FindBugs.cpp revision 8ba15cb7099d9eadcb345328228d77ffa5afa42d 
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
33BugDriver::runManyPasses(const std::vector<const StaticPassInfo*> &AllPasses,
34                              std::string &ErrMsg) {
35  setPassesToRun(AllPasses);
36  outs() << "Starting bug finding procedure...\n\n";
37
38  // Creating a reference output if necessary
39  if (initializeExecutionEnvironment()) return false;
40
41  outs() << "\n";
42  if (ReferenceOutputFile.empty()) {
43    outs() << "Generating reference output from raw program: \n";
44    if (!createReferenceFile(Program))
45      return false;
46  }
47
48  srand(time(NULL));
49
50  unsigned num = 1;
51  while(1) {
52    //
53    // Step 1: Randomize the order of the optimizer passes.
54    //
55    std::random_shuffle(PassesToRun.begin(), PassesToRun.end());
56
57    //
58    // Step 2: Run optimizer passes on the program and check for success.
59    //
60    outs() << "Running selected passes on program to test for crash: ";
61    for(int i = 0, e = PassesToRun.size(); i != e; i++) {
62      outs() << "-" << PassesToRun[i]->getPassArgument() << " ";
63    }
64
65    std::string Filename;
66    if(runPasses(PassesToRun, Filename, false)) {
67      outs() << "\n";
68      outs() << "Optimizer passes caused failure!\n\n";
69      debugOptimizerCrash();
70      return true;
71    } else {
72      outs() << "Combination " << num << " optimized successfully!\n";
73    }
74
75    //
76    // Step 3: Compile the optimized code.
77    //
78    outs() << "Running the code generator to test for a crash: ";
79    std::string Error;
80    compileProgram(Program, &Error);
81    if (!Error.empty()) {
82      outs() << "\n*** compileProgram threw an exception: ";
83      outs() << Error;
84      return debugCodeGeneratorCrash(ErrMsg);
85    }
86    outs() << '\n';
87
88    //
89    // Step 4: Run the program and compare its output to the reference
90    // output (created above).
91    //
92    outs() << "*** Checking if passes caused miscompliation:\n";
93    bool Diff = diffProgram(Filename, "", false, &Error);
94    if (Error.empty() && Diff) {
95      outs() << "\n*** diffProgram returned true!\n";
96      debugMiscompilation(&Error);
97      if (Error.empty())
98        return true;
99    }
100    if (!Error.empty()) {
101      errs() << Error;
102      debugCodeGeneratorCrash(ErrMsg);
103      return true;
104    }
105    outs() << "\n*** diff'd output matches!\n";
106
107    sys::Path(Filename).eraseFromDisk();
108
109    outs() << "\n\n";
110    num++;
111  } //end while
112
113  // Unreachable.
114}
115