path: root/tools/bugpoint/Miscompilation.cpp

//===- Miscompilation.cpp - Debug program miscompilations -----------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements optimizer and code generation miscompilation debugging
// support.
//
//===----------------------------------------------------------------------===//

#include "BugDriver.h"
#include "ListReducer.h"
#include "ToolRunner.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Linker.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Config/config.h"   // for HAVE_LINK_R
using namespace llvm;

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

namespace {
  static llvm::cl::opt<bool>
    DisableLoopExtraction("disable-loop-extraction",
        cl::desc("Don't extract loops when searching for miscompilations"),
        cl::init(false));
  static llvm::cl::opt<bool>
    DisableBlockExtraction("disable-block-extraction",
        cl::desc("Don't extract blocks when searching for miscompilations"),
        cl::init(false));

  class ReduceMiscompilingPasses : public ListReducer<std::string> {
    BugDriver &BD;
  public:
    ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}

    virtual TestResult doTest(std::vector<std::string> &Prefix,
                              std::vector<std::string> &Suffix,
                              std::string &Error);
  };
}

/// TestResult - After passes have been split into a test group and a control
/// group, see if they still break the program.
///
ReduceMiscompilingPasses::TestResult
ReduceMiscompilingPasses::doTest(std::vector<std::string> &Prefix,
                                 std::vector<std::string> &Suffix,
                                 std::string &Error) {
  // First, run the program with just the Suffix passes.  If it is still broken
  // with JUST the kept passes, discard the prefix passes.
  outs() << "Checking to see if '" << getPassesString(Suffix)
         << "' compiles correctly: ";

  std::string BitcodeResult;
  if (BD.runPasses(BD.getProgram(), Suffix, BitcodeResult, false/*delete*/,
                   true/*quiet*/)) {
    errs() << " Error running this sequence of passes"
           << " on the input program!\n";
    BD.setPassesToRun(Suffix);
    BD.EmitProgressBitcode(BD.getProgram(), "pass-error",  false);
    exit(BD.debugOptimizerCrash());
  }

  // Check to see if the finished program matches the reference output...
  bool Diff = BD.diffProgram(BD.getProgram(), BitcodeResult, "",
                             true /*delete bitcode*/, &Error);
  if (!Error.empty())
    return InternalError;
  if (Diff) {
    outs() << " nope.\n";
    if (Suffix.empty()) {
      errs() << BD.getToolName() << ": I'm confused: the test fails when "
             << "no passes are run, nondeterministic program?\n";
      exit(1);
    }
    return KeepSuffix;         // Miscompilation detected!
  }
  outs() << " yup.\n";      // No miscompilation!

  if (Prefix.empty()) return NoFailure;

  // Next, see if the program is broken if we run the "prefix" passes first,
  // then separately run the "kept" passes.
  outs() << "Checking to see if '" << getPassesString(Prefix)
         << "' compiles correctly: ";

  // If it is not broken with the kept passes, it's possible that the prefix
  // passes must be run before the kept passes to break it.  If the program
  // WORKS after the prefix passes, but then fails if running the prefix AND
  // kept passes, we can update our bitcode file to include the result of the
  // prefix passes, then discard the prefix passes.
  //
  if (BD.runPasses(BD.getProgram(), Prefix, BitcodeResult, false/*delete*/,
                   true/*quiet*/)) {
    errs() << " Error running this sequence of passes"
           << " on the input pr