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"
24 class ReduceMiscompilingPasses : public ListReducer<const PassInfo*> {
27 ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}
29 virtual TestResult doTest(std::vector<const PassInfo*> &Prefix,
30 std::vector<const PassInfo*> &Suffix);
34 ReduceMiscompilingPasses::TestResult
35 ReduceMiscompilingPasses::doTest(std::vector<const PassInfo*> &Prefix,
36 std::vector<const PassInfo*> &Suffix) {
37 // First, run the program with just the Suffix passes. If it is still broken
38 // with JUST the kept passes, discard the prefix passes.
39 std::cout << "Checking to see if '" << getPassesString(Suffix)
40 << "' compile correctly: ";
42 std::string BytecodeResult;
43 if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
44 std::cerr << " Error running this sequence of passes"
45 << " on the input program!\n";
46 BD.setPassesToRun(Suffix);
47 BD.EmitProgressBytecode("pass-error", false);
48 exit(BD.debugOptimizerCrash());
51 // Check to see if the finished program matches the reference output...
52 if (BD.diffProgram(BytecodeResult, "", true /*delete bytecode*/)) {
53 std::cout << "nope.\n";
54 return KeepSuffix; // Miscompilation detected!
56 std::cout << "yup.\n"; // No miscompilation!
58 if (Prefix.empty()) return NoFailure;
60 // Next, see if the program is broken if we run the "prefix" passes first,
61 // then separately run the "kept" passes.
62 std::cout << "Checking to see if '" << getPassesString(Prefix)
63 << "' compile correctly: ";
65 // If it is not broken with the kept passes, it's possible that the prefix
66 // passes must be run before the kept passes to break it. If the program
67 // WORKS after the prefix passes, but then fails if running the prefix AND
68 // kept passes, we can update our bytecode file to include the result of the
69 // prefix passes, then discard the prefix passes.
71 if (BD.runPasses(Prefix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
72 std::cerr << " Error running this sequence of passes"
73 << " on the input program!\n";
74 BD.setPassesToRun(Prefix);
75 BD.EmitProgressBytecode("pass-error", false);
76 exit(BD.debugOptimizerCrash());
79 // If the prefix maintains the predicate by itself, only keep the prefix!
80 if (BD.diffProgram(BytecodeResult)) {
81 std::cout << "nope.\n";
82 removeFile(BytecodeResult);
85 std::cout << "yup.\n"; // No miscompilation!
87 // Ok, so now we know that the prefix passes work, try running the suffix
88 // passes on the result of the prefix passes.
90 Module *PrefixOutput = ParseInputFile(BytecodeResult);
91 if (PrefixOutput == 0) {
92 std::cerr << BD.getToolName() << ": Error reading bytecode file '"
93 << BytecodeResult << "'!\n";
96 removeFile(BytecodeResult); // No longer need the file on disk
98 std::cout << "Checking to see if '" << getPassesString(Suffix)
99 << "' passes compile correctly after the '"
100 << getPassesString(Prefix) << "' passes: ";
102 Module *OriginalInput = BD.swapProgramIn(PrefixOutput);
103 if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) {
104 std::cerr << " Error running this sequence of passes"
105 << " on the input program!\n";
106 BD.setPassesToRun(Suffix);
107 BD.EmitProgressBytecode("pass-error", false);
108 exit(BD.debugOptimizerCrash());
112 if (BD.diffProgram(BytecodeResult, "", true/*delete bytecode*/)) {
113 std::cout << "nope.\n";
114 delete OriginalInput; // We pruned down the original input...
118 // Otherwise, we must not be running the bad pass anymore.
119 std::cout << "yup.\n"; // No miscompilation!
120 delete BD.swapProgramIn(OriginalInput); // Restore orig program & free test
125 class ReduceMiscompilingFunctions : public ListReducer<Function*> {
127 bool (*TestFn)(BugDriver &, Module *, Module *);
129 ReduceMiscompilingFunctions(BugDriver &bd,
130 bool (*F)(BugDriver &, Module *, Module *))
131 : BD(bd), TestFn(F) {}
133 virtual TestResult doTest(std::vector<Function*> &Prefix,
134 std::vector<Function*> &Suffix) {
135 if (!Suffix.empty() && TestFuncs(Suffix))
137 if (!Prefix.empty() && TestFuncs(Prefix))
142 bool TestFuncs(const std::vector<Function*> &Prefix);
146 /// TestMergedProgram - Given two modules, link them together and run the
147 /// program, checking to see if the program matches the diff. If the diff
148 /// matches, return false, otherwise return true. If the DeleteInputs argument
149 /// is set to true then this function deletes both input modules before it
151 static bool TestMergedProgram(BugDriver &BD, Module *M1, Module *M2,
153 // Link the two portions of the program back to together.
154 std::string ErrorMsg;
155 if (!DeleteInputs) M1 = CloneModule(M1);
156 if (LinkModules(M1, M2, &ErrorMsg)) {
157 std::cerr << BD.getToolName() << ": Error linking modules together:"
161 if (DeleteInputs) delete M2; // We are done with this module...
163 Module *OldProgram = BD.swapProgramIn(M1);
165 // Execute the program. If it does not match the expected output, we must
167 bool Broken = BD.diffProgram();
169 // Delete the linked module & restore the original
170 BD.swapProgramIn(OldProgram);
175 bool ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function*>&Funcs){
176 // Test to see if the function is misoptimized if we ONLY run it on the
177 // functions listed in Funcs.
178 std::cout << "Checking to see if the program is misoptimized when "
179 << (Funcs.size()==1 ? "this function is" : "these functions are")
180 << " run through the pass"
181 << (BD.getPassesToRun().size() == 1 ? "" : "es") << ":";
182 PrintFunctionList(Funcs);
185 // Split the module into the two halves of the program we want.
186 Module *ToNotOptimize = CloneModule(BD.getProgram());
187 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, Funcs);
189 // Run the predicate, not that the predicate will delete both input modules.
190 return TestFn(BD, ToOptimize, ToNotOptimize);
193 /// ExtractLoops - Given a reduced list of functions that still exposed the bug,
194 /// check to see if we can extract the loops in the region without obscuring the
195 /// bug. If so, it reduces the amount of code identified.
196 static bool ExtractLoops(BugDriver &BD,
197 bool (*TestFn)(BugDriver &, Module *, Module *),
198 std::vector<Function*> &MiscompiledFunctions) {
199 bool MadeChange = false;
201 Module *ToNotOptimize = CloneModule(BD.getProgram());
202 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
203 MiscompiledFunctions);
204 Module *ToOptimizeLoopExtracted = BD.ExtractLoop(ToOptimize);
205 if (!ToOptimizeLoopExtracted) {
206 // If the loop extractor crashed or if there were no extractible loops,
207 // then this chapter of our odyssey is over with.
208 delete ToNotOptimize;
213 std::cerr << "Extracted a loop from the breaking portion of the program.\n";
216 // Bugpoint is intentionally not very trusting of LLVM transformations. In
217 // particular, we're not going to assume that the loop extractor works, so
218 // we're going to test the newly loop extracted program to make sure nothing
219 // has broken. If something broke, then we'll inform the user and stop
221 if (TestMergedProgram(BD, ToOptimizeLoopExtracted, ToNotOptimize, false)) {
222 // Merged program doesn't work anymore!
223 std::cerr << " *** ERROR: Loop extraction broke the program. :("
224 << " Please report a bug!\n";
225 std::cerr << " Continuing on with un-loop-extracted version.\n";
226 delete ToNotOptimize;
227 delete ToOptimizeLoopExtracted;
231 std::cout << " Testing after loop extraction:\n";
232 // Clone modules, the tester function will free them.
233 Module *TOLEBackup = CloneModule(ToOptimizeLoopExtracted);
234 Module *TNOBackup = CloneModule(ToNotOptimize);
235 if (!TestFn(BD, ToOptimizeLoopExtracted, ToNotOptimize)) {
236 std::cout << "*** Loop extraction masked the problem. Undoing.\n";
237 // If the program is not still broken, then loop extraction did something
238 // that masked the error. Stop loop extraction now.
243 ToOptimizeLoopExtracted = TOLEBackup;
244 ToNotOptimize = TNOBackup;
246 std::cout << "*** Loop extraction successful!\n";
248 // Okay, great! Now we know that we extracted a loop and that loop
249 // extraction both didn't break the program, and didn't mask the problem.
250 // Replace the current program with the loop extracted version, and try to
251 // extract another loop.
252 std::string ErrorMsg;
253 if (LinkModules(ToNotOptimize, ToOptimizeLoopExtracted, &ErrorMsg)) {
254 std::cerr << BD.getToolName() << ": Error linking modules together:"
259 // All of the Function*'s in the MiscompiledFunctions list are in the old
260 // module. Update this list to include all of the functions in the
261 // optimized and loop extracted module.
262 MiscompiledFunctions.clear();
263 for (Module::iterator I = ToOptimizeLoopExtracted->begin(),
264 E = ToOptimizeLoopExtracted->end(); I != E; ++I) {
265 if (!I->isExternal()) {
266 Function *NewF = ToNotOptimize->getFunction(I->getName(),
267 I->getFunctionType());
268 assert(NewF && "Function not found??");
269 MiscompiledFunctions.push_back(NewF);
272 delete ToOptimizeLoopExtracted;
274 BD.setNewProgram(ToNotOptimize);
279 /// DebugAMiscompilation - This is a generic driver to narrow down
280 /// miscompilations, either in an optimization or a code generator.
281 static std::vector<Function*>
282 DebugAMiscompilation(BugDriver &BD,
283 bool (*TestFn)(BugDriver &, Module *, Module *)) {
284 // Okay, now that we have reduced the list of passes which are causing the
285 // failure, see if we can pin down which functions are being
286 // miscompiled... first build a list of all of the non-external functions in
288 std::vector<Function*> MiscompiledFunctions;
289 Module *Prog = BD.getProgram();
290 for (Module::iterator I = Prog->begin(), E = Prog->end(); I != E; ++I)
291 if (!I->isExternal())
292 MiscompiledFunctions.push_back(I);
294 // Do the reduction...
295 ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
297 std::cout << "\n*** The following function"
298 << (MiscompiledFunctions.size() == 1 ? " is" : "s are")
299 << " being miscompiled: ";
300 PrintFunctionList(MiscompiledFunctions);
303 // See if we can rip any loops out of the miscompiled functions and still
304 // trigger the problem.
305 if (ExtractLoops(BD, TestFn, MiscompiledFunctions)) {
306 // Okay, we extracted some loops and the problem still appears. See if we
307 // can eliminate some of the created functions from being candidates.
309 // Do the reduction...
310 ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
312 std::cout << "\n*** The following function"
313 << (MiscompiledFunctions.size() == 1 ? " is" : "s are")
314 << " being miscompiled: ";
315 PrintFunctionList(MiscompiledFunctions);
319 return MiscompiledFunctions;
322 static bool TestOptimizer(BugDriver &BD, Module *Test, Module *Safe) {
323 // Run the optimization passes on ToOptimize, producing a transformed version
324 // of the functions being tested.
325 std::cout << " Optimizing functions being tested: ";
326 Module *Optimized = BD.runPassesOn(Test, BD.getPassesToRun(),
327 /*AutoDebugCrashes*/true);
328 std::cout << "done.\n";
331 std::cout << " Checking to see if the merged program executes correctly: ";
332 bool Broken = TestMergedProgram(BD, Test, Safe, true);
333 std::cout << (Broken ? " nope.\n" : " yup.\n");
338 /// debugMiscompilation - This method is used when the passes selected are not
339 /// crashing, but the generated output is semantically different from the
342 bool BugDriver::debugMiscompilation() {
343 // Make sure something was miscompiled...
344 if (!ReduceMiscompilingPasses(*this).reduceList(PassesToRun)) {
345 std::cerr << "*** Optimized program matches reference output! No problem "
346 << "detected...\nbugpoint can't help you with your problem!\n";
350 std::cout << "\n*** Found miscompiling pass"
351 << (getPassesToRun().size() == 1 ? "" : "es") << ": "
352 << getPassesString(getPassesToRun()) << "\n";
353 EmitProgressBytecode("passinput");
355 std::vector<Function*> MiscompiledFunctions =
356 DebugAMiscompilation(*this, TestOptimizer);
358 // Output a bunch of bytecode files for the user...
359 std::cout << "Outputting reduced bytecode files which expose the problem:\n";
360 Module *ToNotOptimize = CloneModule(getProgram());
361 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
362 MiscompiledFunctions);
364 std::cout << " Non-optimized portion: ";
365 ToNotOptimize = swapProgramIn(ToNotOptimize);
366 EmitProgressBytecode("tonotoptimize", true);
367 setNewProgram(ToNotOptimize); // Delete hacked module.
369 std::cout << " Portion that is input to optimizer: ";
370 ToOptimize = swapProgramIn(ToOptimize);
371 EmitProgressBytecode("tooptimize");
372 setNewProgram(ToOptimize); // Delete hacked module.