tools/bugpoint/Miscompilation.cpp

   1 //===- Miscompilation.cpp - Debug program miscompilations -----------------===//
   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 implements optimizer and code generation miscompilation debugging
  11 // support.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "BugDriver.h"
  16 #include "ListReducer.h"
  17 #include "ToolRunner.h"
  18 #include "llvm/Constants.h"
  19 #include "llvm/DerivedTypes.h"
  20 #include "llvm/Instructions.h"
  21 #include "llvm/Linker.h"
  22 #include "llvm/Module.h"
  23 #include "llvm/Pass.h"
  24 #include "llvm/Analysis/Verifier.h"
  25 #include "llvm/Support/Mangler.h"
  26 #include "llvm/Transforms/Utils/Cloning.h"
  27 #include "llvm/Support/CommandLine.h"
  28 #include "llvm/Support/FileUtilities.h"
  29 #include "llvm/Config/config.h"   // for HAVE_LINK_R
  30 using namespace llvm;
  31
  32 namespace llvm {
  33   extern cl::list<std::string> InputArgv;
  34 }
  35
  36 namespace {
  37   static llvm::cl::opt<bool>
  38     DisableLoopExtraction("disable-loop-extraction",
  39         cl::desc("Don't extract loops when searching for miscompilations"),
  40         cl::init(false));
  41   static llvm::cl::opt<bool>
  42     DisableBlockExtraction("disable-block-extraction",
  43         cl::desc("Don't extract blocks when searching for miscompilations"),
  44         cl::init(false));
  45
  46   class ReduceMiscompilingPasses : public ListReducer<const PassInfo*> {
  47     BugDriver &BD;
  48   public:
  49     ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {}
  50
  51     virtual TestResult doTest(std::vector<const PassInfo*> &Prefix,
  52                               std::vector<const PassInfo*> &Suffix);
  53   };
  54 }
  55
  56 /// TestResult - After passes have been split into a test group and a control
  57 /// group, see if they still break the program.
  58 ///
  59 ReduceMiscompilingPasses::TestResult
  60 ReduceMiscompilingPasses::doTest(std::vector<const PassInfo*> &Prefix,
  61                                  std::vector<const PassInfo*> &Suffix) {
  62   // First, run the program with just the Suffix passes.  If it is still broken
  63   // with JUST the kept passes, discard the prefix passes.
  64   outs() << "Checking to see if '" << getPassesString(Suffix)
  65          << "' compiles correctly: ";
  66
  67   std::string BitcodeResult;
  68   if (BD.runPasses(Suffix, BitcodeResult, false/*delete*/, true/*quiet*/)) {
  69     errs() << " Error running this sequence of passes"
  70            << " on the input program!\n";
  71     BD.setPassesToRun(Suffix);
  72     BD.EmitProgressBitcode("pass-error",  false);
  73     exit(BD.debugOptimizerCrash());
  74   }
  75
  76   // Check to see if the finished program matches the reference output...
  77   if (BD.diffProgram(BitcodeResult, "", true /*delete bitcode*/)) {
  78     outs() << " nope.\n";
  79     if (Suffix.empty()) {
  80       errs() << BD.getToolName() << ": I'm confused: the test fails when "
  81              << "no passes are run, nondeterministic program?\n";
  82       exit(1);
  83     }
  84     return KeepSuffix;         // Miscompilation detected!
  85   }
  86   outs() << " yup.\n";      // No miscompilation!
  87
  88   if (Prefix.empty()) return NoFailure;
  89
  90   // Next, see if the program is broken if we run the "prefix" passes first,
  91   // then separately run the "kept" passes.
  92   outs() << "Checking to see if '" << getPassesString(Prefix)
  93          << "' compiles correctly: ";
  94
  95   // If it is not broken with the kept passes, it's possible that the prefix
  96   // passes must be run before the kept passes to break it.  If the program
  97   // WORKS after the prefix passes, but then fails if running the prefix AND
  98   // kept passes, we can update our bitcode file to include the result of the
  99   // prefix passes, then discard the prefix passes.
 100   //
 101   if (BD.runPasses(Prefix, BitcodeResult, false/*delete*/, true/*quiet*/)) {
 102     errs() << " Error running this sequence of passes"
 103            << " on the input program!\n";
 104     BD.setPassesToRun(Prefix);
 105     BD.EmitProgressBitcode("pass-error",  false);
 106     exit(BD.debugOptimizerCrash());
 107   }
 108
 109   // If the prefix maintains the predicate by itself, only keep the prefix!
 110   if (BD.diffProgram(BitcodeResult)) {
 111     outs() << " nope.\n";
 112     sys::Path(BitcodeResult).eraseFromDisk();
 113     return KeepPrefix;
 114   }
 115   outs() << " yup.\n";      // No miscompilation!
 116
 117   // Ok, so now we know that the prefix passes work, try running the suffix
 118   // passes on the result of the prefix passes.
 119   //
 120   Module *PrefixOutput = ParseInputFile(BitcodeResult, BD.getContext());
 121   if (PrefixOutput == 0) {
 122     errs() << BD.getToolName() << ": Error reading bitcode file '"
 123            << BitcodeResult << "'!\n";
 124     exit(1);
 125   }
 126   sys::Path(BitcodeResult).eraseFromDisk();  // No longer need the file on disk
 127
 128   // Don't check if there are no passes in the suffix.
 129   if (Suffix.empty())
 130     return NoFailure;
 131
 132   outs() << "Checking to see if '" << getPassesString(Suffix)
 133             << "' passes compile correctly after the '"
 134             << getPassesString(Prefix) << "' passes: ";
 135
 136   Module *OriginalInput = BD.swapProgramIn(PrefixOutput);
 137   if (BD.runPasses(Suffix, BitcodeResult, false/*delete*/, true/*quiet*/)) {
 138     errs() << " Error running this sequence of passes"
 139            << " on the input program!\n";
 140     BD.setPassesToRun(Suffix);
 141     BD.EmitProgressBitcode("pass-error",  false);
 142     exit(BD.debugOptimizerCrash());
 143   }
 144
 145   // Run the result...
 146   if (BD.diffProgram(BitcodeResult, "", true/*delete bitcode*/)) {
 147     outs() << " nope.\n";
 148     delete OriginalInput;     // We pruned down the original input...
 149     return KeepSuffix;
 150   }
 151
 152   // Otherwise, we must not be running the bad pass anymore.
 153   outs() << " yup.\n";      // No miscompilation!
 154   delete BD.swapProgramIn(OriginalInput); // Restore orig program & free test
 155   return NoFailure;
 156 }
 157
 158 namespace {
 159   class ReduceMiscompilingFunctions : public ListReducer<Function*> {
 160     BugDriver &BD;
 161     bool (*TestFn)(BugDriver &, Module *, Module *);
 162   public:
 163     ReduceMiscompilingFunctions(BugDriver &bd,
 164                                 bool (*F)(BugDriver &, Module *, Module *))
 165       : BD(bd), TestFn(F) {}
 166
 167     virtual TestResult doTest(std::vector<Function*> &Prefix,
 168                               std::vector<Function*> &Suffix) {
 169       if (!Suffix.empty() && TestFuncs(Suffix))
 170         return KeepSuffix;
 171       if (!Prefix.empty() && TestFuncs(Prefix))
 172         return KeepPrefix;
 173       return NoFailure;
 174     }
 175
 176     bool TestFuncs(const std::vector<Function*> &Prefix);
 177   };
 178 }
 179
 180 /// TestMergedProgram - Given two modules, link them together and run the
 181 /// program, checking to see if the program matches the diff.  If the diff
 182 /// matches, return false, otherwise return true.  If the DeleteInputs argument
 183 /// is set to true then this function deletes both input modules before it
 184 /// returns.
 185 ///
 186 static bool TestMergedProgram(BugDriver &BD, Module *M1, Module *M2,
 187                               bool DeleteInputs) {
 188   // Link the two portions of the program back to together.
 189   std::string ErrorMsg;
 190   if (!DeleteInputs) {
 191     M1 = CloneModule(M1);
 192     M2 = CloneModule(M2);
 193   }
 194   if (Linker::LinkModules(M1, M2, &ErrorMsg)) {
 195     errs() << BD.getToolName() << ": Error linking modules together:"
 196            << ErrorMsg << '\n';
 197     exit(1);
 198   }
 199   delete M2;   // We are done with this module.
 200
 201   Module *OldProgram = BD.swapProgramIn(M1);
 202
 203   // Execute the program.  If it does not match the expected output, we must
 204   // return true.
 205   bool Broken = BD.diffProgram();
 206
 207   // Delete the linked module & restore the original
 208   BD.swapProgramIn(OldProgram);
 209   delete M1;
 210   return Broken;
 211 }
 212
 213 /// TestFuncs - split functions in a Module into two groups: those that are
 214 /// under consideration for miscompilation vs. those that are not, and test
 215 /// accordingly. Each group of functions becomes a separate Module.
 216 ///
 217 bool ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function*>&Funcs){
 218   // Test to see if the function is misoptimized if we ONLY run it on the
 219   // functions listed in Funcs.
 220   outs() << "Checking to see if the program is misoptimized when "
 221          << (Funcs.size()==1 ? "this function is" : "these functions are")
 222          << " run through the pass"
 223          << (BD.getPassesToRun().size() == 1 ? "" : "es") << ":";
 224   PrintFunctionList(Funcs);
 225   outs() << '\n';
 226
 227   // Split the module into the two halves of the program we want.
 228   DenseMap<const Value*, Value*> ValueMap;
 229   Module *ToNotOptimize = CloneModule(BD.getProgram(), ValueMap);
 230   Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, Funcs,
 231                                                  ValueMap);
 232
 233   // Run the predicate, note that the predicate will delete both input modules.
 234   return TestFn(BD, ToOptimize, ToNotOptimize);
 235 }
 236
 237 /// DisambiguateGlobalSymbols - Mangle symbols to guarantee uniqueness by
 238 /// modifying predominantly internal symbols rather than external ones.
 239 ///
 240 static void DisambiguateGlobalSymbols(Module *M) {
 241   // Try not to cause collisions by minimizing chances of renaming an
 242   // already-external symbol, so take in external globals and functions as-is.
 243   // The code should work correctly without disambiguation (assuming the same
 244   // mangler is used by the two code generators), but having symbols with the
 245   // same name causes warnings to be emitted by the code generator.
 246   Mangler Mang(*M);
 247   // Agree with the CBE on symbol naming
 248   Mang.markCharUnacceptable('.');
 249   for (Module::global_iterator I = M->global_begin(), E = M->global_end();
 250        I != E; ++I) {
 251     // Don't mangle asm names.
 252     if (!I->hasName() || I->getName()[0] != 1)
 253       I->setName(Mang.getMangledName(I));
 254   }
 255   for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) {
 256     // Don't mangle asm names or intrinsics.
 257     if ((!I->hasName() || I->getName()[0] != 1) &&
 258         I->getIntrinsicID() == 0)
 259       I->setName(Mang.getMangledName(I));
 260   }
 261 }
 262
 263 /// ExtractLoops - Given a reduced list of functions that still exposed the bug,
 264 /// check to see if we can extract the loops in the region without obscuring the
 265 /// bug.  If so, it reduces the amount of code identified.
 266 ///
 267 static bool ExtractLoops(BugDriver &BD,
 268                          bool (*TestFn)(BugDriver &, Module *, Module *),
 269                          std::vector<Function*> &MiscompiledFunctions) {
 270   bool MadeChange = false;
 271   while (1) {
 272     if (BugpointIsInterrupted) return MadeChange;
 273
 274     DenseMap<const Value*, Value*> ValueMap;
 275     Module *ToNotOptimize = CloneModule(BD.getProgram(), ValueMap);
 276     Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
 277                                                    MiscompiledFunctions,
 278                                                    ValueMap);
 279     Module *ToOptimizeLoopExtracted = BD.ExtractLoop(ToOptimize);
 280     if (!ToOptimizeLoopExtracted) {
 281       // If the loop extractor crashed or if there were no extractible loops,
 282       // then this chapter of our odyssey is over with.
 283       delete ToNotOptimize;
 284       delete ToOptimize;
 285       return MadeChange;
 286     }
 287
 288     errs() << "Extracted a loop from the breaking portion of the program.\n";
 289
 290     // Bugpoint is intentionally not very trusting of LLVM transformations.  In
 291     // particular, we're not going to assume that the loop extractor works, so
 292     // we're going to test the newly loop extracted program to make sure nothing
 293     // has broken.  If something broke, then we'll inform the user and stop
 294     // extraction.
 295     AbstractInterpreter *AI = BD.switchToSafeInterpreter();
 296     if (TestMergedProgram(BD, ToOptimizeLoopExtracted, ToNotOptimize, false)) {
 297       BD.switchToInterpreter(AI);
 298
 299       // Merged program doesn't work anymore!
 300       errs() << "  *** ERROR: Loop extraction broke the program. :("
 301              << " Please report a bug!\n";
 302       errs() << "      Continuing on with un-loop-extracted version.\n";
 303
 304       BD.writeProgramToFile("bugpoint-loop-extract-fail-tno.bc", ToNotOptimize);
 305       BD.writeProgramToFile("bugpoint-loop-extract-fail-to.bc", ToOptimize);
 306       BD.writeProgramToFile("bugpoint-loop-extract-fail-to-le.bc",
 307                             ToOptimizeLoopExtracted);
 308
 309       errs() << "Please submit the bugpoint-loop-extract-fail-*.bc files.\n";
 310       delete ToOptimize;
 311       delete ToNotOptimize;
 312       delete ToOptimizeLoopExtracted;
 313       return MadeChange;
 314     }
 315     delete ToOptimize;
 316     BD.switchToInterpreter(AI);
 317
 318     outs() << "  Testing after loop extraction:\n";
 319     // Clone modules, the tester function will free them.
 320     Module *TOLEBackup = CloneModule(ToOptimizeLoopExtracted);
 321     Module *TNOBackup  = CloneModule(ToNotOptimize);
 322     if (!TestFn(BD, ToOptimizeLoopExtracted, ToNotOptimize)) {
 323       outs() << "*** Loop extraction masked the problem.  Undoing.\n";
 324       // If the program is not still broken, then loop extraction did something
 325       // that masked the error.  Stop loop extraction now.
 326       delete TOLEBackup;
 327       delete TNOBackup;
 328       return MadeChange;
 329     }
 330     ToOptimizeLoopExtracted = TOLEBackup;
 331     ToNotOptimize = TNOBackup;
 332
 333     outs() << "*** Loop extraction successful!\n";
 334
 335     std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions;
 336     for (Module::iterator I = ToOptimizeLoopExtracted->begin(),
 337            E = ToOptimizeLoopExtracted->end(); I != E; ++I)
 338       if (!I->isDeclaration())
 339         MisCompFunctions.push_back(std::make_pair(I->getName(),
 340                                                   I->getFunctionType()));
 341
 342     // Okay, great!  Now we know that we extracted a loop and that loop
 343     // extraction both didn't break the program, and didn't mask the problem.
 344     // Replace the current program with the loop extracted version, and try to
 345     // extract another loop.
 346     std::string ErrorMsg;
 347     if (Linker::LinkModules(ToNotOptimize, ToOptimizeLoopExtracted, &ErrorMsg)){
 348       errs() << BD.getToolName() << ": Error linking modules together:"
 349              << ErrorMsg << '\n';
 350       exit(1);
 351     }
 352     delete ToOptimizeLoopExtracted;
 353
 354     // All of the Function*'s in the MiscompiledFunctions list are in the old
 355     // module.  Update this list to include all of the functions in the
 356     // optimized and loop extracted module.
 357     MiscompiledFunctions.clear();
 358     for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
 359       Function *NewF = ToNotOptimize->getFunction(MisCompFunctions[i].first);
 360
 361       assert(NewF && "Function not found??");
 362       assert(NewF->getFunctionType() == MisCompFunctions[i].second &&
 363              "found wrong function type?");
 364       MiscompiledFunctions.push_back(NewF);
 365     }
 366
 367     BD.setNewProgram(ToNotOptimize);
 368     MadeChange = true;
 369   }
 370 }
 371
 372 namespace {
 373   class ReduceMiscompiledBlocks : public ListReducer<BasicBlock*> {
 374     BugDriver &BD;
 375     bool (*TestFn)(BugDriver &, Module *, Module *);
 376     std::vector<Function*> FunctionsBeingTested;
 377   public:
 378     ReduceMiscompiledBlocks(BugDriver &bd,
 379                             bool (*F)(BugDriver &, Module *, Module *),
 380                             const std::vector<Function*> &Fns)
 381       : BD(bd), TestFn(F), FunctionsBeingTested(Fns) {}
 382
 383     virtual TestResult doTest(std::vector<BasicBlock*> &Prefix,
 384                               std::vector<BasicBlock*> &Suffix) {
 385       if (!Suffix.empty() && TestFuncs(Suffix))
 386         return KeepSuffix;
 387       if (TestFuncs(Prefix))
 388         return KeepPrefix;
 389       return NoFailure;
 390     }
 391
 392     bool TestFuncs(const std::vector<BasicBlock*> &Prefix);
 393   };
 394 }
 395
 396 /// TestFuncs - Extract all blocks for the miscompiled functions except for the
 397 /// specified blocks.  If the problem still exists, return true.
 398 ///
 399 bool ReduceMiscompiledBlocks::TestFuncs(const std::vector<BasicBlock*> &BBs) {
 400   // Test to see if the function is misoptimized if we ONLY run it on the
 401   // functions listed in Funcs.
 402   outs() << "Checking to see if the program is misoptimized when all ";
 403   if (!BBs.empty()) {
 404     outs() << "but these " << BBs.size() << " blocks are extracted: ";
 405     for (unsigned i = 0, e = BBs.size() < 10 ? BBs.size() : 10; i != e; ++i)
 406       outs() << BBs[i]->getName() << " ";
 407     if (BBs.size() > 10) outs() << "...";
 408   } else {
 409     outs() << "blocks are extracted.";
 410   }
 411   outs() << '\n';
 412
 413   // Split the module into the two halves of the program we want.
 414   DenseMap<const Value*, Value*> ValueMap;
 415   Module *ToNotOptimize = CloneModule(BD.getProgram(), ValueMap);
 416   Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
 417                                                  FunctionsBeingTested,
 418                                                  ValueMap);
 419
 420   // Try the extraction.  If it doesn't work, then the block extractor crashed
 421   // or something, in which case bugpoint can't chase down this possibility.
 422   if (Module *New = BD.ExtractMappedBlocksFromModule(BBs, ToOptimize)) {
 423     delete ToOptimize;
 424     // Run the predicate, not that the predicate will delete both input modules.
 425     return TestFn(BD, New, ToNotOptimize);
 426   }
 427   delete ToOptimize;
 428   delete ToNotOptimize;
 429   return false;
 430 }
 431
 432
 433 /// ExtractBlocks - Given a reduced list of functions that still expose the bug,
 434 /// extract as many basic blocks from the region as possible without obscuring
 435 /// the bug.
 436 ///
 437 static bool ExtractBlocks(BugDriver &BD,
 438                           bool (*TestFn)(BugDriver &, Module *, Module *),
 439                           std::vector<Function*> &MiscompiledFunctions) {
 440   if (BugpointIsInterrupted) return false;
 441
 442   std::vector<BasicBlock*> Blocks;
 443   for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i)
 444     for (Function::iterator I = MiscompiledFunctions[i]->begin(),
 445            E = MiscompiledFunctions[i]->end(); I != E; ++I)
 446       Blocks.push_back(I);
 447
 448   // Use the list reducer to identify blocks that can be extracted without
 449   // obscuring the bug.  The Blocks list will end up containing blocks that must
 450   // be retained from the original program.
 451   unsigned OldSize = Blocks.size();
 452
 453   // Check to see if all blocks are extractible first.
 454   if (ReduceMiscompiledBlocks(BD, TestFn,
 455                   MiscompiledFunctions).TestFuncs(std::vector<BasicBlock*>())) {
 456     Blocks.clear();
 457   } else {
 458     ReduceMiscompiledBlocks(BD, TestFn,MiscompiledFunctions).reduceList(Blocks);
 459     if (Blocks.size() == OldSize)
 460       return false;
 461   }
 462
 463   DenseMap<const Value*, Value*> ValueMap;
 464   Module *ProgClone = CloneModule(BD.getProgram(), ValueMap);
 465   Module *ToExtract = SplitFunctionsOutOfModule(ProgClone,
 466                                                 MiscompiledFunctions,
 467                                                 ValueMap);
 468   Module *Extracted = BD.ExtractMappedBlocksFromModule(Blocks, ToExtract);
 469   if (Extracted == 0) {
 470     // Weird, extraction should have worked.
 471     errs() << "Nondeterministic problem extracting blocks??\n";
 472     delete ProgClone;
 473     delete ToExtract;
 474     return false;
 475   }
 476
 477   // Otherwise, block extraction succeeded.  Link the two program fragments back
 478   // together.
 479   delete ToExtract;
 480
 481   std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions;
 482   for (Module::iterator I = Extracted->begin(), E = Extracted->end();
 483        I != E; ++I)
 484     if (!I->isDeclaration())
 485       MisCompFunctions.push_back(std::make_pair(I->getName(),
 486                                                 I->getFunctionType()));
 487
 488   std::string ErrorMsg;
 489   if (Linker::LinkModules(ProgClone, Extracted, &ErrorMsg)) {
 490     errs() << BD.getToolName() << ": Error linking modules together:"
 491            << ErrorMsg << '\n';
 492     exit(1);
 493   }
 494   delete Extracted;
 495
 496   // Set the new program and delete the old one.
 497   BD.setNewProgram(ProgClone);
 498
 499   // Update the list of miscompiled functions.
 500   MiscompiledFunctions.clear();
 501
 502   for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) {
 503     Function *NewF = ProgClone->getFunction(MisCompFunctions[i].first);
 504     assert(NewF && "Function not found??");
 505     assert(NewF->getFunctionType() == MisCompFunctions[i].second &&
 506            "Function has wrong type??");
 507     MiscompiledFunctions.push_back(NewF);
 508   }
 509
 510   return true;
 511 }
 512
 513
 514 /// DebugAMiscompilation - This is a generic driver to narrow down
 515 /// miscompilations, either in an optimization or a code generator.
 516 ///
 517 static std::vector<Function*>
 518 DebugAMiscompilation(BugDriver &BD,
 519                      bool (*TestFn)(BugDriver &, Module *, Module *)) {
 520   // Okay, now that we have reduced the list of passes which are causing the
 521   // failure, see if we can pin down which functions are being
 522   // miscompiled... first build a list of all of the non-external functions in
 523   // the program.
 524   std::vector<Function*> MiscompiledFunctions;
 525   Module *Prog = BD.getProgram();
 526   for (Module::iterator I = Prog->begin(), E = Prog->end(); I != E; ++I)
 527     if (!I->isDeclaration())
 528       MiscompiledFunctions.push_back(I);
 529
 530   // Do the reduction...
 531   if (!BugpointIsInterrupted)
 532     ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
 533
 534   outs() << "\n*** The following function"
 535          << (MiscompiledFunctions.size() == 1 ? " is" : "s are")
 536          << " being miscompiled: ";
 537   PrintFunctionList(MiscompiledFunctions);
 538   outs() << '\n';
 539
 540   // See if we can rip any loops out of the miscompiled functions and still
 541   // trigger the problem.
 542
 543   if (!BugpointIsInterrupted && !DisableLoopExtraction &&
 544       ExtractLoops(BD, TestFn, MiscompiledFunctions)) {
 545     // Okay, we extracted some loops and the problem still appears.  See if we
 546     // can eliminate some of the created functions from being candidates.
 547
 548     // Loop extraction can introduce functions with the same name (foo_code).
 549     // Make sure to disambiguate the symbols so that when the program is split
 550     // apart that we can link it back together again.
 551     DisambiguateGlobalSymbols(BD.getProgram());
 552
 553     // Do the reduction...
 554     if (!BugpointIsInterrupted)
 555       ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
 556
 557     outs() << "\n*** The following function"
 558            << (MiscompiledFunctions.size() == 1 ? " is" : "s are")
 559            << " being miscompiled: ";
 560     PrintFunctionList(MiscompiledFunctions);
 561     outs() << '\n';
 562   }
 563
 564   if (!BugpointIsInterrupted && !DisableBlockExtraction &&
 565       ExtractBlocks(BD, TestFn, MiscompiledFunctions)) {
 566     // Okay, we extracted some blocks and the problem still appears.  See if we
 567     // can eliminate some of the created functions from being candidates.
 568
 569     // Block extraction can introduce functions with the same name (foo_code).
 570     // Make sure to disambiguate the symbols so that when the program is split
 571     // apart that we can link it back together again.
 572     DisambiguateGlobalSymbols(BD.getProgram());
 573
 574     // Do the reduction...
 575     ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions);
 576
 577     outs() << "\n*** The following function"
 578            << (MiscompiledFunctions.size() == 1 ? " is" : "s are")
 579            << " being miscompiled: ";
 580     PrintFunctionList(MiscompiledFunctions);
 581     outs() << '\n';
 582   }
 583
 584   return MiscompiledFunctions;
 585 }
 586
 587 /// TestOptimizer - This is the predicate function used to check to see if the
 588 /// "Test" portion of the program is misoptimized.  If so, return true.  In any
 589 /// case, both module arguments are deleted.
 590 ///
 591 static bool TestOptimizer(BugDriver &BD, Module *Test, Module *Safe) {
 592   // Run the optimization passes on ToOptimize, producing a transformed version
 593   // of the functions being tested.
 594   outs() << "  Optimizing functions being tested: ";
 595   Module *Optimized = BD.runPassesOn(Test, BD.getPassesToRun(),
 596                                      /*AutoDebugCrashes*/true);
 597   outs() << "done.\n";
 598   delete Test;
 599
 600   outs() << "  Checking to see if the merged program executes correctly: ";
 601   bool Broken = TestMergedProgram(BD, Optimized, Safe, true);
 602   outs() << (Broken ? " nope.\n" : " yup.\n");
 603   return Broken;
 604 }
 605
 606
 607 /// debugMiscompilation - This method is used when the passes selected are not
 608 /// crashing, but the generated output is semantically different from the
 609 /// input.
 610 ///
 611 bool BugDriver::debugMiscompilation() {
 612   // Make sure something was miscompiled...
 613   if (!BugpointIsInterrupted)
 614     if (!ReduceMiscompilingPasses(*this).reduceList(PassesToRun)) {
 615       errs() << "*** Optimized program matches reference output!  No problem"
 616              << " detected...\nbugpoint can't help you with your problem!\n";
 617       return false;
 618     }
 619
 620   outs() << "\n*** Found miscompiling pass"
 621          << (getPassesToRun().size() == 1 ? "" : "es") << ": "
 622          << getPassesString(getPassesToRun()) << '\n';
 623   EmitProgressBitcode("passinput");
 624
 625   std::vector<Function*> MiscompiledFunctions =
 626     DebugAMiscompilation(*this, TestOptimizer);
 627
 628   // Output a bunch of bitcode files for the user...
 629   outs() << "Outputting reduced bitcode files which expose the problem:\n";
 630   DenseMap<const Value*, Value*> ValueMap;
 631   Module *ToNotOptimize = CloneModule(getProgram(), ValueMap);
 632   Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize,
 633                                                  MiscompiledFunctions,
 634                                                  ValueMap);
 635
 636   outs() << "  Non-optimized portion: ";
 637   ToNotOptimize = swapProgramIn(ToNotOptimize);
 638   EmitProgressBitcode("tonotoptimize", true);
 639   setNewProgram(ToNotOptimize);   // Delete hacked module.
 640
 641   outs() << "  Portion that is input to optimizer: ";
 642   ToOptimize = swapProgramIn(ToOptimize);
 643   EmitProgressBitcode("tooptimize");
 644   setNewProgram(ToOptimize);      // Delete hacked module.
 645
 646   return false;
 647 }
 648
 649 /// CleanupAndPrepareModules - Get the specified modules ready for code
 650 /// generator testing.
 651 ///
 652 static void CleanupAndPrepareModules(BugDriver &BD, Module *&Test,
 653                                      Module *Safe) {
 654   // Clean up the modules, removing extra cruft that we don't need anymore...
 655   Test = BD.performFinalCleanups(Test);
 656
 657   // If we are executing the JIT, we have several nasty issues to take care of.
 658   if (!BD.isExecutingJIT()) return;
 659
 660   // First, if the main function is in the Safe module, we must add a stub to
 661   // the Test module to call into it.  Thus, we create a new function `main'
 662   // which just calls the old one.
 663   if (Function *oldMain = Safe->getFunction("main"))
 664     if (!oldMain->isDeclaration()) {
 665       // Rename it
 666       oldMain->setName("llvm_bugpoint_old_main");
 667       // Create a NEW `main' function with same type in the test module.
 668       Function *newMain = Function::Create(oldMain->getFunctionType(),
 669                                            GlobalValue::ExternalLinkage,
 670                                            "main", Test);
 671       // Create an `oldmain' prototype in the test module, which will
 672       // corresponds to the real main function in the same module.
 673       Function *oldMainProto = Function::Create(oldMain->getFunctionType(),
 674                                                 GlobalValue::ExternalLinkage,
 675                                                 oldMain->getName(), Test);
 676       // Set up and remember the argument list for the main function.
 677       std::vector<Value*> args;
 678       for (Function::arg_iterator
 679              I = newMain->arg_begin(), E = newMain->arg_end(),
 680              OI = oldMain->arg_begin(); I != E; ++I, ++OI) {
 681         I->setName(OI->getName());    // Copy argument names from oldMain
 682         args.push_back(I);
 683       }
 684
 685       // Call the old main function and return its result
 686       BasicBlock *BB = BasicBlock::Create(Safe->getContext(), "entry", newMain);
 687       CallInst *call = CallInst::Create(oldMainProto, args.begin(), args.end(),
 688                                         "", BB);
 689
 690       // If the type of old function wasn't void, return value of call
 691       ReturnInst::Create(Safe->getContext(), call, BB);
 692     }
 693
 694   // The second nasty issue we must deal with in the JIT is that the Safe
 695   // module cannot directly reference any functions defined in the test
 696   // module.  Instead, we use a JIT API call to dynamically resolve the
 697   // symbol.
 698
 699   // Add the resolver to the Safe module.
 700   // Prototype: void *getPointerToNamedFunction(const char* Name)
 701   Constant *resolverFunc =
 702     Safe->getOrInsertFunction("getPointerToNamedFunction",
 703                     PointerType::getUnqual(Type::getInt8Ty(Safe->getContext())),
 704                     PointerType::getUnqual(Type::getInt8Ty(Safe->getContext())),
 705                        (Type *)0);
 706
 707   // Use the function we just added to get addresses of functions we need.
 708   for (Module::iterator F = Safe->begin(), E = Safe->end(); F != E; ++F) {
 709     if (F->isDeclaration() && !F->use_empty() && &*F != resolverFunc &&
 710         !F->isIntrinsic() /* ignore intrinsics */) {
 711       Function *TestFn = Test->getFunction(F->getName());
 712
 713       // Don't forward functions which are external in the test module too.
 714       if (TestFn && !TestFn->isDeclaration()) {
 715         // 1. Add a string constant with its name to the global file
 716         Constant *InitArray = ConstantArray::get(F->getContext(), F->getName());
 717         GlobalVariable *funcName =
 718           new GlobalVariable(*Safe, InitArray->getType(), true /*isConstant*/,
 719                              GlobalValue::InternalLinkage, InitArray,
 720                              F->getName() + "_name");
 721
 722         // 2. Use `GetElementPtr *funcName, 0, 0' to convert the string to an
 723         // sbyte* so it matches the signature of the resolver function.
 724
 725         // GetElementPtr *funcName, ulong 0, ulong 0
 726         std::vector<Constant*> GEPargs(2,
 727                      Constant::getNullValue(Type::getInt32Ty(F->getContext())));
 728         Value *GEP =
 729                 ConstantExpr::getGetElementPtr(funcName, &GEPargs[0], 2);
 730         std::vector<Value*> ResolverArgs;
 731         ResolverArgs.push_back(GEP);
 732
 733         // Rewrite uses of F in global initializers, etc. to uses of a wrapper
 734         // function that dynamically resolves the calls to F via our JIT API
 735         if (!F->use_empty()) {
 736           // Create a new global to hold the cached function pointer.
 737           Constant *NullPtr = ConstantPointerNull::get(F->getType());
 738           GlobalVariable *Cache =
 739             new GlobalVariable(*F->getParent(), F->getType(),
 740                                false, GlobalValue::InternalLinkage,
 741                                NullPtr,F->getName()+".fpcache");
 742
 743           // Construct a new stub function that will re-route calls to F
 744           const FunctionType *FuncTy = F->getFunctionType();
 745           Function *FuncWrapper = Function::Create(FuncTy,
 746                                                    GlobalValue::InternalLinkage,
 747                                                    F->getName() + "_wrapper",
 748                                                    F->getParent());
 749           BasicBlock *EntryBB  = BasicBlock::Create(F->getContext(),
 750                                                     "entry", FuncWrapper);
 751           BasicBlock *DoCallBB = BasicBlock::Create(F->getContext(),
 752                                                     "usecache", FuncWrapper);
 753           BasicBlock *LookupBB = BasicBlock::Create(F->getContext(),
 754                                                     "lookupfp", FuncWrapper);
 755
 756           // Check to see if we already looked up the value.
 757           Value *CachedVal = new LoadInst(Cache, "fpcache", EntryBB);
 758           Value *IsNull = new ICmpInst(*EntryBB, ICmpInst::ICMP_EQ, CachedVal,
 759                                        NullPtr, "isNull");
 760           BranchInst::Create(LookupBB, DoCallBB, IsNull, EntryBB);
 761
 762           // Resolve the call to function F via the JIT API:
 763           //
 764           // call resolver(GetElementPtr...)
 765           CallInst *Resolver =
 766             CallInst::Create(resolverFunc, ResolverArgs.begin(),
 767                              ResolverArgs.end(), "resolver", LookupBB);
 768
 769           // Cast the result from the resolver to correctly-typed function.
 770           CastInst *CastedResolver =
 771             new BitCastInst(Resolver,
 772                             PointerType::getUnqual(F->getFunctionType()),
 773                             "resolverCast", LookupBB);
 774
 775           // Save the value in our cache.
 776           new StoreInst(CastedResolver, Cache, LookupBB);
 777           BranchInst::Create(DoCallBB, LookupBB);
 778
 779           PHINode *FuncPtr = PHINode::Create(NullPtr->getType(),
 780                                              "fp", DoCallBB);
 781           FuncPtr->addIncoming(CastedResolver, LookupBB);
 782           FuncPtr->addIncoming(CachedVal, EntryBB);
 783
 784           // Save the argument list.
 785           std::vector<Value*> Args;
 786           for (Function::arg_iterator i = FuncWrapper->arg_begin(),
 787                  e = FuncWrapper->arg_end(); i != e; ++i)
 788             Args.push_back(i);
 789
 790           // Pass on the arguments to the real function, return its result
 791           if (F->getReturnType() == Type::getVoidTy(F->getContext())) {
 792             CallInst::Create(FuncPtr, Args.begin(), Args.end(), "", DoCallBB);
 793             ReturnInst::Create(F->getContext(), DoCallBB);
 794           } else {
 795             CallInst *Call = CallInst::Create(FuncPtr, Args.begin(), Args.end(),
 796                                               "retval", DoCallBB);
 797             ReturnInst::Create(F->getContext(),Call, DoCallBB);
 798           }
 799
 800           // Use the wrapper function instead of the old function
 801           F->replaceAllUsesWith(FuncWrapper);
 802         }
 803       }
 804     }
 805   }
 806
 807   if (verifyModule(*Test) || verifyModule(*Safe)) {
 808     errs() << "Bugpoint has a bug, which corrupted a module!!\n";
 809     abort();
 810   }
 811 }
 812
 813
 814
 815 /// TestCodeGenerator - This is the predicate function used to check to see if
 816 /// the "Test" portion of the program is miscompiled by the code generator under
 817 /// test.  If so, return true.  In any case, both module arguments are deleted.
 818 ///
 819 static bool TestCodeGenerator(BugDriver &BD, Module *Test, Module *Safe) {
 820   CleanupAndPrepareModules(BD, Test, Safe);
 821
 822   sys::Path TestModuleBC("bugpoint.test.bc");
 823   std::string ErrMsg;
 824   if (TestModuleBC.makeUnique(true, &ErrMsg)) {
 825     errs() << BD.getToolName() << "Error making unique filename: "
 826            << ErrMsg << "\n";
 827     exit(1);
 828   }
 829   if (BD.writeProgramToFile(TestModuleBC.str(), Test)) {
 830     errs() << "Error writing bitcode to `" << TestModuleBC.str()
 831            << "'\nExiting.";
 832     exit(1);
 833   }
 834   delete Test;
 835
 836   // Make the shared library
 837   sys::Path SafeModuleBC("bugpoint.safe.bc");
 838   if (SafeModuleBC.makeUnique(true, &ErrMsg)) {
 839     errs() << BD.getToolName() << "Error making unique filename: "
 840            << ErrMsg << "\n";
 841     exit(1);
 842   }
 843
 844   if (BD.writeProgramToFile(SafeModuleBC.str(), Safe)) {
 845     errs() << "Error writing bitcode to `" << SafeModuleBC.str()
 846            << "'\nExiting.";
 847     exit(1);
 848   }
 849   std::string SharedObject = BD.compileSharedObject(SafeModuleBC.str());
 850   delete Safe;
 851
 852   // Run the code generator on the `Test' code, loading the shared library.
 853   // The function returns whether or not the new output differs from reference.
 854   int Result = BD.diffProgram(TestModuleBC.str(), SharedObject, false);
 855
 856   if (Result)
 857     errs() << ": still failing!\n";
 858   else
 859     errs() << ": didn't fail.\n";
 860   TestModuleBC.eraseFromDisk();
 861   SafeModuleBC.eraseFromDisk();
 862   sys::Path(SharedObject).eraseFromDisk();
 863
 864   return Result;
 865 }
 866
 867
 868 /// debugCodeGenerator - debug errors in LLC, LLI, or CBE.
 869 ///
 870 bool BugDriver::debugCodeGenerator() {
 871   if ((void*)SafeInterpreter == (void*)Interpreter) {
 872     std::string Result = executeProgramSafely("bugpoint.safe.out");
 873     outs() << "\n*** The \"safe\" i.e. 'known good' backend cannot match "
 874            << "the reference diff.  This may be due to a\n    front-end "
 875            << "bug or a bug in the original program, but this can also "
 876            << "happen if bugpoint isn't running the program with the "
 877            << "right flags or input.\n    I left the result of executing "
 878            << "the program with the \"safe\" backend in this file for "
 879            << "you: '"
 880            << Result << "'.\n";
 881     return true;
 882   }
 883
 884   DisambiguateGlobalSymbols(Program);
 885
 886   std::vector<Function*> Funcs = DebugAMiscompilation(*this, TestCodeGenerator);
 887
 888   // Split the module into the two halves of the program we want.
 889   DenseMap<const Value*, Value*> ValueMap;
 890   Module *ToNotCodeGen = CloneModule(getProgram(), ValueMap);
 891   Module *ToCodeGen = SplitFunctionsOutOfModule(ToNotCodeGen, Funcs, ValueMap);
 892
 893   // Condition the modules
 894   CleanupAndPrepareModules(*this, ToCodeGen, ToNotCodeGen);
 895
 896   sys::Path TestModuleBC("bugpoint.test.bc");
 897   std::string ErrMsg;
 898   if (TestModuleBC.makeUnique(true, &ErrMsg)) {
 899     errs() << getToolName() << "Error making unique filename: "
 900            << ErrMsg << "\n";
 901     exit(1);
 902   }
 903
 904   if (writeProgramToFile(TestModuleBC.str(), ToCodeGen)) {
 905     errs() << "Error writing bitcode to `" << TestModuleBC.str()
 906            << "'\nExiting.";
 907     exit(1);
 908   }
 909   delete ToCodeGen;
 910
 911   // Make the shared library
 912   sys::Path SafeModuleBC("bugpoint.safe.bc");
 913   if (SafeModuleBC.makeUnique(true, &ErrMsg)) {
 914     errs() << getToolName() << "Error making unique filename: "
 915            << ErrMsg << "\n";
 916     exit(1);
 917   }
 918
 919   if (writeProgramToFile(SafeModuleBC.str(), ToNotCodeGen)) {
 920     errs() << "Error writing bitcode to `" << SafeModuleBC.str()
 921            << "'\nExiting.";
 922     exit(1);
 923   }
 924   std::string SharedObject = compileSharedObject(SafeModuleBC.str());
 925   delete ToNotCodeGen;
 926
 927   outs() << "You can reproduce the problem with the command line: \n";
 928   if (isExecutingJIT()) {
 929     outs() << "  lli -load " << SharedObject << " " << TestModuleBC.str();
 930   } else {
 931     outs() << "  llc -f " << TestModuleBC.str() << " -o " << TestModuleBC.str()
 932            << ".s\n";
 933     outs() << "  gcc " << SharedObject << " " << TestModuleBC.str()
 934               << ".s -o " << TestModuleBC.str() << ".exe";
 935 #if defined (HAVE_LINK_R)
 936     outs() << " -Wl,-R.";
 937 #endif
 938     outs() << "\n";
 939     outs() << "  " << TestModuleBC.str() << ".exe";
 940   }
 941   for (unsigned i=0, e = InputArgv.size(); i != e; ++i)
 942     outs() << " " << InputArgv[i];
 943   outs() << '\n';
 944   outs() << "The shared object was created with:\n  llc -march=c "
 945          << SafeModuleBC.str() << " -o temporary.c\n"
 946          << "  gcc -xc temporary.c -O2 -o " << SharedObject;
 947   if (TargetTriple.getArch() == Triple::sparc)
 948     outs() << " -G";              // Compile a shared library, `-G' for Sparc
 949   else
 950     outs() << " -fPIC -shared";   // `-shared' for Linux/X86, maybe others
 951
 952   outs() << " -fno-strict-aliasing\n";
 953
 954   return false;
 955 }