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/FileSystem.h"
21 #include "llvm/Support/raw_ostream.h"
22 #include <algorithm>
23 #include <ctime>
24 using namespace llvm;
25 
26 /// runManyPasses - Take the specified pass list and create different
27 /// combinations of passes to compile the program with. Compile the program with
28 /// each set and mark test to see if it compiled correctly. If the passes
29 /// compiled correctly output nothing and rearrange the passes into a new order.
30 /// If the passes did not compile correctly, output the command required to
31 /// recreate the failure. This returns true if a compiler error is found.
32 ///
runManyPasses(const std::vector<std::string> & AllPasses,std::string & ErrMsg)33 bool BugDriver::runManyPasses(const std::vector<std::string> &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(nullptr));
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] << " ";
63     }
64 
65     std::string Filename;
66     if(runPasses(Program, 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(Program, 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::fs::remove(Filename);
108 
109     outs() << "\n\n";
110     num++;
111   } //end while
112 
113   // Unreachable.
114 }
115