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