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Diffstat (limited to 'llvm/tools/bugpoint/Miscompilation.cpp')
| -rw-r--r-- | llvm/tools/bugpoint/Miscompilation.cpp | 1096 |
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diff --git a/llvm/tools/bugpoint/Miscompilation.cpp b/llvm/tools/bugpoint/Miscompilation.cpp new file mode 100644 index 000000000000..1621a51c91d6 --- /dev/null +++ b/llvm/tools/bugpoint/Miscompilation.cpp @@ -0,0 +1,1096 @@ +//===- Miscompilation.cpp - Debug program miscompilations -----------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements optimizer and code generation miscompilation debugging +// support. +// +//===----------------------------------------------------------------------===// + +#include "BugDriver.h" +#include "ListReducer.h" +#include "ToolRunner.h" +#include "llvm/Config/config.h" // for HAVE_LINK_R +#include "llvm/IR/Constants.h" +#include "llvm/IR/DerivedTypes.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/Verifier.h" +#include "llvm/Linker/Linker.h" +#include "llvm/Pass.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/FileUtilities.h" +#include "llvm/Transforms/Utils/Cloning.h" + +using namespace llvm; + +namespace llvm { +extern cl::opt<std::string> OutputPrefix; +extern cl::list<std::string> InputArgv; +} // end namespace llvm + +namespace { +static llvm::cl::opt<bool> DisableLoopExtraction( + "disable-loop-extraction", + cl::desc("Don't extract loops when searching for miscompilations"), + cl::init(false)); +static llvm::cl::opt<bool> DisableBlockExtraction( + "disable-block-extraction", + cl::desc("Don't extract blocks when searching for miscompilations"), + cl::init(false)); + +class ReduceMiscompilingPasses : public ListReducer<std::string> { + BugDriver &BD; + +public: + ReduceMiscompilingPasses(BugDriver &bd) : BD(bd) {} + + Expected<TestResult> doTest(std::vector<std::string> &Prefix, + std::vector<std::string> &Suffix) override; +}; +} // end anonymous namespace + +/// TestResult - After passes have been split into a test group and a control +/// group, see if they still break the program. +/// +Expected<ReduceMiscompilingPasses::TestResult> +ReduceMiscompilingPasses::doTest(std::vector<std::string> &Prefix, + std::vector<std::string> &Suffix) { + // First, run the program with just the Suffix passes. If it is still broken + // with JUST the kept passes, discard the prefix passes. + outs() << "Checking to see if '" << getPassesString(Suffix) + << "' compiles correctly: "; + + std::string BitcodeResult; + if (BD.runPasses(BD.getProgram(), Suffix, BitcodeResult, false /*delete*/, + true /*quiet*/)) { + errs() << " Error running this sequence of passes" + << " on the input program!\n"; + BD.setPassesToRun(Suffix); + BD.EmitProgressBitcode(BD.getProgram(), "pass-error", false); + // TODO: This should propagate the error instead of exiting. + if (Error E = BD.debugOptimizerCrash()) + exit(1); + exit(0); + } + + // Check to see if the finished program matches the reference output... + Expected<bool> Diff = BD.diffProgram(BD.getProgram(), BitcodeResult, "", + true /*delete bitcode*/); + if (Error E = Diff.takeError()) + return std::move(E); + if (*Diff) { + outs() << " nope.\n"; + if (Suffix.empty()) { + errs() << BD.getToolName() << ": I'm confused: the test fails when " + << "no passes are run, nondeterministic program?\n"; + exit(1); + } + return KeepSuffix; // Miscompilation detected! + } + outs() << " yup.\n"; // No miscompilation! + + if (Prefix.empty()) + return NoFailure; + + // Next, see if the program is broken if we run the "prefix" passes first, + // then separately run the "kept" passes. + outs() << "Checking to see if '" << getPassesString(Prefix) + << "' compiles correctly: "; + + // If it is not broken with the kept passes, it's possible that the prefix + // passes must be run before the kept passes to break it. If the program + // WORKS after the prefix passes, but then fails if running the prefix AND + // kept passes, we can update our bitcode file to include the result of the + // prefix passes, then discard the prefix passes. + // + if (BD.runPasses(BD.getProgram(), Prefix, BitcodeResult, false /*delete*/, + true /*quiet*/)) { + errs() << " Error running this sequence of passes" + << " on the input program!\n"; + BD.setPassesToRun(Prefix); + BD.EmitProgressBitcode(BD.getProgram(), "pass-error", false); + // TODO: This should propagate the error instead of exiting. + if (Error E = BD.debugOptimizerCrash()) + exit(1); + exit(0); + } + + // If the prefix maintains the predicate by itself, only keep the prefix! + Diff = BD.diffProgram(BD.getProgram(), BitcodeResult, "", false); + if (Error E = Diff.takeError()) + return std::move(E); + if (*Diff) { + outs() << " nope.\n"; + sys::fs::remove(BitcodeResult); + return KeepPrefix; + } + outs() << " yup.\n"; // No miscompilation! + + // Ok, so now we know that the prefix passes work, try running the suffix + // passes on the result of the prefix passes. + // + std::unique_ptr<Module> PrefixOutput = + parseInputFile(BitcodeResult, BD.getContext()); + if (!PrefixOutput) { + errs() << BD.getToolName() << ": Error reading bitcode file '" + << BitcodeResult << "'!\n"; + exit(1); + } + sys::fs::remove(BitcodeResult); + + // Don't check if there are no passes in the suffix. + if (Suffix.empty()) + return NoFailure; + + outs() << "Checking to see if '" << getPassesString(Suffix) + << "' passes compile correctly after the '" << getPassesString(Prefix) + << "' passes: "; + + std::unique_ptr<Module> OriginalInput = + BD.swapProgramIn(std::move(PrefixOutput)); + if (BD.runPasses(BD.getProgram(), Suffix, BitcodeResult, false /*delete*/, + true /*quiet*/)) { + errs() << " Error running this sequence of passes" + << " on the input program!\n"; + BD.setPassesToRun(Suffix); + BD.EmitProgressBitcode(BD.getProgram(), "pass-error", false); + // TODO: This should propagate the error instead of exiting. + if (Error E = BD.debugOptimizerCrash()) + exit(1); + exit(0); + } + + // Run the result... + Diff = BD.diffProgram(BD.getProgram(), BitcodeResult, "", + true /*delete bitcode*/); + if (Error E = Diff.takeError()) + return std::move(E); + if (*Diff) { + outs() << " nope.\n"; + return KeepSuffix; + } + + // Otherwise, we must not be running the bad pass anymore. + outs() << " yup.\n"; // No miscompilation! + // Restore orig program & free test. + BD.setNewProgram(std::move(OriginalInput)); + return NoFailure; +} + +namespace { +class ReduceMiscompilingFunctions : public ListReducer<Function *> { + BugDriver &BD; + Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>, + std::unique_ptr<Module>); + +public: + ReduceMiscompilingFunctions(BugDriver &bd, + Expected<bool> (*F)(BugDriver &, + std::unique_ptr<Module>, + std::unique_ptr<Module>)) + : BD(bd), TestFn(F) {} + + Expected<TestResult> doTest(std::vector<Function *> &Prefix, + std::vector<Function *> &Suffix) override { + if (!Suffix.empty()) { + Expected<bool> Ret = TestFuncs(Suffix); + if (Error E = Ret.takeError()) + return std::move(E); + if (*Ret) + return KeepSuffix; + } + if (!Prefix.empty()) { + Expected<bool> Ret = TestFuncs(Prefix); + if (Error E = Ret.takeError()) + return std::move(E); + if (*Ret) + return KeepPrefix; + } + return NoFailure; + } + + Expected<bool> TestFuncs(const std::vector<Function *> &Prefix); +}; +} // end anonymous namespace + +/// Given two modules, link them together and run the program, checking to see +/// if the program matches the diff. If there is an error, return NULL. If not, +/// return the merged module. The Broken argument will be set to true if the +/// output is different. If the DeleteInputs argument is set to true then this +/// function deletes both input modules before it returns. +/// +static Expected<std::unique_ptr<Module>> testMergedProgram(const BugDriver &BD, + const Module &M1, + const Module &M2, + bool &Broken) { + // Resulting merge of M1 and M2. + auto Merged = CloneModule(M1); + if (Linker::linkModules(*Merged, CloneModule(M2))) + // TODO: Shouldn't we thread the error up instead of exiting? + exit(1); + + // Execute the program. + Expected<bool> Diff = BD.diffProgram(*Merged, "", "", false); + if (Error E = Diff.takeError()) + return std::move(E); + Broken = *Diff; + return std::move(Merged); +} + +/// split functions in a Module into two groups: those that are under +/// consideration for miscompilation vs. those that are not, and test +/// accordingly. Each group of functions becomes a separate Module. +Expected<bool> +ReduceMiscompilingFunctions::TestFuncs(const std::vector<Function *> &Funcs) { + // Test to see if the function is misoptimized if we ONLY run it on the + // functions listed in Funcs. + outs() << "Checking to see if the program is misoptimized when " + << (Funcs.size() == 1 ? "this function is" : "these functions are") + << " run through the pass" + << (BD.getPassesToRun().size() == 1 ? "" : "es") << ":"; + PrintFunctionList(Funcs); + outs() << '\n'; + + // Create a clone for two reasons: + // * If the optimization passes delete any function, the deleted function + // will be in the clone and Funcs will still point to valid memory + // * If the optimization passes use interprocedural information to break + // a function, we want to continue with the original function. Otherwise + // we can conclude that a function triggers the bug when in fact one + // needs a larger set of original functions to do so. + ValueToValueMapTy VMap; + std::unique_ptr<Module> Clone = CloneModule(BD.getProgram(), VMap); + std::unique_ptr<Module> Orig = BD.swapProgramIn(std::move(Clone)); + + std::vector<Function *> FuncsOnClone; + for (unsigned i = 0, e = Funcs.size(); i != e; ++i) { + Function *F = cast<Function>(VMap[Funcs[i]]); + FuncsOnClone.push_back(F); + } + + // Split the module into the two halves of the program we want. + VMap.clear(); + std::unique_ptr<Module> ToNotOptimize = CloneModule(BD.getProgram(), VMap); + std::unique_ptr<Module> ToOptimize = + SplitFunctionsOutOfModule(ToNotOptimize.get(), FuncsOnClone, VMap); + + Expected<bool> Broken = + TestFn(BD, std::move(ToOptimize), std::move(ToNotOptimize)); + + BD.setNewProgram(std::move(Orig)); + + return Broken; +} + +/// Give anonymous global values names. +static void DisambiguateGlobalSymbols(Module &M) { + for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; + ++I) + if (!I->hasName()) + I->setName("anon_global"); + for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) + if (!I->hasName()) + I->setName("anon_fn"); +} + +/// Given a reduced list of functions that still exposed the bug, check to see +/// if we can extract the loops in the region without obscuring the bug. If so, +/// it reduces the amount of code identified. +/// +static Expected<bool> +ExtractLoops(BugDriver &BD, + Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>, + std::unique_ptr<Module>), + std::vector<Function *> &MiscompiledFunctions) { + bool MadeChange = false; + while (1) { + if (BugpointIsInterrupted) + return MadeChange; + + ValueToValueMapTy VMap; + std::unique_ptr<Module> ToNotOptimize = CloneModule(BD.getProgram(), VMap); + std::unique_ptr<Module> ToOptimize = SplitFunctionsOutOfModule( + ToNotOptimize.get(), MiscompiledFunctions, VMap); + std::unique_ptr<Module> ToOptimizeLoopExtracted = + BD.extractLoop(ToOptimize.get()); + if (!ToOptimizeLoopExtracted) + // If the loop extractor crashed or if there were no extractible loops, + // then this chapter of our odyssey is over with. + return MadeChange; + + errs() << "Extracted a loop from the breaking portion of the program.\n"; + + // Bugpoint is intentionally not very trusting of LLVM transformations. In + // particular, we're not going to assume that the loop extractor works, so + // we're going to test the newly loop extracted program to make sure nothing + // has broken. If something broke, then we'll inform the user and stop + // extraction. + AbstractInterpreter *AI = BD.switchToSafeInterpreter(); + bool Failure; + Expected<std::unique_ptr<Module>> New = testMergedProgram( + BD, *ToOptimizeLoopExtracted, *ToNotOptimize, Failure); + if (Error E = New.takeError()) + return std::move(E); + if (!*New) + return false; + + // Delete the original and set the new program. + std::unique_ptr<Module> Old = BD.swapProgramIn(std::move(*New)); + for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i) + MiscompiledFunctions[i] = cast<Function>(VMap[MiscompiledFunctions[i]]); + + if (Failure) { + BD.switchToInterpreter(AI); + + // Merged program doesn't work anymore! + errs() << " *** ERROR: Loop extraction broke the program. :(" + << " Please report a bug!\n"; + errs() << " Continuing on with un-loop-extracted version.\n"; + + BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-tno.bc", + *ToNotOptimize); + BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-to.bc", + *ToOptimize); + BD.writeProgramToFile(OutputPrefix + "-loop-extract-fail-to-le.bc", + *ToOptimizeLoopExtracted); + + errs() << "Please submit the " << OutputPrefix + << "-loop-extract-fail-*.bc files.\n"; + return MadeChange; + } + BD.switchToInterpreter(AI); + + outs() << " Testing after loop extraction:\n"; + // Clone modules, the tester function will free them. + std::unique_ptr<Module> TOLEBackup = + CloneModule(*ToOptimizeLoopExtracted, VMap); + std::unique_ptr<Module> TNOBackup = CloneModule(*ToNotOptimize, VMap); + + for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i) + MiscompiledFunctions[i] = cast<Function>(VMap[MiscompiledFunctions[i]]); + + Expected<bool> Result = TestFn(BD, std::move(ToOptimizeLoopExtracted), + std::move(ToNotOptimize)); + if (Error E = Result.takeError()) + return std::move(E); + + ToOptimizeLoopExtracted = std::move(TOLEBackup); + ToNotOptimize = std::move(TNOBackup); + + if (!*Result) { + outs() << "*** Loop extraction masked the problem. Undoing.\n"; + // If the program is not still broken, then loop extraction did something + // that masked the error. Stop loop extraction now. + + std::vector<std::pair<std::string, FunctionType *>> MisCompFunctions; + for (Function *F : MiscompiledFunctions) { + MisCompFunctions.emplace_back(F->getName(), F->getFunctionType()); + } + + if (Linker::linkModules(*ToNotOptimize, + std::move(ToOptimizeLoopExtracted))) + exit(1); + + MiscompiledFunctions.clear(); + for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) { + Function *NewF = ToNotOptimize->getFunction(MisCompFunctions[i].first); + + assert(NewF && "Function not found??"); + MiscompiledFunctions.push_back(NewF); + } + + BD.setNewProgram(std::move(ToNotOptimize)); + return MadeChange; + } + + outs() << "*** Loop extraction successful!\n"; + + std::vector<std::pair<std::string, FunctionType *>> MisCompFunctions; + for (Module::iterator I = ToOptimizeLoopExtracted->begin(), + E = ToOptimizeLoopExtracted->end(); + I != E; ++I) + if (!I->isDeclaration()) + MisCompFunctions.emplace_back(I->getName(), I->getFunctionType()); + + // Okay, great! Now we know that we extracted a loop and that loop + // extraction both didn't break the program, and didn't mask the problem. + // Replace the current program with the loop extracted version, and try to + // extract another loop. + if (Linker::linkModules(*ToNotOptimize, std::move(ToOptimizeLoopExtracted))) + exit(1); + + // All of the Function*'s in the MiscompiledFunctions list are in the old + // module. Update this list to include all of the functions in the + // optimized and loop extracted module. + MiscompiledFunctions.clear(); + for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) { + Function *NewF = ToNotOptimize->getFunction(MisCompFunctions[i].first); + + assert(NewF && "Function not found??"); + MiscompiledFunctions.push_back(NewF); + } + + BD.setNewProgram(std::move(ToNotOptimize)); + MadeChange = true; + } +} + +namespace { +class ReduceMiscompiledBlocks : public ListReducer<BasicBlock *> { + BugDriver &BD; + Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>, + std::unique_ptr<Module>); + std::vector<Function *> FunctionsBeingTested; + +public: + ReduceMiscompiledBlocks(BugDriver &bd, + Expected<bool> (*F)(BugDriver &, + std::unique_ptr<Module>, + std::unique_ptr<Module>), + const std::vector<Function *> &Fns) + : BD(bd), TestFn(F), FunctionsBeingTested(Fns) {} + + Expected<TestResult> doTest(std::vector<BasicBlock *> &Prefix, + std::vector<BasicBlock *> &Suffix) override { + if (!Suffix.empty()) { + Expected<bool> Ret = TestFuncs(Suffix); + if (Error E = Ret.takeError()) + return std::move(E); + if (*Ret) + return KeepSuffix; + } + if (!Prefix.empty()) { + Expected<bool> Ret = TestFuncs(Prefix); + if (Error E = Ret.takeError()) + return std::move(E); + if (*Ret) + return KeepPrefix; + } + return NoFailure; + } + + Expected<bool> TestFuncs(const std::vector<BasicBlock *> &BBs); +}; +} // end anonymous namespace + +/// TestFuncs - Extract all blocks for the miscompiled functions except for the +/// specified blocks. If the problem still exists, return true. +/// +Expected<bool> +ReduceMiscompiledBlocks::TestFuncs(const std::vector<BasicBlock *> &BBs) { + // Test to see if the function is misoptimized if we ONLY run it on the + // functions listed in Funcs. + outs() << "Checking to see if the program is misoptimized when all "; + if (!BBs.empty()) { + outs() << "but these " << BBs.size() << " blocks are extracted: "; + for (unsigned i = 0, e = BBs.size() < 10 ? BBs.size() : 10; i != e; ++i) + outs() << BBs[i]->getName() << " "; + if (BBs.size() > 10) + outs() << "..."; + } else { + outs() << "blocks are extracted."; + } + outs() << '\n'; + + // Split the module into the two halves of the program we want. + ValueToValueMapTy VMap; + std::unique_ptr<Module> Clone = CloneModule(BD.getProgram(), VMap); + std::unique_ptr<Module> Orig = BD.swapProgramIn(std::move(Clone)); + std::vector<Function *> FuncsOnClone; + std::vector<BasicBlock *> BBsOnClone; + for (unsigned i = 0, e = FunctionsBeingTested.size(); i != e; ++i) { + Function *F = cast<Function>(VMap[FunctionsBeingTested[i]]); + FuncsOnClone.push_back(F); + } + for (unsigned i = 0, e = BBs.size(); i != e; ++i) { + BasicBlock *BB = cast<BasicBlock>(VMap[BBs[i]]); + BBsOnClone.push_back(BB); + } + VMap.clear(); + + std::unique_ptr<Module> ToNotOptimize = CloneModule(BD.getProgram(), VMap); + std::unique_ptr<Module> ToOptimize = + SplitFunctionsOutOfModule(ToNotOptimize.get(), FuncsOnClone, VMap); + + // Try the extraction. If it doesn't work, then the block extractor crashed + // or something, in which case bugpoint can't chase down this possibility. + if (std::unique_ptr<Module> New = + BD.extractMappedBlocksFromModule(BBsOnClone, ToOptimize.get())) { + Expected<bool> Ret = TestFn(BD, std::move(New), std::move(ToNotOptimize)); + BD.setNewProgram(std::move(Orig)); + return Ret; + } + BD.setNewProgram(std::move(Orig)); + return false; +} + +/// Given a reduced list of functions that still expose the bug, extract as many +/// basic blocks from the region as possible without obscuring the bug. +/// +static Expected<bool> +ExtractBlocks(BugDriver &BD, + Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>, + std::unique_ptr<Module>), + std::vector<Function *> &MiscompiledFunctions) { + if (BugpointIsInterrupted) + return false; + + std::vector<BasicBlock *> Blocks; + for (unsigned i = 0, e = MiscompiledFunctions.size(); i != e; ++i) + for (BasicBlock &BB : *MiscompiledFunctions[i]) + Blocks.push_back(&BB); + + // Use the list reducer to identify blocks that can be extracted without + // obscuring the bug. The Blocks list will end up containing blocks that must + // be retained from the original program. + unsigned OldSize = Blocks.size(); + + // Check to see if all blocks are extractible first. + Expected<bool> Ret = ReduceMiscompiledBlocks(BD, TestFn, MiscompiledFunctions) + .TestFuncs(std::vector<BasicBlock *>()); + if (Error E = Ret.takeError()) + return std::move(E); + if (*Ret) { + Blocks.clear(); + } else { + Expected<bool> Ret = + ReduceMiscompiledBlocks(BD, TestFn, MiscompiledFunctions) + .reduceList(Blocks); + if (Error E = Ret.takeError()) + return std::move(E); + if (Blocks.size() == OldSize) + return false; + } + + ValueToValueMapTy VMap; + std::unique_ptr<Module> ProgClone = CloneModule(BD.getProgram(), VMap); + std::unique_ptr<Module> ToExtract = + SplitFunctionsOutOfModule(ProgClone.get(), MiscompiledFunctions, VMap); + std::unique_ptr<Module> Extracted = + BD.extractMappedBlocksFromModule(Blocks, ToExtract.get()); + if (!Extracted) { + // Weird, extraction should have worked. + errs() << "Nondeterministic problem extracting blocks??\n"; + return false; + } + + // Otherwise, block extraction succeeded. Link the two program fragments back + // together. + + std::vector<std::pair<std::string, FunctionType *>> MisCompFunctions; + for (Module::iterator I = Extracted->begin(), E = Extracted->end(); I != E; + ++I) + if (!I->isDeclaration()) + MisCompFunctions.emplace_back(I->getName(), I->getFunctionType()); + + if (Linker::linkModules(*ProgClone, std::move(Extracted))) + exit(1); + + // Update the list of miscompiled functions. + MiscompiledFunctions.clear(); + + for (unsigned i = 0, e = MisCompFunctions.size(); i != e; ++i) { + Function *NewF = ProgClone->getFunction(MisCompFunctions[i].first); + assert(NewF && "Function not found??"); + MiscompiledFunctions.push_back(NewF); + } + + // Set the new program and delete the old one. + BD.setNewProgram(std::move(ProgClone)); + + return true; +} + +/// This is a generic driver to narrow down miscompilations, either in an +/// optimization or a code generator. +/// +static Expected<std::vector<Function *>> DebugAMiscompilation( + BugDriver &BD, + Expected<bool> (*TestFn)(BugDriver &, std::unique_ptr<Module>, + std::unique_ptr<Module>)) { + // Okay, now that we have reduced the list of passes which are causing the + // failure, see if we can pin down which functions are being + // miscompiled... first build a list of all of the non-external functions in + // the program. + std::vector<Function *> MiscompiledFunctions; + Module &Prog = BD.getProgram(); + for (Function &F : Prog) + if (!F.isDeclaration()) + MiscompiledFunctions.push_back(&F); + + // Do the reduction... + if (!BugpointIsInterrupted) { + Expected<bool> Ret = ReduceMiscompilingFunctions(BD, TestFn) + .reduceList(MiscompiledFunctions); + if (Error E = Ret.takeError()) { + errs() << "\n***Cannot reduce functions: "; + return std::move(E); + } + } + outs() << "\n*** The following function" + << (MiscompiledFunctions.size() == 1 ? " is" : "s are") + << " being miscompiled: "; + PrintFunctionList(MiscompiledFunctions); + outs() << '\n'; + + // See if we can rip any loops out of the miscompiled functions and still + // trigger the problem. + + if (!BugpointIsInterrupted && !DisableLoopExtraction) { + Expected<bool> Ret = ExtractLoops(BD, TestFn, MiscompiledFunctions); + if (Error E = Ret.takeError()) + return std::move(E); + if (*Ret) { + // Okay, we extracted some loops and the problem still appears. See if + // we can eliminate some of the created functions from being candidates. + DisambiguateGlobalSymbols(BD.getProgram()); + + // Do the reduction... + if (!BugpointIsInterrupted) + Ret = ReduceMiscompilingFunctions(BD, TestFn) + .reduceList(MiscompiledFunctions); + if (Error E = Ret.takeError()) + return std::move(E); + + outs() << "\n*** The following function" + << (MiscompiledFunctions.size() == 1 ? " is" : "s are") + << " being miscompiled: "; + PrintFunctionList(MiscompiledFunctions); + outs() << '\n'; + } + } + + if (!BugpointIsInterrupted && !DisableBlockExtraction) { + Expected<bool> Ret = ExtractBlocks(BD, TestFn, MiscompiledFunctions); + if (Error E = Ret.takeError()) + return std::move(E); + if (*Ret) { + // Okay, we extracted some blocks and the problem still appears. See if + // we can eliminate some of the created functions from being candidates. + DisambiguateGlobalSymbols(BD.getProgram()); + + // Do the reduction... + Ret = ReduceMiscompilingFunctions(BD, TestFn) + .reduceList(MiscompiledFunctions); + if (Error E = Ret.takeError()) + return std::move(E); + + outs() << "\n*** The following function" + << (MiscompiledFunctions.size() == 1 ? " is" : "s are") + << " being miscompiled: "; + PrintFunctionList(MiscompiledFunctions); + outs() << '\n'; + } + } + + return MiscompiledFunctions; +} + +/// This is the predicate function used to check to see if the "Test" portion of +/// the program is misoptimized. If so, return true. In any case, both module +/// arguments are deleted. +/// +static Expected<bool> TestOptimizer(BugDriver &BD, std::unique_ptr<Module> Test, + std::unique_ptr<Module> Safe) { + // Run the optimization passes on ToOptimize, producing a transformed version + // of the functions being tested. + outs() << " Optimizing functions being tested: "; + std::unique_ptr<Module> Optimized = + BD.runPassesOn(Test.get(), BD.getPassesToRun()); + if (!Optimized) { + errs() << " Error running this sequence of passes" + << " on the input program!\n"; + BD.EmitProgressBitcode(*Test, "pass-error", false); + BD.setNewProgram(std::move(Test)); + if (Error E = BD.debugOptimizerCrash()) + return std::move(E); + return false; + } + outs() << "done.\n"; + + outs() << " Checking to see if the merged program executes correctly: "; + bool Broken; + auto Result = testMergedProgram(BD, *Optimized, *Safe, Broken); + if (Error E = Result.takeError()) + return std::move(E); + if (auto New = std::move(*Result)) { + outs() << (Broken ? " nope.\n" : " yup.\n"); + // Delete the original and set the new program. + BD.setNewProgram(std::move(New)); + } + return Broken; +} + +/// debugMiscompilation - This method is used when the passes selected are not +/// crashing, but the generated output is semantically different from the +/// input. +/// +Error BugDriver::debugMiscompilation() { + // Make sure something was miscompiled... + if (!BugpointIsInterrupted) { + Expected<bool> Result = + ReduceMiscompilingPasses(*this).reduceList(PassesToRun); + if (Error E = Result.takeError()) + return E; + if (!*Result) + return make_error<StringError>( + "*** Optimized program matches reference output! No problem" + " detected...\nbugpoint can't help you with your problem!\n", + inconvertibleErrorCode()); + } + + outs() << "\n*** Found miscompiling pass" + << (getPassesToRun().size() == 1 ? "" : "es") << ": " + << getPassesString(getPassesToRun()) << '\n'; + EmitProgressBitcode(*Program, "passinput"); + + Expected<std::vector<Function *>> MiscompiledFunctions = + DebugAMiscompilation(*this, TestOptimizer); + if (Error E = MiscompiledFunctions.takeError()) + return E; + + // Output a bunch of bitcode files for the user... + outs() << "Outputting reduced bitcode files which expose the problem:\n"; + ValueToValueMapTy VMap; + Module *ToNotOptimize = CloneModule(getProgram(), VMap).release(); + Module *ToOptimize = + SplitFunctionsOutOfModule(ToNotOptimize, *MiscompiledFunctions, VMap) + .release(); + + outs() << " Non-optimized portion: "; + EmitProgressBitcode(*ToNotOptimize, "tonotoptimize", true); + delete ToNotOptimize; // Delete hacked module. + + outs() << " Portion that is input to optimizer: "; + EmitProgressBitcode(*ToOptimize, "tooptimize"); + delete ToOptimize; // Delete hacked module. + + return Error::success(); +} + +/// Get the specified modules ready for code generator testing. +/// +static std::unique_ptr<Module> +CleanupAndPrepareModules(BugDriver &BD, std::unique_ptr<Module> Test, + Module *Safe) { + // Clean up the modules, removing extra cruft that we don't need anymore... + Test = BD.performFinalCleanups(std::move(Test)); + + // If we are executing the JIT, we have several nasty issues to take care of. + if (!BD.isExecutingJIT()) + return Test; + + // First, if the main function is in the Safe module, we must add a stub to + // the Test module to call into it. Thus, we create a new function `main' + // which just calls the old one. + if (Function *oldMain = Safe->getFunction("main")) + if (!oldMain->isDeclaration()) { + // Rename it + oldMain->setName("llvm_bugpoint_old_main"); + // Create a NEW `main' function with same type in the test module. + Function *newMain = + Function::Create(oldMain->getFunctionType(), + GlobalValue::ExternalLinkage, "main", Test.get()); + // Create an `oldmain' prototype in the test module, which will + // corresponds to the real main function in the same module. + Function *oldMainProto = Function::Create(oldMain->getFunctionType(), + GlobalValue::ExternalLinkage, + oldMain->getName(), Test.get()); + // Set up and remember the argument list for the main function. + std::vector<Value *> args; + for (Function::arg_iterator I = newMain->arg_begin(), + E = newMain->arg_end(), + OI = oldMain->arg_begin(); + I != E; ++I, ++OI) { + I->setName(OI->getName()); // Copy argument names from oldMain + args.push_back(&*I); + } + + // Call the old main function and return its result + BasicBlock *BB = BasicBlock::Create(Safe->getContext(), "entry", newMain); + CallInst *call = CallInst::Create(oldMainProto, args, "", BB); + + // If the type of old function wasn't void, return value of call + ReturnInst::Create(Safe->getContext(), call, BB); + } + + // The second nasty issue we must deal with in the JIT is that the Safe + // module cannot directly reference any functions defined in the test + // module. Instead, we use a JIT API call to dynamically resolve the + // symbol. + + // Add the resolver to the Safe module. + // Prototype: void *getPointerToNamedFunction(const char* Name) + FunctionCallee resolverFunc = Safe->getOrInsertFunction( + "getPointerToNamedFunction", Type::getInt8PtrTy(Safe->getContext()), + Type::getInt8PtrTy(Safe->getContext())); + + // Use the function we just added to get addresses of functions we need. + for (Module::iterator F = Safe->begin(), E = Safe->end(); F != E; ++F) { + if (F->isDeclaration() && !F->use_empty() && + &*F != resolverFunc.getCallee() && + !F->isIntrinsic() /* ignore intrinsics */) { + Function *TestFn = Test->getFunction(F->getName()); + + // Don't forward functions which are external in the test module too. + if (TestFn && !TestFn->isDeclaration()) { + // 1. Add a string constant with its name to the global file + Constant *InitArray = + ConstantDataArray::getString(F->getContext(), F->getName()); + GlobalVariable *funcName = new GlobalVariable( + *Safe, InitArray->getType(), true /*isConstant*/, + GlobalValue::InternalLinkage, InitArray, F->getName() + "_name"); + + // 2. Use `GetElementPtr *funcName, 0, 0' to convert the string to an + // sbyte* so it matches the signature of the resolver function. + + // GetElementPtr *funcName, ulong 0, ulong 0 + std::vector<Constant *> GEPargs( + 2, Constant::getNullValue(Type::getInt32Ty(F->getContext()))); + Value *GEP = ConstantExpr::getGetElementPtr(InitArray->getType(), + funcName, GEPargs); + std::vector<Value *> ResolverArgs; + ResolverArgs.push_back(GEP); + + // Rewrite uses of F in global initializers, etc. to uses of a wrapper + // function that dynamically resolves the calls to F via our JIT API + if (!F->use_empty()) { + // Create a new global to hold the cached function pointer. + Constant *NullPtr = ConstantPointerNull::get(F->getType()); + GlobalVariable *Cache = new GlobalVariable( + *F->getParent(), F->getType(), false, + GlobalValue::InternalLinkage, NullPtr, F->getName() + ".fpcache"); + + // Construct a new stub function that will re-route calls to F + FunctionType *FuncTy = F->getFunctionType(); + Function *FuncWrapper = + Function::Create(FuncTy, GlobalValue::InternalLinkage, + F->getName() + "_wrapper", F->getParent()); + BasicBlock *EntryBB = + BasicBlock::Create(F->getContext(), "entry", FuncWrapper); + BasicBlock *DoCallBB = + BasicBlock::Create(F->getContext(), "usecache", FuncWrapper); + BasicBlock *LookupBB = + BasicBlock::Create(F->getContext(), "lookupfp", FuncWrapper); + + // Check to see if we already looked up the value. + Value *CachedVal = + new LoadInst(F->getType(), Cache, "fpcache", EntryBB); + Value *IsNull = new ICmpInst(*EntryBB, ICmpInst::ICMP_EQ, CachedVal, + NullPtr, "isNull"); + BranchInst::Create(LookupBB, DoCallBB, IsNull, EntryBB); + + // Resolve the call to function F via the JIT API: + // + // call resolver(GetElementPtr...) + CallInst *Resolver = CallInst::Create(resolverFunc, ResolverArgs, + "resolver", LookupBB); + + // Cast the result from the resolver to correctly-typed function. + CastInst *CastedResolver = new BitCastInst( + Resolver, PointerType::getUnqual(F->getFunctionType()), + "resolverCast", LookupBB); + + // Save the value in our cache. + new StoreInst(CastedResolver, Cache, LookupBB); + BranchInst::Create(DoCallBB, LookupBB); + + PHINode *FuncPtr = + PHINode::Create(NullPtr->getType(), 2, "fp", DoCallBB); + FuncPtr->addIncoming(CastedResolver, LookupBB); + FuncPtr->addIncoming(CachedVal, EntryBB); + + // Save the argument list. + std::vector<Value *> Args; + for (Argument &A : FuncWrapper->args()) + Args.push_back(&A); + + // Pass on the arguments to the real function, return its result + if (F->getReturnType()->isVoidTy()) { + CallInst::Create(FuncTy, FuncPtr, Args, "", DoCallBB); + ReturnInst::Create(F->getContext(), DoCallBB); + } else { + CallInst *Call = + CallInst::Create(FuncTy, FuncPtr, Args, "retval", DoCallBB); + ReturnInst::Create(F->getContext(), Call, DoCallBB); + } + + // Use the wrapper function instead of the old function + F->replaceAllUsesWith(FuncWrapper); + } + } + } + } + + if (verifyModule(*Test) || verifyModule(*Safe)) { + errs() << "Bugpoint has a bug, which corrupted a module!!\n"; + abort(); + } + + return Test; +} + +/// This is the predicate function used to check to see if the "Test" portion of +/// the program is miscompiled by the code generator under test. If so, return +/// true. In any case, both module arguments are deleted. +/// +static Expected<bool> TestCodeGenerator(BugDriver &BD, + std::unique_ptr<Module> Test, + std::unique_ptr<Module> Safe) { + Test = CleanupAndPrepareModules(BD, std::move(Test), Safe.get()); + + SmallString<128> TestModuleBC; + int TestModuleFD; + std::error_code EC = sys::fs::createTemporaryFile("bugpoint.test", "bc", + TestModuleFD, TestModuleBC); + if (EC) { + errs() << BD.getToolName() + << "Error making unique filename: " << EC.message() << "\n"; + exit(1); + } + if (BD.writeProgramToFile(TestModuleBC.str(), TestModuleFD, *Test)) { + errs() << "Error writing bitcode to `" << TestModuleBC.str() + << "'\nExiting."; + exit(1); + } + + FileRemover TestModuleBCRemover(TestModuleBC.str(), !SaveTemps); + + // Make the shared library + SmallString<128> SafeModuleBC; + int SafeModuleFD; + EC = sys::fs::createTemporaryFile("bugpoint.safe", "bc", SafeModuleFD, + SafeModuleBC); + if (EC) { + errs() << BD.getToolName() + << "Error making unique filename: " << EC.message() << "\n"; + exit(1); + } + + if (BD.writeProgramToFile(SafeModuleBC.str(), SafeModuleFD, *Safe)) { + errs() << "Error writing bitcode to `" << SafeModuleBC << "'\nExiting."; + exit(1); + } + + FileRemover SafeModuleBCRemover(SafeModuleBC.str(), !SaveTemps); + + Expected<std::string> SharedObject = + BD.compileSharedObject(SafeModuleBC.str()); + if (Error E = SharedObject.takeError()) + return std::move(E); + + FileRemover SharedObjectRemover(*SharedObject, !SaveTemps); + + // Run the code generator on the `Test' code, loading the shared library. + // The function returns whether or not the new output differs from reference. + Expected<bool> Result = + BD.diffProgram(BD.getProgram(), TestModuleBC.str(), *SharedObject, false); + if (Error E = Result.takeError()) + return std::move(E); + + if (*Result) + errs() << ": still failing!\n"; + else + errs() << ": didn't fail.\n"; + + return Result; +} + +/// debugCodeGenerator - debug errors in LLC, LLI, or CBE. +/// +Error BugDriver::debugCodeGenerator() { + if ((void *)SafeInterpreter == (void *)Interpreter) { + Expected<std::string> Result = + executeProgramSafely(*Program, "bugpoint.safe.out"); + if (Result) { + outs() << "\n*** The \"safe\" i.e. 'known good' backend cannot match " + << "the reference diff. This may be due to a\n front-end " + << "bug or a bug in the original program, but this can also " + << "happen if bugpoint isn't running the program with the " + << "right flags or input.\n I left the result of executing " + << "the program with the \"safe\" backend in this file for " + << "you: '" << *Result << "'.\n"; + } + return Error::success(); + } + + DisambiguateGlobalSymbols(*Program); + + Expected<std::vector<Function *>> Funcs = + DebugAMiscompilation(*this, TestCodeGenerator); + if (Error E = Funcs.takeError()) + return E; + + // Split the module into the two halves of the program we want. + ValueToValueMapTy VMap; + std::unique_ptr<Module> ToNotCodeGen = CloneModule(getProgram(), VMap); + std::unique_ptr<Module> ToCodeGen = + SplitFunctionsOutOfModule(ToNotCodeGen.get(), *Funcs, VMap); + + // Condition the modules + ToCodeGen = + CleanupAndPrepareModules(*this, std::move(ToCodeGen), ToNotCodeGen.get()); + + SmallString<128> TestModuleBC; + int TestModuleFD; + std::error_code EC = sys::fs::createTemporaryFile("bugpoint.test", "bc", + TestModuleFD, TestModuleBC); + if (EC) { + errs() << getToolName() << "Error making unique filename: " << EC.message() + << "\n"; + exit(1); + } + + if (writeProgramToFile(TestModuleBC.str(), TestModuleFD, *ToCodeGen)) { + errs() << "Error writing bitcode to `" << TestModuleBC << "'\nExiting."; + exit(1); + } + + // Make the shared library + SmallString<128> SafeModuleBC; + int SafeModuleFD; + EC = sys::fs::createTemporaryFile("bugpoint.safe", "bc", SafeModuleFD, + SafeModuleBC); + if (EC) { + errs() << getToolName() << "Error making unique filename: " << EC.message() + << "\n"; + exit(1); + } + + if (writeProgramToFile(SafeModuleBC.str(), SafeModuleFD, *ToNotCodeGen)) { + errs() << "Error writing bitcode to `" << SafeModuleBC << "'\nExiting."; + exit(1); + } + Expected<std::string> SharedObject = compileSharedObject(SafeModuleBC.str()); + if (Error E = SharedObject.takeError()) + return E; + + outs() << "You can reproduce the problem with the command line: \n"; + if (isExecutingJIT()) { + outs() << " lli -load " << *SharedObject << " " << TestModuleBC; + } else { + outs() << " llc " << TestModuleBC << " -o " << TestModuleBC << ".s\n"; + outs() << " cc " << *SharedObject << " " << TestModuleBC.str() << ".s -o " + << TestModuleBC << ".exe\n"; + outs() << " ./" << TestModuleBC << ".exe"; + } + for (unsigned i = 0, e = InputArgv.size(); i != e; ++i) + outs() << " " << InputArgv[i]; + outs() << '\n'; + outs() << "The shared object was created with:\n llc -march=c " + << SafeModuleBC.str() << " -o temporary.c\n" + << " cc -xc temporary.c -O2 -o " << *SharedObject; + if (TargetTriple.getArch() == Triple::sparc) + outs() << " -G"; // Compile a shared library, `-G' for Sparc + else + outs() << " -fPIC -shared"; // `-shared' for Linux/X86, maybe others + + outs() << " -fno-strict-aliasing\n"; + + return Error::success(); +} |