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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 ///
runManyPasses(const std::vector<std::string> & AllPasses,std::string & ErrMsg)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 }
114