Miscompilation.cpp revision ac53a0b272452013124bfc70480aea5e41b60f40
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 30using namespace llvm; 31 32namespace llvm { 33 extern cl::opt<std::string> OutputPrefix; 34 extern cl::list<std::string> InputArgv; 35} 36 37namespace { 38 static llvm::cl::opt<bool> 39 DisableLoopExtraction("disable-loop-extraction", 40 cl::desc("Don't extract loops when searching for miscompilations"), 41 cl::init(false)); 42 static llvm::cl::opt<bool> 43 DisableBlockExtraction("disable-block-extraction", 44 cl::desc("Don't extract blocks when searching for miscompilations"), 45 cl::init(false)); 46 47 class ReduceMiscompilingPasses : public ListReducer<const PassInfo*> { 48 BugDriver &BD; 49 public: 50 ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {} 51 52 virtual TestResult doTest(std::vector<const PassInfo*> &Prefix, 53 std::vector<const PassInfo*> &Suffix); 54 }; 55} 56 57/// TestResult - After passes have been split into a test group and a control 58/// group, see if they still break the program. 59/// 60ReduceMiscompilingPasses::TestResult 61ReduceMiscompilingPasses::doTest(std::vector<const PassInfo*> &Prefix, 62 std::vector<const PassInfo*> &Suffix) { 63 // First, run the program with just the Suffix passes. If it is still broken 64 // with JUST the kept passes, discard the prefix passes. 65 outs() << "Checking to see if '" << getPassesString(Suffix) 66 << "' compiles correctly: "; 67 68 std::string BitcodeResult; 69 if (BD.runPasses(Suffix, BitcodeResult, false/*delete*/, true/*quiet*/)) { 70 errs() << " Error running this sequence of passes" 71 << " on the input program!\n"; 72 BD.setPassesToRun(Suffix); 73 BD.EmitProgressBitcode("pass-error", false); 74 exit(BD.debugOptimizerCrash()); 75 } 76 77 // Check to see if the finished program matches the reference output... 78 if (BD.diffProgram(BitcodeResult, "", true /*delete bitcode*/)) { 79 outs() << " nope.\n"; 80 if (Suffix.empty()) { 81 errs() << BD.getToolName() << ": I'm confused: the test fails when " 82 << "no passes are run, nondeterministic program?\n"; 83 exit(1); 84 } 85 return KeepSuffix; // Miscompilation detected! 86 } 87 outs() << " yup.\n"; // No miscompilation! 88 89 if (Prefix.empty()) return NoFailure; 90 91 // Next, see if the program is broken if we run the "prefix" passes first, 92 // then separately run the "kept" passes. 93 outs() << "Checking to see if '" << getPassesString(Prefix) 94 << "' compiles correctly: "; 95 96 // If it is not broken with the kept passes, it's possible that the prefix 97 // passes must be run before the kept passes to break it. If the program 98 // WORKS after the prefix passes, but then fails if running the prefix AND 99 // kept passes, we can update our bitcode file to include the result of the 100 // prefix passes, then discard the prefix passes. 101 // 102 if (BD.runPasses(Prefix, BitcodeResult, false/*delete*/, true/*quiet*/)) { 103 errs() << " Error running this sequence of passes" 104 << " on the input program!\n"; 105 BD.setPassesToRun(Prefix); 106 BD.EmitProgressBitcode("pass-error", false); 107 exit(BD.debugOptimizerCrash()); 108 } 109 110 // If the prefix maintains the predicate by itself, only keep the prefix! 111 if (BD.diffProgram(BitcodeResult)) { 112 outs() << " nope.\n"; 113 sys::Path(BitcodeResult).eraseFromDisk(); 114 return KeepPrefix; 115 } 116 outs() << " yup.\n"; // No miscompilation! 117 118 // Ok, so now we know that the prefix passes work, try running the suffix 119 // passes on the result of the prefix passes. 120 // 121 Module *PrefixOutput = ParseInputFile(BitcodeResult, BD.getContext()); 122 if (PrefixOutput == 0) { 123 errs() << BD.getToolName() << ": Error reading bitcode file '" 124 << BitcodeResult << "'!\n"; 125 exit(1); 126 } 127 sys::Path(BitcodeResult).eraseFromDisk(); // No longer need the file on disk 128 129 // Don't check if there are no passes in the suffix. 130 if (Suffix.empty()) 131 return NoFailure; 132 133 outs() << "Checking to see if '" << getPassesString(Suffix) 134 << "' passes compile correctly after the '" 135 << getPassesString(Prefix) << "' passes: "; 136 137 Module *OriginalInput = BD.swapProgramIn(PrefixOutput); 138 if (BD.runPasses(Suffix, BitcodeResult, false/*delete*/, true/*quiet*/)) { 139 errs() << " Error running this sequence of passes" 140 << " on the input program!\n"; 141 BD.setPassesToRun(Suffix); 142 BD.EmitProgressBitcode("pass-error", false); 143 exit(BD.debugOptimizerCrash()); 144 } 145 146 // Run the result... 147 if (BD.diffProgram(BitcodeResult, "", true/*delete bitcode*/)) { 148 outs() << " nope.\n"; 149 delete OriginalInput; // We pruned down the original input... 150 return KeepSuffix; 151 } 152 153 // Otherwise, we must not be running the bad pass anymore. 154 outs() << " yup.\n"; // No miscompilation! 155 delete BD.swapProgramIn(OriginalInput); // Restore orig program & free test 156 return NoFailure; 157} 158 159namespace { 160 class ReduceMiscompilingFunctions : public ListReducer<Function*> { 161 BugDriver &BD; 162 bool (*TestFn)(BugDriver &, Module *, Module *); 163 public: 164 ReduceMiscompilingFunctions(BugDriver &bd, 165 bool (*F)(BugDriver &, Module *, Module *)) 166 : BD(bd), TestFn(F) {} 167 168 virtual TestResult doTest(std::vector<Function*> &Prefix, 169 std::vector<Function*> &Suffix) { 170 if (!Suffix.empty() && TestFuncs(Suffix)) 171 return KeepSuffix; 172 if (!Prefix.empty() && TestFuncs(Prefix)) 173 return KeepPrefix; 174 return NoFailure; 175 } 176 177 bool TestFuncs(const std::vector<Function*> &Prefix); 178 }; 179} 180 181/// TestMergedProgram - Given two modules, link them together and run the 182/// program, checking to see if the program matches the diff. If the diff 183/// matches, return false, otherwise return true. If the DeleteInputs argument 184/// is set to true then this function deletes both input modules before it 185/// returns. 186/// 187static bool TestMergedProgram(BugDriver &BD, Module *M1, Module *M2, 188 bool DeleteInputs) { 189 // Link the two portions of the program back to together. 190 std::string ErrorMsg; 191 if (!DeleteInputs) { 192 M1 = CloneModule(M1); 193 M2 = CloneModule(M2); 194 } 195 if (Linker::LinkModules(M1, M2, &ErrorMsg)) { 196 errs() << BD.getToolName() << ": Error linking modules together:" 197 << ErrorMsg << '\n'; 198 exit(1); 199 } 200 delete M2; // We are done with this module. 201 202 Module *OldProgram = BD.swapProgramIn(M1); 203 204 // Execute the program. If it does not match the expected output, we must 205 // return true. 206 bool Broken = BD.diffProgram(); 207 208 // Delete the linked module & restore the original 209 BD.swapProgramIn(OldProgram); 210 delete M1; 211 return Broken; 212} 213 214/// TestFuncs - split functions in a Module into two groups: those that are 215/// under consideration for miscompilation vs. those that are not, and test 216/// accordingly. Each group of functions becomes a separate Module. 217/// 218bool ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function*>&Funcs){ 219 // Test to see if the function is misoptimized if we ONLY run it on the 220 // functions listed in Funcs. 221 outs() << "Checking to see if the program is misoptimized when " 222 << (Funcs.size()==1 ? "this function is" : "these functions are") 223 << " run through the pass" 224 << (BD.getPassesToRun().size() == 1 ? "" : "es") << ":"; 225 PrintFunctionList(Funcs); 226 outs() << '\n'; 227 228 // Split the module into the two halves of the program we want. 229 DenseMap<const Value*, Value*> ValueMap; 230 Module *ToNotOptimize = CloneModule(BD.getProgram(), ValueMap); 231 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, Funcs, 232 ValueMap); 233 234 // Run the predicate, note that the predicate will delete both input modules. 235 return TestFn(BD, ToOptimize, ToNotOptimize); 236} 237 238/// DisambiguateGlobalSymbols - Mangle symbols to guarantee uniqueness by 239/// modifying predominantly internal symbols rather than external ones. 240/// 241static void DisambiguateGlobalSymbols(Module *M) { 242 // Try not to cause collisions by minimizing chances of renaming an 243 // already-external symbol, so take in external globals and functions as-is. 244 // The code should work correctly without disambiguation (assuming the same 245 // mangler is used by the two code generators), but having symbols with the 246 // same name causes warnings to be emitted by the code generator. 247 Mangler Mang(*M); 248 // Agree with the CBE on symbol naming 249 Mang.markCharUnacceptable('.'); 250 for (Module::global_iterator I = M->global_begin(), E = M->global_end(); 251 I != E; ++I) { 252 // Don't mangle asm names. 253 if (!I->hasName() || I->getName()[0] != 1) 254 I->setName(Mang.getMangledName(I)); 255 } 256 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) { 257 // Don't mangle asm names or intrinsics. 258 if ((!I->hasName() || I->getName()[0] != 1) && 259 I->getIntrinsicID() == 0) 260 I->setName(Mang.getMangledName(I)); 261 } 262} 263 264/// ExtractLoops - Given a reduced list of functions that still exposed the bug, 265/// check to see if we can extract the loops in the region without obscuring the 266/// bug. If so, it reduces the amount of code identified. 267/// 268static bool ExtractLoops(BugDriver &BD, 269 bool (*TestFn)(BugDriver &, Module *, Module *), 270 std::vector<Function*> &MiscompiledFunctions) { 271 bool MadeChange = false; 272 while (1) { 273 if (BugpointIsInterrupted) return MadeChange; 274 275 DenseMap<const Value*, Value*> ValueMap; 276 Module *ToNotOptimize = CloneModule(BD.getProgram(), ValueMap); 277 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, 278 MiscompiledFunctions, 279 ValueMap); 280 Module *ToOptimizeLoopExtracted = BD.ExtractLoop(ToOptimize); 281 if (!ToOptimizeLoopExtracted) { 282 // If the loop extractor crashed or if there were no extractible loops, 283 // then this chapter of our odyssey is over with. 284 delete ToNotOptimize; 285 delete ToOptimize; 286 return MadeChange; 287 } 288 289 errs() << "Extracted a loop from the breaking portion of the program.\n"; 290 291 // Bugpoint is intentionally not very trusting of LLVM transformations. In 292 // particular, we're not going to assume that the loop extractor works, so 293 // we're going to test the newly loop extracted program to make sure nothing 294 // has broken. If something broke, then we'll inform the user and stop 295 // extraction. 296 AbstractInterpreter *AI = BD.switchToSafeInterpreter(); 297 if (TestMergedProgram(BD, ToOptimizeLoopExtracted, ToNotOptimize, false)) { 298 BD.switchToInterpreter(AI); 299 300 // Merged program doesn't work anymore! 301 errs() << " *** ERROR: Loop extraction broke the program. :(" 302 << " Please report a bug!\n"; 303 errs() << " Continuing on with un-loop-extracted version.\n"; 304 305 BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-tno.bc", 306 ToNotOptimize); 307 BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-to.bc", 308 ToOptimize); 309 BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-to-le.bc", 310 ToOptimizeLoopExtracted); 311 312 errs() << "Please submit the " 313 << OutputPrefix << "-loop-extract-fail-*.bc files.\n"; 314 delete ToOptimize; 315 delete ToNotOptimize; 316 delete ToOptimizeLoopExtracted; 317 return MadeChange; 318 } 319 delete ToOptimize; 320 BD.switchToInterpreter(AI); 321 322 outs() << " Testing after loop extraction:\n"; 323 // Clone modules, the tester function will free them. 324 Module *TOLEBackup = CloneModule(ToOptimizeLoopExtracted); 325 Module *TNOBackup = CloneModule(ToNotOptimize); 326 if (!TestFn(BD, ToOptimizeLoopExtracted, ToNotOptimize)) { 327 outs() << "*** Loop extraction masked the problem. Undoing.\n"; 328 // If the program is not still broken, then loop extraction did something 329 // that masked the error. Stop loop extraction now. 330 delete TOLEBackup; 331 delete TNOBackup; 332 return MadeChange; 333 } 334 ToOptimizeLoopExtracted = TOLEBackup; 335 ToNotOptimize = TNOBackup; 336 337 outs() << "*** Loop extraction successful!\n"; 338 339 std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions; 340 for (Module::iterator I = ToOptimizeLoopExtracted->begin(), 341 E = ToOptimizeLoopExtracted->end(); I != E; ++I) 342 if (!I->isDeclaration()) 343 MisCompFunctions.push_back(std::make_pair(I->getName(), 344 I->getFunctionType())); 345 346 // Okay, great! Now we know that we extracted a loop and that loop 347 // extraction both didn't break the program, and didn't mask the problem. 348 // Replace the current program with the loop extracted version, and try to 349 // extract another loop. 350 std::string ErrorMsg; 351 if (Linker::LinkModules(ToNotOptimize, ToOptimizeLoopExtracted, &ErrorMsg)){ 352 errs() << BD.getToolName() << ": Error linking modules together:" 353 << ErrorMsg << '\n'; 354 exit(1); 355 } 356 delete ToOptimizeLoopExtracted; 357 358 // All of the Function*'s in the MiscompiledFunctions list are in the old 359 // module. Update this list to include all of the functions in the 360 // optimized and loop extracted module. 361 MiscompiledFunctions.clear(); 362 for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) { 363 Function *NewF = ToNotOptimize->getFunction(MisCompFunctions[i].first); 364 365 assert(NewF && "Function not found??"); 366 assert(NewF->getFunctionType() == MisCompFunctions[i].second && 367 "found wrong function type?"); 368 MiscompiledFunctions.push_back(NewF); 369 } 370 371 BD.setNewProgram(ToNotOptimize); 372 MadeChange = true; 373 } 374} 375 376namespace { 377 class ReduceMiscompiledBlocks : public ListReducer<BasicBlock*> { 378 BugDriver &BD; 379 bool (*TestFn)(BugDriver &, Module *, Module *); 380 std::vector<Function*> FunctionsBeingTested; 381 public: 382 ReduceMiscompiledBlocks(BugDriver &bd, 383 bool (*F)(BugDriver &, Module *, Module *), 384 const std::vector<Function*> &Fns) 385 : BD(bd), TestFn(F), FunctionsBeingTested(Fns) {} 386 387 virtual TestResult doTest(std::vector<BasicBlock*> &Prefix, 388 std::vector<BasicBlock*> &Suffix) { 389 if (!Suffix.empty() && TestFuncs(Suffix)) 390 return KeepSuffix; 391 if (TestFuncs(Prefix)) 392 return KeepPrefix; 393 return NoFailure; 394 } 395 396 bool TestFuncs(const std::vector<BasicBlock*> &Prefix); 397 }; 398} 399 400/// TestFuncs - Extract all blocks for the miscompiled functions except for the 401/// specified blocks. If the problem still exists, return true. 402/// 403bool ReduceMiscompiledBlocks::TestFuncs(const std::vector<BasicBlock*> &BBs) { 404 // Test to see if the function is misoptimized if we ONLY run it on the 405 // functions listed in Funcs. 406 outs() << "Checking to see if the program is misoptimized when all "; 407 if (!BBs.empty()) { 408 outs() << "but these " << BBs.size() << " blocks are extracted: "; 409 for (unsigned i = 0, e = BBs.size() < 10 ? BBs.size() : 10; i != e; ++i) 410 outs() << BBs[i]->getName() << " "; 411 if (BBs.size() > 10) outs() << "..."; 412 } else { 413 outs() << "blocks are extracted."; 414 } 415 outs() << '\n'; 416 417 // Split the module into the two halves of the program we want. 418 DenseMap<const Value*, Value*> ValueMap; 419 Module *ToNotOptimize = CloneModule(BD.getProgram(), ValueMap); 420 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, 421 FunctionsBeingTested, 422 ValueMap); 423 424 // Try the extraction. If it doesn't work, then the block extractor crashed 425 // or something, in which case bugpoint can't chase down this possibility. 426 if (Module *New = BD.ExtractMappedBlocksFromModule(BBs, ToOptimize)) { 427 delete ToOptimize; 428 // Run the predicate, not that the predicate will delete both input modules. 429 return TestFn(BD, New, ToNotOptimize); 430 } 431 delete ToOptimize; 432 delete ToNotOptimize; 433 return false; 434} 435 436 437/// ExtractBlocks - Given a reduced list of functions that still expose the bug, 438/// extract as many basic blocks from the region as possible without obscuring 439/// the bug. 440/// 441static bool ExtractBlocks(BugDriver &BD, 442 bool (*TestFn)(BugDriver &, Module *, Module *), 443 std::vector<Function*> &MiscompiledFunctions) { 444 if (BugpointIsInterrupted) return false; 445 446 std::vector<BasicBlock*> Blocks; 447 for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i) 448 for (Function::iterator I = MiscompiledFunctions[i]->begin(), 449 E = MiscompiledFunctions[i]->end(); I != E; ++I) 450 Blocks.push_back(I); 451 452 // Use the list reducer to identify blocks that can be extracted without 453 // obscuring the bug. The Blocks list will end up containing blocks that must 454 // be retained from the original program. 455 unsigned OldSize = Blocks.size(); 456 457 // Check to see if all blocks are extractible first. 458 if (ReduceMiscompiledBlocks(BD, TestFn, 459 MiscompiledFunctions).TestFuncs(std::vector<BasicBlock*>())) { 460 Blocks.clear(); 461 } else { 462 ReduceMiscompiledBlocks(BD, TestFn,MiscompiledFunctions).reduceList(Blocks); 463 if (Blocks.size() == OldSize) 464 return false; 465 } 466 467 DenseMap<const Value*, Value*> ValueMap; 468 Module *ProgClone = CloneModule(BD.getProgram(), ValueMap); 469 Module *ToExtract = SplitFunctionsOutOfModule(ProgClone, 470 MiscompiledFunctions, 471 ValueMap); 472 Module *Extracted = BD.ExtractMappedBlocksFromModule(Blocks, ToExtract); 473 if (Extracted == 0) { 474 // Weird, extraction should have worked. 475 errs() << "Nondeterministic problem extracting blocks??\n"; 476 delete ProgClone; 477 delete ToExtract; 478 return false; 479 } 480 481 // Otherwise, block extraction succeeded. Link the two program fragments back 482 // together. 483 delete ToExtract; 484 485 std::vector<std::pair<std::string, const FunctionType*> > MisCompFunctions; 486 for (Module::iterator I = Extracted->begin(), E = Extracted->end(); 487 I != E; ++I) 488 if (!I->isDeclaration()) 489 MisCompFunctions.push_back(std::make_pair(I->getName(), 490 I->getFunctionType())); 491 492 std::string ErrorMsg; 493 if (Linker::LinkModules(ProgClone, Extracted, &ErrorMsg)) { 494 errs() << BD.getToolName() << ": Error linking modules together:" 495 << ErrorMsg << '\n'; 496 exit(1); 497 } 498 delete Extracted; 499 500 // Set the new program and delete the old one. 501 BD.setNewProgram(ProgClone); 502 503 // Update the list of miscompiled functions. 504 MiscompiledFunctions.clear(); 505 506 for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) { 507 Function *NewF = ProgClone->getFunction(MisCompFunctions[i].first); 508 assert(NewF && "Function not found??"); 509 assert(NewF->getFunctionType() == MisCompFunctions[i].second && 510 "Function has wrong type??"); 511 MiscompiledFunctions.push_back(NewF); 512 } 513 514 return true; 515} 516 517 518/// DebugAMiscompilation - This is a generic driver to narrow down 519/// miscompilations, either in an optimization or a code generator. 520/// 521static std::vector<Function*> 522DebugAMiscompilation(BugDriver &BD, 523 bool (*TestFn)(BugDriver &, Module *, Module *)) { 524 // Okay, now that we have reduced the list of passes which are causing the 525 // failure, see if we can pin down which functions are being 526 // miscompiled... first build a list of all of the non-external functions in 527 // the program. 528 std::vector<Function*> MiscompiledFunctions; 529 Module *Prog = BD.getProgram(); 530 for (Module::iterator I = Prog->begin(), E = Prog->end(); I != E; ++I) 531 if (!I->isDeclaration()) 532 MiscompiledFunctions.push_back(I); 533 534 // Do the reduction... 535 if (!BugpointIsInterrupted) 536 ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions); 537 538 outs() << "\n*** The following function" 539 << (MiscompiledFunctions.size() == 1 ? " is" : "s are") 540 << " being miscompiled: "; 541 PrintFunctionList(MiscompiledFunctions); 542 outs() << '\n'; 543 544 // See if we can rip any loops out of the miscompiled functions and still 545 // trigger the problem. 546 547 if (!BugpointIsInterrupted && !DisableLoopExtraction && 548 ExtractLoops(BD, TestFn, MiscompiledFunctions)) { 549 // Okay, we extracted some loops and the problem still appears. See if we 550 // can eliminate some of the created functions from being candidates. 551 552 // Loop extraction can introduce functions with the same name (foo_code). 553 // Make sure to disambiguate the symbols so that when the program is split 554 // apart that we can link it back together again. 555 DisambiguateGlobalSymbols(BD.getProgram()); 556 557 // Do the reduction... 558 if (!BugpointIsInterrupted) 559 ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions); 560 561 outs() << "\n*** The following function" 562 << (MiscompiledFunctions.size() == 1 ? " is" : "s are") 563 << " being miscompiled: "; 564 PrintFunctionList(MiscompiledFunctions); 565 outs() << '\n'; 566 } 567 568 if (!BugpointIsInterrupted && !DisableBlockExtraction && 569 ExtractBlocks(BD, TestFn, MiscompiledFunctions)) { 570 // Okay, we extracted some blocks and the problem still appears. See if we 571 // can eliminate some of the created functions from being candidates. 572 573 // Block extraction can introduce functions with the same name (foo_code). 574 // Make sure to disambiguate the symbols so that when the program is split 575 // apart that we can link it back together again. 576 DisambiguateGlobalSymbols(BD.getProgram()); 577 578 // Do the reduction... 579 ReduceMiscompilingFunctions(BD, TestFn).reduceList(MiscompiledFunctions); 580 581 outs() << "\n*** The following function" 582 << (MiscompiledFunctions.size() == 1 ? " is" : "s are") 583 << " being miscompiled: "; 584 PrintFunctionList(MiscompiledFunctions); 585 outs() << '\n'; 586 } 587 588 return MiscompiledFunctions; 589} 590 591/// TestOptimizer - This is the predicate function used to check to see if the 592/// "Test" portion of the program is misoptimized. If so, return true. In any 593/// case, both module arguments are deleted. 594/// 595static bool TestOptimizer(BugDriver &BD, Module *Test, Module *Safe) { 596 // Run the optimization passes on ToOptimize, producing a transformed version 597 // of the functions being tested. 598 outs() << " Optimizing functions being tested: "; 599 Module *Optimized = BD.runPassesOn(Test, BD.getPassesToRun(), 600 /*AutoDebugCrashes*/true); 601 outs() << "done.\n"; 602 delete Test; 603 604 outs() << " Checking to see if the merged program executes correctly: "; 605 bool Broken = TestMergedProgram(BD, Optimized, Safe, true); 606 outs() << (Broken ? " nope.\n" : " yup.\n"); 607 return Broken; 608} 609 610 611/// debugMiscompilation - This method is used when the passes selected are not 612/// crashing, but the generated output is semantically different from the 613/// input. 614/// 615bool BugDriver::debugMiscompilation() { 616 // Make sure something was miscompiled... 617 if (!BugpointIsInterrupted) 618 if (!ReduceMiscompilingPasses(*this).reduceList(PassesToRun)) { 619 errs() << "*** Optimized program matches reference output! No problem" 620 << " detected...\nbugpoint can't help you with your problem!\n"; 621 return false; 622 } 623 624 outs() << "\n*** Found miscompiling pass" 625 << (getPassesToRun().size() == 1 ? "" : "es") << ": " 626 << getPassesString(getPassesToRun()) << '\n'; 627 EmitProgressBitcode("passinput"); 628 629 std::vector<Function*> MiscompiledFunctions = 630 DebugAMiscompilation(*this, TestOptimizer); 631 632 // Output a bunch of bitcode files for the user... 633 outs() << "Outputting reduced bitcode files which expose the problem:\n"; 634 DenseMap<const Value*, Value*> ValueMap; 635 Module *ToNotOptimize = CloneModule(getProgram(), ValueMap); 636 Module *ToOptimize = SplitFunctionsOutOfModule(ToNotOptimize, 637 MiscompiledFunctions, 638 ValueMap); 639 640 outs() << " Non-optimized portion: "; 641 ToNotOptimize = swapProgramIn(ToNotOptimize); 642 EmitProgressBitcode("tonotoptimize", true); 643 setNewProgram(ToNotOptimize); // Delete hacked module. 644 645 outs() << " Portion that is input to optimizer: "; 646 ToOptimize = swapProgramIn(ToOptimize); 647 EmitProgressBitcode("tooptimize"); 648 setNewProgram(ToOptimize); // Delete hacked module. 649 650 return false; 651} 652 653/// CleanupAndPrepareModules - Get the specified modules ready for code 654/// generator testing. 655/// 656static void CleanupAndPrepareModules(BugDriver &BD, Module *&Test, 657 Module *Safe) { 658 // Clean up the modules, removing extra cruft that we don't need anymore... 659 Test = BD.performFinalCleanups(Test); 660 661 // If we are executing the JIT, we have several nasty issues to take care of. 662 if (!BD.isExecutingJIT()) return; 663 664 // First, if the main function is in the Safe module, we must add a stub to 665 // the Test module to call into it. Thus, we create a new function `main' 666 // which just calls the old one. 667 if (Function *oldMain = Safe->getFunction("main")) 668 if (!oldMain->isDeclaration()) { 669 // Rename it 670 oldMain->setName("llvm_bugpoint_old_main"); 671 // Create a NEW `main' function with same type in the test module. 672 Function *newMain = Function::Create(oldMain->getFunctionType(), 673 GlobalValue::ExternalLinkage, 674 "main", Test); 675 // Create an `oldmain' prototype in the test module, which will 676 // corresponds to the real main function in the same module. 677 Function *oldMainProto = Function::Create(oldMain->getFunctionType(), 678 GlobalValue::ExternalLinkage, 679 oldMain->getName(), Test); 680 // Set up and remember the argument list for the main function. 681 std::vector<Value*> args; 682 for (Function::arg_iterator 683 I = newMain->arg_begin(), E = newMain->arg_end(), 684 OI = oldMain->arg_begin(); I != E; ++I, ++OI) { 685 I->setName(OI->getName()); // Copy argument names from oldMain 686 args.push_back(I); 687 } 688 689 // Call the old main function and return its result 690 BasicBlock *BB = BasicBlock::Create(Safe->getContext(), "entry", newMain); 691 CallInst *call = CallInst::Create(oldMainProto, args.begin(), args.end(), 692 "", BB); 693 694 // If the type of old function wasn't void, return value of call 695 ReturnInst::Create(Safe->getContext(), call, BB); 696 } 697 698 // The second nasty issue we must deal with in the JIT is that the Safe 699 // module cannot directly reference any functions defined in the test 700 // module. Instead, we use a JIT API call to dynamically resolve the 701 // symbol. 702 703 // Add the resolver to the Safe module. 704 // Prototype: void *getPointerToNamedFunction(const char* Name) 705 Constant *resolverFunc = 706 Safe->getOrInsertFunction("getPointerToNamedFunction", 707 Type::getInt8PtrTy(Safe->getContext()), 708 Type::getInt8PtrTy(Safe->getContext()), 709 (Type *)0); 710 711 // Use the function we just added to get addresses of functions we need. 712 for (Module::iterator F = Safe->begin(), E = Safe->end(); F != E; ++F) { 713 if (F->isDeclaration() && !F->use_empty() && &*F != resolverFunc && 714 !F->isIntrinsic() /* ignore intrinsics */) { 715 Function *TestFn = Test->getFunction(F->getName()); 716 717 // Don't forward functions which are external in the test module too. 718 if (TestFn && !TestFn->isDeclaration()) { 719 // 1. Add a string constant with its name to the global file 720 Constant *InitArray = ConstantArray::get(F->getContext(), F->getName()); 721 GlobalVariable *funcName = 722 new GlobalVariable(*Safe, InitArray->getType(), true /*isConstant*/, 723 GlobalValue::InternalLinkage, InitArray, 724 F->getName() + "_name"); 725 726 // 2. Use `GetElementPtr *funcName, 0, 0' to convert the string to an 727 // sbyte* so it matches the signature of the resolver function. 728 729 // GetElementPtr *funcName, ulong 0, ulong 0 730 std::vector<Constant*> GEPargs(2, 731 Constant::getNullValue(Type::getInt32Ty(F->getContext()))); 732 Value *GEP = 733 ConstantExpr::getGetElementPtr(funcName, &GEPargs[0], 2); 734 std::vector<Value*> ResolverArgs; 735 ResolverArgs.push_back(GEP); 736 737 // Rewrite uses of F in global initializers, etc. to uses of a wrapper 738 // function that dynamically resolves the calls to F via our JIT API 739 if (!F->use_empty()) { 740 // Create a new global to hold the cached function pointer. 741 Constant *NullPtr = ConstantPointerNull::get(F->getType()); 742 GlobalVariable *Cache = 743 new GlobalVariable(*F->getParent(), F->getType(), 744 false, GlobalValue::InternalLinkage, 745 NullPtr,F->getName()+".fpcache"); 746 747 // Construct a new stub function that will re-route calls to F 748 const FunctionType *FuncTy = F->getFunctionType(); 749 Function *FuncWrapper = Function::Create(FuncTy, 750 GlobalValue::InternalLinkage, 751 F->getName() + "_wrapper", 752 F->getParent()); 753 BasicBlock *EntryBB = BasicBlock::Create(F->getContext(), 754 "entry", FuncWrapper); 755 BasicBlock *DoCallBB = BasicBlock::Create(F->getContext(), 756 "usecache", FuncWrapper); 757 BasicBlock *LookupBB = BasicBlock::Create(F->getContext(), 758 "lookupfp", FuncWrapper); 759 760 // Check to see if we already looked up the value. 761 Value *CachedVal = new LoadInst(Cache, "fpcache", EntryBB); 762 Value *IsNull = new ICmpInst(*EntryBB, ICmpInst::ICMP_EQ, CachedVal, 763 NullPtr, "isNull"); 764 BranchInst::Create(LookupBB, DoCallBB, IsNull, EntryBB); 765 766 // Resolve the call to function F via the JIT API: 767 // 768 // call resolver(GetElementPtr...) 769 CallInst *Resolver = 770 CallInst::Create(resolverFunc, ResolverArgs.begin(), 771 ResolverArgs.end(), "resolver", LookupBB); 772 773 // Cast the result from the resolver to correctly-typed function. 774 CastInst *CastedResolver = 775 new BitCastInst(Resolver, 776 PointerType::getUnqual(F->getFunctionType()), 777 "resolverCast", LookupBB); 778 779 // Save the value in our cache. 780 new StoreInst(CastedResolver, Cache, LookupBB); 781 BranchInst::Create(DoCallBB, LookupBB); 782 783 PHINode *FuncPtr = PHINode::Create(NullPtr->getType(), 784 "fp", DoCallBB); 785 FuncPtr->addIncoming(CastedResolver, LookupBB); 786 FuncPtr->addIncoming(CachedVal, EntryBB); 787 788 // Save the argument list. 789 std::vector<Value*> Args; 790 for (Function::arg_iterator i = FuncWrapper->arg_begin(), 791 e = FuncWrapper->arg_end(); i != e; ++i) 792 Args.push_back(i); 793 794 // Pass on the arguments to the real function, return its result 795 if (F->getReturnType() == Type::getVoidTy(F->getContext())) { 796 CallInst::Create(FuncPtr, Args.begin(), Args.end(), "", DoCallBB); 797 ReturnInst::Create(F->getContext(), DoCallBB); 798 } else { 799 CallInst *Call = CallInst::Create(FuncPtr, Args.begin(), Args.end(), 800 "retval", DoCallBB); 801 ReturnInst::Create(F->getContext(),Call, DoCallBB); 802 } 803 804 // Use the wrapper function instead of the old function 805 F->replaceAllUsesWith(FuncWrapper); 806 } 807 } 808 } 809 } 810 811 if (verifyModule(*Test) || verifyModule(*Safe)) { 812 errs() << "Bugpoint has a bug, which corrupted a module!!\n"; 813 abort(); 814 } 815} 816 817 818 819/// TestCodeGenerator - This is the predicate function used to check to see if 820/// the "Test" portion of the program is miscompiled by the code generator under 821/// test. If so, return true. In any case, both module arguments are deleted. 822/// 823static bool TestCodeGenerator(BugDriver &BD, Module *Test, Module *Safe) { 824 CleanupAndPrepareModules(BD, Test, Safe); 825 826 sys::Path TestModuleBC("bugpoint.test.bc"); 827 std::string ErrMsg; 828 if (TestModuleBC.makeUnique(true, &ErrMsg)) { 829 errs() << BD.getToolName() << "Error making unique filename: " 830 << ErrMsg << "\n"; 831 exit(1); 832 } 833 if (BD.writeProgramToFile(TestModuleBC.str(), Test)) { 834 errs() << "Error writing bitcode to `" << TestModuleBC.str() 835 << "'\nExiting."; 836 exit(1); 837 } 838 delete Test; 839 840 // Make the shared library 841 sys::Path SafeModuleBC("bugpoint.safe.bc"); 842 if (SafeModuleBC.makeUnique(true, &ErrMsg)) { 843 errs() << BD.getToolName() << "Error making unique filename: " 844 << ErrMsg << "\n"; 845 exit(1); 846 } 847 848 if (BD.writeProgramToFile(SafeModuleBC.str(), Safe)) { 849 errs() << "Error writing bitcode to `" << SafeModuleBC.str() 850 << "'\nExiting."; 851 exit(1); 852 } 853 std::string SharedObject = BD.compileSharedObject(SafeModuleBC.str()); 854 delete Safe; 855 856 // Run the code generator on the `Test' code, loading the shared library. 857 // The function returns whether or not the new output differs from reference. 858 int Result = BD.diffProgram(TestModuleBC.str(), SharedObject, false); 859 860 if (Result) 861 errs() << ": still failing!\n"; 862 else 863 errs() << ": didn't fail.\n"; 864 TestModuleBC.eraseFromDisk(); 865 SafeModuleBC.eraseFromDisk(); 866 sys::Path(SharedObject).eraseFromDisk(); 867 868 return Result; 869} 870 871 872/// debugCodeGenerator - debug errors in LLC, LLI, or CBE. 873/// 874bool BugDriver::debugCodeGenerator() { 875 if ((void*)SafeInterpreter == (void*)Interpreter) { 876 std::string Result = executeProgramSafely("bugpoint.safe.out"); 877 outs() << "\n*** The \"safe\" i.e. 'known good' backend cannot match " 878 << "the reference diff. This may be due to a\n front-end " 879 << "bug or a bug in the original program, but this can also " 880 << "happen if bugpoint isn't running the program with the " 881 << "right flags or input.\n I left the result of executing " 882 << "the program with the \"safe\" backend in this file for " 883 << "you: '" 884 << Result << "'.\n"; 885 return true; 886 } 887 888 DisambiguateGlobalSymbols(Program); 889 890 std::vector<Function*> Funcs = DebugAMiscompilation(*this, TestCodeGenerator); 891 892 // Split the module into the two halves of the program we want. 893 DenseMap<const Value*, Value*> ValueMap; 894 Module *ToNotCodeGen = CloneModule(getProgram(), ValueMap); 895 Module *ToCodeGen = SplitFunctionsOutOfModule(ToNotCodeGen, Funcs, ValueMap); 896 897 // Condition the modules 898 CleanupAndPrepareModules(*this, ToCodeGen, ToNotCodeGen); 899 900 sys::Path TestModuleBC("bugpoint.test.bc"); 901 std::string ErrMsg; 902 if (TestModuleBC.makeUnique(true, &ErrMsg)) { 903 errs() << getToolName() << "Error making unique filename: " 904 << ErrMsg << "\n"; 905 exit(1); 906 } 907 908 if (writeProgramToFile(TestModuleBC.str(), ToCodeGen)) { 909 errs() << "Error writing bitcode to `" << TestModuleBC.str() 910 << "'\nExiting."; 911 exit(1); 912 } 913 delete ToCodeGen; 914 915 // Make the shared library 916 sys::Path SafeModuleBC("bugpoint.safe.bc"); 917 if (SafeModuleBC.makeUnique(true, &ErrMsg)) { 918 errs() << getToolName() << "Error making unique filename: " 919 << ErrMsg << "\n"; 920 exit(1); 921 } 922 923 if (writeProgramToFile(SafeModuleBC.str(), ToNotCodeGen)) { 924 errs() << "Error writing bitcode to `" << SafeModuleBC.str() 925 << "'\nExiting."; 926 exit(1); 927 } 928 std::string SharedObject = compileSharedObject(SafeModuleBC.str()); 929 delete ToNotCodeGen; 930 931 outs() << "You can reproduce the problem with the command line: \n"; 932 if (isExecutingJIT()) { 933 outs() << " lli -load " << SharedObject << " " << TestModuleBC.str(); 934 } else { 935 outs() << " llc -f " << TestModuleBC.str() << " -o " << TestModuleBC.str() 936 << ".s\n"; 937 outs() << " gcc " << SharedObject << " " << TestModuleBC.str() 938 << ".s -o " << TestModuleBC.str() << ".exe"; 939#if defined (HAVE_LINK_R) 940 outs() << " -Wl,-R."; 941#endif 942 outs() << "\n"; 943 outs() << " " << TestModuleBC.str() << ".exe"; 944 } 945 for (unsigned i=0, e = InputArgv.size(); i != e; ++i) 946 outs() << " " << InputArgv[i]; 947 outs() << '\n'; 948 outs() << "The shared object was created with:\n llc -march=c " 949 << SafeModuleBC.str() << " -o temporary.c\n" 950 << " gcc -xc temporary.c -O2 -o " << SharedObject; 951 if (TargetTriple.getArch() == Triple::sparc) 952 outs() << " -G"; // Compile a shared library, `-G' for Sparc 953 else 954 outs() << " -fPIC -shared"; // `-shared' for Linux/X86, maybe others 955 956 outs() << " -fno-strict-aliasing\n"; 957 958 return false; 959} 960