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 "llvm/Support/raw_ostream.h"
  21 #include <algorithm>
  22 #include <ctime>
  23 using namespace llvm;
  24
  25 /// runManyPasses - Take the specified pass list and create different
  26 /// combinations of passes to compile the program with. Compile the program with
  27 /// each set and mark test to see if it compiled correctly. If the passes
  28 /// compiled correctly output nothing and rearrange the passes into a new order.
  29 /// If the passes did not compile correctly, output the command required to
  30 /// recreate the failure. This returns true if a compiler error is found.
  31 ///
  32 bool BugDriver::runManyPasses(const std::vector<std::string> &AllPasses,
  33                               std::string &ErrMsg) {
  34   setPassesToRun(AllPasses);
  35   outs() << "Starting bug finding procedure...\n\n";
  36
  37   // Creating a reference output if necessary
  38   if (initializeExecutionEnvironment()) return false;
  39
  40   outs() << "\n";
  41   if (ReferenceOutputFile.empty()) {
  42     outs() << "Generating reference output from raw program: \n";
  43     if (!createReferenceFile(Program))
  44       return false;
  45   }
  46
  47   srand(time(NULL));
  48
  49   unsigned num = 1;
  50   while(1) {
  51     //
  52     // Step 1: Randomize the order of the optimizer passes.
  53     //
  54     std::random_shuffle(PassesToRun.begin(), PassesToRun.end());
  55
  56     //
  57     // Step 2: Run optimizer passes on the program and check for success.
  58     //
  59     outs() << "Running selected passes on program to test for crash: ";
  60     for(int i = 0, e = PassesToRun.size(); i != e; i++) {
  61       outs() << "-" << PassesToRun[i] << " ";
  62     }
  63
  64     std::string Filename;
  65     if(runPasses(Program, PassesToRun, Filename, false)) {
  66       outs() << "\n";
  67       outs() << "Optimizer passes caused failure!\n\n";
  68       debugOptimizerCrash();
  69       return true;
  70     } else {
  71       outs() << "Combination " << num << " optimized successfully!\n";
  72     }
  73
  74     //
  75     // Step 3: Compile the optimized code.
  76     //
  77     outs() << "Running the code generator to test for a crash: ";
  78     std::string Error;
  79     compileProgram(Program, &Error);
  80     if (!Error.empty()) {
  81       outs() << "\n*** compileProgram threw an exception: ";
  82       outs() << Error;
  83       return debugCodeGeneratorCrash(ErrMsg);
  84     }
  85     outs() << '\n';
  86
  87     //
  88     // Step 4: Run the program and compare its output to the reference
  89     // output (created above).
  90     //
  91     outs() << "*** Checking if passes caused miscompliation:\n";
  92     bool Diff = diffProgram(Program, Filename, "", false, &Error);
  93     if (Error.empty() && Diff) {
  94       outs() << "\n*** diffProgram returned true!\n";
  95       debugMiscompilation(&Error);
  96       if (Error.empty())
  97         return true;
  98     }
  99     if (!Error.empty()) {
 100       errs() << Error;
 101       debugCodeGeneratorCrash(ErrMsg);
 102       return true;
 103     }
 104     outs() << "\n*** diff'd output matches!\n";
 105
 106     sys::Path(Filename).eraseFromDisk();
 107
 108     outs() << "\n\n";
 109     num++;
 110   } //end while
 111
 112   // Unreachable.
 113 }