Miscompilation.cpp revision 2db43c864e8372823d961d961ca520ed20edca82
1//===- Miscompilation.cpp - Debug program miscompilations -----------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source License. See LICENSE.TXT for details. 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 "llvm/Constants.h" 18#include "llvm/DerivedTypes.h" 19#include "llvm/Instructions.h" 20#include "llvm/Linker.h" 21#include "llvm/Module.h" 22#include "llvm/Pass.h" 23#include "llvm/Analysis/Verifier.h" 24#include "llvm/Support/Mangler.h" 25#include "llvm/Transforms/Utils/Cloning.h" 26#include "llvm/Support/CommandLine.h" 27#include "llvm/Support/FileUtilities.h" 28#include "llvm/Config/config.h" // for HAVE_LINK_R 29using namespace llvm; 30 31namespace llvm { 32 extern cl::list<std::string> InputArgv; 33} 34 35namespace { 36 static llvm::cl::opt<bool> 37 DisableLoopExtraction("disable-loop-extraction", 38 cl::desc("Don't extract loops when searching for miscompilations"), 39 cl::init(false)); 40 41 class ReduceMiscompilingPasses : public ListReducer<const PassInfo*> { 42 BugDriver &BD; 43 public: 44 ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {} 45 46 virtual TestResult doTest(std::vector<const PassInfo*> &Prefix, 47 std::vector<const PassInfo*> &Suffix); 48 }; 49} 50 51/// TestResult - After passes have been split into a test group and a control 52/// group, see if they still break the program. 53/// 54ReduceMiscompilingPasses::TestResult 55ReduceMiscompilingPasses::doTest(std::vector<const PassInfo*> &Prefix, 56 std::vector<const PassInfo*> &Suffix) { 57 // First, run the program with just the Suffix passes. If it is still broken 58 // with JUST the kept passes, discard the prefix passes. 59 std::cout << "Checking to see if '" << getPassesString(Suffix) 60 << "' compile correctly: "; 61 62 std::string BytecodeResult; 63 if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) { 64 std::cerr << " Error running this sequence of passes" 65 << " on the input program!\n"; 66 BD.setPassesToRun(Suffix); 67 BD.EmitProgressBytecode("pass-error", false); 68 exit(BD.debugOptimizerCrash()); 69 } 70 71 // Check to see if the finished program matches the reference output... 72 if (BD.diffProgram(BytecodeResult, "", true /*delete bytecode*/)) { 73 std::cout << " nope.\n"; 74 if (Suffix.empty()) { 75 std::cerr << BD.getToolName() << ": I'm confused: the test fails when " 76 << "no passes are run, nondeterministic program?\n"; 77 exit(1); 78 } 79 return KeepSuffix; // Miscompilation detected! 80 } 81 std::cout << " yup.\n"; // No miscompilation! 82 83 if (Prefix.empty()) return NoFailure; 84 85 // Next, see if the program is broken if we run the "prefix" passes first, 86 // then separately run the "kept" passes. 87 std::cout << "Checking to see if '" << getPassesString(Prefix) 88 << "' compile correctly: "; 89 90 // If it is not broken with the kept passes, it's possible that the prefix 91 // passes must be run before the kept passes to break it. If the program 92 // WORKS after the prefix passes, but then fails if running the prefix AND 93 // kept passes, we can update our bytecode file to include the result of the 94 // prefix passes, then discard the prefix passes. 95 // 96 if (BD.runPasses(Prefix, BytecodeResult, false/*delete*/, true/*quiet*/)) { 97 std::cerr << " Error running this sequence of passes" 98 << " on the input program!\n"; 99 BD.setPassesToRun(Prefix); 100 BD.EmitProgressBytecode("pass-error", false); 101 exit(BD.debugOptimizerCrash()); 102 } 103 104 // If the prefix maintains the predicate by itself, only keep the prefix! 105 if (BD.diffProgram(BytecodeResult)) { 106 std::cout << " nope.\n"; 107 sys::Path(BytecodeResult).eraseFromDisk(); 108 return KeepPrefix; 109 } 110 std::cout << " yup.\n"; // No miscompilation! 111 112 // Ok, so now we know that the prefix passes work, try running the suffix 113 // passes on the result of the prefix passes. 114 // 115 Module *PrefixOutput = ParseInputFile(BytecodeResult); 116 if (PrefixOutput == 0) { 117 std::cerr << BD.getToolName() << ": Error reading bytecode file '" 118 << BytecodeResult << "'!\n"; 119 exit(1); 120 } 121 sys::Path(BytecodeResult).eraseFromDisk(); // No longer need the file on disk 122 123 // Don't check if there are no passes in the suffix. 124 if (Suffix.empty()) 125 return NoFailure; 126 127 std::cout << "Checking to see if '" << getPassesString(Suffix) 128 << "' passes compile correctly after the '" 129 << getPassesString(Prefix) << "' passes: "; 130 131 Module *OriginalInput = BD.swapProgramIn(PrefixOutput); 132 if (BD.runPasses(Suffix, BytecodeResult, false/*delete*/, true/*quiet*/)) { 133 std::cerr << " Error running this sequence of passes" 134 << " on the input program!\n"; 135 BD.setPassesToRun(Suffix); 136 BD.EmitProgressBytecode("pass-error", false); 137 exit(BD.debugOptimizerCrash()); 138 } 139 140 // Run the result... 141 if (BD.diffProgram(BytecodeResult, "", true/*delete bytecode*/)) { 142 std::cout << " nope.\n"; 143 delete OriginalInput; // We pruned down the original input... 144 return KeepSuffix; 145 } 146 147 // Otherwise, we must not be running the bad pass anymore. 148 std::cout << " yup.\n"; // No miscompilation! 149 delete BD.swapProgramIn(OriginalInput); // Restore orig program & free test 150 return NoFailure; 151} 152 153namespace { 154 class ReduceMiscompilingFunctions : public ListReducer<Function*> { 155 BugDriver &BD; 156 bool (*TestFn)(BugDriver &, Module *, Module *); 157 public: 158 ReduceMiscompilingFunctions(BugDriver &bd, 159 bool (*F)(BugDriver &, Module *, Module *)) 160 : BD(bd), TestFn(F) {} 161 162 virtual TestResult doTest(std::vector<Function*> &Prefix, 163 std::vector<Function*> &Suffix) { 164 if (!Suffix.empty() && TestFuncs(Suffix)) 165 return KeepSuffix; 166 if (!Prefix.empty() && TestFuncs(Prefix)) 167 return KeepPrefix; 168 return NoFailure; 169 } 170 171 bool TestFuncs(const std::vector<Function*> &Prefix); 172 }; 173} 174 175/// TestMergedProgram - Given two modules, link them together and run the 176/// program, checking to see if the program matches the diff. If the diff 177/// matches, return false, otherwise return true. If the DeleteInputs argument 178/// is set to true then this function deletes both input modules before it 179/// returns. 180/// 181static bool TestMergedProgram(BugDriver &BD, Module *M1, Module *M2, 182 bool DeleteInputs) { 183 // Link the two portions of the program back to together. 184 std::string ErrorMsg; 185 if (!DeleteInputs) { 186 M1 = CloneModule(M1); 187 M2 = CloneModule(M2); 188 } 189 if (Linker::LinkModules(M1, M2, &ErrorMsg)) { 190 std::cerr << BD.getToolName() << ": Error linking modules together:" 191 << ErrorMsg << '\n'; 192 exit(1); 193 } 194 delete M2; // We are done with this module. 195 196 Module *OldProgram = BD.swapProgramIn(M1); 197 198 // Execute the program. If it does not match the expected output, we must 199 // return true. 200 bool Broken = BD.diffProgram(); 201 202 // Delete the linked module & restore the original 203 BD.swapProgramIn(OldProgram); 204 delete M1; 205 return Broken; 206} 207 208/// TestFuncs - split functions in a Module into two groups: those that are 209/// under consideration for miscompilation vs. those that are not, and test 210/// accordingly. Each group of functions becomes a separate Module. 211/// 212bool ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function*>&Funcs){ 213 // Test to see if the function is misoptimized if we ONLY run it on the 214 // functions listed in Funcs. 215 std::cout << "Checking to see if the program is misoptimized when " 216 << (Funcs.size()==1 ? "this function is" : "these functions are") 217 << " run through the pass" 218 << (BD.getPassesToRun().size() == 1 ? "" : "es") << ":"; 219 PrintFunctionList(Funcs); 220 std::cout << '\n'; 221 222 // Split the module into the two halves of the program we want. 223 Module *ToNotOptimize = CloneModule(BD.getProgram()); 224 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, Funcs); 225 226 // Run the predicate, not that the predicate will delete both input modules. 227 return TestFn(BD, ToOptimize, ToNotOptimize); 228} 229 230/// DisambiguateGlobalSymbols - Mangle symbols to guarantee uniqueness by 231/// modifying predominantly internal symbols rather than external ones. 232/// 233static void DisambiguateGlobalSymbols(Module *M) { 234 // Try not to cause collisions by minimizing chances of renaming an 235 // already-external symbol, so take in external globals and functions as-is. 236 // The code should work correctly without disambiguation (assuming the same 237 // mangler is used by the two code generators), but having symbols with the 238 // same name causes warnings to be emitted by the code generator. 239 Mangler Mang(*M); 240 // Agree with the CBE on symbol naming 241 Mang.markCharUnacceptable('.'); 242 Mang.setPreserveAsmNames(true); 243 for (Module::global_iterator I = M->global_begin(), E = M->global_end(); 244 I != E; ++I) 245 I->setName(Mang.getValueName(I)); 246 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) 247 I->setName(Mang.getValueName(I)); 248} 249 250/// ExtractLoops - Given a reduced list of functions that still exposed the bug, 251/// check to see if we can extract the loops in the region without obscuring the 252/// bug. If so, it reduces the amount of code identified. 253/// 254static bool ExtractLoops(BugDriver &BD, 255 bool (*TestFn)(BugDriver &, Module *, Module *), 256 std::vector<Function*> &MiscompiledFunctions) { 257 bool MadeChange = false; 258 while (1) { 259 if (BugpointIsInterrupted) return MadeChange; 260 261 Module *ToNotOptimize = CloneModule(BD.getProgram()); 262 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, 263 MiscompiledFunctions); 264 Module *ToOptimizeLoopExtracted = BD.ExtractLoop(ToOptimize); 265 if (!ToOptimizeLoopExtracted) { 266 // If the loop extractor crashed or if there were no extractible loops, 267 // then this chapter of our odyssey is over with. 268 delete ToNotOptimize; 269 delete ToOptimize; 270 return MadeChange; 271 } 272 273 std::cerr << "Extracted a loop from the breaking portion of the program.\n"; 274 275 // Bugpoint is intentionally not very trusting of LLVM transformations. In 276 // particular, we're not going to assume that the loop extractor works, so 277 // we're going to test the newly loop extracted program to make sure nothing 278 // has broken. If something broke, then we'll inform the user and stop 279 // extraction. 280 AbstractInterpreter *AI = BD.switchToCBE(); 281 if (TestMergedProgram(BD, ToOptimizeLoopExtracted, ToNotOptimize, false)) { 282 BD.switchToInterpreter(AI); 283 284 // Merged program doesn't work anymore! 285 std::cerr << " *** ERROR: Loop extraction broke the program. :(" 286 << " Please report a bug!\n"; 287 std::cerr << " Continuing on with un-loop-extracted version.\n"; 288 289 BD.writeProgramToFile("bugpoint-loop-extract-fail-tno.bc", ToNotOptimize); 290 BD.writeProgramToFile("bugpoint-loop-extract-fail-to.bc", ToOptimize); 291 BD.writeProgramToFile("bugpoint-loop-extract-fail-to-le.bc", 292 ToOptimizeLoopExtracted); 293 294 std::cerr << "Please submit the bugpoint-loop-extract-fail-*.bc files.\n"; 295 delete ToOptimize; 296 delete ToNotOptimize; 297 delete ToOptimizeLoopExtracted; 298 return MadeChange; 299 } 300 delete ToOptimize; 301 BD.switchToInterpreter(AI); 302 303 std::cout << " Testing after loop extraction:\n"; 304 // Clone modules, the tester function will free them. 305 Module *TOLEBackup = CloneModule(ToOptimizeLoopExtracted); 306 Module *TNOBackup = CloneModule(ToNotOptimize); 307 if (!TestFn(BD, ToOptimizeLoopExtracted, ToNotOptimize)) { 308 std::cout << "*** Loop extraction masked the problem. Undoing.\n"; 309 // If the program is not still broken, then loop extraction did something 310 // that masked the error. Stop loop extraction now. 311 delete TOLEBackup; 312 delete TNOBackup; 313 return MadeChange; 314 } 315 ToOptimizeLoopExtracted = TOLEBackup; 316 ToNotOptimize = TNOBackup; 317 318 std::cout << "*** Loop extraction successful!\n"; 319 320 std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions; 321 for (Module::iterator I = ToOptimizeLoopExtracted->begin(), 322 E = ToOptimizeLoopExtracted->end(); I != E; ++I) 323 if (!I->isExternal()) 324 MisCompFunctions.push_back(std::make_pair(I->getName(), 325 I->getFunctionType())); 326 327 // Okay, great! Now we know that we extracted a loop and that loop 328 // extraction both didn't break the program, and didn't mask the problem. 329 // Replace the current program with the loop extracted version, and try to 330 // extract another loop. 331 std::string ErrorMsg; 332 if (Linker::LinkModules(ToNotOptimize, ToOptimizeLoopExtracted, &ErrorMsg)){ 333 std::cerr << BD.getToolName() << ": Error linking modules together:" 334 << ErrorMsg << '\n'; 335 exit(1); 336 } 337 delete ToOptimizeLoopExtracted; 338 339 // All of the Function*'s in the MiscompiledFunctions list are in the old 340 // module. Update this list to include all of the functions in the 341 // optimized and loop extracted module. 342 MiscompiledFunctions.clear(); 343 for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) { 344 Function *NewF = ToNotOptimize->getFunction(MisCompFunctions[i].first, 345 MisCompFunctions[i].second); 346 assert(NewF && "Function not found??"); 347 MiscompiledFunctions.push_back(NewF); 348 } 349 350 BD.setNewProgram(ToNotOptimize); 351 MadeChange = true; 352 } 353} 354 355namespace { 356 class ReduceMiscompiledBlocks : public ListReducer<BasicBlock*> { 357 BugDriver &BD; 358 bool (*TestFn)(BugDriver &, Module *, Module *); 359 std::vector<Function*> FunctionsBeingTested; 360 public: 361 ReduceMiscompiledBlocks(BugDriver &bd, 362 bool (*F)(BugDriver &, Module *, Module *), 363 const std::vector<Function*> &Fns) 364 : BD(bd), TestFn(F), FunctionsBeingTested(Fns) {} 365 366 virtual TestResult doTest(std::vector<BasicBlock*> &Prefix, 367 std::vector<BasicBlock*> &Suffix) { 368 if (!Suffix.empty() && TestFuncs(Suffix)) 369 return KeepSuffix; 370 if (TestFuncs(Prefix)) 371 return KeepPrefix; 372 return NoFailure; 373 } 374 375 bool TestFuncs(const std::vector<BasicBlock*> &Prefix); 376 }; 377} 378 379/// TestFuncs - Extract all blocks for the miscompiled functions except for the 380/// specified blocks. If the problem still exists, return true. 381/// 382bool ReduceMiscompiledBlocks::TestFuncs(const std::vector<BasicBlock*> &BBs) { 383 // Test to see if the function is misoptimized if we ONLY run it on the 384 // functions listed in Funcs. 385 std::cout << "Checking to see if the program is misoptimized when all "; 386 if (!BBs.empty()) { 387 std::cout << "but these " << BBs.size() << " blocks are extracted: "; 388 for (unsigned i = 0, e = BBs.size() < 10 ? BBs.size() : 10; i != e; ++i) 389 std::cout << BBs[i]->getName() << " "; 390 if (BBs.size() > 10) std::cout << "..."; 391 } else { 392 std::cout << "blocks are extracted."; 393 } 394 std::cout << '\n'; 395 396 // Split the module into the two halves of the program we want. 397 Module *ToNotOptimize = CloneModule(BD.getProgram()); 398 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, 399 FunctionsBeingTested); 400 401 // Try the extraction. If it doesn't work, then the block extractor crashed 402 // or something, in which case bugpoint can't chase down this possibility. 403 if (Module *New = BD.ExtractMappedBlocksFromModule(BBs, ToOptimize)) { 404 delete ToOptimize; 405 // Run the predicate, not that the predicate will delete both input modules. 406 return TestFn(BD, New, ToNotOptimize); 407 } 408 delete ToOptimize; 409 delete ToNotOptimize; 410 return false; 411} 412 413 414/// ExtractBlocks - Given a reduced list of functions that still expose the bug, 415/// extract as many basic blocks from the region as possible without obscuring 416/// the bug. 417/// 418static bool ExtractBlocks(BugDriver &BD, 419 bool (*TestFn)(BugDriver &, Module *, Module *), 420 std::vector<Function*> &MiscompiledFunctions) { 421 if (BugpointIsInterrupted) return false; 422 423 std::vector<BasicBlock*> Blocks; 424 for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i) 425 for (Function::iterator I = MiscompiledFunctions[i]->begin(), 426 E = MiscompiledFunctions[i]->end(); I != E; ++I) 427 Blocks.push_back(I); 428 429 // Use the list reducer to identify blocks that can be extracted without 430 // obscuring the bug. The Blocks list will end up containing blocks that must 431 // be retained from the original program. 432 unsigned OldSize = Blocks.size(); 433 434 // Check to see if all blocks are extractible first. 435 if (ReduceMiscompiledBlocks(BD, TestFn, 436 MiscompiledFunctions).TestFuncs(std::vector<BasicBlock*>())) { 437 Blocks.clear(); 438 } else { 439 ReduceMiscompiledBlocks(BD, TestFn,MiscompiledFunctions).reduceList(Blocks); 440 if (Blocks.size() == OldSize) 441 return false; 442 } 443 444 Module *ProgClone = CloneModule(BD.getProgram()); 445 Module *ToExtract = SplitFunctionsOutOfModule(ProgClone, 446 MiscompiledFunctions); 447 Module *Extracted = BD.ExtractMappedBlocksFromModule(Blocks, ToExtract); 448 if (Extracted == 0) { 449 // Weird, extraction should have worked. 450 std::cerr << "Nondeterministic problem extracting blocks??\n"; 451 delete ProgClone; 452 delete ToExtract; 453 return false; 454 } 455 456 // Otherwise, block extraction succeeded. Link the two program fragments back 457 // together. 458 delete ToExtract; 459 460 std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions; 461 for (Module::iterator I = Extracted->begin(), E = Extracted->end(); 462 I != E; ++I) 463 if (!I->isExternal()) 464 MisCompFunctions.push_back(std::make_pair(I->getName(), 465 I->getFunctionType())); 466 467 std::string ErrorMsg; 468 if (Linker::LinkModules(ProgClone, Extracted, &ErrorMsg)) { 469 std::cerr << BD.getToolName() << ": Error linking modules together:" 470 << ErrorMsg << '\n'; 471 exit(1); 472 } 473 delete Extracted; 474 475 // Set the new program and delete the old one. 476 BD.setNewProgram(ProgClone); 477 478 // Update the list of miscompiled functions. 479 MiscompiledFunctions.clear(); 480 481 for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) { 482 Function *NewF = ProgClone->getFunction(MisCompFunctions[i].first, 483 MisCompFunctions[i].second); 484 assert(NewF && "Function not found??"); 485 MiscompiledFunctions.push_back(NewF); 486 } 487 488 return true; 489} 490 491 492/// DebugAMiscompilation - This is a generic driver to narrow down 493/// miscompilations, either in an optimization or a code generator. 494/// 495static std::vector<Function*> 496DebugAMiscompilation(BugDriver &BD, 497 bool (*TestFn)(BugDriver &, Module *, Module *)) { 498 // Okay, now that we have reduced the list of passes which are causing the 499 // failure, see if we can pin down which functions are being 500 // miscompiled... first build a list of all of the non-external functions in 501 // the program. 502 std::vector<Function*> MiscompiledFunctions; 503 Module *Prog = BD.getProgram(); 504 for (Module::iterator I = Prog->begin(), E = Prog->end(); I != E; ++I) 505 if (!I->isExternal()) 506 MiscompiledFunctions.push_back(I); 507 508 // Do the reduction... 509 if (!BugpointIsInterrupted) 510 ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions); 511 512 std::cout << "\n*** The following function" 513 << (MiscompiledFunctions.size() == 1 ? " is" : "s are") 514 << " being miscompiled: "; 515 PrintFunctionList(MiscompiledFunctions); 516 std::cout << '\n'; 517 518 // See if we can rip any loops out of the miscompiled functions and still 519 // trigger the problem. 520 521 if (!BugpointIsInterrupted && !DisableLoopExtraction && 522 ExtractLoops(BD, TestFn, MiscompiledFunctions)) { 523 // Okay, we extracted some loops and the problem still appears. See if we 524 // can eliminate some of the created functions from being candidates. 525 526 // Loop extraction can introduce functions with the same name (foo_code). 527 // Make sure to disambiguate the symbols so that when the program is split 528 // apart that we can link it back together again. 529 DisambiguateGlobalSymbols(BD.getProgram()); 530 531 // Do the reduction... 532 if (!BugpointIsInterrupted) 533 ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions); 534 535 std::cout << "\n*** The following function" 536 << (MiscompiledFunctions.size() == 1 ? " is" : "s are") 537 << " being miscompiled: "; 538 PrintFunctionList(MiscompiledFunctions); 539 std::cout << '\n'; 540 } 541 542 if (!BugpointIsInterrupted && 543 ExtractBlocks(BD, TestFn, MiscompiledFunctions)) { 544 // Okay, we extracted some blocks and the problem still appears. See if we 545 // can eliminate some of the created functions from being candidates. 546 547 // Block extraction can introduce functions with the same name (foo_code). 548 // Make sure to disambiguate the symbols so that when the program is split 549 // apart that we can link it back together again. 550 DisambiguateGlobalSymbols(BD.getProgram()); 551 552 // Do the reduction... 553 ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions); 554 555 std::cout << "\n*** The following function" 556 << (MiscompiledFunctions.size() == 1 ? " is" : "s are") 557 << " being miscompiled: "; 558 PrintFunctionList(MiscompiledFunctions); 559 std::cout << '\n'; 560 } 561 562 return MiscompiledFunctions; 563} 564 565/// TestOptimizer - This is the predicate function used to check to see if the 566/// "Test" portion of the program is misoptimized. If so, return true. In any 567/// case, both module arguments are deleted. 568/// 569static bool TestOptimizer(BugDriver &BD, Module *Test, Module *Safe) { 570 // Run the optimization passes on ToOptimize, producing a transformed version 571 // of the functions being tested. 572 std::cout << " Optimizing functions being tested: "; 573 Module *Optimized = BD.runPassesOn(Test, BD.getPassesToRun(), 574 /*AutoDebugCrashes*/true); 575 std::cout << "done.\n"; 576 delete Test; 577 578 std::cout << " Checking to see if the merged program executes correctly: "; 579 bool Broken = TestMergedProgram(BD, Optimized, Safe, true); 580 std::cout << (Broken ? " nope.\n" : " yup.\n"); 581 return Broken; 582} 583 584 585/// debugMiscompilation - This method is used when the passes selected are not 586/// crashing, but the generated output is semantically different from the 587/// input. 588/// 589bool BugDriver::debugMiscompilation() { 590 // Make sure something was miscompiled... 591 if (!BugpointIsInterrupted) 592 if (!ReduceMiscompilingPasses(*this).reduceList(PassesToRun)) { 593 std::cerr << "*** Optimized program matches reference output! No problem" 594 << " detected...\nbugpoint can't help you with your problem!\n"; 595 return false; 596 } 597 598 std::cout << "\n*** Found miscompiling pass" 599 << (getPassesToRun().size() == 1 ? "" : "es") << ": " 600 << getPassesString(getPassesToRun()) << '\n'; 601 EmitProgressBytecode("passinput"); 602 603 std::vector<Function*> MiscompiledFunctions = 604 DebugAMiscompilation(*this, TestOptimizer); 605 606 // Output a bunch of bytecode files for the user... 607 std::cout << "Outputting reduced bytecode files which expose the problem:\n"; 608 Module *ToNotOptimize = CloneModule(getProgram()); 609 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, 610 MiscompiledFunctions); 611 612 std::cout << " Non-optimized portion: "; 613 ToNotOptimize = swapProgramIn(ToNotOptimize); 614 EmitProgressBytecode("tonotoptimize", true); 615 setNewProgram(ToNotOptimize); // Delete hacked module. 616 617 std::cout << " Portion that is input to optimizer: "; 618 ToOptimize = swapProgramIn(ToOptimize); 619 EmitProgressBytecode("tooptimize"); 620 setNewProgram(ToOptimize); // Delete hacked module. 621 622 return false; 623} 624 625/// CleanupAndPrepareModules - Get the specified modules ready for code 626/// generator testing. 627/// 628static void CleanupAndPrepareModules(BugDriver &BD, Module *&Test, 629 Module *Safe) { 630 // Clean up the modules, removing extra cruft that we don't need anymore... 631 Test = BD.performFinalCleanups(Test); 632 633 // If we are executing the JIT, we have several nasty issues to take care of. 634 if (!BD.isExecutingJIT()) return; 635 636 // First, if the main function is in the Safe module, we must add a stub to 637 // the Test module to call into it. Thus, we create a new function `main' 638 // which just calls the old one. 639 if (Function *oldMain = Safe->getNamedFunction("main")) 640 if (!oldMain->isExternal()) { 641 // Rename it 642 oldMain->setName("llvm_bugpoint_old_main"); 643 // Create a NEW `main' function with same type in the test module. 644 Function *newMain = new Function(oldMain->getFunctionType(), 645 GlobalValue::ExternalLinkage, 646 "main", Test); 647 // Create an `oldmain' prototype in the test module, which will 648 // corresponds to the real main function in the same module. 649 Function *oldMainProto = new Function(oldMain->getFunctionType(), 650 GlobalValue::ExternalLinkage, 651 oldMain->getName(), Test); 652 // Set up and remember the argument list for the main function. 653 std::vector<Value*> args; 654 for (Function::arg_iterator 655 I = newMain->arg_begin(), E = newMain->arg_end(), 656 OI = oldMain->arg_begin(); I != E; ++I, ++OI) { 657 I->setName(OI->getName()); // Copy argument names from oldMain 658 args.push_back(I); 659 } 660 661 // Call the old main function and return its result 662 BasicBlock *BB = new BasicBlock("entry", newMain); 663 CallInst *call = new CallInst(oldMainProto, args, "", BB); 664 665 // If the type of old function wasn't void, return value of call 666 new ReturnInst(call, BB); 667 } 668 669 // The second nasty issue we must deal with in the JIT is that the Safe 670 // module cannot directly reference any functions defined in the test 671 // module. Instead, we use a JIT API call to dynamically resolve the 672 // symbol. 673 674 // Add the resolver to the Safe module. 675 // Prototype: void *getPointerToNamedFunction(const char* Name) 676 Constant *resolverFunc = 677 Safe->getOrInsertFunction("getPointerToNamedFunction", 678 PointerType::get(Type::Int8Ty), 679 PointerType::get(Type::Int8Ty), (Type *)0); 680 681 // Use the function we just added to get addresses of functions we need. 682 for (Module::iterator F = Safe->begin(), E = Safe->end(); F != E; ++F) { 683 if (F->isExternal() && !F->use_empty() && &*F != resolverFunc && 684 F->getIntrinsicID() == 0 /* ignore intrinsics */) { 685 Function *TestFn = Test->getNamedFunction(F->getName()); 686 687 // Don't forward functions which are external in the test module too. 688 if (TestFn && !TestFn->isExternal()) { 689 // 1. Add a string constant with its name to the global file 690 Constant *InitArray = ConstantArray::get(F->getName()); 691 GlobalVariable *funcName = 692 new GlobalVariable(InitArray->getType(), true /*isConstant*/, 693 GlobalValue::InternalLinkage, InitArray, 694 F->getName() + "_name", Safe); 695 696 // 2. Use `GetElementPtr *funcName, 0, 0' to convert the string to an 697 // sbyte* so it matches the signature of the resolver function. 698 699 // GetElementPtr *funcName, ulong 0, ulong 0 700 std::vector<Constant*> GEPargs(2,Constant::getNullValue(Type::Int32Ty)); 701 Value *GEP = 702 ConstantExpr::getGetElementPtr(funcName, GEPargs); 703 std::vector<Value*> ResolverArgs; 704 ResolverArgs.push_back(GEP); 705 706 // Rewrite uses of F in global initializers, etc. to uses of a wrapper 707 // function that dynamically resolves the calls to F via our JIT API 708 if (!F->use_empty()) { 709 // Create a new global to hold the cached function pointer. 710 Constant *NullPtr = ConstantPointerNull::get(F->getType()); 711 GlobalVariable *Cache = 712 new GlobalVariable(F->getType(), false,GlobalValue::InternalLinkage, 713 NullPtr,F->getName()+".fpcache", F->getParent()); 714 715 // Construct a new stub function that will re-route calls to F 716 const FunctionType *FuncTy = F->getFunctionType(); 717 Function *FuncWrapper = new Function(FuncTy, 718 GlobalValue::InternalLinkage, 719 F->getName() + "_wrapper", 720 F->getParent()); 721 BasicBlock *EntryBB = new BasicBlock("entry", FuncWrapper); 722 BasicBlock *DoCallBB = new BasicBlock("usecache", FuncWrapper); 723 BasicBlock *LookupBB = new BasicBlock("lookupfp", FuncWrapper); 724 725 // Check to see if we already looked up the value. 726 Value *CachedVal = new LoadInst(Cache, "fpcache", EntryBB); 727 Value *IsNull = new ICmpInst(ICmpInst::ICMP_EQ, CachedVal, 728 NullPtr, "isNull", EntryBB); 729 new BranchInst(LookupBB, DoCallBB, IsNull, EntryBB); 730 731 // Resolve the call to function F via the JIT API: 732 // 733 // call resolver(GetElementPtr...) 734 CallInst *Resolver = new CallInst(resolverFunc, ResolverArgs, 735 "resolver", LookupBB); 736 // cast the result from the resolver to correctly-typed function 737 CastInst *CastedResolver = new BitCastInst(Resolver, 738 PointerType::get(F->getFunctionType()), "resolverCast", LookupBB); 739 740 // Save the value in our cache. 741 new StoreInst(CastedResolver, Cache, LookupBB); 742 new BranchInst(DoCallBB, LookupBB); 743 744 PHINode *FuncPtr = new PHINode(NullPtr->getType(), "fp", DoCallBB); 745 FuncPtr->addIncoming(CastedResolver, LookupBB); 746 FuncPtr->addIncoming(CachedVal, EntryBB); 747 748 // Save the argument list. 749 std::vector<Value*> Args; 750 for (Function::arg_iterator i = FuncWrapper->arg_begin(), 751 e = FuncWrapper->arg_end(); i != e; ++i) 752 Args.push_back(i); 753 754 // Pass on the arguments to the real function, return its result 755 if (F->getReturnType() == Type::VoidTy) { 756 new CallInst(FuncPtr, Args, "", DoCallBB); 757 new ReturnInst(DoCallBB); 758 } else { 759 CallInst *Call = new CallInst(FuncPtr, Args, "retval", DoCallBB); 760 new ReturnInst(Call, DoCallBB); 761 } 762 763 // Use the wrapper function instead of the old function 764 F->replaceAllUsesWith(FuncWrapper); 765 } 766 } 767 } 768 } 769 770 if (verifyModule(*Test) || verifyModule(*Safe)) { 771 std::cerr << "Bugpoint has a bug, which corrupted a module!!\n"; 772 abort(); 773 } 774} 775 776 777 778/// TestCodeGenerator - This is the predicate function used to check to see if 779/// the "Test" portion of the program is miscompiled by the code generator under 780/// test. If so, return true. In any case, both module arguments are deleted. 781/// 782static bool TestCodeGenerator(BugDriver &BD, Module *Test, Module *Safe) { 783 CleanupAndPrepareModules(BD, Test, Safe); 784 785 sys::Path TestModuleBC("bugpoint.test.bc"); 786 std::string ErrMsg; 787 if (TestModuleBC.makeUnique(true, &ErrMsg)) { 788 std::cerr << BD.getToolName() << "Error making unique filename: " 789 << ErrMsg << "\n"; 790 exit(1); 791 } 792 if (BD.writeProgramToFile(TestModuleBC.toString(), Test)) { 793 std::cerr << "Error writing bytecode to `" << TestModuleBC << "'\nExiting."; 794 exit(1); 795 } 796 delete Test; 797 798 // Make the shared library 799 sys::Path SafeModuleBC("bugpoint.safe.bc"); 800 if (SafeModuleBC.makeUnique(true, &ErrMsg)) { 801 std::cerr << BD.getToolName() << "Error making unique filename: " 802 << ErrMsg << "\n"; 803 exit(1); 804 } 805 806 if (BD.writeProgramToFile(SafeModuleBC.toString(), Safe)) { 807 std::cerr << "Error writing bytecode to `" << SafeModuleBC << "'\nExiting."; 808 exit(1); 809 } 810 std::string SharedObject = BD.compileSharedObject(SafeModuleBC.toString()); 811 delete Safe; 812 813 // Run the code generator on the `Test' code, loading the shared library. 814 // The function returns whether or not the new output differs from reference. 815 int Result = BD.diffProgram(TestModuleBC.toString(), SharedObject, false); 816 817 if (Result) 818 std::cerr << ": still failing!\n"; 819 else 820 std::cerr << ": didn't fail.\n"; 821 TestModuleBC.eraseFromDisk(); 822 SafeModuleBC.eraseFromDisk(); 823 sys::Path(SharedObject).eraseFromDisk(); 824 825 return Result; 826} 827 828 829/// debugCodeGenerator - debug errors in LLC, LLI, or CBE. 830/// 831bool BugDriver::debugCodeGenerator() { 832 if ((void*)cbe == (void*)Interpreter) { 833 std::string Result = executeProgramWithCBE("bugpoint.cbe.out"); 834 std::cout << "\n*** The C backend cannot match the reference diff, but it " 835 << "is used as the 'known good'\n code generator, so I can't" 836 << " debug it. Perhaps you have a front-end problem?\n As a" 837 << " sanity check, I left the result of executing the program " 838 << "with the C backend\n in this file for you: '" 839 << Result << "'.\n"; 840 return true; 841 } 842 843 DisambiguateGlobalSymbols(Program); 844 845 std::vector<Function*> Funcs = DebugAMiscompilation(*this, TestCodeGenerator); 846 847 // Split the module into the two halves of the program we want. 848 Module *ToNotCodeGen = CloneModule(getProgram()); 849 Module *ToCodeGen = SplitFunctionsOutOfModule(ToNotCodeGen, Funcs); 850 851 // Condition the modules 852 CleanupAndPrepareModules(*this, ToCodeGen, ToNotCodeGen); 853 854 sys::Path TestModuleBC("bugpoint.test.bc"); 855 std::string ErrMsg; 856 if (TestModuleBC.makeUnique(true, &ErrMsg)) { 857 std::cerr << getToolName() << "Error making unique filename: " 858 << ErrMsg << "\n"; 859 exit(1); 860 } 861 862 if (writeProgramToFile(TestModuleBC.toString(), ToCodeGen)) { 863 std::cerr << "Error writing bytecode to `" << TestModuleBC << "'\nExiting."; 864 exit(1); 865 } 866 delete ToCodeGen; 867 868 // Make the shared library 869 sys::Path SafeModuleBC("bugpoint.safe.bc"); 870 if (SafeModuleBC.makeUnique(true, &ErrMsg)) { 871 std::cerr << getToolName() << "Error making unique filename: " 872 << ErrMsg << "\n"; 873 exit(1); 874 } 875 876 if (writeProgramToFile(SafeModuleBC.toString(), ToNotCodeGen)) { 877 std::cerr << "Error writing bytecode to `" << SafeModuleBC << "'\nExiting."; 878 exit(1); 879 } 880 std::string SharedObject = compileSharedObject(SafeModuleBC.toString()); 881 delete ToNotCodeGen; 882 883 std::cout << "You can reproduce the problem with the command line: \n"; 884 if (isExecutingJIT()) { 885 std::cout << " lli -load " << SharedObject << " " << TestModuleBC; 886 } else { 887 std::cout << " llc -f " << TestModuleBC << " -o " << TestModuleBC<< ".s\n"; 888 std::cout << " gcc " << SharedObject << " " << TestModuleBC 889 << ".s -o " << TestModuleBC << ".exe"; 890#if defined (HAVE_LINK_R) 891 std::cout << " -Wl,-R."; 892#endif 893 std::cout << "\n"; 894 std::cout << " " << TestModuleBC << ".exe"; 895 } 896 for (unsigned i=0, e = InputArgv.size(); i != e; ++i) 897 std::cout << " " << InputArgv[i]; 898 std::cout << '\n'; 899 std::cout << "The shared object was created with:\n llc -march=c " 900 << SafeModuleBC << " -o temporary.c\n" 901 << " gcc -xc temporary.c -O2 -o " << SharedObject 902#if defined(sparc) || defined(__sparc__) || defined(__sparcv9) 903 << " -G" // Compile a shared library, `-G' for Sparc 904#else 905 << " -shared" // `-shared' for Linux/X86, maybe others 906#endif 907 << " -fno-strict-aliasing\n"; 908 909 return false; 910} 911