FindBugs.cpp revision 10757dd8e1a66128b205bd04797c8aed0cb7a1bd 
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>
23using 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///
32bool BugDriver::runManyPasses(const std::vector<const PassInfo*> &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]->getPassArgument() << " ";
62    }
63
64    std::string Filename;
65    if(runPasses(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}
114