1//===-- FindBugs.cpp - Run Many Different Optimizations -------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines an interface that allows bugpoint to choose different
10// combinations of optimizations to run on the selected input. Bugpoint will
11// run these optimizations and record the success/failure of each. This way
12// we can hopefully spot bugs in the optimizations.
13//
14//===----------------------------------------------------------------------===//
15
16#include "BugDriver.h"
17#include "llvm/Support/FileSystem.h"
18#include "llvm/Support/raw_ostream.h"
19#include <random>
20using namespace llvm;
21
22Error
23BugDriver::runManyPasses(const std::vector<std::string> &AllPasses) {
24 setPassesToRun(AllPasses);
25 outs() << "Starting bug finding procedure...\n\n";
26
27 // Creating a reference output if necessary
28 if (Error E = initializeExecutionEnvironment())
29 return E;
30
31 outs() << "\n";
32 if (ReferenceOutputFile.empty()) {
33 outs() << "Generating reference output from raw program: \n";
34 if (Error E = createReferenceFile(M&: *Program))
35 return E;
36 }
37
38 std::mt19937 randomness(std::random_device{}());
39 unsigned num = 1;
40 while (true) {
41 //
42 // Step 1: Randomize the order of the optimizer passes.
43 //
44 llvm::shuffle(first: PassesToRun.begin(), last: PassesToRun.end(), g&: randomness);
45
46 //
47 // Step 2: Run optimizer passes on the program and check for success.
48 //
49 outs() << "Running selected passes on program to test for crash: ";
50 for (const std::string &Pass : PassesToRun)
51 outs() << "-" << Pass << " ";
52
53 std::string Filename;
54 if (runPasses(Program&: *Program, PassesToRun, OutputFilename&: Filename, DeleteOutput: false)) {
55 outs() << "\n";
56 outs() << "Optimizer passes caused failure!\n\n";
57 return debugOptimizerCrash();
58 } else {
59 outs() << "Combination " << num << " optimized successfully!\n";
60 }
61
62 //
63 // Step 3: Compile the optimized code.
64 //
65 outs() << "Running the code generator to test for a crash: ";
66 if (Error E = compileProgram(M&: *Program)) {
67 outs() << "\n*** compileProgram threw an exception: ";
68 outs() << toString(E: std::move(E));
69 return debugCodeGeneratorCrash();
70 }
71 outs() << '\n';
72
73 //
74 // Step 4: Run the program and compare its output to the reference
75 // output (created above).
76 //
77 outs() << "*** Checking if passes caused miscompliation:\n";
78 Expected<bool> Diff = diffProgram(Program: *Program, BitcodeFile: Filename, SharedObj: "", RemoveBitcode: false);
79 if (Error E = Diff.takeError()) {
80 errs() << toString(E: std::move(E));
81 return debugCodeGeneratorCrash();
82 }
83 if (*Diff) {
84 outs() << "\n*** diffProgram returned true!\n";
85 Error E = debugMiscompilation();
86 if (!E)
87 return Error::success();
88 }
89 outs() << "\n*** diff'd output matches!\n";
90
91 sys::fs::remove(path: Filename);
92
93 outs() << "\n\n";
94 num++;
95 } // end while
96
97 // Unreachable.
98}
99