//===- OptimizerDriver.cpp - Allow BugPoint to run passes safely ----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines an interface that allows bugpoint to run various passes
// without the threat of a buggy pass corrupting bugpoint (of course, bugpoint
// may have its own bugs, but that's another story...).  It achieves this by
// forking a copy of itself and having the child process do the optimizations.
// If this client dies, we can always fork a new one.  :)
//
//===----------------------------------------------------------------------===//

#include "BugDriver.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/SystemUtils.h"
#include "llvm/Support/ToolOutputFile.h"

#define DONT_GET_PLUGIN_LOADER_OPTION
#include "llvm/Support/PluginLoader.h"

#include <fstream>

using namespace llvm;

#define DEBUG_TYPE "bugpoint"

namespace llvm {
  extern cl::opt<std::string> OutputPrefix;
}

static cl::opt<bool> PreserveBitcodeUseListOrder(
    "preserve-bc-uselistorder",
    cl::desc("Preserve use-list order when writing LLVM bitcode."),
    cl::init(true), cl::Hidden);

namespace {
  // ChildOutput - This option captures the name of the child output file that
  // is set up by the parent bugpoint process
  cl::opt<std::string> ChildOutput("child-output", cl::ReallyHidden);
  cl::opt<std::string> OptCmd("opt-command", cl::init(""),
                              cl::desc("Path to opt. (default: search path "
                                       "for 'opt'.)"));
}

/// writeProgramToFile - This writes the current "Program" to the named bitcode
/// file.  If an error occurs, true is returned.
///
static bool writeProgramToFileAux(tool_output_file &Out, const Module *M) {
  WriteBitcodeToFile(M, Out.os(), PreserveBitcodeUseListOrder);
  Out.os().close();
  if (!Out.os().has_error()) {
    Out.keep();
    return false;
  }
  return true;
}

bool BugDriver::writeProgramToFile(const std::string &Filename, int FD,
                                   const Module *M) const {
  tool_output_file Out(Filename, FD);
  return writeProgramToFileAux(Out, M);
}

bool BugDriver::writeProgramToFile(const std::string &Filename,
                                   const Module *M) const {
  std::error_code EC;
  tool_output_file Out(Filename, EC, sys::fs::F_None);
  if (!EC)
    return writeProgramToFileAux(Out, M);
  return true;
}


/// EmitProgressBitcode - This function is used to output the current Program
/// to a file named "bugpoint-ID.bc".
///
void BugDriver::EmitProgressBitcode(const Module *M,
                                    const std::string &ID,
                                    bool NoFlyer)  const {
  // Output the input to the current pass to a bitcode file, emit a message
  // telling the user how to reproduce it: opt -foo blah.bc
  //
  std::string Filename = OutputPrefix + "-" + ID + ".bc";
  if (writeProgramToFile(Filename, M)) {
    errs() <<  "Error opening file '" << Filename << "' for writing!\n";
    return;
  }

  outs() << "Emitted bitcode to '" << Filename << "'\n";
  if (NoFlyer || PassesToRun.empty()) return;
  outs() << "\n*** You can reproduce the problem with: ";
  if (UseValgrind) outs() << "valgrind ";
  outs() << "opt " << Filename;
  for (unsigned i = 0, e = PluginLoader::getNumPlugins(); i != e; ++i) {
    outs() << " -load " << PluginLoader::getPlugin(i);
  }
  outs() << " " << getPassesString(PassesToRun) << "\n";
}

cl::opt<bool> SilencePasses("silence-passes",
        cl::desc("Suppress output of running passes (both stdout and stderr)"));

static cl::list<std::string> OptArgs("opt-args", cl::Positional,
                                     cl::desc("<opt arguments>..."),
                                     cl::ZeroOrMore, cl::PositionalEatsArgs);

/// runPasses - Run the specified passes on Program, outputting a bitcode file
/// and writing the filename into OutputFile if successful.  If the
/// optimizations fail for some reason (optimizer crashes), return true,
/// otherwise return false.  If DeleteOutput is set to true, the bitcode is
/// deleted on success, and the filename string is undefined.  This prints to
/// outs() a single line message indicating whether compilation was successful
/// or failed.
///
bool BugDriver::runPasses(Module *Program,
                          const std::vector<std::string> &Passes,
                          std::string &OutputFilename, bool DeleteOutput,
                          bool Quiet, unsigned NumExtraArgs,
                          const char * const *ExtraArgs) const {
  // setup the output file name
  outs().flush();
  SmallString<128> UniqueFilename;
  std::error_code EC = sys::fs::createUniqueFile(
      OutputPrefix + "-output-%%%%%%%.bc", UniqueFilename);
  if (EC) {
    errs() << getToolName() << ": Error making unique filename: "
           << EC.message() << "\n";
    return 1;
  }
  OutputFilename = UniqueFilename.str();

  // set up the input file name
  SmallString<128> InputFilename;
  int InputFD;
  EC = sys::fs::createUniqueFile(OutputPrefix + "-input-%%%%%%%.bc", InputFD,
                                 InputFilename);
  if (EC) {
    errs() << getToolName() << ": Error making unique filename: "
           << EC.message() << "\n";
    return 1;
  }

  tool_output_file InFile(InputFilename, InputFD);

  WriteBitcodeToFile(Program, InFile.os(), PreserveBitcodeUseListOrder);
  InFile.os().close();
  if (InFile.os().has_error()) {
    errs() << "Error writing bitcode file: " << InputFilename << "\n";
    InFile.os().clear_error();
    return 1;
  }

  std::string tool = OptCmd;
  if (OptCmd.empty()) {
    if (ErrorOr<std::string> Path = sys::findProgramByName("opt"))
      tool = *Path;
    else
      errs() << Path.getError().message() << "\n";
  }
  if (tool.empty()) {
    errs() << "Cannot find `opt' in PATH!\n";
    return 1;
  }

  std::string Prog;
  if (UseValgrind) {
    if (ErrorOr<std::string> Path = sys::findProgramByName("valgrind"))
      Prog = *Path;
    else
      errs() << Path.getError().message() << "\n";
  } else
    Prog = tool;
  if (Prog.empty()) {
    errs() << "Cannot find `valgrind' in PATH!\n";
    return 1;
  }

  // Ok, everything that could go wrong before running opt is done.
  InFile.keep();

  // setup the child process' arguments
  SmallVector<const char*, 8> Args;
  if (UseValgrind) {
    Args.push_back("valgrind");
    Args.push_back("--error-exitcode=1");
    Args.push_back("-q");
    Args.push_back(tool.c_str());
  } else
    Args.push_back(tool.c_str());

  Args.push_back("-o");
  Args.push_back(OutputFilename.c_str());
  for (unsigned i = 0, e = OptArgs.size(); i != e; ++i)
    Args.push_back(OptArgs[i].c_str());
  std::vector<std::string> pass_args;
  for (unsigned i = 0, e = PluginLoader::getNumPlugins(); i != e; ++i) {
    pass_args.push_back( std::string("-load"));
    pass_args.push_back( PluginLoader::getPlugin(i));
  }
  for (std::vector<std::string>::const_iterator I = Passes.begin(),
       E = Passes.end(); I != E; ++I )
    pass_args.push_back( std::string("-") + (*I) );
  for (std::vector<std::string>::const_iterator I = pass_args.begin(),
       E = pass_args.end(); I != E; ++I )
    Args.push_back(I->c_str());
  Args.push_back(InputFilename.c_str());
  for (unsigned i = 0; i < NumExtraArgs; ++i)
    Args.push_back(*ExtraArgs);
  Args.push_back(nullptr);

  DEBUG(errs() << "\nAbout to run:\t";
        for (unsigned i = 0, e = Args.size()-1; i != e; ++i)
          errs() << " " << Args[i];
        errs() << "\n";
        );

  // Redirect stdout and stderr to nowhere if SilencePasses is given
  StringRef Nowhere;
  const StringRef *Redirects[3] = {nullptr, &Nowhere, &Nowhere};

  std::string ErrMsg;
  int result = sys::ExecuteAndWait(Prog, Args.data(), nullptr,
                                   (SilencePasses ? Redirects : nullptr),
                                   Timeout, MemoryLimit, &ErrMsg);

  // If we are supposed to delete the bitcode file or if the passes crashed,
  // remove it now.  This may fail if the file was never created, but that's ok.
  if (DeleteOutput || result != 0)
    sys::fs::remove(OutputFilename);

  // Remove the temporary input file as well
  sys::fs::remove(InputFilename.c_str());

  if (!Quiet) {
    if (result == 0)
      outs() << "Success!\n";
    else if (result > 0)
      outs() << "Exited with error code '" << result << "'\n";
    else if (result < 0) {
      if (result == -1)
        outs() << "Execute failed: " << ErrMsg << "\n";
      else
        outs() << "Crashed: " << ErrMsg << "\n";
    }
    if (result & 0x01000000)
      outs() << "Dumped core\n";
  }

  // Was the child successful?
  return result != 0;
}


std::unique_ptr<Module>
BugDriver::runPassesOn(Module *M, const std::vector<std::string> &Passes,
                       bool AutoDebugCrashes, unsigned NumExtraArgs,
                       const char *const *ExtraArgs) {
  std::string BitcodeResult;
  if (runPasses(M, Passes, BitcodeResult, false/*delete*/, true/*quiet*/,
                NumExtraArgs, ExtraArgs)) {
    if (AutoDebugCrashes) {
      errs() << " Error running this sequence of passes"
             << " on the input program!\n";
      delete swapProgramIn(M);
      EmitProgressBitcode(M, "pass-error",  false);
      exit(debugOptimizerCrash());
    }
    return nullptr;
  }

  std::unique_ptr<Module> Ret = parseInputFile(BitcodeResult, Context);
  if (!Ret) {
    errs() << getToolName() << ": Error reading bitcode file '"
           << BitcodeResult << "'!\n";
    exit(1);
  }
  sys::fs::remove(BitcodeResult);
  return Ret;
}
