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      1 //===-LTOCodeGenerator.cpp - LLVM Link Time Optimizer ---------------------===//
      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 // This file implements the Link Time Optimization library. This library is
     11 // intended to be used by linker to optimize code at link time.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "llvm/LTO/legacy/LTOCodeGenerator.h"
     16 
     17 #include "llvm/ADT/Statistic.h"
     18 #include "llvm/ADT/StringExtras.h"
     19 #include "llvm/Analysis/Passes.h"
     20 #include "llvm/Analysis/TargetLibraryInfo.h"
     21 #include "llvm/Analysis/TargetTransformInfo.h"
     22 #include "llvm/Bitcode/ReaderWriter.h"
     23 #include "llvm/CodeGen/ParallelCG.h"
     24 #include "llvm/CodeGen/RuntimeLibcalls.h"
     25 #include "llvm/Config/config.h"
     26 #include "llvm/IR/Constants.h"
     27 #include "llvm/IR/DataLayout.h"
     28 #include "llvm/IR/DebugInfo.h"
     29 #include "llvm/IR/DerivedTypes.h"
     30 #include "llvm/IR/DiagnosticInfo.h"
     31 #include "llvm/IR/DiagnosticPrinter.h"
     32 #include "llvm/IR/LLVMContext.h"
     33 #include "llvm/IR/LegacyPassManager.h"
     34 #include "llvm/IR/Mangler.h"
     35 #include "llvm/IR/Module.h"
     36 #include "llvm/IR/Verifier.h"
     37 #include "llvm/InitializePasses.h"
     38 #include "llvm/LTO/legacy/LTOModule.h"
     39 #include "llvm/LTO/legacy/UpdateCompilerUsed.h"
     40 #include "llvm/Linker/Linker.h"
     41 #include "llvm/MC/MCAsmInfo.h"
     42 #include "llvm/MC/MCContext.h"
     43 #include "llvm/MC/SubtargetFeature.h"
     44 #include "llvm/Support/CommandLine.h"
     45 #include "llvm/Support/FileSystem.h"
     46 #include "llvm/Support/Host.h"
     47 #include "llvm/Support/MemoryBuffer.h"
     48 #include "llvm/Support/Signals.h"
     49 #include "llvm/Support/TargetRegistry.h"
     50 #include "llvm/Support/TargetSelect.h"
     51 #include "llvm/Support/ToolOutputFile.h"
     52 #include "llvm/Support/raw_ostream.h"
     53 #include "llvm/Target/TargetLowering.h"
     54 #include "llvm/Target/TargetOptions.h"
     55 #include "llvm/Target/TargetRegisterInfo.h"
     56 #include "llvm/Target/TargetSubtargetInfo.h"
     57 #include "llvm/Transforms/IPO.h"
     58 #include "llvm/Transforms/IPO/Internalize.h"
     59 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
     60 #include "llvm/Transforms/ObjCARC.h"
     61 #include <system_error>
     62 using namespace llvm;
     63 
     64 const char* LTOCodeGenerator::getVersionString() {
     65 #ifdef LLVM_VERSION_INFO
     66   return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
     67 #else
     68   return PACKAGE_NAME " version " PACKAGE_VERSION;
     69 #endif
     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> LTOStripInvalidDebugInfo(
     84     "lto-strip-invalid-debug-info",
     85     cl::desc("Strip invalid debug info metadata during LTO instead of aborting."),
     86 #ifdef NDEBUG
     87     cl::init(true),
     88 #else
     89     cl::init(false),
     90 #endif
     91     cl::Hidden);
     92 }
     93 
     94 LTOCodeGenerator::LTOCodeGenerator(LLVMContext &Context)
     95     : Context(Context), MergedModule(new Module("ld-temp.o", Context)),
     96       TheLinker(new Linker(*MergedModule)) {
     97   Context.setDiscardValueNames(LTODiscardValueNames);
     98   Context.enableDebugTypeODRUniquing();
     99   initializeLTOPasses();
    100 }
    101 
    102 LTOCodeGenerator::~LTOCodeGenerator() {}
    103 
    104 // Initialize LTO passes. Please keep this function in sync with
    105 // PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
    106 // passes are initialized.
    107 void LTOCodeGenerator::initializeLTOPasses() {
    108   PassRegistry &R = *PassRegistry::getPassRegistry();
    109 
    110   initializeInternalizeLegacyPassPass(R);
    111   initializeIPSCCPLegacyPassPass(R);
    112   initializeGlobalOptLegacyPassPass(R);
    113   initializeConstantMergeLegacyPassPass(R);
    114   initializeDAHPass(R);
    115   initializeInstructionCombiningPassPass(R);
    116   initializeSimpleInlinerPass(R);
    117   initializePruneEHPass(R);
    118   initializeGlobalDCELegacyPassPass(R);
    119   initializeArgPromotionPass(R);
    120   initializeJumpThreadingPass(R);
    121   initializeSROALegacyPassPass(R);
    122   initializePostOrderFunctionAttrsLegacyPassPass(R);
    123   initializeReversePostOrderFunctionAttrsLegacyPassPass(R);
    124   initializeGlobalsAAWrapperPassPass(R);
    125   initializeLegacyLICMPassPass(R);
    126   initializeMergedLoadStoreMotionLegacyPassPass(R);
    127   initializeGVNLegacyPassPass(R);
    128   initializeMemCpyOptLegacyPassPass(R);
    129   initializeDCELegacyPassPass(R);
    130   initializeCFGSimplifyPassPass(R);
    131 }
    132 
    133 bool LTOCodeGenerator::addModule(LTOModule *Mod) {
    134   assert(&Mod->getModule().getContext() == &Context &&
    135          "Expected module in same context");
    136 
    137   bool ret = TheLinker->linkInModule(Mod->takeModule());
    138 
    139   const std::vector<const char *> &undefs = Mod->getAsmUndefinedRefs();
    140   for (int i = 0, e = undefs.size(); i != e; ++i)
    141     AsmUndefinedRefs[undefs[i]] = 1;
    142 
    143   // We've just changed the input, so let's make sure we verify it.
    144   HasVerifiedInput = false;
    145 
    146   return !ret;
    147 }
    148 
    149 void LTOCodeGenerator::setModule(std::unique_ptr<LTOModule> Mod) {
    150   assert(&Mod->getModule().getContext() == &Context &&
    151          "Expected module in same context");
    152 
    153   AsmUndefinedRefs.clear();
    154 
    155   MergedModule = Mod->takeModule();
    156   TheLinker = make_unique<Linker>(*MergedModule);
    157 
    158   const std::vector<const char*> &Undefs = Mod->getAsmUndefinedRefs();
    159   for (int I = 0, E = Undefs.size(); I != E; ++I)
    160     AsmUndefinedRefs[Undefs[I]] = 1;
    161 
    162   // We've just changed the input, so let's make sure we verify it.
    163   HasVerifiedInput = false;
    164 }
    165 
    166 void LTOCodeGenerator::setTargetOptions(const TargetOptions &Options) {
    167   this->Options = Options;
    168 }
    169 
    170 void LTOCodeGenerator::setDebugInfo(lto_debug_model Debug) {
    171   switch (Debug) {
    172   case LTO_DEBUG_MODEL_NONE:
    173     EmitDwarfDebugInfo = false;
    174     return;
    175 
    176   case LTO_DEBUG_MODEL_DWARF:
    177     EmitDwarfDebugInfo = true;
    178     return;
    179   }
    180   llvm_unreachable("Unknown debug format!");
    181 }
    182 
    183 void LTOCodeGenerator::setOptLevel(unsigned Level) {
    184   OptLevel = Level;
    185   switch (OptLevel) {
    186   case 0:
    187     CGOptLevel = CodeGenOpt::None;
    188     break;
    189   case 1:
    190     CGOptLevel = CodeGenOpt::Less;
    191     break;
    192   case 2:
    193     CGOptLevel = CodeGenOpt::Default;
    194     break;
    195   case 3:
    196     CGOptLevel = CodeGenOpt::Aggressive;
    197     break;
    198   }
    199 }
    200 
    201 bool LTOCodeGenerator::writeMergedModules(const char *Path) {
    202   if (!determineTarget())
    203     return false;
    204 
    205   // We always run the verifier once on the merged module.
    206   verifyMergedModuleOnce();
    207 
    208   // mark which symbols can not be internalized
    209   applyScopeRestrictions();
    210 
    211   // create output file
    212   std::error_code EC;
    213   tool_output_file Out(Path, EC, sys::fs::F_None);
    214   if (EC) {
    215     std::string ErrMsg = "could not open bitcode file for writing: ";
    216     ErrMsg += Path;
    217     emitError(ErrMsg);
    218     return false;
    219   }
    220 
    221   // write bitcode to it
    222   WriteBitcodeToFile(MergedModule.get(), Out.os(), ShouldEmbedUselists);
    223   Out.os().close();
    224 
    225   if (Out.os().has_error()) {
    226     std::string ErrMsg = "could not write bitcode file: ";
    227     ErrMsg += Path;
    228     emitError(ErrMsg);
    229     Out.os().clear_error();
    230     return false;
    231   }
    232 
    233   Out.keep();
    234   return true;
    235 }
    236 
    237 bool LTOCodeGenerator::compileOptimizedToFile(const char **Name) {
    238   // make unique temp output file to put generated code
    239   SmallString<128> Filename;
    240   int FD;
    241 
    242   const char *Extension =
    243       (FileType == TargetMachine::CGFT_AssemblyFile ? "s" : "o");
    244 
    245   std::error_code EC =
    246       sys::fs::createTemporaryFile("lto-llvm", Extension, FD, Filename);
    247   if (EC) {
    248     emitError(EC.message());
    249     return false;
    250   }
    251 
    252   // generate object file
    253   tool_output_file objFile(Filename.c_str(), FD);
    254 
    255   bool genResult = compileOptimized(&objFile.os());
    256   objFile.os().close();
    257   if (objFile.os().has_error()) {
    258     objFile.os().clear_error();
    259     sys::fs::remove(Twine(Filename));
    260     return false;
    261   }
    262 
    263   objFile.keep();
    264   if (!genResult) {
    265     sys::fs::remove(Twine(Filename));
    266     return false;
    267   }
    268 
    269   NativeObjectPath = Filename.c_str();
    270   *Name = NativeObjectPath.c_str();
    271   return true;
    272 }
    273 
    274 std::unique_ptr<MemoryBuffer>
    275 LTOCodeGenerator::compileOptimized() {
    276   const char *name;
    277   if (!compileOptimizedToFile(&name))
    278     return nullptr;
    279 
    280   // read .o file into memory buffer
    281   ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
    282       MemoryBuffer::getFile(name, -1, false);
    283   if (std::error_code EC = BufferOrErr.getError()) {
    284     emitError(EC.message());
    285     sys::fs::remove(NativeObjectPath);
    286     return nullptr;
    287   }
    288 
    289   // remove temp files
    290   sys::fs::remove(NativeObjectPath);
    291 
    292   return std::move(*BufferOrErr);
    293 }
    294 
    295 bool LTOCodeGenerator::compile_to_file(const char **Name, bool DisableVerify,
    296                                        bool DisableInline,
    297                                        bool DisableGVNLoadPRE,
    298                                        bool DisableVectorization) {
    299   if (!optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
    300                 DisableVectorization))
    301     return false;
    302 
    303   return compileOptimizedToFile(Name);
    304 }
    305 
    306 std::unique_ptr<MemoryBuffer>
    307 LTOCodeGenerator::compile(bool DisableVerify, bool DisableInline,
    308                           bool DisableGVNLoadPRE, bool DisableVectorization) {
    309   if (!optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
    310                 DisableVectorization))
    311     return nullptr;
    312 
    313   return compileOptimized();
    314 }
    315 
    316 bool LTOCodeGenerator::determineTarget() {
    317   if (TargetMach)
    318     return true;
    319 
    320   TripleStr = MergedModule->getTargetTriple();
    321   if (TripleStr.empty()) {
    322     TripleStr = sys::getDefaultTargetTriple();
    323     MergedModule->setTargetTriple(TripleStr);
    324   }
    325   llvm::Triple Triple(TripleStr);
    326 
    327   // create target machine from info for merged modules
    328   std::string ErrMsg;
    329   MArch = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
    330   if (!MArch) {
    331     emitError(ErrMsg);
    332     return false;
    333   }
    334 
    335   // Construct LTOModule, hand over ownership of module and target. Use MAttr as
    336   // the default set of features.
    337   SubtargetFeatures Features(MAttr);
    338   Features.getDefaultSubtargetFeatures(Triple);
    339   FeatureStr = Features.getString();
    340   // Set a default CPU for Darwin triples.
    341   if (MCpu.empty() && Triple.isOSDarwin()) {
    342     if (Triple.getArch() == llvm::Triple::x86_64)
    343       MCpu = "core2";
    344     else if (Triple.getArch() == llvm::Triple::x86)
    345       MCpu = "yonah";
    346     else if (Triple.getArch() == llvm::Triple::aarch64)
    347       MCpu = "cyclone";
    348   }
    349 
    350   TargetMach = createTargetMachine();
    351   return true;
    352 }
    353 
    354 std::unique_ptr<TargetMachine> LTOCodeGenerator::createTargetMachine() {
    355   return std::unique_ptr<TargetMachine>(
    356       MArch->createTargetMachine(TripleStr, MCpu, FeatureStr, Options,
    357                                  RelocModel, CodeModel::Default, CGOptLevel));
    358 }
    359 
    360 // If a linkonce global is present in the MustPreserveSymbols, we need to make
    361 // sure we honor this. To force the compiler to not drop it, we add it to the
    362 // "llvm.compiler.used" global.
    363 void LTOCodeGenerator::preserveDiscardableGVs(
    364     Module &TheModule,
    365     llvm::function_ref<bool(const GlobalValue &)> mustPreserveGV) {
    366   SetVector<Constant *> UsedValuesSet;
    367   if (GlobalVariable *LLVMUsed =
    368           TheModule.getGlobalVariable("llvm.compiler.used")) {
    369     ConstantArray *Inits = cast<ConstantArray>(LLVMUsed->getInitializer());
    370     for (auto &V : Inits->operands())
    371       UsedValuesSet.insert(cast<Constant>(&V));
    372     LLVMUsed->eraseFromParent();
    373   }
    374   llvm::Type *i8PTy = llvm::Type::getInt8PtrTy(TheModule.getContext());
    375   auto mayPreserveGlobal = [&](GlobalValue &GV) {
    376     if (!GV.isDiscardableIfUnused() || GV.isDeclaration())
    377       return;
    378     if (!mustPreserveGV(GV))
    379       return;
    380     if (GV.hasAvailableExternallyLinkage()) {
    381       emitWarning(
    382           (Twine("Linker asked to preserve available_externally global: '") +
    383            GV.getName() + "'").str());
    384       return;
    385     }
    386     if (GV.hasInternalLinkage()) {
    387       emitWarning((Twine("Linker asked to preserve internal global: '") +
    388                    GV.getName() + "'").str());
    389       return;
    390     }
    391     UsedValuesSet.insert(ConstantExpr::getBitCast(&GV, i8PTy));
    392   };
    393   for (auto &GV : TheModule)
    394     mayPreserveGlobal(GV);
    395   for (auto &GV : TheModule.globals())
    396     mayPreserveGlobal(GV);
    397   for (auto &GV : TheModule.aliases())
    398     mayPreserveGlobal(GV);
    399 
    400   if (UsedValuesSet.empty())
    401     return;
    402 
    403   llvm::ArrayType *ATy = llvm::ArrayType::get(i8PTy, UsedValuesSet.size());
    404   auto *LLVMUsed = new llvm::GlobalVariable(
    405       TheModule, ATy, false, llvm::GlobalValue::AppendingLinkage,
    406       llvm::ConstantArray::get(ATy, UsedValuesSet.getArrayRef()),
    407       "llvm.compiler.used");
    408   LLVMUsed->setSection("llvm.metadata");
    409 }
    410 
    411 void LTOCodeGenerator::applyScopeRestrictions() {
    412   if (ScopeRestrictionsDone)
    413     return;
    414 
    415   // Declare a callback for the internalize pass that will ask for every
    416   // candidate GlobalValue if it can be internalized or not.
    417   SmallString<64> MangledName;
    418   auto mustPreserveGV = [&](const GlobalValue &GV) -> bool {
    419     // Unnamed globals can't be mangled, but they can't be preserved either.
    420     if (!GV.hasName())
    421       return false;
    422 
    423     // Need to mangle the GV as the "MustPreserveSymbols" StringSet is filled
    424     // with the linker supplied name, which on Darwin includes a leading
    425     // underscore.
    426     MangledName.clear();
    427     MangledName.reserve(GV.getName().size() + 1);
    428     Mangler::getNameWithPrefix(MangledName, GV.getName(),
    429                                MergedModule->getDataLayout());
    430     return MustPreserveSymbols.count(MangledName);
    431   };
    432 
    433   // Preserve linkonce value on linker request
    434   preserveDiscardableGVs(*MergedModule, mustPreserveGV);
    435 
    436   if (!ShouldInternalize)
    437     return;
    438 
    439   if (ShouldRestoreGlobalsLinkage) {
    440     // Record the linkage type of non-local symbols so they can be restored
    441     // prior
    442     // to module splitting.
    443     auto RecordLinkage = [&](const GlobalValue &GV) {
    444       if (!GV.hasAvailableExternallyLinkage() && !GV.hasLocalLinkage() &&
    445           GV.hasName())
    446         ExternalSymbols.insert(std::make_pair(GV.getName(), GV.getLinkage()));
    447     };
    448     for (auto &GV : *MergedModule)
    449       RecordLinkage(GV);
    450     for (auto &GV : MergedModule->globals())
    451       RecordLinkage(GV);
    452     for (auto &GV : MergedModule->aliases())
    453       RecordLinkage(GV);
    454   }
    455 
    456   // Update the llvm.compiler_used globals to force preserving libcalls and
    457   // symbols referenced from asm
    458   updateCompilerUsed(*MergedModule, *TargetMach, AsmUndefinedRefs);
    459 
    460   internalizeModule(*MergedModule, mustPreserveGV);
    461 
    462   ScopeRestrictionsDone = true;
    463 }
    464 
    465 /// Restore original linkage for symbols that may have been internalized
    466 void LTOCodeGenerator::restoreLinkageForExternals() {
    467   if (!ShouldInternalize || !ShouldRestoreGlobalsLinkage)
    468     return;
    469 
    470   assert(ScopeRestrictionsDone &&
    471          "Cannot externalize without internalization!");
    472 
    473   if (ExternalSymbols.empty())
    474     return;
    475 
    476   auto externalize = [this](GlobalValue &GV) {
    477     if (!GV.hasLocalLinkage() || !GV.hasName())
    478       return;
    479 
    480     auto I = ExternalSymbols.find(GV.getName());
    481     if (I == ExternalSymbols.end())
    482       return;
    483 
    484     GV.setLinkage(I->second);
    485   };
    486 
    487   std::for_each(MergedModule->begin(), MergedModule->end(), externalize);
    488   std::for_each(MergedModule->global_begin(), MergedModule->global_end(),
    489                 externalize);
    490   std::for_each(MergedModule->alias_begin(), MergedModule->alias_end(),
    491                 externalize);
    492 }
    493 
    494 void LTOCodeGenerator::verifyMergedModuleOnce() {
    495   // Only run on the first call.
    496   if (HasVerifiedInput)
    497     return;
    498   HasVerifiedInput = true;
    499 
    500   if (LTOStripInvalidDebugInfo) {
    501     bool BrokenDebugInfo = false;
    502     if (verifyModule(*MergedModule, &dbgs(), &BrokenDebugInfo))
    503       report_fatal_error("Broken module found, compilation aborted!");
    504     if (BrokenDebugInfo) {
    505       emitWarning("Invalid debug info found, debug info will be stripped");
    506       StripDebugInfo(*MergedModule);
    507     }
    508   }
    509   if (verifyModule(*MergedModule, &dbgs()))
    510     report_fatal_error("Broken module found, compilation aborted!");
    511 }
    512 
    513 /// Optimize merged modules using various IPO passes
    514 bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
    515                                 bool DisableGVNLoadPRE,
    516                                 bool DisableVectorization) {
    517   if (!this->determineTarget())
    518     return false;
    519 
    520   // We always run the verifier once on the merged module, the `DisableVerify`
    521   // parameter only applies to subsequent verify.
    522   verifyMergedModuleOnce();
    523 
    524   // Mark which symbols can not be internalized
    525   this->applyScopeRestrictions();
    526 
    527   // Instantiate the pass manager to organize the passes.
    528   legacy::PassManager passes;
    529 
    530   // Add an appropriate DataLayout instance for this module...
    531   MergedModule->setDataLayout(TargetMach->createDataLayout());
    532 
    533   passes.add(
    534       createTargetTransformInfoWrapperPass(TargetMach->getTargetIRAnalysis()));
    535 
    536   Triple TargetTriple(TargetMach->getTargetTriple());
    537   PassManagerBuilder PMB;
    538   PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
    539   PMB.LoopVectorize = !DisableVectorization;
    540   PMB.SLPVectorize = !DisableVectorization;
    541   if (!DisableInline)
    542     PMB.Inliner = createFunctionInliningPass();
    543   PMB.LibraryInfo = new TargetLibraryInfoImpl(TargetTriple);
    544   PMB.OptLevel = OptLevel;
    545   PMB.VerifyInput = !DisableVerify;
    546   PMB.VerifyOutput = !DisableVerify;
    547 
    548   PMB.populateLTOPassManager(passes);
    549 
    550   // Run our queue of passes all at once now, efficiently.
    551   passes.run(*MergedModule);
    552 
    553   return true;
    554 }
    555 
    556 bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
    557   if (!this->determineTarget())
    558     return false;
    559 
    560   // We always run the verifier once on the merged module.  If it has already
    561   // been called in optimize(), this call will return early.
    562   verifyMergedModuleOnce();
    563 
    564   legacy::PassManager preCodeGenPasses;
    565 
    566   // If the bitcode files contain ARC code and were compiled with optimization,
    567   // the ObjCARCContractPass must be run, so do it unconditionally here.
    568   preCodeGenPasses.add(createObjCARCContractPass());
    569   preCodeGenPasses.run(*MergedModule);
    570 
    571   // Re-externalize globals that may have been internalized to increase scope
    572   // for splitting
    573   restoreLinkageForExternals();
    574 
    575   // Do code generation. We need to preserve the module in case the client calls
    576   // writeMergedModules() after compilation, but we only need to allow this at
    577   // parallelism level 1. This is achieved by having splitCodeGen return the
    578   // original module at parallelism level 1 which we then assign back to
    579   // MergedModule.
    580   MergedModule = splitCodeGen(std::move(MergedModule), Out, {},
    581                               [&]() { return createTargetMachine(); }, FileType,
    582                               ShouldRestoreGlobalsLinkage);
    583 
    584   // If statistics were requested, print them out after codegen.
    585   if (llvm::AreStatisticsEnabled())
    586     llvm::PrintStatistics();
    587 
    588   return true;
    589 }
    590 
    591 /// setCodeGenDebugOptions - Set codegen debugging options to aid in debugging
    592 /// LTO problems.
    593 void LTOCodeGenerator::setCodeGenDebugOptions(const char *Options) {
    594   for (std::pair<StringRef, StringRef> o = getToken(Options); !o.first.empty();
    595        o = getToken(o.second))
    596     CodegenOptions.push_back(o.first);
    597 }
    598 
    599 void LTOCodeGenerator::parseCodeGenDebugOptions() {
    600   // if options were requested, set them
    601   if (!CodegenOptions.empty()) {
    602     // ParseCommandLineOptions() expects argv[0] to be program name.
    603     std::vector<const char *> CodegenArgv(1, "libLLVMLTO");
    604     for (std::string &Arg : CodegenOptions)
    605       CodegenArgv.push_back(Arg.c_str());
    606     cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
    607   }
    608 }
    609 
    610 void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI,
    611                                          void *Context) {
    612   ((LTOCodeGenerator *)Context)->DiagnosticHandler2(DI);
    613 }
    614 
    615 void LTOCodeGenerator::DiagnosticHandler2(const DiagnosticInfo &DI) {
    616   // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
    617   lto_codegen_diagnostic_severity_t Severity;
    618   switch (DI.getSeverity()) {
    619   case DS_Error:
    620     Severity = LTO_DS_ERROR;
    621     break;
    622   case DS_Warning:
    623     Severity = LTO_DS_WARNING;
    624     break;
    625   case DS_Remark:
    626     Severity = LTO_DS_REMARK;
    627     break;
    628   case DS_Note:
    629     Severity = LTO_DS_NOTE;
    630     break;
    631   }
    632   // Create the string that will be reported to the external diagnostic handler.
    633   std::string MsgStorage;
    634   raw_string_ostream Stream(MsgStorage);
    635   DiagnosticPrinterRawOStream DP(Stream);
    636   DI.print(DP);
    637   Stream.flush();
    638 
    639   // If this method has been called it means someone has set up an external
    640   // diagnostic handler. Assert on that.
    641   assert(DiagHandler && "Invalid diagnostic handler");
    642   (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
    643 }
    644 
    645 void
    646 LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
    647                                        void *Ctxt) {
    648   this->DiagHandler = DiagHandler;
    649   this->DiagContext = Ctxt;
    650   if (!DiagHandler)
    651     return Context.setDiagnosticHandler(nullptr, nullptr);
    652   // Register the LTOCodeGenerator stub in the LLVMContext to forward the
    653   // diagnostic to the external DiagHandler.
    654   Context.setDiagnosticHandler(LTOCodeGenerator::DiagnosticHandler, this,
    655                                /* RespectFilters */ true);
    656 }
    657 
    658 namespace {
    659 class LTODiagnosticInfo : public DiagnosticInfo {
    660   const Twine &Msg;
    661 public:
    662   LTODiagnosticInfo(const Twine &DiagMsg, DiagnosticSeverity Severity=DS_Error)
    663       : DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
    664   void print(DiagnosticPrinter &DP) const override { DP << Msg; }
    665 };
    666 }
    667 
    668 void LTOCodeGenerator::emitError(const std::string &ErrMsg) {
    669   if (DiagHandler)
    670     (*DiagHandler)(LTO_DS_ERROR, ErrMsg.c_str(), DiagContext);
    671   else
    672     Context.diagnose(LTODiagnosticInfo(ErrMsg));
    673 }
    674 
    675 void LTOCodeGenerator::emitWarning(const std::string &ErrMsg) {
    676   if (DiagHandler)
    677     (*DiagHandler)(LTO_DS_WARNING, ErrMsg.c_str(), DiagContext);
    678   else
    679     Context.diagnose(LTODiagnosticInfo(ErrMsg, DS_Warning));
    680 }
    681