1 //===- Miscompilation.cpp - Debug program miscompilations -----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements program miscompilation debugging support.
12 //===----------------------------------------------------------------------===//
14 #include "BugDriver.h"
15 #include "ListReducer.h"
16 #include "llvm/Module.h"
17 #include "llvm/Pass.h"
18 #include "llvm/Transforms/Utils/Cloning.h"
19 #include "llvm/Transforms/Utils/Linker.h"
20 #include "Support/FileUtilities.h"
25 class ReduceMiscompilingPasses : public ListReducer<const PassInfo*> {
28 ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}
30 virtual TestResult doTest(std::vector<const PassInfo*> &Prefix,
31 std::vector<const PassInfo*> &Suffix);
35 ReduceMiscompilingPasses::TestResult
36 ReduceMiscompilingPasses::doTest(std::vector<const PassInfo*> &Prefix,
37 std::vector<const PassInfo*> &Suffix) {
38 // First, run the program with just the Suffix passes. If it is still broken
39 // with JUST the kept passes, discard the prefix passes.
40 std::cout << "Checking to see if '" << getPassesString(Suffix)
41 << "' compile correctly: ";
43 std::string BytecodeResult;
44 if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
45 std::cerr << " Error running this sequence of passes"
46 << " on the input program!\n";
47 BD.setPassesToRun(Suffix);
48 BD.EmitProgressBytecode("pass-error", false);
49 exit(BD.debugOptimizerCrash());
52 // Check to see if the finished program matches the reference output...
53 if (BD.diffProgram(BytecodeResult, "", true /*delete bytecode*/)) {
54 std::cout << "nope.\n";
55 return KeepSuffix; // Miscompilation detected!
57 std::cout << "yup.\n"; // No miscompilation!
59 if (Prefix.empty()) return NoFailure;
61 // Next, see if the program is broken if we run the "prefix" passes first,
62 // then separately run the "kept" passes.
63 std::cout << "Checking to see if '" << getPassesString(Prefix)
64 << "' compile correctly: ";
66 // If it is not broken with the kept passes, it's possible that the prefix
67 // passes must be run before the kept passes to break it. If the program
68 // WORKS after the prefix passes, but then fails if running the prefix AND
69 // kept passes, we can update our bytecode file to include the result of the
70 // prefix passes, then discard the prefix passes.
72 if (BD.runPasses(Prefix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
73 std::cerr << " Error running this sequence of passes"
74 << " on the input program!\n";
75 BD.setPassesToRun(Prefix);
76 BD.EmitProgressBytecode("pass-error", false);
77 exit(BD.debugOptimizerCrash());
80 // If the prefix maintains the predicate by itself, only keep the prefix!
81 if (BD.diffProgram(BytecodeResult)) {
82 std::cout << "nope.\n";
83 removeFile(BytecodeResult);
86 std::cout << "yup.\n"; // No miscompilation!
88 // Ok, so now we know that the prefix passes work, try running the suffix
89 // passes on the result of the prefix passes.
91 Module *PrefixOutput = BD.ParseInputFile(BytecodeResult);
92 if (PrefixOutput == 0) {
93 std::cerr << BD.getToolName() << ": Error reading bytecode file '"
94 << BytecodeResult << "'!\n";
97 removeFile(BytecodeResult); // No longer need the file on disk
99 std::cout << "Checking to see if '" << getPassesString(Suffix)
100 << "' passes compile correctly after the '"
101 << getPassesString(Prefix) << "' passes: ";
103 Module *OriginalInput = BD.Program;
104 BD.Program = PrefixOutput;
105 if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
106 std::cerr << " Error running this sequence of passes"
107 << " on the input program!\n";
108 BD.setPassesToRun(Suffix);
109 BD.EmitProgressBytecode("pass-error", false);
110 exit(BD.debugOptimizerCrash());
114 if (BD.diffProgram(BytecodeResult, "", true/*delete bytecode*/)) {
115 std::cout << "nope.\n";
116 delete OriginalInput; // We pruned down the original input...
120 // Otherwise, we must not be running the bad pass anymore.
121 std::cout << "yup.\n"; // No miscompilation!
122 BD.Program = OriginalInput; // Restore original program
123 delete PrefixOutput; // Free experiment
128 class ReduceMiscompilingFunctions : public ListReducer<Function*> {
131 ReduceMiscompilingFunctions(BugDriver &bd) : BD(bd) {}
133 virtual TestResult doTest(std::vector<Function*> &Prefix,
134 std::vector<Function*> &Suffix) {
135 if (!Suffix.empty() && TestFuncs(Suffix, false))
137 if (!Prefix.empty() && TestFuncs(Prefix, false))
142 bool TestFuncs(const std::vector<Function*> &Prefix, bool EmitBytecode);
146 bool ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function*> &Funcs,
148 // Test to see if the function is misoptimized if we ONLY run it on the
149 // functions listed in Funcs.
151 std::cout << "Checking to see if the program is misoptimized when "
152 << (Funcs.size()==1 ? "this function is" : "these functions are")
153 << " run through the pass"
154 << (BD.PassesToRun.size() == 1 ? "" : "es") << ": ";
155 BD.PrintFunctionList(Funcs);
158 std::cout <<"Outputting reduced bytecode files which expose the problem:\n";
161 // First step: clone the module for the two halves of the program we want.
162 Module *ToOptimize = CloneModule(BD.getProgram());
164 // Second step: Make sure functions & globals are all external so that linkage
165 // between the two modules will work.
166 for (Module::iterator I = ToOptimize->begin(), E = ToOptimize->end();I!=E;++I)
167 I->setLinkage(GlobalValue::ExternalLinkage);
168 for (Module::giterator I = ToOptimize->gbegin(), E = ToOptimize->gend();
170 I->setLinkage(GlobalValue::ExternalLinkage);
172 // Third step: make a clone of the externalized program for the non-optimized
174 Module *ToNotOptimize = CloneModule(ToOptimize);
176 // Fourth step: Remove the test functions from the ToNotOptimize module, and
177 // all of the global variables.
178 for (unsigned i = 0, e = Funcs.size(); i != e; ++i) {
179 Function *TNOF = ToNotOptimize->getFunction(Funcs[i]->getName(),
180 Funcs[i]->getFunctionType());
181 assert(TNOF && "Function doesn't exist in module!");
182 DeleteFunctionBody(TNOF); // Function is now external in this module!
184 for (Module::giterator I = ToNotOptimize->gbegin(), E = ToNotOptimize->gend();
186 I->setInitializer(0); // Delete the initializer to make it external
189 std::cout << " Non-optimized portion: ";
190 std::swap(BD.Program, ToNotOptimize);
191 BD.EmitProgressBytecode("tonotoptimize", true);
192 std::swap(BD.Program, ToNotOptimize);
195 // Fifth step: Remove all functions from the ToOptimize module EXCEPT for the
196 // ones specified in Funcs. We know which ones these are because they are
197 // non-external in ToOptimize, but external in ToNotOptimize.
199 for (Module::iterator I = ToOptimize->begin(), E = ToOptimize->end();I!=E;++I)
200 if (!I->isExternal()) {
201 Function *TNOF = ToNotOptimize->getFunction(I->getName(),
202 I->getFunctionType());
203 assert(TNOF && "Function doesn't exist in ToNotOptimize module??");
204 if (!TNOF->isExternal())
205 DeleteFunctionBody(I);
209 std::cout << " Portion that is input to optimizer: ";
210 std::swap(BD.Program, ToOptimize);
211 BD.EmitProgressBytecode("tooptimize");
212 std::swap(BD.Program, ToOptimize);
215 // Sixth step: Run the optimization passes on ToOptimize, producing a
216 // transformed version of the functions being tested.
217 Module *OldProgram = BD.Program;
218 BD.Program = ToOptimize;
221 std::cout << " Optimizing functions being tested: ";
222 std::string BytecodeResult;
223 if (BD.runPasses(BD.PassesToRun, BytecodeResult, false/*delete*/,
225 std::cerr << " Error running this sequence of passes"
226 << " on the input program!\n";
227 BD.EmitProgressBytecode("pass-error", false);
228 exit(BD.debugOptimizerCrash());
232 std::cout << "done.\n";
234 delete BD.getProgram(); // Delete the old "ToOptimize" module
235 BD.Program = BD.ParseInputFile(BytecodeResult);
238 std::cout << " 'tooptimize' after being optimized: ";
239 BD.EmitProgressBytecode("optimized", true);
242 if (BD.Program == 0) {
243 std::cerr << BD.getToolName() << ": Error reading bytecode file '"
244 << BytecodeResult << "'!\n";
247 removeFile(BytecodeResult); // No longer need the file on disk
249 // Seventh step: Link the optimized part of the program back to the
250 // unoptimized part of the program.
252 if (LinkModules(BD.Program, ToNotOptimize, &BytecodeResult)) {
253 std::cerr << BD.getToolName() << ": Error linking modules together:"
254 << BytecodeResult << "\n";
257 delete ToNotOptimize; // We are done with this module...
260 std::cout << " Program as tested: ";
261 BD.EmitProgressBytecode("linked", true);
263 BD.Program = OldProgram;
264 return false; // We don't need to actually execute the program here.
267 std::cout << " Checking to see if the merged program executes correctly: ";
269 // Eighth step: Execute the program. If it does not match the expected
270 // output, then 'Funcs' are being misoptimized!
271 bool Broken = BD.diffProgram();
273 delete BD.Program; // Delete the hacked up program
274 BD.Program = OldProgram; // Restore the original
276 std::cout << (Broken ? " nope.\n" : " yup.\n");
281 /// debugMiscompilation - This method is used when the passes selected are not
282 /// crashing, but the generated output is semantically different from the
285 bool BugDriver::debugMiscompilation() {
286 // Make sure something was miscompiled...
287 if (!ReduceMiscompilingPasses(*this).reduceList(PassesToRun)) {
288 std::cerr << "*** Optimized program matches reference output! No problem "
289 << "detected...\nbugpoint can't help you with your problem!\n";
293 std::cout << "\n*** Found miscompiling pass"
294 << (PassesToRun.size() == 1 ? "" : "es") << ": "
295 << getPassesString(PassesToRun) << "\n";
296 EmitProgressBytecode("passinput");
298 // Okay, now that we have reduced the list of passes which are causing the
299 // failure, see if we can pin down which functions are being
300 // miscompiled... first build a list of all of the non-external functions in
302 std::vector<Function*> MiscompiledFunctions;
303 for (Module::iterator I = Program->begin(), E = Program->end(); I != E; ++I)
304 if (!I->isExternal())
305 MiscompiledFunctions.push_back(I);
307 // Do the reduction...
308 ReduceMiscompilingFunctions(*this).reduceList(MiscompiledFunctions);
310 std::cout << "\n*** The following function"
311 << (MiscompiledFunctions.size() == 1 ? " is" : "s are")
312 << " being miscompiled: ";
313 PrintFunctionList(MiscompiledFunctions);
316 // Output a bunch of bytecode files for the user...
317 ReduceMiscompilingFunctions(*this).TestFuncs(MiscompiledFunctions, true);