//===-- llvm-dis.cpp - The low-level LLVM disassembler --------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/Assembly/PrintModulePass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/PrettyStackTrace.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/System/Signals.h"
#include <memory>
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("Overwrite output files"));

static cl::opt<bool>
DontPrint("disable-output", cl::desc("Don't output the .ll file"), cl::Hidden);

int main(int argc, char **argv) {
  // Print a stack trace if we signal out.
  sys::PrintStackTraceOnErrorSignal();
  PrettyStackTraceProgram X(argc, argv);
  
  LLVMContext &Context = getGlobalContext();
  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
  try {
    cl::ParseCommandLineOptions(argc, argv, "llvm .bc -> .ll disassembler\n");

    raw_ostream *Out = &outs();  // Default to printing to stdout.
    std::string ErrorMessage;

    std::auto_ptr<Module> M;
   
    if (MemoryBuffer *Buffer
           = MemoryBuffer::getFileOrSTDIN(InputFilename, &ErrorMessage)) {
      M.reset(ParseBitcodeFile(Buffer, Context, &ErrorMessage));
      delete Buffer;
    }

    if (M.get() == 0) {
      errs() << argv[0] << ": ";
      if (ErrorMessage.size())
        errs() << ErrorMessage << "\n";
      else
        errs() << "bitcode didn't read correctly.\n";
      return 1;
    }
    
    if (DontPrint) {
      // Just use stdout.  We won't actually print anything on it.
    } else if (OutputFilename != "") {   // Specified an output filename?
      if (OutputFilename != "-") { // Not stdout?
        std::string ErrorInfo;
        Out = new raw_fd_ostream(OutputFilename.c_str(), /*Binary=*/false,
                                 Force, ErrorInfo);
        if (!ErrorInfo.empty()) {
          errs() << ErrorInfo << '\n';
          if (!Force)
            errs() << "Use -f command line argument to force output\n";
          delete Out;
          return 1;
        }
      }
    } else {
      if (InputFilename == "-") {
        OutputFilename = "-";
      } else {
        std::string IFN = InputFilename;
        int Len = IFN.length();
        if (IFN[Len-3] == '.' && IFN[Len-2] == 'b' && IFN[Len-1] == 'c') {
          // Source ends in .bc
          OutputFilename = std::string(IFN.begin(), IFN.end()-3)+".ll";
        } else {
          OutputFilename = IFN+".ll";
        }

        std::string ErrorInfo;
        Out = new raw_fd_ostream(OutputFilename.c_str(), /*Binary=*/false,
                                 Force, ErrorInfo);
        if (!ErrorInfo.empty()) {
          errs() << ErrorInfo << '\n';
          if (!Force)
            errs() << "Use -f command line argument to force output\n";
          delete Out;
          return 1;
        }

        // Make sure that the Out file gets unlinked from the disk if we get a
        // SIGINT
        sys::RemoveFileOnSignal(sys::Path(OutputFilename));
      }
    }

    // All that llvm-dis does is write the assembly to a file.
    if (!DontPrint) {
      PassManager Passes;
      Passes.add(createPrintModulePass(Out));
      Passes.run(*M.get());
    }

    if (Out != &outs())
      delete Out;
    return 0;
  } catch (const std::string& msg) {
    errs() << argv[0] << ": " << msg << "\n";
  } catch (...) {
    errs() << argv[0] << ": Unexpected unknown exception occurred.\n";
  }

  return 1;
}