tools/bugpoint/CrashDebugger.cpp

   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:
  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
  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:
 111     ReduceCrashingGlobalVariables(BugDriver &bd,
 112                                   bool (*testFn)(const BugDriver &, Module *))
 113       : BD(bd), TestFn(testFn) {}
 114
 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
 130 ReduceCrashingGlobalVariables::TestGlobalVariables(
 131                               std::vector<GlobalVariable*> &GVs) {
 132   // Clone the program to try hacking it apart...
 133   ValueMap<const Value*, Value*> 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 llvm {
 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:
 181     ReduceCrashingFunctions(BugDriver &bd,
 182                             bool (*testFn)(const BugDriver &, Module *))
 183       : BD(bd), TestFn(testFn) {}
 184
 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
 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   ValueMap<const Value*, Value*> 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:
 254     ReduceCrashingBlocks(BugDriver &bd,
 255                          bool (*testFn)(const BugDriver &, Module *))
 256       : BD(bd), TestFn(testFn) {}
 257
 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
 272 bool ReduceCrashingBlocks::TestBlocks(std::vector<const BasicBlock*> &BBs) {
 273   // Clone the program to try hacking it apart...
 274   ValueMap<const Value*, Value*> 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<Function*, 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(), (*I)->getName()));
 320
 321   // Now run the CFG simplify pass on the function...
 322   PassManager Passes;
 323   Passes.add(createCFGSimplificationPass());
 324   Passes.add(createVerifierPass());
 325   Passes.run(*M);
 326
 327   // Try running on the hacked up program...
 328   if (TestFn(BD, M)) {
 329     BD.setNewProgram(M);      // It crashed, keep the trimmed version...
 330
 331     // Make sure to use basic block pointers that point into the now-current
 332     // module, and that they don't include any deleted blocks.
 333     BBs.clear();
 334     for (unsigned i = 0, e = BlockInfo.size(); i != e; ++i) {
 335       ValueSymbolTable &ST = BlockInfo[i].first->getValueSymbolTable();
 336       Value* V = ST.lookup(BlockInfo[i].second);
 337       if (V && V->getType() == Type::getLabelTy(V->getContext()))
 338         BBs.push_back(cast<BasicBlock>(V));
 339     }
 340     return true;
 341   }
 342   delete M;  // It didn't crash, try something else.
 343   return false;
 344 }
 345
 346 namespace {
 347   /// ReduceCrashingInstructions reducer - This works by removing the specified
 348   /// non-terminator instructions and replacing them with undef.
 349   ///
 350   class ReduceCrashingInstructions : public ListReducer<const Instruction*> {
 351     BugDriver &BD;
 352     bool (*TestFn)(const BugDriver &, Module *);
 353   public:
 354     ReduceCrashingInstructions(BugDriver &bd,
 355                                bool (*testFn)(const BugDriver &, Module *))
 356       : BD(bd), TestFn(testFn) {}
 357
 358     virtual TestResult doTest(std::vector<const Instruction*> &Prefix,
 359                               std::vector<const Instruction*> &Kept,
 360                               std::string &Error) {
 361       if (!Kept.empty() && TestInsts(Kept))
 362         return KeepSuffix;
 363       if (!Prefix.empty() && TestInsts(Prefix))
 364         return KeepPrefix;
 365       return NoFailure;
 366     }
 367
 368     bool TestInsts(std::vector<const Instruction*> &Prefix);
 369   };
 370 }
 371
 372 bool ReduceCrashingInstructions::TestInsts(std::vector<const Instruction*>
 373                                            &Insts) {
 374   // Clone the program to try hacking it apart...
 375   ValueMap<const Value*, Value*> VMap;
 376   Module *M = CloneModule(BD.getProgram(), VMap);
 377
 378   // Convert list to set for fast lookup...
 379   SmallPtrSet<Instruction*, 64> Instructions;
 380   for (unsigned i = 0, e = Insts.size(); i != e; ++i) {
 381     assert(!isa<TerminatorInst>(Insts[i]));
 382     Instructions.insert(cast<Instruction>(VMap[Insts[i]]));
 383   }
 384
 385   outs() << "Checking for crash with only " << Instructions.size();
 386   if (Instructions.size() == 1)
 387     outs() << " instruction: ";
 388   else
 389     outs() << " instructions: ";
 390
 391   for (Module::iterator MI = M->begin(), ME = M->end(); MI != ME; ++MI)
 392     for (Function::iterator FI = MI->begin(), FE = MI->end(); FI != FE; ++FI)
 393       for (BasicBlock::iterator I = FI->begin(), E = FI->end(); I != E;) {
 394         Instruction *Inst = I++;
 395         if (!Instructions.count(Inst) && !isa<TerminatorInst>(Inst)) {
 396           if (!Inst->getType()->isVoidTy())
 397             Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
 398           Inst->eraseFromParent();
 399         }
 400       }
 401
 402   // Verify that this is still valid.
 403   PassManager Passes;
 404   Passes.add(createVerifierPass());
 405   Passes.run(*M);
 406
 407   // Try running on the hacked up program...
 408   if (TestFn(BD, M)) {
 409     BD.setNewProgram(M);      // It crashed, keep the trimmed version...
 410
 411     // Make sure to use instruction pointers that point into the now-current
 412     // module, and that they don't include any deleted blocks.
 413     Insts.clear();
 414     for (SmallPtrSet<Instruction*, 64>::const_iterator I = Instructions.begin(),
 415              E = Instructions.end(); I != E; ++I)
 416       Insts.push_back(*I);
 417     return true;
 418   }
 419   delete M;  // It didn't crash, try something else.
 420   return false;
 421 }
 422
 423 /// DebugACrash - Given a predicate that determines whether a component crashes
 424 /// on a program, try to destructively reduce the program while still keeping
 425 /// the predicate true.
 426 static bool DebugACrash(BugDriver &BD,
 427                         bool (*TestFn)(const BugDriver &, Module *),
 428                         std::string &Error) {
 429   // See if we can get away with nuking some of the global variable initializers
 430   // in the program...
 431   if (!NoGlobalRM &&
 432       BD.getProgram()->global_begin() != BD.getProgram()->global_end()) {
 433     // Now try to reduce the number of global variable initializers in the
 434     // module to something small.
 435     Module *M = CloneModule(BD.getProgram());
 436     bool DeletedInit = false;
 437
 438     for (Module::global_iterator I = M->global_begin(), E = M->global_end();
 439          I != E; ++I)
 440       if (I->hasInitializer()) {
 441         I->setInitializer(0);
 442         I->setLinkage(GlobalValue::ExternalLinkage);
 443         DeletedInit = true;
 444       }
 445
 446     if (!DeletedInit) {
 447       delete M;  // No change made...
 448     } else {
 449       // See if the program still causes a crash...
 450       outs() << "\nChecking to see if we can delete global inits: ";
 451
 452       if (TestFn(BD, M)) {      // Still crashes?
 453         BD.setNewProgram(M);
 454         outs() << "\n*** Able to remove all global initializers!\n";
 455       } else {                  // No longer crashes?
 456         outs() << "  - Removing all global inits hides problem!\n";
 457         delete M;
 458
 459         std::vector<GlobalVariable*> GVs;
 460
 461         for (Module::global_iterator I = BD.getProgram()->global_begin(),
 462                E = BD.getProgram()->global_end(); I != E; ++I)
 463           if (I->hasInitializer())
 464             GVs.push_back(I);
 465
 466         if (GVs.size() > 1 && !BugpointIsInterrupted) {
 467           outs() << "\n*** Attempting to reduce the number of global "
 468                     << "variables in the testcase\n";
 469
 470           unsigned OldSize = GVs.size();
 471           ReduceCrashingGlobalVariables(BD, TestFn).reduceList(GVs, Error);
 472           if (!Error.empty())
 473             return true;
 474
 475           if (GVs.size() < OldSize)
 476             BD.EmitProgressBitcode(BD.getProgram(), "reduced-global-variables");
 477         }
 478       }
 479     }
 480   }
 481
 482   // Now try to reduce the number of functions in the module to something small.
 483   std::vector<Function*> Functions;
 484   for (Module::iterator I = BD.getProgram()->begin(),
 485          E = BD.getProgram()->end(); I != E; ++I)
 486     if (!I->isDeclaration())
 487       Functions.push_back(I);
 488
 489   if (Functions.size() > 1 && !BugpointIsInterrupted) {
 490     outs() << "\n*** Attempting to reduce the number of functions "
 491       "in the testcase\n";
 492
 493     unsigned OldSize = Functions.size();
 494     ReduceCrashingFunctions(BD, TestFn).reduceList(Functions, Error);
 495
 496     if (Functions.size() < OldSize)
 497       BD.EmitProgressBitcode(BD.getProgram(), "reduced-function");
 498   }
 499
 500   // Attempt to delete entire basic blocks at a time to speed up
 501   // convergence... this actually works by setting the terminator of the blocks
 502   // to a return instruction then running simplifycfg, which can potentially
 503   // shrinks the code dramatically quickly
 504   //
 505   if (!DisableSimplifyCFG && !BugpointIsInterrupted) {
 506     std::vector<const BasicBlock*> Blocks;
 507     for (Module::const_iterator I = BD.getProgram()->begin(),
 508            E = BD.getProgram()->end(); I != E; ++I)
 509       for (Function::const_iterator FI = I->begin(), E = I->end(); FI !=E; ++FI)
 510         Blocks.push_back(FI);
 511     unsigned OldSize = Blocks.size();
 512     ReduceCrashingBlocks(BD, TestFn).reduceList(Blocks, Error);
 513     if (Blocks.size() < OldSize)
 514       BD.EmitProgressBitcode(BD.getProgram(), "reduced-blocks");
 515   }
 516
 517   // Attempt to delete instructions using bisection. This should help out nasty
 518   // cases with large basic blocks where the problem is at one end.
 519   if (!BugpointIsInterrupted) {
 520     std::vector<const Instruction*> Insts;
 521     for (Module::const_iterator MI = BD.getProgram()->begin(),
 522            ME = BD.getProgram()->end(); MI != ME; ++MI)
 523       for (Function::const_iterator FI = MI->begin(), FE = MI->end(); FI != FE;
 524            ++FI)
 525         for (BasicBlock::const_iterator I = FI->begin(), E = FI->end();
 526              I != E; ++I)
 527           if (!isa<TerminatorInst>(I))
 528             Insts.push_back(I);
 529
 530     ReduceCrashingInstructions(BD, TestFn).reduceList(Insts, Error);
 531   }
 532
 533   // FIXME: This should use the list reducer to converge faster by deleting
 534   // larger chunks of instructions at a time!
 535   unsigned Simplification = 2;
 536   do {
 537     if (BugpointIsInterrupted) break;
 538     --Simplification;
 539     outs() << "\n*** Attempting to reduce testcase by deleting instruc"
 540            << "tions: Simplification Level #" << Simplification << '\n';
 541
 542     // Now that we have deleted the functions that are unnecessary for the
 543     // program, try to remove instructions that are not necessary to cause the
 544     // crash.  To do this, we loop through all of the instructions in the
 545     // remaining functions, deleting them (replacing any values produced with
 546     // nulls), and then running ADCE and SimplifyCFG.  If the transformed input
 547     // still triggers failure, keep deleting until we cannot trigger failure
 548     // anymore.
 549     //
 550     unsigned InstructionsToSkipBeforeDeleting = 0;
 551   TryAgain:
 552
 553     // Loop over all of the (non-terminator) instructions remaining in the
 554     // function, attempting to delete them.
 555     unsigned CurInstructionNum = 0;
 556     for (Module::const_iterator FI = BD.getProgram()->begin(),
 557            E = BD.getProgram()->end(); FI != E; ++FI)
 558       if (!FI->isDeclaration())
 559         for (Function::const_iterator BI = FI->begin(), E = FI->end(); BI != E;
 560              ++BI)
 561           for (BasicBlock::const_iterator I = BI->begin(), E = --BI->end();
 562                I != E; ++I, ++CurInstructionNum)
 563             if (InstructionsToSkipBeforeDeleting) {
 564               --InstructionsToSkipBeforeDeleting;
 565             } else {
 566               if (BugpointIsInterrupted) goto ExitLoops;
 567
 568               outs() << "Checking instruction: " << *I;
 569               Module *M = BD.deleteInstructionFromProgram(I, Simplification);
 570
 571               // Find out if the pass still crashes on this pass...
 572               if (TestFn(BD, M)) {
 573                 // Yup, it does, we delete the old module, and continue trying
 574                 // to reduce the testcase...
 575                 BD.setNewProgram(M);
 576                 InstructionsToSkipBeforeDeleting = CurInstructionNum;
 577                 goto TryAgain;  // I wish I had a multi-level break here!
 578               }
 579
 580               // This pass didn't crash without this instruction, try the next
 581               // one.
 582               delete M;
 583             }
 584
 585     if (InstructionsToSkipBeforeDeleting) {
 586       InstructionsToSkipBeforeDeleting = 0;
 587       goto TryAgain;
 588     }
 589
 590   } while (Simplification);
 591 ExitLoops:
 592
 593   // Try to clean up the testcase by running funcresolve and globaldce...
 594   if (!BugpointIsInterrupted) {
 595     outs() << "\n*** Attempting to perform final cleanups: ";
 596     Module *M = CloneModule(BD.getProgram());
 597     M = BD.performFinalCleanups(M, true);
 598
 599     // Find out if the pass still crashes on the cleaned up program...
 600     if (TestFn(BD, M)) {
 601       BD.setNewProgram(M);     // Yup, it does, keep the reduced version...
 602     } else {
 603       delete M;
 604     }
 605   }
 606
 607   BD.EmitProgressBitcode(BD.getProgram(), "reduced-simplified");
 608
 609   return false;
 610 }
 611
 612 static bool TestForOptimizerCrash(const BugDriver &BD, Module *M) {
 613   return BD.runPasses(M);
 614 }
 615
 616 /// debugOptimizerCrash - This method is called when some pass crashes on input.
 617 /// It attempts to prune down the testcase to something reasonable, and figure
 618 /// out exactly which pass is crashing.
 619 ///
 620 bool BugDriver::debugOptimizerCrash(const std::string &ID) {
 621   outs() << "\n*** Debugging optimizer crash!\n";
 622
 623   std::string Error;
 624   // Reduce the list of passes which causes the optimizer to crash...
 625   if (!BugpointIsInterrupted)
 626     ReducePassList(*this).reduceList(PassesToRun, Error);
 627   assert(Error.empty());
 628
 629   outs() << "\n*** Found crashing pass"
 630          << (PassesToRun.size() == 1 ? ": " : "es: ")
 631          << getPassesString(PassesToRun) << '\n';
 632
 633   EmitProgressBitcode(Program, ID);
 634
 635   bool Success = DebugACrash(*this, TestForOptimizerCrash, Error);
 636   assert(Error.empty());
 637   return Success;
 638 }
 639
 640 static bool TestForCodeGenCrash(const BugDriver &BD, Module *M) {
 641   std::string Error;
 642   BD.compileProgram(M, &Error);
 643   if (!Error.empty()) {
 644     errs() << "<crash>\n";
 645     return true;  // Tool is still crashing.
 646   }
 647   errs() << '\n';
 648   return false;
 649 }
 650
 651 /// debugCodeGeneratorCrash - This method is called when the code generator
 652 /// crashes on an input.  It attempts to reduce the input as much as possible
 653 /// while still causing the code generator to crash.
 654 bool BugDriver::debugCodeGeneratorCrash(std::string &Error) {
 655   errs() << "*** Debugging code generator crash!\n";
 656
 657   return DebugACrash(*this, TestForCodeGenCrash, Error);
 658 }