//===- verify-uselistorder.cpp - The LLVM Modular Optimizer ---------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // Verify that use-list order can be serialized correctly. After reading the // provided IR, this tool shuffles the use-lists and then writes and reads to a // separate Module whose use-list orders are compared to the original. // // The shuffles are deterministic, but guarantee that use-lists will change. // The algorithm per iteration is as follows: // // 1. Seed the random number generator. The seed is different for each // shuffle. Shuffle 0 uses default+0, shuffle 1 uses default+1, and so on. // // 2. Visit every Value in a deterministic order. // // 3. Assign a random number to each Use in the Value's use-list in order. // // 4. If the numbers are already in order, reassign numbers until they aren't. // // 5. Sort the use-list using Value::sortUseList(), which is a stable sort. // //===----------------------------------------------------------------------===// #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/DenseSet.h" #include "llvm/AsmParser/Parser.h" #include "llvm/Bitcode/ReaderWriter.h" #include "llvm/IR/LLVMContext.h" #include "llvm/IR/Module.h" #include "llvm/IR/UseListOrder.h" #include "llvm/IR/Verifier.h" #include "llvm/IRReader/IRReader.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/FileSystem.h" #include "llvm/Support/FileUtilities.h" #include "llvm/Support/ManagedStatic.h" #include "llvm/Support/MemoryBuffer.h" #include "llvm/Support/PrettyStackTrace.h" #include "llvm/Support/Signals.h" #include "llvm/Support/SourceMgr.h" #include "llvm/Support/SystemUtils.h" #include "llvm/Support/raw_ostream.h" #include <random> #include <vector> using namespace llvm; #define DEBUG_TYPE "uselistorder" static cl::opt<std::string> InputFilename(cl::Positional, cl::desc("<input bitcode file>"), cl::init("-"), cl::value_desc("filename")); static cl::opt<bool> SaveTemps("save-temps", cl::desc("Save temp files"), cl::init(false)); static cl::opt<unsigned> NumShuffles("num-shuffles", cl::desc("Number of times to shuffle and verify use-lists"), cl::init(1)); namespace { struct TempFile { std::string Filename; FileRemover Remover; bool init(const std::string &Ext); bool writeBitcode(const Module &M) const; bool writeAssembly(const Module &M) const; std::unique_ptr<Module> readBitcode(LLVMContext &Context) const; std::unique_ptr<Module> readAssembly(LLVMContext &Context) const; }; struct ValueMapping { DenseMap<const Value *, unsigned> IDs; std::vector<const Value *> Values; /// \brief Construct a value mapping for module. /// /// Creates mapping from every value in \c M to an ID. This mapping includes /// un-referencable values. /// /// Every \a Value that gets serialized in some way should be represented /// here. The order needs to be deterministic, but it's unnecessary to match /// the value-ids in the bitcode writer. /// /// All constants that are referenced by other values are included in the /// mapping, but others -- which wouldn't be serialized -- are not. ValueMapping(const Module &M); /// \brief Map a value. /// /// Maps a value. If it's a constant, maps all of its operands first. void map(const Value *V); unsigned lookup(const Value *V) const { return IDs.lookup(V); } }; } // end namespace bool TempFile::init(const std::string &Ext) { SmallVector<char, 64> Vector; DEBUG(dbgs() << " - create-temp-file\n"); if (auto EC = sys::fs::createTemporaryFile("uselistorder", Ext, Vector)) { errs() << "verify-uselistorder: error: " << EC.message() << "\n"; return true; } assert(!Vector.empty()); Filename.assign(Vector.data(), Vector.data() + Vector.size()); Remover.setFile(Filename, !SaveTemps); if (SaveTemps) outs() << " - filename = " << Filename << "\n"; return false; } bool TempFile::writeBitcode(const Module &M) const { DEBUG(dbgs() << " - write bitcode\n"); std::error_code EC; raw_fd_ostream OS(Filename, EC, sys::fs::F_None); if (EC) { errs() << "verify-uselistorder: error: " << EC.message() << "\n"; return true; } WriteBitcodeToFile(&M, OS, /* ShouldPreserveUseListOrder */ true); return false; } bool TempFile::writeAssembly(const Module &M) const { DEBUG(dbgs() << " - write assembly\n"); std::error_code EC; raw_fd_ostream OS(Filename, EC, sys::fs::F_Text); if (EC) { errs() << "verify-uselistorder: error: " << EC.message() << "\n"; return true; } M.print(OS, nullptr, /* ShouldPreserveUseListOrder */ true); return false; } std::unique_ptr<Module> TempFile::readBitcode(LLVMContext &Context) const { DEBUG(dbgs() << " - read bitcode\n"); ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOr = MemoryBuffer::getFile(Filename); if (!BufferOr) { errs() << "verify-uselistorder: error: " << BufferOr.getError().message() << "\n"; return nullptr; } MemoryBuffer *Buffer = BufferOr.get().get(); ErrorOr<std::unique_ptr<Module>> ModuleOr = parseBitcodeFile(Buffer->getMemBufferRef(), Context); if (!ModuleOr) { errs() << "verify-uselistorder: error: " << ModuleOr.getError().message() << "\n"; return nullptr; } return std::move(ModuleOr.get()); } std::unique_ptr<Module> TempFile::readAssembly(LLVMContext &Context) const { DEBUG(dbgs() << " - read assembly\n"); SMDiagnostic Err; std::unique_ptr<Module> M = parseAssemblyFile(Filename, Err, Context); if (!M.get()) Err.print("verify-uselistorder", errs()); return M; } ValueMapping::ValueMapping(const Module &M) { // Every value should be mapped, including things like void instructions and // basic blocks that are kept out of the ValueEnumerator. // // The current mapping order makes it easier to debug the tables. It happens // to be similar to the ID mapping when writing ValueEnumerator, but they // aren't (and needn't be) in sync. // Globals. for (const GlobalVariable &G : M.globals()) map(&G); for (const GlobalAlias &A : M.aliases()) map(&A); for (const GlobalIFunc &IF : M.ifuncs()) map(&IF); for (const Function &F : M) map(&F); // Constants used by globals. for (const GlobalVariable &G : M.globals()) if (G.hasInitializer()) map(G.getInitializer()); for (const GlobalAlias &A : M.aliases()) map(A.getAliasee()); for (const GlobalIFunc &IF : M.ifuncs()) map(IF.getResolver()); for (const Function &F : M) { if (F.hasPrefixData()) map(F.getPrefixData()); if (F.hasPrologueData()) map(F.getPrologueData()); if (F.hasPersonalityFn()) map(F.getPersonalityFn()); } // Function bodies. for (const Function &F : M) { for (const Argument &A : F.args()) map(&A); for (const BasicBlock &BB : F) map(&BB); for (const BasicBlock &BB : F) for (const Instruction &I : BB) map(&I); // Constants used by instructions. for (const BasicBlock &BB : F) for (const Instruction &I : BB) for (const Value *Op : I.operands()) if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) || isa<InlineAsm>(Op)) map(Op); } } void ValueMapping::map(const Value *V) { if (IDs.lookup(V)) return; if (auto *C = dyn_cast<Constant>(V)) if (!isa<GlobalValue>(C)) for (const Value *Op : C->operands()) map(Op); Values.push_back(V); IDs[V] = Values.size(); } #ifndef NDEBUG static void dumpMapping(const ValueMapping &VM) { dbgs() << "value-mapping (size = " << VM.Values.size() << "):\n"; for (unsigned I = 0, E = VM.Values.size(); I != E; ++I) { dbgs() << " - id = " << I << ", value = "; VM.Values[I]->dump(); } } static void debugValue(const ValueMapping &M, unsigned I, StringRef Desc) { const Value *V = M.Values[I]; dbgs() << " - " << Desc << " value = "; V->dump(); for (const Use &U : V->uses()) { dbgs() << " => use: op = " << U.getOperandNo() << ", user-id = " << M.IDs.lookup(U.getUser()) << ", user = "; U.getUser()->dump(); } } static void debugUserMismatch(const ValueMapping &L, const ValueMapping &R, unsigned I) { dbgs() << " - fail: user mismatch: ID = " << I << "\n"; debugValue(L, I, "LHS"); debugValue(R, I, "RHS"); dbgs() << "\nlhs-"; dumpMapping(L); dbgs() << "\nrhs-"; dumpMapping(R); } static void debugSizeMismatch(const ValueMapping &L, const ValueMapping &R) { dbgs() << " - fail: map size: " << L.Values.size() << " != " << R.Values.size() << "\n"; dbgs() << "\nlhs-"; dumpMapping(L); dbgs() << "\nrhs-"; dumpMapping(R); } #endif static bool matches(const ValueMapping &LM, const ValueMapping &RM) { DEBUG(dbgs() << "compare value maps\n"); if (LM.Values.size() != RM.Values.size()) { DEBUG(debugSizeMismatch(LM, RM)); return false; } // This mapping doesn't include dangling constant users, since those don't // get serialized. However, checking if users are constant and calling // isConstantUsed() on every one is very expensive. Instead, just check if // the user is mapped. auto skipUnmappedUsers = [&](Value::const_use_iterator &U, Value::const_use_iterator E, const ValueMapping &M) { while (U != E && !M.lookup(U->getUser())) ++U; }; // Iterate through all values, and check that both mappings have the same // users. for (unsigned I = 0, E = LM.Values.size(); I != E; ++I) { const Value *L = LM.Values[I]; const Value *R = RM.Values[I]; auto LU = L->use_begin(), LE = L->use_end(); auto RU = R->use_begin(), RE = R->use_end(); skipUnmappedUsers(LU, LE, LM); skipUnmappedUsers(RU, RE, RM); while (LU != LE) { if (RU == RE) { DEBUG(debugUserMismatch(LM, RM, I)); return false; } if (LM.lookup(LU->getUser()) != RM.lookup(RU->getUser())) { DEBUG(debugUserMismatch(LM, RM, I)); return false; } if (LU->getOperandNo() != RU->getOperandNo()) { DEBUG(debugUserMismatch(LM, RM, I)); return false; } skipUnmappedUsers(++LU, LE, LM); skipUnmappedUsers(++RU, RE, RM); } if (RU != RE) { DEBUG(debugUserMismatch(LM, RM, I)); return false; } } return true; } static void verifyAfterRoundTrip(const Module &M, std::unique_ptr<Module> OtherM) { if (!OtherM) report_fatal_error("parsing failed"); if (verifyModule(*OtherM, &errs())) report_fatal_error("verification failed"); if (!matches(ValueMapping(M), ValueMapping(*OtherM))) report_fatal_error("use-list order changed"); } static void verifyBitcodeUseListOrder(const Module &M) { TempFile F; if (F.init("bc")) report_fatal_error("failed to initialize bitcode file"); if (F.writeBitcode(M)) report_fatal_error("failed to write bitcode"); LLVMContext Context; verifyAfterRoundTrip(M, F.readBitcode(Context)); } static void verifyAssemblyUseListOrder(const Module &M) { TempFile F; if (F.init("ll")) report_fatal_error("failed to initialize assembly file"); if (F.writeAssembly(M)) report_fatal_error("failed to write assembly"); LLVMContext Context; verifyAfterRoundTrip(M, F.readAssembly(Context)); } static void verifyUseListOrder(const Module &M) { outs() << "verify bitcode\n"; verifyBitcodeUseListOrder(M); outs() << "verify assembly\n"; verifyAssemblyUseListOrder(M); } static void shuffleValueUseLists(Value *V, std::minstd_rand0 &Gen, DenseSet<Value *> &Seen) { if (!Seen.insert(V).second) return; if (auto *C = dyn_cast<Constant>(V)) if (!isa<GlobalValue>(C)) for (Value *Op : C->operands()) shuffleValueUseLists(Op, Gen, Seen); if (V->use_empty() || std::next(V->use_begin()) == V->use_end()) // Nothing to shuffle for 0 or 1 users. return; // Generate random numbers between 10 and 99, which will line up nicely in // debug output. We're not worried about collisons here. DEBUG(dbgs() << "V = "; V->dump()); std::uniform_int_distribution<short> Dist(10, 99); SmallDenseMap<const Use *, short, 16> Order; auto compareUses = [&Order](const Use &L, const Use &R) { return Order[&L] < Order[&R]; }; do { for (const Use &U : V->uses()) { auto I = Dist(Gen); Order[&U] = I; DEBUG(dbgs() << " - order: " << I << ", op = " << U.getOperandNo() << ", U = "; U.getUser()->dump()); } } while (std::is_sorted(V->use_begin(), V->use_end(), compareUses)); DEBUG(dbgs() << " => shuffle\n"); V->sortUseList(compareUses); DEBUG({ for (const Use &U : V->uses()) { dbgs() << " - order: " << Order.lookup(&U) << ", op = " << U.getOperandNo() << ", U = "; U.getUser()->dump(); } }); } static void reverseValueUseLists(Value *V, DenseSet<Value *> &Seen) { if (!Seen.insert(V).second) return; if (auto *C = dyn_cast<Constant>(V)) if (!isa<GlobalValue>(C)) for (Value *Op : C->operands()) reverseValueUseLists(Op, Seen); if (V->use_empty() || std::next(V->use_begin()) == V->use_end()) // Nothing to shuffle for 0 or 1 users. return; DEBUG({ dbgs() << "V = "; V->dump(); for (const Use &U : V->uses()) { dbgs() << " - order: op = " << U.getOperandNo() << ", U = "; U.getUser()->dump(); } dbgs() << " => reverse\n"; }); V->reverseUseList(); DEBUG({ for (const Use &U : V->uses()) { dbgs() << " - order: op = " << U.getOperandNo() << ", U = "; U.getUser()->dump(); } }); } template <class Changer> static void changeUseLists(Module &M, Changer changeValueUseList) { // Visit every value that would be serialized to an IR file. // // Globals. for (GlobalVariable &G : M.globals()) changeValueUseList(&G); for (GlobalAlias &A : M.aliases()) changeValueUseList(&A); for (GlobalIFunc &IF : M.ifuncs()) changeValueUseList(&IF); for (Function &F : M) changeValueUseList(&F); // Constants used by globals. for (GlobalVariable &G : M.globals()) if (G.hasInitializer()) changeValueUseList(G.getInitializer()); for (GlobalAlias &A : M.aliases()) changeValueUseList(A.getAliasee()); for (GlobalIFunc &IF : M.ifuncs()) changeValueUseList(IF.getResolver()); for (Function &F : M) { if (F.hasPrefixData()) changeValueUseList(F.getPrefixData()); if (F.hasPrologueData()) changeValueUseList(F.getPrologueData()); if (F.hasPersonalityFn()) changeValueUseList(F.getPersonalityFn()); } // Function bodies. for (Function &F : M) { for (Argument &A : F.args()) changeValueUseList(&A); for (BasicBlock &BB : F) changeValueUseList(&BB); for (BasicBlock &BB : F) for (Instruction &I : BB) changeValueUseList(&I); // Constants used by instructions. for (BasicBlock &BB : F) for (Instruction &I : BB) for (Value *Op : I.operands()) if ((isa<Constant>(Op) && !isa<GlobalValue>(*Op)) || isa<InlineAsm>(Op)) changeValueUseList(Op); } if (verifyModule(M, &errs())) report_fatal_error("verification failed"); } static void shuffleUseLists(Module &M, unsigned SeedOffset) { std::minstd_rand0 Gen(std::minstd_rand0::default_seed + SeedOffset); DenseSet<Value *> Seen; changeUseLists(M, [&](Value *V) { shuffleValueUseLists(V, Gen, Seen); }); DEBUG(dbgs() << "\n"); } static void reverseUseLists(Module &M) { DenseSet<Value *> Seen; changeUseLists(M, [&](Value *V) { reverseValueUseLists(V, Seen); }); DEBUG(dbgs() << "\n"); } int main(int argc, char **argv) { sys::PrintStackTraceOnErrorSignal(argv[0]); llvm::PrettyStackTraceProgram X(argc, argv); // Enable debug stream buffering. EnableDebugBuffering = true; llvm_shutdown_obj Y; // Call llvm_shutdown() on exit. LLVMContext Context; cl::ParseCommandLineOptions(argc, argv, "llvm tool to verify use-list order\n"); SMDiagnostic Err; // Load the input module... std::unique_ptr<Module> M = parseIRFile(InputFilename, Err, Context); if (!M.get()) { Err.print(argv[0], errs()); return 1; } if (verifyModule(*M, &errs())) { errs() << argv[0] << ": " << InputFilename << ": error: input module is broken!\n"; return 1; } // Verify the use lists now and after reversing them. outs() << "*** verify-uselistorder ***\n"; verifyUseListOrder(*M); outs() << "reverse\n"; reverseUseLists(*M); verifyUseListOrder(*M); for (unsigned I = 0, E = NumShuffles; I != E; ++I) { outs() << "\n"; // Shuffle with a different (deterministic) seed each time. outs() << "shuffle (" << I + 1 << " of " << E << ")\n"; shuffleUseLists(*M, I); // Verify again before and after reversing. verifyUseListOrder(*M); outs() << "reverse\n"; reverseUseLists(*M); verifyUseListOrder(*M); } return 0; }