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1 //===- CrashDebugger.cpp - Debug compilation crashes ----------------------===//
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 the bugpoint internals that narrow down compilation crashes
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "BugDriver.h"
15 #include "ToolRunner.h"
16 #include "ListReducer.h"
17 #include "llvm/Constants.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/Instructions.h"
20 #include "llvm/Module.h"
21 #include "llvm/Pass.h"
22 #include "llvm/PassManager.h"
23 #include "llvm/ValueSymbolTable.h"
24 #include "llvm/ADT/SmallPtrSet.h"
25 #include "llvm/Analysis/Verifier.h"
26 #include "llvm/Support/CFG.h"
27 #include "llvm/Transforms/Scalar.h"
28 #include "llvm/Transforms/Utils/Cloning.h"
29 #include "llvm/Support/FileUtilities.h"
30 #include "llvm/Support/CommandLine.h"
31 #include <set>
32 using namespace llvm;
33 
34 namespace {
35   cl::opt<bool>
36   KeepMain("keep-main",
37            cl::desc("Force function reduction to keep main"),
38            cl::init(false));
39   cl::opt<bool>
40   NoGlobalRM ("disable-global-remove",
41          cl::desc("Do not remove global variables"),
42          cl::init(false));
43 }
44 
45 namespace llvm {
46   class ReducePassList : public ListReducer<std::string> {
47     BugDriver &BD;
48   public:
ReducePassList(BugDriver & bd)49     ReducePassList(BugDriver &bd) : BD(bd) {}
50 
51     // doTest - Return true iff running the "removed" passes succeeds, and
52     // running the "Kept" passes fail when run on the output of the "removed"
53     // passes.  If we return true, we update the current module of bugpoint.
54     //
55     virtual TestResult doTest(std::vector<std::string> &Removed,
56                               std::vector<std::string> &Kept,
57                               std::string &Error);
58   };
59 }
60 
61 ReducePassList::TestResult
doTest(std::vector<std::string> & Prefix,std::vector<std::string> & Suffix,std::string & Error)62 ReducePassList::doTest(std::vector<std::string> &Prefix,
63                        std::vector<std::string> &Suffix,
64                        std::string &Error) {
65   sys::Path PrefixOutput;
66   Module *OrigProgram = 0;
67   if (!Prefix.empty()) {
68     outs() << "Checking to see if these passes crash: "
69            << getPassesString(Prefix) << ": ";
70     std::string PfxOutput;
71     if (BD.runPasses(BD.getProgram(), Prefix, PfxOutput))
72       return KeepPrefix;
73 
74     PrefixOutput.set(PfxOutput);
75     OrigProgram = BD.Program;
76 
77     BD.Program = ParseInputFile(PrefixOutput.str(), BD.getContext());
78     if (BD.Program == 0) {
79       errs() << BD.getToolName() << ": Error reading bitcode file '"
80              << PrefixOutput.str() << "'!\n";
81       exit(1);
82     }
83     PrefixOutput.eraseFromDisk();
84   }
85 
86   outs() << "Checking to see if these passes crash: "
87          << getPassesString(Suffix) << ": ";
88 
89   if (BD.runPasses(BD.getProgram(), Suffix)) {
90     delete OrigProgram;            // The suffix crashes alone...
91     return KeepSuffix;
92   }
93 
94   // Nothing failed, restore state...
95   if (OrigProgram) {
96     delete BD.Program;
97     BD.Program = OrigProgram;
98   }
99   return NoFailure;
100 }
101 
102 namespace {
103   /// ReduceCrashingGlobalVariables - This works by removing the global
104   /// variable's initializer and seeing if the program still crashes. If it
105   /// does, then we keep that program and try again.
106   ///
107   class ReduceCrashingGlobalVariables : public ListReducer<GlobalVariable*> {
108     BugDriver &BD;
109     bool (*TestFn)(const BugDriver &, Module *);
110   public:
ReduceCrashingGlobalVariables(BugDriver & bd,bool (* testFn)(const BugDriver &,Module *))111     ReduceCrashingGlobalVariables(BugDriver &bd,
112                                   bool (*testFn)(const BugDriver &, Module *))
113       : BD(bd), TestFn(testFn) {}
114 
doTest(std::vector<GlobalVariable * > & Prefix,std::vector<GlobalVariable * > & Kept,std::string & Error)115     virtual TestResult doTest(std::vector<GlobalVariable*> &Prefix,
116                               std::vector<GlobalVariable*> &Kept,
117                               std::string &Error) {
118       if (!Kept.empty() && TestGlobalVariables(Kept))
119         return KeepSuffix;
120       if (!Prefix.empty() && TestGlobalVariables(Prefix))
121         return KeepPrefix;
122       return NoFailure;
123     }
124 
125     bool TestGlobalVariables(std::vector<GlobalVariable*> &GVs);
126   };
127 }
128 
129 bool
TestGlobalVariables(std::vector<GlobalVariable * > & GVs)130 ReduceCrashingGlobalVariables::TestGlobalVariables(
131                               std::vector<GlobalVariable*> &GVs) {
132   // Clone the program to try hacking it apart...
133   ValueToValueMapTy VMap;
134   Module *M = CloneModule(BD.getProgram(), VMap);
135 
136   // Convert list to set for fast lookup...
137   std::set<GlobalVariable*> GVSet;
138 
139   for (unsigned i = 0, e = GVs.size(); i != e; ++i) {
140     GlobalVariable* CMGV = cast<GlobalVariable>(VMap[GVs[i]]);
141     assert(CMGV && "Global Variable not in module?!");
142     GVSet.insert(CMGV);
143   }
144 
145   outs() << "Checking for crash with only these global variables: ";
146   PrintGlobalVariableList(GVs);
147   outs() << ": ";
148 
149   // Loop over and delete any global variables which we aren't supposed to be
150   // playing with...
151   for (Module::global_iterator I = M->global_begin(), E = M->global_end();
152        I != E; ++I)
153     if (I->hasInitializer() && !GVSet.count(I)) {
154       I->setInitializer(0);
155       I->setLinkage(GlobalValue::ExternalLinkage);
156     }
157 
158   // Try running the hacked up program...
159   if (TestFn(BD, M)) {
160     BD.setNewProgram(M);        // It crashed, keep the trimmed version...
161 
162     // Make sure to use global variable pointers that point into the now-current
163     // module.
164     GVs.assign(GVSet.begin(), GVSet.end());
165     return true;
166   }
167 
168   delete M;
169   return false;
170 }
171 
172 namespace {
173   /// ReduceCrashingFunctions reducer - This works by removing functions and
174   /// seeing if the program still crashes. If it does, then keep the newer,
175   /// smaller program.
176   ///
177   class ReduceCrashingFunctions : public ListReducer<Function*> {
178     BugDriver &BD;
179     bool (*TestFn)(const BugDriver &, Module *);
180   public:
ReduceCrashingFunctions(BugDriver & bd,bool (* testFn)(const BugDriver &,Module *))181     ReduceCrashingFunctions(BugDriver &bd,
182                             bool (*testFn)(const BugDriver &, Module *))
183       : BD(bd), TestFn(testFn) {}
184 
doTest(std::vector<Function * > & Prefix,std::vector<Function * > & Kept,std::string & Error)185     virtual TestResult doTest(std::vector<Function*> &Prefix,
186                               std::vector<Function*> &Kept,
187                               std::string &Error) {
188       if (!Kept.empty() && TestFuncs(Kept))
189         return KeepSuffix;
190       if (!Prefix.empty() && TestFuncs(Prefix))
191         return KeepPrefix;
192       return NoFailure;
193     }
194 
195     bool TestFuncs(std::vector<Function*> &Prefix);
196   };
197 }
198 
TestFuncs(std::vector<Function * > & Funcs)199 bool ReduceCrashingFunctions::TestFuncs(std::vector<Function*> &Funcs) {
200 
201   //if main isn't present, claim there is no problem
202   if (KeepMain && find(Funcs.begin(), Funcs.end(),
203                        BD.getProgram()->getFunction("main")) == Funcs.end())
204     return false;
205 
206   // Clone the program to try hacking it apart...
207   ValueToValueMapTy VMap;
208   Module *M = CloneModule(BD.getProgram(), VMap);
209 
210   // Convert list to set for fast lookup...
211   std::set<Function*> Functions;
212   for (unsigned i = 0, e = Funcs.size(); i != e; ++i) {
213     Function *CMF = cast<Function>(VMap[Funcs[i]]);
214     assert(CMF && "Function not in module?!");
215     assert(CMF->getFunctionType() == Funcs[i]->getFunctionType() && "wrong ty");
216     assert(CMF->getName() == Funcs[i]->getName() && "wrong name");
217     Functions.insert(CMF);
218   }
219 
220   outs() << "Checking for crash with only these functions: ";
221   PrintFunctionList(Funcs);
222   outs() << ": ";
223 
224   // Loop over and delete any functions which we aren't supposed to be playing
225   // with...
226   for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
227     if (!I->isDeclaration() && !Functions.count(I))
228       DeleteFunctionBody(I);
229 
230   // Try running the hacked up program...
231   if (TestFn(BD, M)) {
232     BD.setNewProgram(M);        // It crashed, keep the trimmed version...
233 
234     // Make sure to use function pointers that point into the now-current
235     // module.
236     Funcs.assign(Functions.begin(), Functions.end());
237     return true;
238   }
239   delete M;
240   return false;
241 }
242 
243 
244 namespace {
245   /// ReduceCrashingBlocks reducer - This works by setting the terminators of
246   /// all terminators except the specified basic blocks to a 'ret' instruction,
247   /// then running the simplify-cfg pass.  This has the effect of chopping up
248   /// the CFG really fast which can reduce large functions quickly.
249   ///
250   class ReduceCrashingBlocks : public ListReducer<const BasicBlock*> {
251     BugDriver &BD;
252     bool (*TestFn)(const BugDriver &, Module *);
253   public:
ReduceCrashingBlocks(BugDriver & bd,bool (* testFn)(const BugDriver &,Module *))254     ReduceCrashingBlocks(BugDriver &bd,
255                          bool (*testFn)(const BugDriver &, Module *))
256       : BD(bd), TestFn(testFn) {}
257 
doTest(std::vector<const BasicBlock * > & Prefix,std::vector<const BasicBlock * > & Kept,std::string & Error)258     virtual TestResult doTest(std::vector<const BasicBlock*> &Prefix,
259                               std::vector<const BasicBlock*> &Kept,
260                               std::string &Error) {
261       if (!Kept.empty() && TestBlocks(Kept))
262         return KeepSuffix;
263       if (!Prefix.empty() && TestBlocks(Prefix))
264         return KeepPrefix;
265       return NoFailure;
266     }
267 
268     bool TestBlocks(std::vector<const BasicBlock*> &Prefix);
269   };
270 }
271 
TestBlocks(std::vector<const BasicBlock * > & BBs)272 bool ReduceCrashingBlocks::TestBlocks(std::vector<const BasicBlock*> &BBs) {
273   // Clone the program to try hacking it apart...
274   ValueToValueMapTy VMap;
275   Module *M = CloneModule(BD.getProgram(), VMap);
276 
277   // Convert list to set for fast lookup...
278   SmallPtrSet<BasicBlock*, 8> Blocks;
279   for (unsigned i = 0, e = BBs.size(); i != e; ++i)
280     Blocks.insert(cast<BasicBlock>(VMap[BBs[i]]));
281 
282   outs() << "Checking for crash with only these blocks:";
283   unsigned NumPrint = Blocks.size();
284   if (NumPrint > 10) NumPrint = 10;
285   for (unsigned i = 0, e = NumPrint; i != e; ++i)
286     outs() << " " << BBs[i]->getName();
287   if (NumPrint < Blocks.size())
288     outs() << "... <" << Blocks.size() << " total>";
289   outs() << ": ";
290 
291   // Loop over and delete any hack up any blocks that are not listed...
292   for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
293     for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
294       if (!Blocks.count(BB) && BB->getTerminator()->getNumSuccessors()) {
295         // Loop over all of the successors of this block, deleting any PHI nodes
296         // that might include it.
297         for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI)
298           (*SI)->removePredecessor(BB);
299 
300         TerminatorInst *BBTerm = BB->getTerminator();
301 
302         if (!BB->getTerminator()->getType()->isVoidTy())
303           BBTerm->replaceAllUsesWith(Constant::getNullValue(BBTerm->getType()));
304 
305         // Replace the old terminator instruction.
306         BB->getInstList().pop_back();
307         new UnreachableInst(BB->getContext(), BB);
308       }
309 
310   // The CFG Simplifier pass may delete one of the basic blocks we are
311   // interested in.  If it does we need to take the block out of the list.  Make
312   // a "persistent mapping" by turning basic blocks into <function, name> pairs.
313   // This won't work well if blocks are unnamed, but that is just the risk we
314   // have to take.
315   std::vector<std::pair<std::string, std::string> > BlockInfo;
316 
317   for (SmallPtrSet<BasicBlock*, 8>::iterator I = Blocks.begin(),
318          E = Blocks.end(); I != E; ++I)
319     BlockInfo.push_back(std::make_pair((*I)->getParent()->getName(),
320                                        (*I)->getName()));
321 
322   // Now run the CFG simplify pass on the function...
323   std::vector<std::string> Passes;
324   Passes.push_back("simplifycfg");
325   Passes.push_back("verify");
326   Module *New = BD.runPassesOn(M, Passes);
327   delete M;
328   if (!New) {
329     errs() << "simplifycfg failed!\n";
330     exit(1);
331   }
332   M = New;
333 
334   // Try running on the hacked up program...
335   if (TestFn(BD, M)) {
336     BD.setNewProgram(M);      // It crashed, keep the trimmed version...
337 
338     // Make sure to use basic block pointers that point into the now-current
339     // module, and that they don't include any deleted blocks.
340     BBs.clear();
341     const ValueSymbolTable &GST = M->getValueSymbolTable();
342     for (unsigned i = 0, e = BlockInfo.size(); i != e; ++i) {
343       Function *F = cast<Function>(GST.lookup(BlockInfo[i].first));
344       ValueSymbolTable &ST = F->getValueSymbolTable();
345       Value* V = ST.lookup(BlockInfo[i].second);
346       if (V && V->getType() == Type::getLabelTy(V->getContext()))
347         BBs.push_back(cast<BasicBlock>(V));
348     }
349     return true;
350   }
351   delete M;  // It didn't crash, try something else.
352   return false;
353 }
354 
355 namespace {
356   /// ReduceCrashingInstructions reducer - This works by removing the specified
357   /// non-terminator instructions and replacing them with undef.
358   ///
359   class ReduceCrashingInstructions : public ListReducer<const Instruction*> {
360     BugDriver &BD;
361     bool (*TestFn)(const BugDriver &, Module *);
362   public:
ReduceCrashingInstructions(BugDriver & bd,bool (* testFn)(const BugDriver &,Module *))363     ReduceCrashingInstructions(BugDriver &bd,
364                                bool (*testFn)(const BugDriver &, Module *))
365       : BD(bd), TestFn(testFn) {}
366 
doTest(std::vector<const Instruction * > & Prefix,std::vector<const Instruction * > & Kept,std::string & Error)367     virtual TestResult doTest(std::vector<const Instruction*> &Prefix,
368                               std::vector<const Instruction*> &Kept,
369                               std::string &Error) {
370       if (!Kept.empty() && TestInsts(Kept))
371         return KeepSuffix;
372       if (!Prefix.empty() && TestInsts(Prefix))
373         return KeepPrefix;
374       return NoFailure;
375     }
376 
377     bool TestInsts(std::vector<const Instruction*> &Prefix);
378   };
379 }
380 
TestInsts(std::vector<const Instruction * > & Insts)381 bool ReduceCrashingInstructions::TestInsts(std::vector<const Instruction*>
382                                            &Insts) {
383   // Clone the program to try hacking it apart...
384   ValueToValueMapTy VMap;
385   Module *M = CloneModule(BD.getProgram(), VMap);
386 
387   // Convert list to set for fast lookup...
388   SmallPtrSet<Instruction*, 64> Instructions;
389   for (unsigned i = 0, e = Insts.size(); i != e; ++i) {
390     assert(!isa<TerminatorInst>(Insts[i]));
391     Instructions.insert(cast<Instruction>(VMap[Insts[i]]));
392   }
393 
394   outs() << "Checking for crash with only " << Instructions.size();
395   if (Instructions.size() == 1)
396     outs() << " instruction: ";
397   else
398     outs() << " instructions: ";
399 
400   for (Module::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI)
401     for (Function::iterator FI = MI->begin(), FE = MI->end(); FI != FE; ++FI)
402       for (BasicBlock::iterator I = FI->begin(), E = FI->end(); I != E;) {
403         Instruction *Inst = I++;
404         if (!Instructions.count(Inst) && !isa<TerminatorInst>(Inst) &&
405             !isa<LandingPadInst>(Inst)) {
406           if (!Inst->getType()->isVoidTy())
407             Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
408           Inst->eraseFromParent();
409         }
410       }
411 
412   // Verify that this is still valid.
413   PassManager Passes;
414   Passes.add(createVerifierPass());
415   Passes.run(*M);
416 
417   // Try running on the hacked up program...
418   if (TestFn(BD, M)) {
419     BD.setNewProgram(M);      // It crashed, keep the trimmed version...
420 
421     // Make sure to use instruction pointers that point into the now-current
422     // module, and that they don't include any deleted blocks.
423     Insts.clear();
424     for (SmallPtrSet<Instruction*, 64>::const_iterator I = Instructions.begin(),
425              E = Instructions.end(); I != E; ++I)
426       Insts.push_back(*I);
427     return true;
428   }
429   delete M;  // It didn't crash, try something else.
430   return false;
431 }
432 
433 /// DebugACrash - Given a predicate that determines whether a component crashes
434 /// on a program, try to destructively reduce the program while still keeping
435 /// the predicate true.
DebugACrash(BugDriver & BD,bool (* TestFn)(const BugDriver &,Module *),std::string & Error)436 static bool DebugACrash(BugDriver &BD,
437                         bool (*TestFn)(const BugDriver &, Module *),
438                         std::string &Error) {
439   // See if we can get away with nuking some of the global variable initializers
440   // in the program...
441   if (!NoGlobalRM &&
442       BD.getProgram()->global_begin() != BD.getProgram()->global_end()) {
443     // Now try to reduce the number of global variable initializers in the
444     // module to something small.
445     Module *M = CloneModule(BD.getProgram());
446     bool DeletedInit = false;
447 
448     for (Module::global_iterator I = M->global_begin(), E = M->global_end();
449          I != E; ++I)
450       if (I->hasInitializer()) {
451         I->setInitializer(0);
452         I->setLinkage(GlobalValue::ExternalLinkage);
453         DeletedInit = true;
454       }
455 
456     if (!DeletedInit) {
457       delete M;  // No change made...
458     } else {
459       // See if the program still causes a crash...
460       outs() << "\nChecking to see if we can delete global inits: ";
461 
462       if (TestFn(BD, M)) {      // Still crashes?
463         BD.setNewProgram(M);
464         outs() << "\n*** Able to remove all global initializers!\n";
465       } else {                  // No longer crashes?
466         outs() << "  - Removing all global inits hides problem!\n";
467         delete M;
468 
469         std::vector<GlobalVariable*> GVs;
470 
471         for (Module::global_iterator I = BD.getProgram()->global_begin(),
472                E = BD.getProgram()->global_end(); I != E; ++I)
473           if (I->hasInitializer())
474             GVs.push_back(I);
475 
476         if (GVs.size() > 1 && !BugpointIsInterrupted) {
477           outs() << "\n*** Attempting to reduce the number of global "
478                     << "variables in the testcase\n";
479 
480           unsigned OldSize = GVs.size();
481           ReduceCrashingGlobalVariables(BD, TestFn).reduceList(GVs, Error);
482           if (!Error.empty())
483             return true;
484 
485           if (GVs.size() < OldSize)
486             BD.EmitProgressBitcode(BD.getProgram(), "reduced-global-variables");
487         }
488       }
489     }
490   }
491 
492   // Now try to reduce the number of functions in the module to something small.
493   std::vector<Function*> Functions;
494   for (Module::iterator I = BD.getProgram()->begin(),
495          E = BD.getProgram()->end(); I != E; ++I)
496     if (!I->isDeclaration())
497       Functions.push_back(I);
498 
499   if (Functions.size() > 1 && !BugpointIsInterrupted) {
500     outs() << "\n*** Attempting to reduce the number of functions "
501       "in the testcase\n";
502 
503     unsigned OldSize = Functions.size();
504     ReduceCrashingFunctions(BD, TestFn).reduceList(Functions, Error);
505 
506     if (Functions.size() < OldSize)
507       BD.EmitProgressBitcode(BD.getProgram(), "reduced-function");
508   }
509 
510   // Attempt to delete entire basic blocks at a time to speed up
511   // convergence... this actually works by setting the terminator of the blocks
512   // to a return instruction then running simplifycfg, which can potentially
513   // shrinks the code dramatically quickly
514   //
515   if (!DisableSimplifyCFG && !BugpointIsInterrupted) {
516     std::vector<const BasicBlock*> Blocks;
517     for (Module::const_iterator I = BD.getProgram()->begin(),
518            E = BD.getProgram()->end(); I != E; ++I)
519       for (Function::const_iterator FI = I->begin(), E = I->end(); FI !=E; ++FI)
520         Blocks.push_back(FI);
521     unsigned OldSize = Blocks.size();
522     ReduceCrashingBlocks(BD, TestFn).reduceList(Blocks, Error);
523     if (Blocks.size() < OldSize)
524       BD.EmitProgressBitcode(BD.getProgram(), "reduced-blocks");
525   }
526 
527   // Attempt to delete instructions using bisection. This should help out nasty
528   // cases with large basic blocks where the problem is at one end.
529   if (!BugpointIsInterrupted) {
530     std::vector<const Instruction*> Insts;
531     for (Module::const_iterator MI = BD.getProgram()->begin(),
532            ME = BD.getProgram()->end(); MI != ME; ++MI)
533       for (Function::const_iterator FI = MI->begin(), FE = MI->end(); FI != FE;
534            ++FI)
535         for (BasicBlock::const_iterator I = FI->begin(), E = FI->end();
536              I != E; ++I)
537           if (!isa<TerminatorInst>(I))
538             Insts.push_back(I);
539 
540     ReduceCrashingInstructions(BD, TestFn).reduceList(Insts, Error);
541   }
542 
543   // FIXME: This should use the list reducer to converge faster by deleting
544   // larger chunks of instructions at a time!
545   unsigned Simplification = 2;
546   do {
547     if (BugpointIsInterrupted) break;
548     --Simplification;
549     outs() << "\n*** Attempting to reduce testcase by deleting instruc"
550            << "tions: Simplification Level #" << Simplification << '\n';
551 
552     // Now that we have deleted the functions that are unnecessary for the
553     // program, try to remove instructions that are not necessary to cause the
554     // crash.  To do this, we loop through all of the instructions in the
555     // remaining functions, deleting them (replacing any values produced with
556     // nulls), and then running ADCE and SimplifyCFG.  If the transformed input
557     // still triggers failure, keep deleting until we cannot trigger failure
558     // anymore.
559     //
560     unsigned InstructionsToSkipBeforeDeleting = 0;
561   TryAgain:
562 
563     // Loop over all of the (non-terminator) instructions remaining in the
564     // function, attempting to delete them.
565     unsigned CurInstructionNum = 0;
566     for (Module::const_iterator FI = BD.getProgram()->begin(),
567            E = BD.getProgram()->end(); FI != E; ++FI)
568       if (!FI->isDeclaration())
569         for (Function::const_iterator BI = FI->begin(), E = FI->end(); BI != E;
570              ++BI)
571           for (BasicBlock::const_iterator I = BI->begin(), E = --BI->end();
572                I != E; ++I, ++CurInstructionNum) {
573             if (InstructionsToSkipBeforeDeleting) {
574               --InstructionsToSkipBeforeDeleting;
575             } else {
576               if (BugpointIsInterrupted) goto ExitLoops;
577 
578               if (isa<LandingPadInst>(I))
579                 continue;
580 
581               outs() << "Checking instruction: " << *I;
582               Module *M = BD.deleteInstructionFromProgram(I, Simplification);
583 
584               // Find out if the pass still crashes on this pass...
585               if (TestFn(BD, M)) {
586                 // Yup, it does, we delete the old module, and continue trying
587                 // to reduce the testcase...
588                 BD.setNewProgram(M);
589                 InstructionsToSkipBeforeDeleting = CurInstructionNum;
590                 goto TryAgain;  // I wish I had a multi-level break here!
591               }
592 
593               // This pass didn't crash without this instruction, try the next
594               // one.
595               delete M;
596             }
597           }
598 
599     if (InstructionsToSkipBeforeDeleting) {
600       InstructionsToSkipBeforeDeleting = 0;
601       goto TryAgain;
602     }
603 
604   } while (Simplification);
605 ExitLoops:
606 
607   // Try to clean up the testcase by running funcresolve and globaldce...
608   if (!BugpointIsInterrupted) {
609     outs() << "\n*** Attempting to perform final cleanups: ";
610     Module *M = CloneModule(BD.getProgram());
611     M = BD.performFinalCleanups(M, true);
612 
613     // Find out if the pass still crashes on the cleaned up program...
614     if (TestFn(BD, M)) {
615       BD.setNewProgram(M);     // Yup, it does, keep the reduced version...
616     } else {
617       delete M;
618     }
619   }
620 
621   BD.EmitProgressBitcode(BD.getProgram(), "reduced-simplified");
622 
623   return false;
624 }
625 
TestForOptimizerCrash(const BugDriver & BD,Module * M)626 static bool TestForOptimizerCrash(const BugDriver &BD, Module *M) {
627   return BD.runPasses(M);
628 }
629 
630 /// debugOptimizerCrash - This method is called when some pass crashes on input.
631 /// It attempts to prune down the testcase to something reasonable, and figure
632 /// out exactly which pass is crashing.
633 ///
debugOptimizerCrash(const std::string & ID)634 bool BugDriver::debugOptimizerCrash(const std::string &ID) {
635   outs() << "\n*** Debugging optimizer crash!\n";
636 
637   std::string Error;
638   // Reduce the list of passes which causes the optimizer to crash...
639   if (!BugpointIsInterrupted)
640     ReducePassList(*this).reduceList(PassesToRun, Error);
641   assert(Error.empty());
642 
643   outs() << "\n*** Found crashing pass"
644          << (PassesToRun.size() == 1 ? ": " : "es: ")
645          << getPassesString(PassesToRun) << '\n';
646 
647   EmitProgressBitcode(Program, ID);
648 
649   bool Success = DebugACrash(*this, TestForOptimizerCrash, Error);
650   assert(Error.empty());
651   return Success;
652 }
653 
TestForCodeGenCrash(const BugDriver & BD,Module * M)654 static bool TestForCodeGenCrash(const BugDriver &BD, Module *M) {
655   std::string Error;
656   BD.compileProgram(M, &Error);
657   if (!Error.empty()) {
658     errs() << "<crash>\n";
659     return true;  // Tool is still crashing.
660   }
661   errs() << '\n';
662   return false;
663 }
664 
665 /// debugCodeGeneratorCrash - This method is called when the code generator
666 /// crashes on an input.  It attempts to reduce the input as much as possible
667 /// while still causing the code generator to crash.
debugCodeGeneratorCrash(std::string & Error)668 bool BugDriver::debugCodeGeneratorCrash(std::string &Error) {
669   errs() << "*** Debugging code generator crash!\n";
670 
671   return DebugACrash(*this, TestForCodeGenCrash, Error);
672 }
673