile annotation because it converts
    184   // certain function calls to be inlinable. simplifycfg and sroa are needed
    185   // before instcombine for necessary preparation. E.g. load store is eliminated
    186   // properly so that instcombine will not introduce unecessary liverange.
    187   PM.add(createCFGSimplificationPass());
    188   PM.add(createSROAPass());
    189   PM.add(createInstructionCombiningPass());
    190 }
    191 
    192 static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
    193                                   legacy::PassManagerBase &PM) {
    194   PM.add(createBoundsCheckingPass());
    195 }
    196 
    197 static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
    198                                      legacy::PassManagerBase &PM) {
    199   const PassManagerBuilderWrapper &BuilderWrapper =
    200       static_cast<const PassManagerBuilderWrapper&>(Builder);
    201   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
    202   SanitizerCoverageOptions Opts;
    203   Opts.CoverageType =
    204       static_cast<SanitizerCoverageOptions::Type>(CGOpts.SanitizeCoverageType);
    205   Opts.IndirectCalls = CGOpts.SanitizeCoverageIndirectCalls;
    206   Opts.TraceBB = CGOpts.SanitizeCoverageTraceBB;
    207   Opts.TraceCmp = CGOpts.SanitizeCoverageTraceCmp;
    208   Opts.Use8bitCounters = CGOpts.SanitizeCoverage8bitCounters;
    209   Opts.TracePC = CGOpts.SanitizeCoverageTracePC;
    210   PM.add(createSanitizerCoverageModulePass(Opts));
    211 }
    212 
    213 static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
    214                                       legacy::PassManagerBase &PM) {
    215   const PassManagerBuilderWrapper &BuilderWrapper =
    216       static_cast<const PassManagerBuilderWrapper&>(Builder);
    217   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
    218   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Address);
    219   bool UseAfterScope = CGOpts.SanitizeAddressUseAfterScope;
    220   PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/ false, Recover,
    221                                             UseAfterScope));
    222   PM.add(createAddressSanitizerModulePass(/*CompileKernel*/false, Recover));
    223 }
    224 
    225 static void addKernelAddressSanitizerPasses(const PassManagerBuilder &Builder,
    226                                             legacy::PassManagerBase &PM) {
    227   PM.add(createAddressSanitizerFunctionPass(
    228       /*CompileKernel*/ true,
    229       /*Recover*/ true, /*UseAfterScope*/ false));
    230   PM.add(createAddressSanitizerModulePass(/*CompileKernel*/true,
    231                                           /*Recover*/true));
    232 }
    233 
    234 static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
    235                                    legacy::PassManagerBase &PM) {
    236   const PassManagerBuilderWrapper &BuilderWrapper =
    237       static_cast<const PassManagerBuilderWrapper&>(Builder);
    238   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
    239   PM.add(createMemorySanitizerPass(CGOpts.SanitizeMemoryTrackOrigins));
    240 
    241   // MemorySanitizer inserts complex instrumentation that mostly follows
    242   // the logic of the original code, but operates on "shadow" values.
    243   // It can benefit from re-running some general purpose optimization passes.
    244   if (Builder.OptLevel > 0) {
    245     PM.add(createEarlyCSEPass());
    246     PM.add(createReassociatePass());
    247     PM.add(createLICMPass());
    248     PM.add(createGVNPass());
    249     PM.add(createInstructionCombiningPass());
    250     PM.add(createDeadStoreEliminationPass());
    251   }
    252 }
    253 
    254 static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
    255                                    legacy::PassManagerBase &PM) {
    256   PM.add(createThreadSanitizerPass());
    257 }
    258 
    259 static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
    260                                      legacy::PassManagerBase &PM) {
    261   const PassManagerBuilderWrapper &BuilderWrapper =
    262       static_cast<const PassManagerBuilderWrapper&>(Builder);
    263   const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
    264   PM.add(createDataFlowSanitizerPass(LangOpts.SanitizerBlacklistFiles));
    265 }
    266 
    267 static void addEfficiencySanitizerPass(const PassManagerBuilder &Builder,
    268                                        legacy::PassManagerBase &PM) {
    269   const PassManagerBuilderWrapper &BuilderWrapper =
    270       static_cast<const PassManagerBuilderWrapper&>(Builder);
    271   const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
    272   EfficiencySanitizerOptions Opts;
    273   if (LangOpts.Sanitize.has(SanitizerKind::EfficiencyCacheFrag))
    274     Opts.ToolType = EfficiencySanitizerOptions::ESAN_CacheFrag;
    275   else if (LangOpts.Sanitize.has(SanitizerKind::EfficiencyWorkingSet))
    276     Opts.ToolType = EfficiencySanitizerOptions::ESAN_WorkingSet;
    277   PM.add(createEfficiencySanitizerPass(Opts));
    278 }
    279 
    280 static TargetLibraryInfoImpl *createTLII(llvm::Triple &TargetTriple,
    281                                          const CodeGenOptions &CodeGenOpts) {
    282   TargetLibraryInfoImpl *TLII = new TargetLibraryInfoImpl(TargetTriple);
    283   if (!CodeGenOpts.SimplifyLibCalls)
    284     TLII->disableAllFunctions();
    285   else {
    286     // Disable individual libc/libm calls in TargetLibraryInfo.
    287     LibFunc::Func F;
    288     for (auto &FuncName : CodeGenOpts.getNoBuiltinFuncs())
    289       if (TLII->getLibFunc(FuncName, F))
    290         TLII->setUnavailable(F);
    291   }
    292 
    293   switch (CodeGenOpts.getVecLib()) {
    294   case CodeGenOptions::Accelerate:
    295     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::Accelerate);
    296     break;
    297   default:
    298     break;
    299   }
    300   return TLII;
    301 }
    302 
    303 static void addSymbolRewriterPass(const CodeGenOptions &Opts,
    304                                   legacy::PassManager *MPM) {
    305   llvm::SymbolRewriter::RewriteDescriptorList DL;
    306 
    307   llvm::SymbolRewriter::RewriteMapParser MapParser;
    308   for (const auto &MapFile : Opts.RewriteMapFiles)
    309     MapParser.parse(MapFile, &DL);
    310 
    311   MPM->add(createRewriteSymbolsPass(DL));
    312 }
    313 
    314 void EmitAssemblyHelper::CreatePasses(ModuleSummaryIndex *ModuleSummary) {
    315   if (CodeGenOpts.DisableLLVMPasses)
    316     return;
    317 
    318   unsigned OptLevel = CodeGenOpts.OptimizationLevel;
    319   CodeGenOptions::InliningMethod Inlining = CodeGenOpts.getInlining();
    320 
    321   // Handle disabling of LLVM optimization, where we want to preserve the
    322   // internal module before any optimization.
    323   if (CodeGenOpts.DisableLLVMOpts) {
    324     OptLevel = 0;
    325     Inlining = CodeGenOpts.NoInlining;
    326   }
    327 
    328   PassManagerBuilderWrapper PMBuilder(CodeGenOpts, LangOpts);
    329 
    330   // Figure out TargetLibraryInfo.
    331   Triple TargetTriple(TheModule->getTargetTriple());
    332   PMBuilder.LibraryInfo = createTLII(TargetTriple, CodeGenOpts);
    333 
    334   switch (Inlining) {
    335   case CodeGenOptions::NoInlining:
    336     break;
    337   case CodeGenOptions::NormalInlining:
    338   case CodeGenOptions::OnlyHintInlining: {
    339     PMBuilder.Inliner =
    340         createFunctionInliningPass(OptLevel, CodeGenOpts.OptimizeSize);
    341     break;
    342   }
    343   case CodeGenOptions::OnlyAlwaysInlining:
    344     // Respect always_inline.
    345     if (OptLevel == 0)
    346       // Do not insert lifetime intrinsics at -O0.
    347       PMBuilder.Inliner = createAlwaysInlinerPass(false);
    348     else
    349       PMBuilder.Inliner = createAlwaysInlinerPass();
    350     break;
    351   }
    352 
    353   PMBuilder.OptLevel = OptLevel;
    354   PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
    355   PMBuilder.BBVectorize = CodeGenOpts.VectorizeBB;
    356   PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
    357   PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
    358 
    359   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
    360   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
    361   PMBuilder.PrepareForThinLTO = CodeGenOpts.EmitSummaryIndex;
    362   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
    363   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
    364 
    365   legacy::PassManager *MPM = getPerModulePasses();
    366 
    367   // If we are performing a ThinLTO importing compile, invoke the LTO
    368   // pipeline and pass down the in-memory module summary index.
    369   if (ModuleSummary) {
    370     PMBuilder.ModuleSummary = ModuleSummary;
    371     PMBuilder.populateThinLTOPassManager(*MPM);
    372     return;
    373   }
    374 
    375   // Add target-specific passes that need to run as early as possible.
    376   if (TM)
    377     PMBuilder.addExtension(
    378         PassManagerBuilder::EP_EarlyAsPossible,
    379         [&](const PassManagerBuilder &, legacy::PassManagerBase &PM) {
    380           TM->addEarlyAsPossiblePasses(PM);
    381         });
    382 
    383   PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
    384                          addAddDiscriminatorsPass);
    385 
    386   // In ObjC ARC mode, add the main ARC optimization passes.
    387   if (LangOpts.ObjCAutoRefCount) {
    388     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
    389                            addObjCARCExpandPass);
    390     PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
    391                            addObjCARCAPElimPass);
    392     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
    393                            addObjCARCOptPass);
    394   }
    395 
    396   if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds)) {
    397     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
    398                            addBoundsCheckingPass);
    399     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
    400                            addBoundsCheckingPass);
    401   }
    402 
    403   if (CodeGenOpts.SanitizeCoverageType ||
    404       CodeGenOpts.SanitizeCoverageIndirectCalls ||
    405       CodeGenOpts.SanitizeCoverageTraceCmp) {
    406     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
    407                            addSanitizerCoveragePass);
    408     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
    409                            addSanitizerCoveragePass);
    410   }
    411 
    412   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
    413     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
    414                            addAddressSanitizerPasses);
    415     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
    416                            addAddressSanitizerPasses);
    417   }
    418 
    419   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
    420     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
    421                            addKernelAddressSanitizerPasses);
    422     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
    423                            addKernelAddressSanitizerPasses);
    424   }
    425 
    426   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
    427     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
    428                            addMemorySanitizerPass);
    429     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
    430                            addMemorySanitizerPass);
    431   }
    432 
    433   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
    434     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
    435                            addThreadSanitizerPass);
    436     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
    437                            addThreadSanitizerPass);
    438   }
    439 
    440   if (LangOpts.Sanitize.has(SanitizerKind::DataFlow)) {
    441     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
    442                            addDataFlowSanitizerPass);
    443     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
    444                            addDataFlowSanitizerPass);
    445   }
    446 
    447   if (LangOpts.Sanitize.hasOneOf(SanitizerKind::Efficiency)) {
    448     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
    449                            addEfficiencySanitizerPass);
    450     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
    451                            addEfficiencySanitizerPass);
    452   }
    453 
    454   // Set up the per-function pass manager.
    455   legacy::FunctionPassManager *FPM = getPerFunctionPasses();
    456   if (CodeGenOpts.VerifyModule)
    457     FPM->add(createVerifierPass());
    458 
    459   // Set up the per-module pass manager.
    460   if (!CodeGenOpts.RewriteMapFiles.empty())
    461     addSymbolRewriterPass(CodeGenOpts, MPM);
    462 
    463   if (!CodeGenOpts.DisableGCov &&
    464       (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes)) {
    465     // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
    466     // LLVM's -default-gcov-version flag is set to something invalid.
    467     GCOVOptions Options;
    468     Options.EmitNotes = CodeGenOpts.EmitGcovNotes;
    469     Options.EmitData = CodeGenOpts.EmitGcovArcs;
    470     memcpy(Options.Version, CodeGenOpts.CoverageVersion, 4);
    471     Options.UseCfgChecksum = CodeGenOpts.CoverageExtraChecksum;
    472     Options.NoRedZone = CodeGenOpts.DisableRedZone;
    473     Options.FunctionNamesInData =
    474         !CodeGenOpts.CoverageNoFunctionNamesInData;
    475     Options.ExitBlockBeforeBody = CodeGenOpts.CoverageExitBlockBeforeBody;
    476     MPM->add(createGCOVProfilerPass(Options));
    477     if (CodeGenOpts.getDebugInfo() == codegenoptions::NoDebugInfo)
    478       MPM->add(createStripSymbolsPass(true));
    479   }
    480 
    481   if (CodeGenOpts.hasProfileClangInstr()) {
    482     InstrProfOptions Options;
    483     Options.NoRedZone = CodeGenOpts.DisableRedZone;
    484     Options.InstrProfileOutput = CodeGenOpts.InstrProfileOutput;
    485     MPM->add(createInstrProfilingLegacyPass(Options));
    486   }
    487   if (CodeGenOpts.hasProfileIRInstr()) {
    488     if (!CodeGenOpts.InstrProfileOutput.empty())
    489       PMBuilder.PGOInstrGen = CodeGenOpts.InstrProfileOutput;
    490     else
    491       PMBuilder.PGOInstrGen = "default.profraw";
    492   }
    493   if (CodeGenOpts.hasProfileIRUse())
    494     PMBuilder.PGOInstrUse = CodeGenOpts.ProfileInstrumentUsePath;
    495 
    496   if (!CodeGenOpts.SampleProfileFile.empty()) {
    497     MPM->add(createPruneEHPass());
    498     MPM->add(createSampleProfileLoaderPass(CodeGenOpts.SampleProfileFile));
    499     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
    500                            addCleanupPassesForSampleProfiler);
    501   }
    502 
    503   PMBuilder.populateFunctionPassManager(*FPM);
    504   PMBuilder.populateModulePassManager(*MPM);
    505 }
    506 
    507 void EmitAssemblyHelper::setCommandLineOpts() {
    508   SmallVector<const char *, 16> BackendArgs;
    509   BackendArgs.push_back("clang"); // Fake program name.
    510   if (!CodeGenOpts.DebugPass.empty()) {
    511     BackendArgs.push_back("-debug-pass");
    512     BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
    513   }
    514   if (!CodeGenOpts.LimitFloatPrecision.empty()) {
    515     BackendArgs.push_back("-limit-float-precision");
    516     BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
    517   }
    518   for (const std::string &BackendOption : CodeGenOpts.BackendOptions)
    519     BackendArgs.push_back(BackendOption.c_str());
    520   BackendArgs.push_back(nullptr);
    521   llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
    522                                     BackendArgs.data());
    523 }
    524 
    525 TargetMachine *EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
    526   // Create the TargetMachine for generating code.
    527   std::string Error;
    528   std::string Triple = TheModule->getTargetTriple();
    529   const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
    530   if (!TheTarget) {
    531     if (MustCreateTM)
    532       Diags.Report(diag::err_fe_unable_to_create_target) << Error;
    533     return nullptr;
    534   }
    535 
    536   unsigned CodeModel =
    537     llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
    538       .Case("small", llvm::CodeModel::Small)
    539       .Case("kernel", llvm::CodeModel::Kernel)
    540       .Case("medium", llvm::CodeModel::Medium)
    541       .Case("large", llvm::CodeModel::Large)
    542       .Case("default", llvm::CodeModel::Default)
    543       .Default(~0u);
    544   assert(CodeModel != ~0u && "invalid code model!");
    545   llvm::CodeModel::Model CM = static_cast<llvm::CodeModel::Model>(CodeModel);
    546 
    547   std::string FeaturesStr =
    548       llvm::join(TargetOpts.Features.begin(), TargetOpts.Features.end(), ",");
    549 
    550   // Keep this synced with the equivalent code in tools/driver/cc1as_main.cpp.
    551   llvm::Optional<llvm::Reloc::Model> RM;
    552   if (CodeGenOpts.RelocationModel == "static") {
    553     RM = llvm::Reloc::Static;
    554   } else if (CodeGenOpts.RelocationModel == "pic") {
    555     RM = llvm::Reloc::PIC_;
    556   } else {
    557     assert(CodeGenOpts.RelocationModel == "dynamic-no-pic" &&
    558            "Invalid PIC model!");
    559     RM = llvm::Reloc::DynamicNoPIC;
    560   }
    561 
    562   CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
    563   switch (CodeGenOpts.OptimizationLevel) {
    564   default: break;
    565   case 0: OptLevel = CodeGenOpt::None; break;
    566   case 3: OptLevel = CodeGenOpt::Aggressive; break;
    567   }
    568 
    569   llvm::TargetOptions Options;
    570 
    571   if (!TargetOpts.Reciprocals.empty())
    572     Options.Reciprocals = TargetRecip(TargetOpts.Reciprocals);
    573 
    574   Options.ThreadModel =
    575     llvm::StringSwitch<llvm::ThreadModel::Model>(CodeGenOpts.ThreadModel)
    576       .Case("posix", llvm::ThreadModel::POSIX)
    577       .Case("single", llvm::ThreadModel::Single);
    578 
    579   // Set float ABI type.
    580   assert((CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp" ||
    581           CodeGenOpts.FloatABI == "hard" || CodeGenOpts.FloatABI.empty()) &&
    582          "Invalid Floating Point ABI!");
    583   Options.FloatABIType =
    584       llvm::StringSwitch<llvm::FloatABI::ABIType>(CodeGenOpts.FloatABI)
    585           .Case("soft", llvm::FloatABI::Soft)
    586           .Case("softfp", llvm::FloatABI::Soft)
    587           .Case("hard", llvm::FloatABI::Hard)
    588           .Default(llvm::FloatABI::Default);
    589 
    590   // Set FP fusion mode.
    591   switch (CodeGenOpts.getFPContractMode()) {
    592   case CodeGenOptions::FPC_Off:
    593     Options.AllowFPOpFusion = llvm::FPOpFusion::Strict;
    594     break;
    595   case CodeGenOptions::FPC_On:
    596     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
    597     break;
    598   case CodeGenOptions::FPC_Fast:
    599     Options.AllowFPOpFusion = llvm::FPOpFusion::Fast;
    600     break;
    601   }
    602 
    603   Options.UseInitArray = CodeGenOpts.UseInitArray;
    604   Options.DisableIntegratedAS = CodeGenOpts.DisableIntegratedAS;
    605   Options.CompressDebugSections = CodeGenOpts.CompressDebugSections;
    606   Options.RelaxELFRelocations = CodeGenOpts.RelaxELFRelocations;
    607 
    608   // Set EABI version.
    609   Options.EABIVersion = llvm::StringSwitch<llvm::EABI>(TargetOpts.EABIVersion)
    610                             .Case("4", llvm::EABI::EABI4)
    611                             .Case("5", llvm::EABI::EABI5)
    612                             .Case("gnu", llvm::EABI::GNU)
    613                             .Default(llvm::EABI::Default);
    614 
    615   if (LangOpts.SjLjExceptions)
    616     Options.ExceptionModel = llvm::ExceptionHandling::SjLj;
    617 
    618   Options.LessPreciseFPMADOption = CodeGenOpts.LessPreciseFPMAD;
    619   Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
    620   Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
    621   Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
    622   Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
    623   Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
    624   Options.FunctionSections = CodeGenOpts.FunctionSections;
    625   Options.DataSections = CodeGenOpts.DataSections;
    626   Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
    627   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
    628   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
    629 
    630   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
    631   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
    632   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
    633   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
    634   Options.MCOptions.MCIncrementalLinkerCompatible =
    635       CodeGenOpts.IncrementalLinkerCompatible;
    636   Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
    637   Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
    638   Options.MCOptions.ABIName = TargetOpts.ABI;
    639 
    640   TargetMachine *TM = TheTarget->createTargetMachine(Triple, TargetOpts.CPU,
    641                                                      FeaturesStr, Options,
    642                                                      RM, CM, OptLevel);
    643 
    644   return TM;
    645 }
    646 
    647 bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
    648                                        raw_pwrite_stream &OS) {
    649 
    650   // Create the code generator passes.
    651   legacy::PassManager *PM = getCodeGenPasses();
    652 
    653   // Add LibraryInfo.
    654   llvm::Triple TargetTriple(TheModule->getTargetTriple());
    655   std::unique_ptr<TargetLibraryInfoImpl> TLII(
    656       createTLII(TargetTriple, CodeGenOpts));
    657   PM->add(new TargetLibraryInfoWrapperPass(*TLII));
    658 
    659   // Normal mode, emit a .s or .o file by running the code generator. Note,
    660   // this also adds codegenerator level optimization passes.
    661   TargetMachine::CodeGenFileType CGFT = TargetMachine::CGFT_AssemblyFile;
    662   if (Action == Backend_EmitObj)
    663     CGFT = TargetMachine::CGFT_ObjectFile;
    664   else if (Action == Backend_EmitMCNull)
    665     CGFT = TargetMachine::CGFT_Null;
    666   else
    667     assert(Action == Backend_EmitAssembly && "Invalid action!");
    668 
    669   // Add ObjC ARC final-cleanup optimizations. This is done as part of the
    670   // "codegen" passes so that it isn't run multiple times when there is
    671   // inlining happening.
    672   if (CodeGenOpts.OptimizationLevel > 0)
    673     PM->add(createObjCARCContractPass());
    674 
    675   if (TM->addPassesToEmitFile(*PM, OS, CGFT,
    676                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
    677     Diags.Report(diag::err_fe_unable_to_interface_with_target);
    678     return false;
    679   }
    680 
    681   return true;
    682 }
    683 
    684 void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
    685                                       raw_pwrite_stream *OS) {
    686   TimeRegion Region(llvm::TimePassesIsEnabled ? &CodeGenerationTime : nullptr);
    687 
    688   setCommandLineOpts();
    689 
    690   bool UsesCodeGen = (Action != Backend_EmitNothing &&
    691                       Action != Backend_EmitBC &&
    692                       Action != Backend_EmitLL);
    693   if (!TM)
    694     TM.reset(CreateTargetMachine(UsesCodeGen));
    695 
    696   if (UsesCodeGen && !TM)
    697     return;
    698   if (TM)
    699     TheModule->setDataLayout(TM->createDataLayout());
    700 
    701   // If we are performing a ThinLTO importing compile, load the function
    702   // index into memory and pass it into CreatePasses, which will add it
    703   // to the PassManagerBuilder and invoke LTO passes.
    704   std::unique_ptr<ModuleSummaryIndex> ModuleSummary;
    705   if (!CodeGenOpts.ThinLTOIndexFile.empty()) {
    706     ErrorOr<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr =
    707         llvm::getModuleSummaryIndexForFile(
    708             CodeGenOpts.ThinLTOIndexFile, [&](const DiagnosticInfo &DI) {
    709               TheModule->getContext().diagnose(DI);
    710             });
    711     if (std::error_code EC = IndexOrErr.getError()) {
    712       std::string Error = EC.message();
    713       errs() << "Error loading index file '" << CodeGenOpts.ThinLTOIndexFile
    714              << "': " << Error << "\n";
    715       return;
    716     }
    717     ModuleSummary = std::move(IndexOrErr.get());
    718     assert(ModuleSummary && "Expected non-empty module summary index");
    719   }
    720 
    721   CreatePasses(ModuleSummary.get());
    722 
    723   switch (Action) {
    724   case Backend_EmitNothing:
    725     break;
    726 
    727   case Backend_EmitBC:
    728     getPerModulePasses()->add(createBitcodeWriterPass(
    729         *OS, CodeGenOpts.EmitLLVMUseLists, CodeGenOpts.EmitSummaryIndex,
    730         CodeGenOpts.EmitSummaryIndex));
    731     break;
    732 
    733   case Backend_EmitLL:
    734     getPerModulePasses()->add(
    735         createPrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
    736     break;
    737 
    738   default:
    739     if (!AddEmitPasses(Action, *OS))
    740       return;
    741   }
    742 
    743   // Before executing passes, print the final values of the LLVM options.
    744   cl::PrintOptionValues();
    745 
    746   // Run passes. For now we do all passes at once, but eventually we
    747   // would like to have the option of streaming code generation.
    748 
    749   if (PerFunctionPasses) {
    750     PrettyStackTraceString CrashInfo("Per-function optimization");
    751 
    752     PerFunctionPasses->doInitialization();
    753     for (Function &F : *TheModule)
    754       if (!F.isDeclaration())
    755         PerFunctionPasses->run(F);
    756     PerFunctionPasses->doFinalization();
    757   }
    758 
    759   if (PerModulePasses) {
    760     PrettyStackTraceString CrashInfo("Per-module optimization passes");
    761     PerModulePasses->run(*TheModule);
    762   }
    763 
    764   if (CodeGenPasses) {
    765     PrettyStackTraceString CrashInfo("Code generation");
    766     CodeGenPasses->run(*TheModule);
    767   }
    768 }
    769 
    770 void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
    771                               const CodeGenOptions &CGOpts,
    772                               const clang::TargetOptions &TOpts,
    773                               const LangOptions &LOpts, const llvm::DataLayout &TDesc,
    774                               Module *M, BackendAction Action,
    775                               raw_pwrite_stream *OS) {
    776   EmitAssemblyHelper AsmHelper(Diags, CGOpts, TOpts, LOpts, M);
    777 
    778   AsmHelper.EmitAssembly(Action, OS);
    779 
    780   // Verify clang's TargetInfo DataLayout against the LLVM TargetMachine's
    781   // DataLayout.
    782   if (AsmHelper.TM) {
    783     std::string DLDesc = M->getDataLayout().getStringRepresentation();
    784     if (DLDesc != TDesc.getStringRepresentation()) {
    785       unsigned DiagID = Diags.getCustomDiagID(
    786           DiagnosticsEngine::Error, "backend data layout '%0' does not match "
    787                                     "expected target description '%1'");
    788       Diags.Report(DiagID) << DLDesc << TDesc.getStringRepresentation();
    789     }
    790   }
    791 }
    792 
    793 static const char* getSectionNameForBitcode(const Triple &T) {
    794   switch (T.getObjectFormat()) {
    795   case Triple::MachO:
    796     return "__LLVM,__bitcode";
    797   case Triple::COFF:
    798   case Triple::ELF:
    799   case Triple::UnknownObjectFormat:
    800     return ".llvmbc";
    801   }
    802   llvm_unreachable("Unimplemented ObjectFormatType");
    803 }
    804 
    805 static const char* getSectionNameForCommandline(const Triple &T) {
    806   switch (T.getObjectFormat()) {
    807   case Triple::MachO:
    808     return "__LLVM,__cmdline";
    809   case Triple::COFF:
    810   case Triple::ELF:
    811   case Triple::UnknownObjectFormat:
    812     return ".llvmcmd";
    813   }
    814   llvm_unreachable("Unimplemented ObjectFormatType");
    815 }
    816 
    817 // With -fembed-bitcode, save a copy of the llvm IR as data in the
    818 // __LLVM,__bitcode section.
    819 void clang::EmbedBitcode(llvm::Module *M, const CodeGenOptions &CGOpts,
    820                          llvm::MemoryBufferRef Buf) {
    821   if (CGOpts.getEmbedBitcode() == CodeGenOptions::Embed_Off)
    822     return;
    823 
    824   // Save llvm.compiler.used and remote it.
    825   SmallVector<Constant*, 2> UsedArray;
    826   SmallSet<GlobalValue*, 4> UsedGlobals;
    827   Type *UsedElementType = Type::getInt8Ty(M->getContext())->getPointerTo(0);
    828   GlobalVariable *Used = collectUsedGlobalVariables(*M, UsedGlobals, true);
    829   for (auto *GV : UsedGlobals) {
    830     if (GV->getName() != "llvm.embedded.module" &&
    831         GV->getName() != "llvm.cmdline")
    832       UsedArray.push_back(
    833           ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
    834   }
    835   if (Used)
    836     Used->eraseFromParent();
    837 
    838   // Embed the bitcode for the llvm module.
    839   std::string Data;
    840   ArrayRef<uint8_t> ModuleData;
    841   Triple T(M->getTargetTriple());
    842   // Create a constant that contains the bitcode.
    843   // In case of embedding a marker, ignore the input Buf and use the empty
    844   // ArrayRef. It is also legal to create a bitcode marker even Buf is empty.
    845   if (CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Marker) {
    846     if (!isBitcode((const unsigned char *)Buf.getBufferStart(),
    847                    (const unsigned char *)Buf.getBufferEnd())) {
    848       // If the input is LLVM Assembly, bitcode is produced by serializing
    849       // the module. Use-lists order need to be perserved in this case.
    850       llvm::raw_string_ostream OS(Data);
    851       llvm::WriteBitcodeToFile(M, OS, /* ShouldPreserveUseListOrder */ true);
    852       ModuleData =
    853           ArrayRef<uint8_t>((const uint8_t *)OS.str().data(), OS.str().size());
    854     } else
    855       // If the input is LLVM bitcode, write the input byte stream directly.
    856       ModuleData = ArrayRef<uint8_t>((const uint8_t *)Buf.getBufferStart(),
    857                                      Buf.getBufferSize());
    858   }
    859   llvm::Constant *ModuleConstant =
    860       llvm::ConstantDataArray::get(M->getContext(), ModuleData);
    861   llvm::GlobalVariable *GV = new llvm::GlobalVariable(
    862       *M, ModuleConstant->getType(), true, llvm::GlobalValue::PrivateLinkage,
    863       ModuleConstant);
    864   GV->setSection(getSectionNameForBitcode(T));
    865   UsedArray.push_back(
    866       ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
    867   if (llvm::GlobalVariable *Old =
    868           M->getGlobalVariable("llvm.embedded.module", true)) {
    869     assert(Old->hasOneUse() &&
    870            "llvm.embedded.module can only be used once in llvm.compiler.used");
    871     GV->takeName(Old);
    872     Old->eraseFromParent();
    873   } else {
    874     GV->setName("llvm.embedded.module");
    875   }
    876 
    877   // Skip if only bitcode needs to be embedded.
    878   if (CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Bitcode) {
    879     // Embed command-line options.
    880     ArrayRef<uint8_t> CmdData(const_cast<uint8_t *>(CGOpts.CmdArgs.data()),
    881                               CGOpts.CmdArgs.size());
    882     llvm::Constant *CmdConstant =
    883       llvm::ConstantDataArray::get(M->getContext(), CmdData);
    884     GV = new llvm::GlobalVariable(*M, CmdConstant->getType(), true,
    885                                   llvm::GlobalValue::PrivateLinkage,
    886                                   CmdConstant);
    887     GV->setSection(getSectionNameForCommandline(T));
    888     UsedArray.push_back(
    889         ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
    890     if (llvm::GlobalVariable *Old =
    891             M->getGlobalVariable("llvm.cmdline", true)) {
    892       assert(Old->hasOneUse() &&
    893              "llvm.cmdline can only be used once in llvm.compiler.used");
    894       GV->takeName(Old);
    895       Old->eraseFromParent();
    896     } else {
    897       GV->setName("llvm.cmdline");
    898     }
    899   }
    900 
    901   if (UsedArray.empty())
    902     return;
    903 
    904   // Recreate llvm.compiler.used.
    905   ArrayType *ATy = ArrayType::get(UsedElementType, UsedArray.size());
    906   auto *NewUsed = new GlobalVariable(
    907       *M, ATy, false, llvm::GlobalValue::AppendingLinkage,
    908       llvm::ConstantArray::get(ATy, UsedArray), "llvm.compiler.used");
    909   NewUsed->setSection("llvm.metadata");
    910 }
    911