tools/bugpoint/FindBugs.cpp

   1 //===-- FindBugs.cpp - Run Many Different Optimizations -------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines an interface that allows bugpoint to choose different
  11 // combinations of optimizations to run on the selected input. Bugpoint will
  12 // run these optimizations and record the success/failure of each. This way
  13 // we can hopefully spot bugs in the optimizations.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "BugDriver.h"
  18 #include "llvm/Support/FileSystem.h"
  19 #include "llvm/Support/raw_ostream.h"
  20 #include <random>
  21 using namespace llvm;
  22
  23 Error
  24 BugDriver::runManyPasses(const std::vector<std::string> &AllPasses) {
  25   setPassesToRun(AllPasses);
  26   outs() << "Starting bug finding procedure...\n\n";
  27
  28   // Creating a reference output if necessary
  29   if (Error E = initializeExecutionEnvironment())
  30     return E;
  31
  32   outs() << "\n";
  33   if (ReferenceOutputFile.empty()) {
  34     outs() << "Generating reference output from raw program: \n";
  35     if (Error E = createReferenceFile(*Program))
  36       return E;
  37   }
  38
  39   std::mt19937 randomness(std::random_device{}());
  40   unsigned num = 1;
  41   while (1) {
  42     //
  43     // Step 1: Randomize the order of the optimizer passes.
  44     //
  45     std::shuffle(PassesToRun.begin(), PassesToRun.end(), randomness);
  46
  47     //
  48     // Step 2: Run optimizer passes on the program and check for success.
  49     //
  50     outs() << "Running selected passes on program to test for crash: ";
  51     for (int i = 0, e = PassesToRun.size(); i != e; i++) {
  52       outs() << "-" << PassesToRun[i] << " ";
  53     }
  54
  55     std::string Filename;
  56     if (runPasses(*Program, PassesToRun, Filename, false)) {
  57       outs() << "\n";
  58       outs() << "Optimizer passes caused failure!\n\n";
  59       return debugOptimizerCrash();
  60     } else {
  61       outs() << "Combination " << num << " optimized successfully!\n";
  62     }
  63
  64     //
  65     // Step 3: Compile the optimized code.
  66     //
  67     outs() << "Running the code generator to test for a crash: ";
  68     if (Error E = compileProgram(*Program)) {
  69       outs() << "\n*** compileProgram threw an exception: ";
  70       outs() << toString(std::move(E));
  71       return debugCodeGeneratorCrash();
  72     }
  73     outs() << '\n';
  74
  75     //
  76     // Step 4: Run the program and compare its output to the reference
  77     // output (created above).
  78     //
  79     outs() << "*** Checking if passes caused miscompliation:\n";
  80     Expected<bool> Diff = diffProgram(*Program, Filename, "", false);
  81     if (Error E = Diff.takeError()) {
  82       errs() << toString(std::move(E));
  83       return debugCodeGeneratorCrash();
  84     }
  85     if (*Diff) {
  86       outs() << "\n*** diffProgram returned true!\n";
  87       Error E = debugMiscompilation();
  88       if (!E)
  89         return Error::success();
  90     }
  91     outs() << "\n*** diff'd output matches!\n";
  92
  93     sys::fs::remove(Filename);
  94
  95     outs() << "\n\n";
  96     num++;
  97   } // end while
  98
  99   // Unreachable.
 100 }