text: //===-- llc.cpp - Implement the LLVM Native Code Generator ----------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  //
  // This is the llc code generator driver. It provides a convenient
  // command-line interface for generating native assembly-language code
  // or C code, given LLVM bitcode.
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/Triple.h"
  #include "llvm/Analysis/TargetLibraryInfo.h"
  #include "llvm/CodeGen/CommandFlags.inc"
  #include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
  #include "llvm/CodeGen/LinkAllCodegenComponents.h"
  #include "llvm/CodeGen/MIRParser/MIRParser.h"
  #include "llvm/CodeGen/MachineFunctionPass.h"
  #include "llvm/CodeGen/MachineModuleInfo.h"
  #include "llvm/CodeGen/TargetPassConfig.h"
  #include "llvm/CodeGen/TargetSubtargetInfo.h"
  #include "llvm/IR/AutoUpgrade.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/DiagnosticInfo.h"
  #include "llvm/IR/DiagnosticPrinter.h"
  #include "llvm/IR/IRPrintingPasses.h"
  #include "llvm/IR/LLVMContext.h"
  #include "llvm/IR/LegacyPassManager.h"
  #include "llvm/IR/Module.h"
  #include "llvm/IR/RemarkStreamer.h"
  #include "llvm/IR/Verifier.h"
  #include "llvm/IRReader/IRReader.h"
  #include "llvm/MC/SubtargetFeature.h"
  #include "llvm/Pass.h"
  #include "llvm/Support/CommandLine.h"
  #include "llvm/Support/Debug.h"
  #include "llvm/Support/FileSystem.h"
  #include "llvm/Support/FormattedStream.h"
  #include "llvm/Support/Host.h"
  #include "llvm/Support/InitLLVM.h"
  #include "llvm/Support/ManagedStatic.h"
  #include "llvm/Support/PluginLoader.h"
  #include "llvm/Support/SourceMgr.h"
  #include "llvm/Support/TargetRegistry.h"
  #include "llvm/Support/TargetSelect.h"
  #include "llvm/Support/ToolOutputFile.h"
  #include "llvm/Support/WithColor.h"
  #include "llvm/Target/TargetMachine.h"
  #include "llvm/Transforms/Utils/Cloning.h"
  #include <memory>
  using namespace llvm;
  
  // General options for llc.  Other pass-specific options are specified
  // within the corresponding llc passes, and target-specific options
  // and back-end code generation options are specified with the target machine.
  //
  static cl::opt<std::string>
  InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
  
  static cl::opt<std::string>
  InputLanguage("x", cl::desc("Input language ('ir' or 'mir')"));
  
  static cl::opt<std::string>
  OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
  
  static cl::opt<std::string>
      SplitDwarfOutputFile("split-dwarf-output",
                           cl::desc(".dwo output filename"),
                           cl::value_desc("filename"));
  
  static cl::opt<unsigned>
  TimeCompilations("time-compilations", cl::Hidden, cl::init(1u),
                   cl::value_desc("N"),
                   cl::desc("Repeat compilation N times for timing"));
  
  static cl::opt<bool>
  NoIntegratedAssembler("no-integrated-as", cl::Hidden,
                        cl::desc("Disable integrated assembler"));
  
  static cl::opt<bool>
      PreserveComments("preserve-as-comments", cl::Hidden,
                       cl::desc("Preserve Comments in outputted assembly"),
                       cl::init(true));
  
  // Determine optimization level.
  static cl::opt<char>
  OptLevel("O",
           cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
                    "(default = '-O2')"),
           cl::Prefix,
           cl::ZeroOrMore,
           cl::init(' '));
  
  static cl::opt<std::string>
  TargetTriple("mtriple", cl::desc("Override target triple for module"));
  
  static cl::opt<std::string> SplitDwarfFile(
      "split-dwarf-file",
      cl::desc(
          "Specify the name of the .dwo file to encode in the DWARF output"));
  
  static cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
                                cl::desc("Do not verify input module"));
  
  static cl::opt<bool> DisableSimplifyLibCalls("disable-simplify-libcalls",
                                               cl::desc("Disable simplify-libcalls"));
  
  static cl::opt<bool> ShowMCEncoding("show-mc-encoding", cl::Hidden,
                                      cl::desc("Show encoding in .s output"));
  
  static cl::opt<bool> EnableDwarfDirectory(
      "enable-dwarf-directory", cl::Hidden,
      cl::desc("Use .file directives with an explicit directory."));
  
  static cl::opt<bool> AsmVerbose("asm-verbose",
                                  cl::desc("Add comments to directives."),
                                  cl::init(true));
  
  static cl::opt<bool>
      CompileTwice("compile-twice", cl::Hidden,
                   cl::desc("Run everything twice, re-using the same pass "
                            "manager and verify the result is the same."),
                   cl::init(false));
  
  static cl::opt<bool> DiscardValueNames(
      "discard-value-names",
      cl::desc("Discard names from Value (other than GlobalValue)."),
      cl::init(false), cl::Hidden);
  
  static cl::list<std::string> IncludeDirs("I", cl::desc("include search path"));
  
  static cl::opt<bool> PassRemarksWithHotness(
      "pass-remarks-with-hotness",
      cl::desc("With PGO, include profile count in optimization remarks"),
      cl::Hidden);
  
  static cl::opt<unsigned> PassRemarksHotnessThreshold(
      "pass-remarks-hotness-threshold",
      cl::desc("Minimum profile count required for an optimization remark to be output"),
      cl::Hidden);
  
  static cl::opt<std::string>
      RemarksFilename("pass-remarks-output",
                      cl::desc("YAML output filename for pass remarks"),
                      cl::value_desc("filename"));
  
  static cl::opt<std::string>
      RemarksPasses("pass-remarks-filter",
                    cl::desc("Only record optimization remarks from passes whose "
                             "names match the given regular expression"),
                    cl::value_desc("regex"));
  
  namespace {
  static ManagedStatic<std::vector<std::string>> RunPassNames;
  
  struct RunPassOption {
    void operator=(const std::string &Val) const {
      if (Val.empty())
        return;
      SmallVector<StringRef, 8> PassNames;
      StringRef(Val).split(PassNames, ',', -1, false);
      for (auto PassName : PassNames)
        RunPassNames->push_back(PassName);
    }
  };
  }
  
  static RunPassOption RunPassOpt;
  
  static cl::opt<RunPassOption, true, cl::parser<std::string>> RunPass(
      "run-pass",
      cl::desc("Run compiler only for specified passes (comma separated list)"),
      cl::value_desc("pass-name"), cl::ZeroOrMore, cl::location(RunPassOpt));
  
  static int compileModule(char **, LLVMContext &);
  
  static std::unique_ptr<ToolOutputFile> GetOutputStream(const char *TargetName,
                                                         Triple::OSType OS,
                                                         const char *ProgName) {
    // If we don't yet have an output filename, make one.
    if (OutputFilename.empty()) {
      if (InputFilename == "-")
        OutputFilename = "-";
      else {
        // If InputFilename ends in .bc or .ll, remove it.
        StringRef IFN = InputFilename;
        if (IFN.endswith(".bc") || IFN.endswith(".ll"))
          OutputFilename = IFN.drop_back(3);
        else if (IFN.endswith(".mir"))
          OutputFilename = IFN.drop_back(4);
        else
          OutputFilename = IFN;
  
        switch (FileType) {
        case TargetMachine::CGFT_AssemblyFile:
          if (TargetName[0] == 'c') {
            if (TargetName[1] == 0)
              OutputFilename += ".cbe.c";
            else if (TargetName[1] == 'p' && TargetName[2] == 'p')
              OutputFilename += ".cpp";
            else
              OutputFilename += ".s";
          } else
            OutputFilename += ".s";
          break;
        case TargetMachine::CGFT_ObjectFile:
          if (OS == Triple::Win32)
            OutputFilename += ".obj";
          else
            OutputFilename += ".o";
          break;
        case TargetMachine::CGFT_Null:
          OutputFilename += ".null";
          break;
        }
      }
    }
  
    // Decide if we need "binary" output.
    bool Binary = false;
    switch (FileType) {
    case TargetMachine::CGFT_AssemblyFile:
      break;
    case TargetMachine::CGFT_ObjectFile:
    case TargetMachine::CGFT_Null:
      Binary = true;
      break;
    }
  
    // Open the file.
    std::error_code EC;
    sys::fs::OpenFlags OpenFlags = sys::fs::F_None;
    if (!Binary)
      OpenFlags |= sys::fs::F_Text;
    auto FDOut = llvm::make_unique<ToolOutputFile>(OutputFilename, EC, OpenFlags);
    if (EC) {
      WithColor::error() << EC.message() << '\n';
      return nullptr;
    }
  
    return FDOut;
  }
  
  struct LLCDiagnosticHandler : public DiagnosticHandler {
    bool *HasError;
    LLCDiagnosticHandler(bool *HasErrorPtr) : HasError(HasErrorPtr) {}
    bool handleDiagnostics(const DiagnosticInfo &DI) override {
      if (DI.getSeverity() == DS_Error)
        *HasError = true;
  
      if (auto *Remark = dyn_cast<DiagnosticInfoOptimizationBase>(&DI))
        if (!Remark->isEnabled())
          return true;
  
      DiagnosticPrinterRawOStream DP(errs());
      errs() << LLVMContext::getDiagnosticMessagePrefix(DI.getSeverity()) << ": ";
      DI.print(DP);
      errs() << "\n";
      return true;
    }
  };
  
  static void InlineAsmDiagHandler(const SMDiagnostic &SMD, void *Context,
                                   unsigned LocCookie) {
    bool *HasError = static_cast<bool *>(Context);
    if (SMD.getKind() == SourceMgr::DK_Error)
      *HasError = true;
  
    SMD.print(nullptr, errs());
  
    // For testing purposes, we print the LocCookie here.
    if (LocCookie)
      WithColor::note() << "!srcloc = " << LocCookie << "\n";
  }
  
  // main - Entry point for the llc compiler.
  //
  int main(int argc, char **argv) {
    InitLLVM X(argc, argv);
  
    // Enable debug stream buffering.
    EnableDebugBuffering = true;
  
    LLVMContext Context;
  
    // Initialize targets first, so that --version shows registered targets.
    InitializeAllTargets();
    InitializeAllTargetMCs();
    InitializeAllAsmPrinters();
    InitializeAllAsmParsers();
  
    // Initialize codegen and IR passes used by llc so that the -print-after,
    // -print-before, and -stop-after options work.
    PassRegistry *Registry = PassRegistry::getPassRegistry();
    initializeCore(*Registry);
    initializeCodeGen(*Registry);
    initializeLoopStrengthReducePass(*Registry);
    initializeLowerIntrinsicsPass(*Registry);
    initializeEntryExitInstrumenterPass(*Registry);
    initializePostInlineEntryExitInstrumenterPass(*Registry);
    initializeUnreachableBlockElimLegacyPassPass(*Registry);
    initializeConstantHoistingLegacyPassPass(*Registry);
    initializeScalarOpts(*Registry);
    initializeVectorization(*Registry);
    initializeScalarizeMaskedMemIntrinPass(*Registry);
    initializeExpandReductionsPass(*Registry);
  
    // Initialize debugging passes.
    initializeScavengerTestPass(*Registry);
  
    // Register the target printer for --version.
    cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
  
    cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
  
    Context.setDiscardValueNames(DiscardValueNames);
  
    // Set a diagnostic handler that doesn't exit on the first error
    bool HasError = false;
    Context.setDiagnosticHandler(
        llvm::make_unique<LLCDiagnosticHandler>(&HasError));
    Context.setInlineAsmDiagnosticHandler(InlineAsmDiagHandler, &HasError);
  
    if (PassRemarksWithHotness)
      Context.setDiagnosticsHotnessRequested(true);
  
    if (PassRemarksHotnessThreshold)
      Context.setDiagnosticsHotnessThreshold(PassRemarksHotnessThreshold);
  
    std::unique_ptr<ToolOutputFile> YamlFile;
    if (RemarksFilename != "") {
      std::error_code EC;
      YamlFile =
          llvm::make_unique<ToolOutputFile>(RemarksFilename, EC, sys::fs::F_None);
      if (EC) {
        WithColor::error(errs(), argv[0]) << EC.message() << '\n';
        return 1;
      }
      Context.setRemarkStreamer(
          llvm::make_unique<RemarkStreamer>(RemarksFilename, YamlFile->os()));
  
      if (!RemarksPasses.empty())
        if (Error E = Context.getRemarkStreamer()->setFilter(RemarksPasses)) {
          WithColor::error(errs(), argv[0]) << E << '\n';
          return 1;
        }
    }
  
    if (InputLanguage != "" && InputLanguage != "ir" &&
        InputLanguage != "mir") {
      WithColor::error(errs(), argv[0])
          << "input language must be '', 'IR' or 'MIR'\n";
      return 1;
    }
  
    // Compile the module TimeCompilations times to give better compile time
    // metrics.
    for (unsigned I = TimeCompilations; I; --I)
      if (int RetVal = compileModule(argv, Context))
        return RetVal;
  
    if (YamlFile)
      YamlFile->keep();
    return 0;
  }
  
  static bool addPass(PassManagerBase &PM, const char *argv0,
                      StringRef PassName, TargetPassConfig &TPC) {
    if (PassName == "none")
      return false;
  
    const PassRegistry *PR = PassRegistry::getPassRegistry();
    const PassInfo *PI = PR->getPassInfo(PassName);
    if (!PI) {
      WithColor::error(errs(), argv0)
          << "run-pass " << PassName << " is not registered.\n";
      return true;
    }
  
    Pass *P;
    if (PI->getNormalCtor())
      P = PI->getNormalCtor()();
    else {
      WithColor::error(errs(), argv0)
          << "cannot create pass: " << PI->getPassName() << "\n";
      return true;
    }
    std::string Banner = std::string("After ") + std::string(P->getPassName());
    PM.add(P);
    TPC.printAndVerify(Banner);
  
    return false;
  }
  
  static int compileModule(char **argv, LLVMContext &Context) {
    // Load the module to be compiled...
    SMDiagnostic Err;
    std::unique_ptr<Module> M;
    std::unique_ptr<MIRParser> MIR;
    Triple TheTriple;
  
    bool SkipModule = MCPU == "help" ||
                      (!MAttrs.empty() && MAttrs.front() == "help");
  
    // If user just wants to list available options, skip module loading
    if (!SkipModule) {
      if (InputLanguage == "mir" ||
          (InputLanguage == "" && StringRef(InputFilename).endswith(".mir"))) {
        MIR = createMIRParserFromFile(InputFilename, Err, Context);
        if (MIR)
          M = MIR->parseIRModule();
      } else
        M = parseIRFile(InputFilename, Err, Context, false);
      if (!M) {
        Err.print(argv[0], WithColor::error(errs(), argv[0]));
        return 1;
      }
  
      // If we are supposed to override the target triple, do so now.
      if (!TargetTriple.empty())
        M->setTargetTriple(Triple::normalize(TargetTriple));
      TheTriple = Triple(M->getTargetTriple());
    } else {
      TheTriple = Triple(Triple::normalize(TargetTriple));
    }
  
    if (TheTriple.getTriple().empty())
      TheTriple.setTriple(sys::getDefaultTargetTriple());
  
    // Get the target specific parser.
    std::string Error;
    const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
                                                           Error);
    if (!TheTarget) {
      WithColor::error(errs(), argv[0]) << Error;
      return 1;
    }
  
    std::string CPUStr = getCPUStr(), FeaturesStr = getFeaturesStr();
  
    CodeGenOpt::Level OLvl = CodeGenOpt::Default;
    switch (OptLevel) {
    default:
      WithColor::error(errs(), argv[0]) << "invalid optimization level.\n";
      return 1;
    case ' ': break;
    case '0': OLvl = CodeGenOpt::None; break;
    case '1': OLvl = CodeGenOpt::Less; break;
    case '2': OLvl = CodeGenOpt::Default; break;
    case '3': OLvl = CodeGenOpt::Aggressive; break;
    }
  
    TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
    Options.DisableIntegratedAS = NoIntegratedAssembler;
    Options.MCOptions.ShowMCEncoding = ShowMCEncoding;
    Options.MCOptions.MCUseDwarfDirectory = EnableDwarfDirectory;
    Options.MCOptions.AsmVerbose = AsmVerbose;
    Options.MCOptions.PreserveAsmComments = PreserveComments;
    Options.MCOptions.IASSearchPaths = IncludeDirs;
    Options.MCOptions.SplitDwarfFile = SplitDwarfFile;
  
    std::unique_ptr<TargetMachine> Target(TheTarget->createTargetMachine(
        TheTriple.getTriple(), CPUStr, FeaturesStr, Options, getRelocModel(),
        getCodeModel(), OLvl));
  
    assert(Target && "Could not allocate target machine!");
  
    // If we don't have a module then just exit now. We do this down
    // here since the CPU/Feature help is underneath the target machine
    // creation.
    if (SkipModule)
      return 0;
  
    assert(M && "Should have exited if we didn't have a module!");
    if (FloatABIForCalls != FloatABI::Default)
      Options.FloatABIType = FloatABIForCalls;
  
    // Figure out where we are going to send the output.
    std::unique_ptr<ToolOutputFile> Out =
        GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]);
    if (!Out) return 1;
  
    std::unique_ptr<ToolOutputFile> DwoOut;
    if (!SplitDwarfOutputFile.empty()) {
      std::error_code EC;
      DwoOut = llvm::make_unique<ToolOutputFile>(SplitDwarfOutputFile, EC,
                                                 sys::fs::F_None);
      if (EC) {
        WithColor::error(errs(), argv[0]) << EC.message() << '\n';
        return 1;
      }
    }
  
    // Build up all of the passes that we want to do to the module.
    legacy::PassManager PM;
  
    // Add an appropriate TargetLibraryInfo pass for the module's triple.
    TargetLibraryInfoImpl TLII(Triple(M->getTargetTriple()));
  
    // The -disable-simplify-libcalls flag actually disables all builtin optzns.
    if (DisableSimplifyLibCalls)
      TLII.disableAllFunctions();
    PM.add(new TargetLibraryInfoWrapperPass(TLII));
  
    // Add the target data from the target machine, if it exists, or the module.
    M->setDataLayout(Target->createDataLayout());
  
    // This needs to be done after setting datalayout since it calls verifier
    // to check debug info whereas verifier relies on correct datalayout.
    UpgradeDebugInfo(*M);
  
    // Verify module immediately to catch problems before doInitialization() is
    // called on any passes.
    if (!NoVerify && verifyModule(*M, &errs())) {
      std::string Prefix =
          (Twine(argv[0]) + Twine(": ") + Twine(InputFilename)).str();
      WithColor::error(errs(), Prefix) << "input module is broken!\n";
      return 1;
    }
  
    // Override function attributes based on CPUStr, FeaturesStr, and command line
    // flags.
    setFunctionAttributes(CPUStr, FeaturesStr, *M);
  
    if (RelaxAll.getNumOccurrences() > 0 &&
        FileType != TargetMachine::CGFT_ObjectFile)
      WithColor::warning(errs(), argv[0])
          << ": warning: ignoring -mc-relax-all because filetype != obj";
  
    {
      raw_pwrite_stream *OS = &Out->os();
  
      // Manually do the buffering rather than using buffer_ostream,
      // so we can memcmp the contents in CompileTwice mode
      SmallVector<char, 0> Buffer;
      std::unique_ptr<raw_svector_ostream> BOS;
      if ((FileType != TargetMachine::CGFT_AssemblyFile &&
           !Out->os().supportsSeeking()) ||
          CompileTwice) {
        BOS = make_unique<raw_svector_ostream>(Buffer);
        OS = BOS.get();
      }
  
      const char *argv0 = argv[0];
      LLVMTargetMachine &LLVMTM = static_cast<LLVMTargetMachine&>(*Target);
      MachineModuleInfo *MMI = new MachineModuleInfo(&LLVMTM);
  
      // Construct a custom pass pipeline that starts after instruction
      // selection.
      if (!RunPassNames->empty()) {
        if (!MIR) {
          WithColor::warning(errs(), argv[0])
              << "run-pass is for .mir file only.\n";
          return 1;
        }
        TargetPassConfig &TPC = *LLVMTM.createPassConfig(PM);
        if (TPC.hasLimitedCodeGenPipeline()) {
          WithColor::warning(errs(), argv[0])
              << "run-pass cannot be used with "
              << TPC.getLimitedCodeGenPipelineReason(" and ") << ".\n";
          return 1;
        }
  
        TPC.setDisableVerify(NoVerify);
        PM.add(&TPC);
        PM.add(MMI);
        TPC.printAndVerify("");
        for (const std::string &RunPassName : *RunPassNames) {
          if (addPass(PM, argv0, RunPassName, TPC))
            return 1;
        }
        TPC.setInitialized();
        PM.add(createPrintMIRPass(*OS));
        PM.add(createFreeMachineFunctionPass());
      } else if (Target->addPassesToEmitFile(PM, *OS,
                                             DwoOut ? &DwoOut->os() : nullptr,
                                             FileType, NoVerify, MMI)) {
        WithColor::warning(errs(), argv[0])
            << "target does not support generation of this"
            << " file type!\n";
        return 1;
      }
  
      if (MIR) {
        assert(MMI && "Forgot to create MMI?");
        if (MIR->parseMachineFunctions(*M, *MMI))
          return 1;
      }
  
      // Before executing passes, print the final values of the LLVM options.
      cl::PrintOptionValues();
  
      // If requested, run the pass manager over the same module again,
      // to catch any bugs due to persistent state in the passes. Note that
      // opt has the same functionality, so it may be worth abstracting this out
      // in the future.
      SmallVector<char, 0> CompileTwiceBuffer;
      if (CompileTwice) {
        std::unique_ptr<Module> M2(llvm::CloneModule(*M));
        PM.run(*M2);
        CompileTwiceBuffer = Buffer;
        Buffer.clear();
      }
  
      PM.run(*M);
  
      auto HasError =
          ((const LLCDiagnosticHandler *)(Context.getDiagHandlerPtr()))->HasError;
      if (*HasError)
        return 1;
  
      // Compare the two outputs and make sure they're the same
      if (CompileTwice) {
        if (Buffer.size() != CompileTwiceBuffer.size() ||
            (memcmp(Buffer.data(), CompileTwiceBuffer.data(), Buffer.size()) !=
             0)) {
          errs()
              << "Running the pass manager twice changed the output.\n"
                 "Writing the result of the second run to the specified output\n"
                 "To generate the one-run comparison binary, just run without\n"
                 "the compile-twice option\n";
          Out->os() << Buffer;
          Out->keep();
          return 1;
        }
      }
  
      if (BOS) {
        Out->os() << Buffer;
      }
    }
  
    // Declare success.
    Out->keep();
    if (DwoOut)
      DwoOut->keep();
  
    return 0;
  }
  