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 "ToolRunner.h"
  19 #include "llvm/Pass.h"
  20 #include <algorithm>
  21 #include <ctime>
  22 using namespace llvm;
  23
  24 /// runManyPasses - Take the specified pass list and create different
  25 /// combinations of passes to compile the program with. Compile the program with
  26 /// each set and mark test to see if it compiled correctly. If the passes
  27 /// compiled correctly output nothing and rearrange the passes into a new order.
  28 /// If the passes did not compile correctly, output the command required to
  29 /// recreate the failure. This returns true if a compiler error is found.
  30 ///
  31 bool BugDriver::runManyPasses(const std::vector<const PassInfo*> &AllPasses) {
  32   setPassesToRun(AllPasses);
  33   outs() << "Starting bug finding procedure...\n\n";
  34
  35   // Creating a reference output if necessary
  36   if (initializeExecutionEnvironment()) return false;
  37
  38   outs() << "\n";
  39   if (ReferenceOutputFile.empty()) {
  40     outs() << "Generating reference output from raw program: \n";
  41     if (!createReferenceFile(Program))
  42       return false;
  43   }
  44
  45   srand(time(NULL));
  46
  47   unsigned num = 1;
  48   while(1) {
  49     //
  50     // Step 1: Randomize the order of the optimizer passes.
  51     //
  52     std::random_shuffle(PassesToRun.begin(), PassesToRun.end());
  53
  54     //
  55     // Step 2: Run optimizer passes on the program and check for success.
  56     //
  57     outs() << "Running selected passes on program to test for crash: ";
  58     for(int i = 0, e = PassesToRun.size(); i != e; i++) {
  59       outs() << "-" << PassesToRun[i]->getPassArgument( )<< " ";
  60     }
  61
  62     std::string Filename;
  63     if(runPasses(PassesToRun, Filename, false)) {
  64       outs() << "\n";
  65       outs() << "Optimizer passes caused failure!\n\n";
  66       debugOptimizerCrash();
  67       return true;
  68     } else {
  69       outs() << "Combination " << num << " optimized successfully!\n";
  70     }
  71
  72     //
  73     // Step 3: Compile the optimized code.
  74     //
  75     outs() << "Running the code generator to test for a crash: ";
  76     try {
  77       compileProgram(Program);
  78       outs() << '\n';
  79     } catch (ToolExecutionError &TEE) {
  80       outs() << "\n*** compileProgram threw an exception: ";
  81       outs() << TEE.what();
  82       return debugCodeGeneratorCrash();
  83     }
  84
  85     //
  86     // Step 4: Run the program and compare its output to the reference
  87     // output (created above).
  88     //
  89     outs() << "*** Checking if passes caused miscompliation:\n";
  90     try {
  91       if (diffProgram(Filename, "", false)) {
  92         outs() << "\n*** diffProgram returned true!\n";
  93         debugMiscompilation();
  94         return true;
  95       } else {
  96         outs() << "\n*** diff'd output matches!\n";
  97       }
  98     } catch (ToolExecutionError &TEE) {
  99       errs() << TEE.what();
 100       debugCodeGeneratorCrash();
 101       return true;
 102     }
 103
 104     sys::Path(Filename).eraseFromDisk();
 105
 106     outs() << "\n\n";
 107     num++;
 108   } //end while
 109
 110   // Unreachable.
 111 }