FindBugs.cpp revision ac95cc79ac0b899d566cc29c0f646f39c2fa35c0 
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>
22using 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///
31bool 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}
112