text: //===-- llvm-dis.cpp - The low-level LLVM disassembler --------------------===//
  //
  // 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 utility may be invoked in the following manner:
  //  llvm-dis [options]      - Read LLVM bitcode from stdin, write asm to stdout
  //  llvm-dis [options] x.bc - Read LLVM bitcode from the x.bc file, write asm
  //                            to the x.ll file.
  //  Options:
  //      --help   - Output information about command line switches
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm/Bitcode/BitcodeReader.h"
  #include "llvm/IR/AssemblyAnnotationWriter.h"
  #include "llvm/IR/DebugInfo.h"
  #include "llvm/IR/DiagnosticInfo.h"
  #include "llvm/IR/DiagnosticPrinter.h"
  #include "llvm/IR/IntrinsicInst.h"
  #include "llvm/IR/LLVMContext.h"
  #include "llvm/IR/Module.h"
  #include "llvm/IR/Type.h"
  #include "llvm/Support/CommandLine.h"
  #include "llvm/Support/Error.h"
  #include "llvm/Support/FileSystem.h"
  #include "llvm/Support/FormattedStream.h"
  #include "llvm/Support/InitLLVM.h"
  #include "llvm/Support/MemoryBuffer.h"
  #include "llvm/Support/ToolOutputFile.h"
  #include "llvm/Support/WithColor.h"
  #include <system_error>
  using namespace llvm;
  
  static cl::opt<std::string>
  InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
  
  static cl::opt<std::string>
  OutputFilename("o", cl::desc("Override output filename"),
                 cl::value_desc("filename"));
  
  static cl::opt<bool>
  Force("f", cl::desc("Enable binary output on terminals"));
  
  static cl::opt<bool>
  DontPrint("disable-output", cl::desc("Don't output the .ll file"), cl::Hidden);
  
  static cl::opt<bool>
      SetImporting("set-importing",
                   cl::desc("Set lazy loading to pretend to import a module"),
                   cl::Hidden);
  
  static cl::opt<bool>
      ShowAnnotations("show-annotations",
                      cl::desc("Add informational comments to the .ll file"));
  
  static cl::opt<bool> PreserveAssemblyUseListOrder(
      "preserve-ll-uselistorder",
      cl::desc("Preserve use-list order when writing LLVM assembly."),
      cl::init(false), cl::Hidden);
  
  static cl::opt<bool>
      MaterializeMetadata("materialize-metadata",
                          cl::desc("Load module without materializing metadata, "
                                   "then materialize only the metadata"));
  
  namespace {
  
  static void printDebugLoc(const DebugLoc &DL, formatted_raw_ostream &OS) {
    OS << DL.getLine() << ":" << DL.getCol();
    if (DILocation *IDL = DL.getInlinedAt()) {
      OS << "@";
      printDebugLoc(IDL, OS);
    }
  }
  class CommentWriter : public AssemblyAnnotationWriter {
  public:
    void emitFunctionAnnot(const Function *F,
                           formatted_raw_ostream &OS) override {
      OS << "; [#uses=" << F->getNumUses() << ']';  // Output # uses
      OS << '\n';
    }
    void printInfoComment(const Value &V, formatted_raw_ostream &OS) override {
      bool Padded = false;
      if (!V.getType()->isVoidTy()) {
        OS.PadToColumn(50);
        Padded = true;
        // Output # uses and type
        OS << "; [#uses=" << V.getNumUses() << " type=" << *V.getType() << "]";
      }
      if (const Instruction *I = dyn_cast<Instruction>(&V)) {
        if (const DebugLoc &DL = I->getDebugLoc()) {
          if (!Padded) {
            OS.PadToColumn(50);
            Padded = true;
            OS << ";";
          }
          OS << " [debug line = ";
          printDebugLoc(DL,OS);
          OS << "]";
        }
        if (const DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(I)) {
          if (!Padded) {
            OS.PadToColumn(50);
            OS << ";";
          }
          OS << " [debug variable = " << DDI->getVariable()->getName() << "]";
        }
        else if (const DbgValueInst *DVI = dyn_cast<DbgValueInst>(I)) {
          if (!Padded) {
            OS.PadToColumn(50);
            OS << ";";
          }
          OS << " [debug variable = " << DVI->getVariable()->getName() << "]";
        }
      }
    }
  };
  
  struct LLVMDisDiagnosticHandler : public DiagnosticHandler {
    char *Prefix;
    LLVMDisDiagnosticHandler(char *PrefixPtr) : Prefix(PrefixPtr) {}
    bool handleDiagnostics(const DiagnosticInfo &DI) override {
      raw_ostream &OS = errs();
      OS << Prefix << ": ";
      switch (DI.getSeverity()) {
        case DS_Error: WithColor::error(OS); break;
        case DS_Warning: WithColor::warning(OS); break;
        case DS_Remark: OS << "remark: "; break;
        case DS_Note: WithColor::note(OS); break;
      }
  
      DiagnosticPrinterRawOStream DP(OS);
      DI.print(DP);
      OS << '\n';
  
      if (DI.getSeverity() == DS_Error)
        exit(1);
      return true;
    }
  };
  } // end anon namespace
  
  static ExitOnError ExitOnErr;
  
  int main(int argc, char **argv) {
    InitLLVM X(argc, argv);
  
    ExitOnErr.setBanner(std::string(argv[0]) + ": error: ");
  
    LLVMContext Context;
    Context.setDiagnosticHandler(
        std::make_unique<LLVMDisDiagnosticHandler>(argv[0]));
    cl::ParseCommandLineOptions(argc, argv, "llvm .bc -> .ll disassembler\n");
  
    std::unique_ptr<MemoryBuffer> MB =
        ExitOnErr(errorOrToExpected(MemoryBuffer::getFileOrSTDIN(InputFilename)));
  
    BitcodeFileContents IF = ExitOnErr(llvm::getBitcodeFileContents(*MB));
  
    const size_t N = IF.Mods.size();
  
    if (OutputFilename == "-" && N > 1)
        errs() << "only single module bitcode files can be written to stdout\n";
  
    for (size_t i = 0; i < N; ++i) {
      BitcodeModule MB = IF.Mods[i];
      std::unique_ptr<Module> M = ExitOnErr(MB.getLazyModule(Context, MaterializeMetadata,
                                            SetImporting));
      if (MaterializeMetadata)
        ExitOnErr(M->materializeMetadata());
      else
        ExitOnErr(M->materializeAll());
  
      BitcodeLTOInfo LTOInfo = ExitOnErr(MB.getLTOInfo());
      std::unique_ptr<ModuleSummaryIndex> Index;
      if (LTOInfo.HasSummary)
        Index = ExitOnErr(MB.getSummary());
  
      std::string FinalFilename(OutputFilename);
  
      // Just use stdout.  We won't actually print anything on it.
      if (DontPrint)
        FinalFilename = "-";
  
      if (FinalFilename.empty()) { // Unspecified output, infer it.
        if (InputFilename == "-") {
          FinalFilename = "-";
        } else {
          StringRef IFN = InputFilename;
          FinalFilename = (IFN.endswith(".bc") ? IFN.drop_back(3) : IFN).str();
          if (N > 1)
            FinalFilename += std::string(".") + std::to_string(i);
          FinalFilename += ".ll";
        }
      } else {
        if (N > 1)
          FinalFilename += std::string(".") + std::to_string(i);
      }
  
      std::error_code EC;
      std::unique_ptr<ToolOutputFile> Out(
          new ToolOutputFile(FinalFilename, EC, sys::fs::OF_TextWithCRLF));
      if (EC) {
        errs() << EC.message() << '\n';
        return 1;
      }
  
      std::unique_ptr<AssemblyAnnotationWriter> Annotator;
      if (ShowAnnotations)
        Annotator.reset(new CommentWriter());
  
      // All that llvm-dis does is write the assembly to a file.
      if (!DontPrint) {
        M->print(Out->os(), Annotator.get(), PreserveAssemblyUseListOrder);
        if (Index)
          Index->print(Out->os());
      }
  
      // Declare success.
      Out->keep();
    }
  
    return 0;
  }
  