tools/bugpoint/OptimizerDriver.cpp

//===- OptimizerDriver.cpp - Allow BugPoint to run passes safely ----------===//
//
// 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 it's own bugs, but that's another story...).  It acheives 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/PassManager.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Bytecode/WriteBytecodePass.h"
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdlib.h>
#include <fstream>

/// removeFile - Delete the specified file
///
void BugDriver::removeFile(const std::string &Filename) const {
  unlink(Filename.c_str());
}

/// writeProgramToFile - This writes the current "Program" to the named bytecode
/// file.  If an error occurs, true is returned.
///
bool BugDriver::writeProgramToFile(const std::string &Filename) const {
  std::ofstream Out(Filename.c_str());
  if (!Out.good()) return true;

  WriteBytecodeToFile(Program, Out);
  return false;
}


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

  std::cout << "Emitted bytecode to 'bugpoint-" << Filename << ".bc'\n";
  std::cout << "\n*** You can reproduce the problem with: ";

  unsigned PassType = Pass->getPassType();
  if (PassType & PassInfo::Analysis)
    std::cout << "analyze";
  else if (PassType & PassInfo::Optimization)
    std::cout << "opt";
  else if (PassType & PassInfo::LLC)
    std::cout << "llc";
  else
    std::cout << "bugpoint";
  std::cout << " " << Filename << " -" << Pass->getPassArgument() << "\n";
}


static void RunChild(Module *Program,const std::vector<const PassInfo*> &Passes,
                     const std::string &OutFilename) {
  std::ofstream OutFile(OutFilename.c_str());
  if (!OutFile.good()) {
    std::cerr << "Error opening bytecode file: " << OutFilename << "\n";
    exit(1);
  }

  PassManager PM;
  for (unsigned i = 0, e = Passes.size(); i != e; ++i) {
    if (Passes[i]->getNormalCtor())
      PM.add(Passes[i]->getNormalCtor()());
    else
      std::cerr << "Cannot create pass yet: " << Passes[i]->getPassName()
                << "\n";
  }
  // Check that the module is well formed on completion of optimization
  PM.add(createVerifierPass());

  // Write bytecode out to disk as the last step...
  PM.add(new WriteBytecodePass(&OutFile));

  // Run all queued passes.
  PM.run(*Program);
}

/// runPasses - Run the specified passes on Program, outputting a bytecode file
/// and writting 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 bytecode is
/// deleted on success, and the filename string is undefined.  This prints to
/// cout a single line message indicating whether compilation was successful or
/// failed.
///
bool BugDriver::runPasses(const std::vector<const PassInfo*> &Passes,
                          std::string &OutputFilename, bool DeleteOutput) const{
  std::cout << std::flush;

  // Agree on a temporary file name to use....
  char FNBuffer[] = "bugpoint-output.bc-XXXXXX";
  int TempFD;
  if ((TempFD = mkstemp(FNBuffer)) == -1) {
    std::cerr << ToolName << ": ERROR: Cannot create temporary"
              << " file in the current directory!\n";
    exit(1);
  }
  OutputFilename = FNBuffer;

  // We don't need to hold the temp file descriptor... we will trust that noone
  // will overwrite/delete the file while we are working on it...
  close(TempFD);
  
  pid_t child_pid;
  switch (child_pid = fork()) {
  case -1:    // Error occurred
    std::cerr << ToolName << ": Error forking!\n";
    exit(1);
  case 0:     // Child process runs passes.
    RunChild(Program, Passes, OutputFilename);
    exit(0);  // If we finish successfully, return 0!
  default:    // Parent continues...
    break;
  }

  // Wait for the child process to get done.
  int Status;
  if (wait(&Status) != child_pid) {
    std::cerr << "Error waiting for child process!\n";
    exit(1);
  }

  // If we are supposed to delete the bytecode file, remove it now
  // unconditionally...  this may fail if the file was never created, but that's
  // ok.
  if (DeleteOutput)
    removeFile(OutputFilename);

  std::cout << (Status ? "Crashed!\n" : "Success!\n");

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