//===-- ThreadSanitizer.cpp - race detector -------------------------------===// // // 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 is a part of ThreadSanitizer, a race detector. // // The tool is under development, for the details about previous versions see // http://code.google.com/p/data-race-test // // The instrumentation phase is quite simple: // - Insert calls to run-time library before every memory access. // - Optimizations may apply to avoid instrumenting some of the accesses. // - Insert calls at function entry/exit. // The rest is handled by the run-time library. //===----------------------------------------------------------------------===// #include "llvm/Transforms/Instrumentation/ThreadSanitizer.h" #include "llvm/ADT/DenseMap.h" #include "llvm/ADT/SmallString.h" #include "llvm/ADT/SmallVector.h" #include "llvm/ADT/Statistic.h" #include "llvm/ADT/StringExtras.h" #include "llvm/Analysis/CaptureTracking.h" #include "llvm/Analysis/TargetLibraryInfo.h" #include "llvm/Analysis/ValueTracking.h" #include "llvm/IR/DataLayout.h" #include "llvm/IR/Function.h" #include "llvm/IR/IRBuilder.h" #include "llvm/IR/Instructions.h" #include "llvm/IR/IntrinsicInst.h" #include "llvm/IR/Intrinsics.h" #include "llvm/IR/LLVMContext.h" #include "llvm/IR/Metadata.h" #include "llvm/IR/Module.h" #include "llvm/IR/Type.h" #include "llvm/ProfileData/InstrProf.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/MathExtras.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Transforms/Instrumentation.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/EscapeEnumerator.h" #include "llvm/Transforms/Utils/Local.h" #include "llvm/Transforms/Utils/ModuleUtils.h" using namespace llvm; #define DEBUG_TYPE "tsan" static cl::opt ClInstrumentMemoryAccesses( "tsan-instrument-memory-accesses", cl::init(true), cl::desc("Instrument memory accesses"), cl::Hidden); static cl::opt ClInstrumentFuncEntryExit("tsan-instrument-func-entry-exit", cl::init(true), cl::desc("Instrument function entry and exit"), cl::Hidden); static cl::opt ClHandleCxxExceptions( "tsan-handle-cxx-exceptions", cl::init(true), cl::desc("Handle C++ exceptions (insert cleanup blocks for unwinding)"), cl::Hidden); static cl::opt ClInstrumentAtomics("tsan-instrument-atomics", cl::init(true), cl::desc("Instrument atomics"), cl::Hidden); static cl::opt ClInstrumentMemIntrinsics( "tsan-instrument-memintrinsics", cl::init(true), cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden); static cl::opt ClDistinguishVolatile( "tsan-distinguish-volatile", cl::init(false), cl::desc("Emit special instrumentation for accesses to volatiles"), cl::Hidden); static cl::opt ClInstrumentReadBeforeWrite( "tsan-instrument-read-before-write", cl::init(false), cl::desc("Do not eliminate read instrumentation for read-before-writes"), cl::Hidden); static cl::opt ClCompoundReadBeforeWrite( "tsan-compound-read-before-write", cl::init(false), cl::desc("Emit special compound instrumentation for reads-before-writes"), cl::Hidden); STATISTIC(NumInstrumentedReads, "Number of instrumented reads"); STATISTIC(NumInstrumentedWrites, "Number of instrumented writes"); STATISTIC(NumOmittedReadsBeforeWrite, "Number of reads ignored due to following writes"); STATISTIC(NumAccessesWithBadSize, "Number of accesses with bad size"); STATISTIC(NumInstrumentedVtableWrites, "Number of vtable ptr writes"); STATISTIC(NumInstrumentedVtableReads, "Number of vtable ptr reads"); STATISTIC(NumOmittedReadsFromConstantGlobals, "Number of reads from constant globals"); STATISTIC(NumOmittedReadsFromVtable, "Number of vtable reads"); STATISTIC(NumOmittedNonCaptured, "Number of accesses ignored due to capturing"); const char kTsanModuleCtorName[] = "tsan.module_ctor"; const char kTsanInitName[] = "__tsan_init"; namespace { /// ThreadSanitizer: instrument the code in module to find races. /// /// Instantiating ThreadSanitizer inserts the tsan runtime library API function /// declarations into the module if they don't exist already. Instantiating /// ensures the __tsan_init function is in the list of global constructors for /// the module. struct ThreadSanitizer { ThreadSanitizer() { // Check options and warn user. if (ClInstrumentReadBeforeWrite && ClCompoundReadBeforeWrite) { errs() << "warning: Option -tsan-compound-read-before-write has no effect " "when -tsan-instrument-read-before-write is set.\n"; } } bool sanitizeFunction(Function &F, const TargetLibraryInfo &TLI); private: // Internal Instruction wrapper that contains more information about the // Instruction from prior analysis. struct InstructionInfo { // Instrumentation emitted for this instruction is for a compounded set of // read and write operations in the same basic block. static constexpr unsigned kCompoundRW = (1U << 0); explicit InstructionInfo(Instruction *Inst) : Inst(Inst) {} Instruction *Inst; unsigned Flags = 0; }; void initialize(Module &M, const TargetLibraryInfo &TLI); bool instrumentLoadOrStore(const InstructionInfo &II, const DataLayout &DL); bool instrumentAtomic(Instruction *I, const DataLayout &DL); bool instrumentMemIntrinsic(Instruction *I); void chooseInstructionsToInstrument(SmallVectorImpl &Local, SmallVectorImpl &All, const DataLayout &DL); bool addrPointsToConstantData(Value *Addr); int getMemoryAccessFuncIndex(Type *OrigTy, Value *Addr, const DataLayout &DL); void InsertRuntimeIgnores(Function &F); Type *IntptrTy; FunctionCallee TsanFuncEntry; FunctionCallee TsanFuncExit; FunctionCallee TsanIgnoreBegin; FunctionCallee TsanIgnoreEnd; // Accesses sizes are powers of two: 1, 2, 4, 8, 16. static const size_t kNumberOfAccessSizes = 5; FunctionCallee TsanRead[kNumberOfAccessSizes]; FunctionCallee TsanWrite[kNumberOfAccessSizes]; FunctionCallee TsanUnalignedRead[kNumberOfAccessSizes]; FunctionCallee TsanUnalignedWrite[kNumberOfAccessSizes]; FunctionCallee TsanVolatileRead[kNumberOfAccessSizes]; FunctionCallee TsanVolatileWrite[kNumberOfAccessSizes]; FunctionCallee TsanUnalignedVolatileRead[kNumberOfAccessSizes]; FunctionCallee TsanUnalignedVolatileWrite[kNumberOfAccessSizes]; FunctionCallee TsanCompoundRW[kNumberOfAccessSizes]; FunctionCallee TsanUnalignedCompoundRW[kNumberOfAccessSizes]; FunctionCallee TsanAtomicLoad[kNumberOfAccessSizes]; FunctionCallee TsanAtomicStore[kNumberOfAccessSizes]; FunctionCallee TsanAtomicRMW[AtomicRMWInst::LAST_BINOP + 1] [kNumberOfAccessSizes]; FunctionCallee TsanAtomicCAS[kNumberOfAccessSizes]; FunctionCallee TsanAtomicThreadFence; FunctionCallee TsanAtomicSignalFence; FunctionCallee TsanVptrUpdate; FunctionCallee TsanVptrLoad; FunctionCallee MemmoveFn, MemcpyFn, MemsetFn; }; void insertModuleCtor(Module &M) { getOrCreateSanitizerCtorAndInitFunctions( M, kTsanModuleCtorName, kTsanInitName, /*InitArgTypes=*/{}, /*InitArgs=*/{}, // This callback is invoked when the functions are created the first // time. Hook them into the global ctors list in that case: [&](Function *Ctor, FunctionCallee) { appendToGlobalCtors(M, Ctor, 0); }); } } // namespace PreservedAnalyses ThreadSanitizerPass::run(Function &F, FunctionAnalysisManager &FAM) { ThreadSanitizer TSan; if (TSan.sanitizeFunction(F, FAM.getResult(F))) return PreservedAnalyses::none(); return PreservedAnalyses::all(); } PreservedAnalyses ModuleThreadSanitizerPass::run(Module &M, ModuleAnalysisManager &MAM) { insertModuleCtor(M); return PreservedAnalyses::none(); } void ThreadSanitizer::initialize(Module &M, const TargetLibraryInfo &TLI) { const DataLayout &DL = M.getDataLayout(); LLVMContext &Ctx = M.getContext(); IntptrTy = DL.getIntPtrType(Ctx); IRBuilder<> IRB(Ctx); AttributeList Attr; Attr = Attr.addFnAttribute(Ctx, Attribute::NoUnwind); // Initialize the callbacks. TsanFuncEntry = M.getOrInsertFunction("__tsan_func_entry", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); TsanFuncExit = M.getOrInsertFunction("__tsan_func_exit", Attr, IRB.getVoidTy()); TsanIgnoreBegin = M.getOrInsertFunction("__tsan_ignore_thread_begin", Attr, IRB.getVoidTy()); TsanIgnoreEnd = M.getOrInsertFunction("__tsan_ignore_thread_end", Attr, IRB.getVoidTy()); IntegerType *OrdTy = IRB.getInt32Ty(); for (size_t i = 0; i < kNumberOfAccessSizes; ++i) { const unsigned ByteSize = 1U << i; const unsigned BitSize = ByteSize * 8; std::string ByteSizeStr = utostr(ByteSize); std::string BitSizeStr = utostr(BitSize); SmallString<32> ReadName("__tsan_read" + ByteSizeStr); TsanRead[i] = M.getOrInsertFunction(ReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); SmallString<32> WriteName("__tsan_write" + ByteSizeStr); TsanWrite[i] = M.getOrInsertFunction(WriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); SmallString<64> UnalignedReadName("__tsan_unaligned_read" + ByteSizeStr); TsanUnalignedRead[i] = M.getOrInsertFunction( UnalignedReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); SmallString<64> UnalignedWriteName("__tsan_unaligned_write" + ByteSizeStr); TsanUnalignedWrite[i] = M.getOrInsertFunction( UnalignedWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); SmallString<64> VolatileReadName("__tsan_volatile_read" + ByteSizeStr); TsanVolatileRead[i] = M.getOrInsertFunction( VolatileReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); SmallString<64> VolatileWriteName("__tsan_volatile_write" + ByteSizeStr); TsanVolatileWrite[i] = M.getOrInsertFunction( VolatileWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); SmallString<64> UnalignedVolatileReadName("__tsan_unaligned_volatile_read" + ByteSizeStr); TsanUnalignedVolatileRead[i] = M.getOrInsertFunction( UnalignedVolatileReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); SmallString<64> UnalignedVolatileWriteName( "__tsan_unaligned_volatile_write" + ByteSizeStr); TsanUnalignedVolatileWrite[i] = M.getOrInsertFunction( UnalignedVolatileWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); SmallString<64> CompoundRWName("__tsan_read_write" + ByteSizeStr); TsanCompoundRW[i] = M.getOrInsertFunction( CompoundRWName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); SmallString<64> UnalignedCompoundRWName("__tsan_unaligned_read_write" + ByteSizeStr); TsanUnalignedCompoundRW[i] = M.getOrInsertFunction( UnalignedCompoundRWName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); Type *Ty = Type::getIntNTy(Ctx, BitSize); Type *PtrTy = Ty->getPointerTo(); SmallString<32> AtomicLoadName("__tsan_atomic" + BitSizeStr + "_load"); TsanAtomicLoad[i] = M.getOrInsertFunction(AtomicLoadName, TLI.getAttrList(&Ctx, {1}, /*Signed=*/true, /*Ret=*/BitSize <= 32, Attr), Ty, PtrTy, OrdTy); // Args of type Ty need extension only when BitSize is 32 or less. using Idxs = std::vector; Idxs Idxs2Or12 ((BitSize <= 32) ? Idxs({1, 2}) : Idxs({2})); Idxs Idxs34Or1234((BitSize <= 32) ? Idxs({1, 2, 3, 4}) : Idxs({3, 4})); SmallString<32> AtomicStoreName("__tsan_atomic" + BitSizeStr + "_store"); TsanAtomicStore[i] = M.getOrInsertFunction( AtomicStoreName, TLI.getAttrList(&Ctx, Idxs2Or12, /*Signed=*/true, /*Ret=*/false, Attr), IRB.getVoidTy(), PtrTy, Ty, OrdTy); for (unsigned Op = AtomicRMWInst::FIRST_BINOP; Op <= AtomicRMWInst::LAST_BINOP; ++Op) { TsanAtomicRMW[Op][i] = nullptr; const char *NamePart = nullptr; if (Op == AtomicRMWInst::Xchg) NamePart = "_exchange"; else if (Op == AtomicRMWInst::Add) NamePart = "_fetch_add"; else if (Op == AtomicRMWInst::Sub) NamePart = "_fetch_sub"; else if (Op == AtomicRMWInst::And) NamePart = "_fetch_and"; else if (Op == AtomicRMWInst::Or) NamePart = "_fetch_or"; else if (Op == AtomicRMWInst::Xor) NamePart = "_fetch_xor"; else if (Op == AtomicRMWInst::Nand) NamePart = "_fetch_nand"; else continue; SmallString<32> RMWName("__tsan_atomic" + itostr(BitSize) + NamePart); TsanAtomicRMW[Op][i] = M.getOrInsertFunction( RMWName, TLI.getAttrList(&Ctx, Idxs2Or12, /*Signed=*/true, /*Ret=*/BitSize <= 32, Attr), Ty, PtrTy, Ty, OrdTy); } SmallString<32> AtomicCASName("__tsan_atomic" + BitSizeStr + "_compare_exchange_val"); TsanAtomicCAS[i] = M.getOrInsertFunction( AtomicCASName, TLI.getAttrList(&Ctx, Idxs34Or1234, /*Signed=*/true, /*Ret=*/BitSize <= 32, Attr), Ty, PtrTy, Ty, Ty, OrdTy, OrdTy); } TsanVptrUpdate = M.getOrInsertFunction("__tsan_vptr_update", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy(), IRB.getInt8PtrTy()); TsanVptrLoad = M.getOrInsertFunction("__tsan_vptr_read", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()); TsanAtomicThreadFence = M.getOrInsertFunction( "__tsan_atomic_thread_fence", TLI.getAttrList(&Ctx, {0}, /*Signed=*/true, /*Ret=*/false, Attr), IRB.getVoidTy(), OrdTy); TsanAtomicSignalFence = M.getOrInsertFunction( "__tsan_atomic_signal_fence", TLI.getAttrList(&Ctx, {0}, /*Signed=*/true, /*Ret=*/false, Attr), IRB.getVoidTy(), OrdTy); MemmoveFn = M.getOrInsertFunction("__tsan_memmove", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy); MemcpyFn = M.getOrInsertFunction("__tsan_memcpy", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy); MemsetFn = M.getOrInsertFunction( "__tsan_memset", TLI.getAttrList(&Ctx, {1}, /*Signed=*/true, /*Ret=*/false, Attr), IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy); } static bool isVtableAccess(Instruction *I) { if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa)) return Tag->isTBAAVtableAccess(); return false; } // Do not instrument known races/"benign races" that come from compiler // instrumentatin. The user has no way of suppressing them. static bool shouldInstrumentReadWriteFromAddress(const Module *M, Value *Addr) { // Peel off GEPs and BitCasts. Addr = Addr->stripInBoundsOffsets(); if (GlobalVariable *GV = dyn_cast(Addr)) { if (GV->hasSection()) { StringRef SectionName = GV->getSection(); // Check if the global is in the PGO counters section. auto OF = Triple(M->getTargetTriple()).getObjectFormat(); if (SectionName.endswith( getInstrProfSectionName(IPSK_cnts, OF, /*AddSegmentInfo=*/false))) return false; } // Check if the global is private gcov data. if (GV->getName().startswith("__llvm_gcov") || GV->getName().startswith("__llvm_gcda")) return false; } // Do not instrument accesses from different address spaces; we cannot deal // with them. if (Addr) { Type *PtrTy = cast(Addr->getType()->getScalarType()); if (PtrTy->getPointerAddressSpace() != 0) return false; } return true; } bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) { // If this is a GEP, just analyze its pointer operand. if (GetElementPtrInst *GEP = dyn_cast(Addr)) Addr = GEP->getPointerOperand(); if (GlobalVariable *GV = dyn_cast(Addr)) { if (GV->isConstant()) { // Reads from constant globals can not race with any writes. NumOmittedReadsFromConstantGlobals++; return true; } } else if (LoadInst *L = dyn_cast(Addr)) { if (isVtableAccess(L)) { // Reads from a vtable pointer can not race with any writes. NumOmittedReadsFromVtable++; return true; } } return false; } // Instrumenting some of the accesses may be proven redundant. // Currently handled: // - read-before-write (within same BB, no calls between) // - not captured variables // // We do not handle some of the patterns that should not survive // after the classic compiler optimizations. // E.g. two reads from the same temp should be eliminated by CSE, // two writes should be eliminated by DSE, etc. // // 'Local' is a vector of insns within the same BB (no calls between). // 'All' is a vector of insns that will be instrumented. void ThreadSanitizer::chooseInstructionsToInstrument( SmallVectorImpl &Local, SmallVectorImpl &All, const DataLayout &DL) { DenseMap WriteTargets; // Map of addresses to index in All // Iterate from the end. for (Instruction *I : reverse(Local)) { const bool IsWrite = isa(*I); Value *Addr = IsWrite ? cast(I)->getPointerOperand() : cast(I)->getPointerOperand(); if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr)) continue; if (!IsWrite) { const auto WriteEntry = WriteTargets.find(Addr); if (!ClInstrumentReadBeforeWrite && WriteEntry != WriteTargets.end()) { auto &WI = All[WriteEntry->second]; // If we distinguish volatile accesses and if either the read or write // is volatile, do not omit any instrumentation. const bool AnyVolatile = ClDistinguishVolatile && (cast(I)->isVolatile() || cast(WI.Inst)->isVolatile()); if (!AnyVolatile) { // We will write to this temp, so no reason to analyze the read. // Mark the write instruction as compound. WI.Flags |= InstructionInfo::kCompoundRW; NumOmittedReadsBeforeWrite++; continue; } } if (addrPointsToConstantData(Addr)) { // Addr points to some constant data -- it can not race with any writes. continue; } } if (isa(getUnderlyingObject(Addr)) && !PointerMayBeCaptured(Addr, true, true)) { // The variable is addressable but not captured, so it cannot be // referenced from a different thread and participate in a data race // (see llvm/Analysis/CaptureTracking.h for details). NumOmittedNonCaptured++; continue; } // Instrument this instruction. All.emplace_back(I); if (IsWrite) { // For read-before-write and compound instrumentation we only need one // write target, and we can override any previous entry if it exists. WriteTargets[Addr] = All.size() - 1; } } Local.clear(); } static bool isTsanAtomic(const Instruction *I) { // TODO: Ask TTI whether synchronization scope is between threads. auto SSID = getAtomicSyncScopeID(I); if (!SSID) return false; if (isa(I) || isa(I)) return *SSID != SyncScope::SingleThread; return true; } void ThreadSanitizer::InsertRuntimeIgnores(Function &F) { InstrumentationIRBuilder IRB(F.getEntryBlock().getFirstNonPHI()); IRB.CreateCall(TsanIgnoreBegin); EscapeEnumerator EE(F, "tsan_ignore_cleanup", ClHandleCxxExceptions); while (IRBuilder<> *AtExit = EE.Next()) { InstrumentationIRBuilder::ensureDebugInfo(*AtExit, F); AtExit->CreateCall(TsanIgnoreEnd); } } bool ThreadSanitizer::sanitizeFunction(Function &F, const TargetLibraryInfo &TLI) { // This is required to prevent instrumenting call to __tsan_init from within // the module constructor. if (F.getName() == kTsanModuleCtorName) return false; // Naked functions can not have prologue/epilogue // (__tsan_func_entry/__tsan_func_exit) generated, so don't instrument them at // all. if (F.hasFnAttribute(Attribute::Naked)) return false; // __attribute__(disable_sanitizer_instrumentation) prevents all kinds of // instrumentation. if (F.hasFnAttribute(Attribute::DisableSanitizerInstrumentation)) return false; initialize(*F.getParent(), TLI); SmallVector AllLoadsAndStores; SmallVector LocalLoadsAndStores; SmallVector AtomicAccesses; SmallVector MemIntrinCalls; bool Res = false; bool HasCalls = false; bool SanitizeFunction = F.hasFnAttribute(Attribute::SanitizeThread); const DataLayout &DL = F.getParent()->getDataLayout(); // Traverse all instructions, collect loads/stores/returns, check for calls. for (auto &BB : F) { for (auto &Inst : BB) { if (isTsanAtomic(&Inst)) AtomicAccesses.push_back(&Inst); else if (isa(Inst) || isa(Inst)) LocalLoadsAndStores.push_back(&Inst); else if ((isa(Inst) && !isa(Inst)) || isa(Inst)) { if (CallInst *CI = dyn_cast(&Inst)) maybeMarkSanitizerLibraryCallNoBuiltin(CI, &TLI); if (isa(Inst)) MemIntrinCalls.push_back(&Inst); HasCalls = true; chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores, DL); } } chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores, DL); } // We have collected all loads and stores. // FIXME: many of these accesses do not need to be checked for races // (e.g. variables that do not escape, etc). // Instrument memory accesses only if we want to report bugs in the function. if (ClInstrumentMemoryAccesses && SanitizeFunction) for (const auto &II : AllLoadsAndStores) { Res |= instrumentLoadOrStore(II, DL); } // Instrument atomic memory accesses in any case (they can be used to // implement synchronization). if (ClInstrumentAtomics) for (auto *Inst : AtomicAccesses) { Res |= instrumentAtomic(Inst, DL); } if (ClInstrumentMemIntrinsics && SanitizeFunction) for (auto *Inst : MemIntrinCalls) { Res |= instrumentMemIntrinsic(Inst); } if (F.hasFnAttribute("sanitize_thread_no_checking_at_run_time")) { assert(!F.hasFnAttribute(Attribute::SanitizeThread)); if (HasCalls) InsertRuntimeIgnores(F); } // Instrument function entry/exit points if there were instrumented accesses. if ((Res || HasCalls) && ClInstrumentFuncEntryExit) { InstrumentationIRBuilder IRB(F.getEntryBlock().getFirstNonPHI()); Value *ReturnAddress = IRB.CreateCall( Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress), IRB.getInt32(0)); IRB.CreateCall(TsanFuncEntry, ReturnAddress); EscapeEnumerator EE(F, "tsan_cleanup", ClHandleCxxExceptions); while (IRBuilder<> *AtExit = EE.Next()) { InstrumentationIRBuilder::ensureDebugInfo(*AtExit, F); AtExit->CreateCall(TsanFuncExit, {}); } Res = true; } return Res; } bool ThreadSanitizer::instrumentLoadOrStore(const InstructionInfo &II, const DataLayout &DL) { InstrumentationIRBuilder IRB(II.Inst); const bool IsWrite = isa(*II.Inst); Value *Addr = IsWrite ? cast(II.Inst)->getPointerOperand() : cast(II.Inst)->getPointerOperand(); Type *OrigTy = getLoadStoreType(II.Inst); // swifterror memory addresses are mem2reg promoted by instruction selection. // As such they cannot have regular uses like an instrumentation function and // it makes no sense to track them as memory. if (Addr->isSwiftError()) return false; int Idx = getMemoryAccessFuncIndex(OrigTy, Addr, DL); if (Idx < 0) return false; if (IsWrite && isVtableAccess(II.Inst)) { LLVM_DEBUG(dbgs() << " VPTR : " << *II.Inst << "\n"); Value *StoredValue = cast(II.Inst)->getValueOperand(); // StoredValue may be a vector type if we are storing several vptrs at once. // In this case, just take the first element of the vector since this is // enough to find vptr races. if (isa(StoredValue->getType())) StoredValue = IRB.CreateExtractElement( StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0)); if (StoredValue->getType()->isIntegerTy()) StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy()); // Call TsanVptrUpdate. IRB.CreateCall(TsanVptrUpdate, {IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()), IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy())}); NumInstrumentedVtableWrites++; return true; } if (!IsWrite && isVtableAccess(II.Inst)) { IRB.CreateCall(TsanVptrLoad, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy())); NumInstrumentedVtableReads++; return true; } const Align Alignment = IsWrite ? cast(II.Inst)->getAlign() : cast(II.Inst)->getAlign(); const bool IsCompoundRW = ClCompoundReadBeforeWrite && (II.Flags & InstructionInfo::kCompoundRW); const bool IsVolatile = ClDistinguishVolatile && (IsWrite ? cast(II.Inst)->isVolatile() : cast(II.Inst)->isVolatile()); assert((!IsVolatile || !IsCompoundRW) && "Compound volatile invalid!"); const uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy); FunctionCallee OnAccessFunc = nullptr; if (Alignment >= Align(8) || (Alignment.value() % (TypeSize / 8)) == 0) { if (IsCompoundRW) OnAccessFunc = TsanCompoundRW[Idx]; else if (IsVolatile) OnAccessFunc = IsWrite ? TsanVolatileWrite[Idx] : TsanVolatileRead[Idx]; else OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx]; } else { if (IsCompoundRW) OnAccessFunc = TsanUnalignedCompoundRW[Idx]; else if (IsVolatile) OnAccessFunc = IsWrite ? TsanUnalignedVolatileWrite[Idx] : TsanUnalignedVolatileRead[Idx]; else OnAccessFunc = IsWrite ? TsanUnalignedWrite[Idx] : TsanUnalignedRead[Idx]; } IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy())); if (IsCompoundRW || IsWrite) NumInstrumentedWrites++; if (IsCompoundRW || !IsWrite) NumInstrumentedReads++; return true; } static ConstantInt *createOrdering(IRBuilder<> *IRB, AtomicOrdering ord) { uint32_t v = 0; switch (ord) { case AtomicOrdering::NotAtomic: llvm_unreachable("unexpected atomic ordering!"); case AtomicOrdering::Unordered: [[fallthrough]]; case AtomicOrdering::Monotonic: v = 0; break; // Not specified yet: // case AtomicOrdering::Consume: v = 1; break; case AtomicOrdering::Acquire: v = 2; break; case AtomicOrdering::Release: v = 3; break; case AtomicOrdering::AcquireRelease: v = 4; break; case AtomicOrdering::SequentiallyConsistent: v = 5; break; } return IRB->getInt32(v); } // If a memset intrinsic gets inlined by the code gen, we will miss races on it. // So, we either need to ensure the intrinsic is not inlined, or instrument it. // We do not instrument memset/memmove/memcpy intrinsics (too complicated), // instead we simply replace them with regular function calls, which are then // intercepted by the run-time. // Since tsan is running after everyone else, the calls should not be // replaced back with intrinsics. If that becomes wrong at some point, // we will need to call e.g. __tsan_memset to avoid the intrinsics. bool ThreadSanitizer::instrumentMemIntrinsic(Instruction *I) { IRBuilder<> IRB(I); if (MemSetInst *M = dyn_cast(I)) { IRB.CreateCall( MemsetFn, {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()), IRB.CreateIntCast(M->getArgOperand(1), IRB.getInt32Ty(), false), IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)}); I->eraseFromParent(); } else if (MemTransferInst *M = dyn_cast(I)) { IRB.CreateCall( isa(M) ? MemcpyFn : MemmoveFn, {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()), IRB.CreatePointerCast(M->getArgOperand(1), IRB.getInt8PtrTy()), IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)}); I->eraseFromParent(); } return false; } // Both llvm and ThreadSanitizer atomic operations are based on C++11/C1x // standards. For background see C++11 standard. A slightly older, publicly // available draft of the standard (not entirely up-to-date, but close enough // for casual browsing) is available here: // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf // The following page contains more background information: // http://www.hpl.hp.com/personal/Hans_Boehm/c++mm/ bool ThreadSanitizer::instrumentAtomic(Instruction *I, const DataLayout &DL) { InstrumentationIRBuilder IRB(I); if (LoadInst *LI = dyn_cast(I)) { Value *Addr = LI->getPointerOperand(); Type *OrigTy = LI->getType(); int Idx = getMemoryAccessFuncIndex(OrigTy, Addr, DL); if (Idx < 0) return false; const unsigned ByteSize = 1U << Idx; const unsigned BitSize = ByteSize * 8; Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize); Type *PtrTy = Ty->getPointerTo(); Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy), createOrdering(&IRB, LI->getOrdering())}; Value *C = IRB.CreateCall(TsanAtomicLoad[Idx], Args); Value *Cast = IRB.CreateBitOrPointerCast(C, OrigTy); I->replaceAllUsesWith(Cast); } else if (StoreInst *SI = dyn_cast(I)) { Value *Addr = SI->getPointerOperand(); int Idx = getMemoryAccessFuncIndex(SI->getValueOperand()->getType(), Addr, DL); if (Idx < 0) return false; const unsigned ByteSize = 1U << Idx; const unsigned BitSize = ByteSize * 8; Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize); Type *PtrTy = Ty->getPointerTo(); Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy), IRB.CreateBitOrPointerCast(SI->getValueOperand(), Ty), createOrdering(&IRB, SI->getOrdering())}; CallInst *C = CallInst::Create(TsanAtomicStore[Idx], Args); ReplaceInstWithInst(I, C); } else if (AtomicRMWInst *RMWI = dyn_cast(I)) { Value *Addr = RMWI->getPointerOperand(); int Idx = getMemoryAccessFuncIndex(RMWI->getValOperand()->getType(), Addr, DL); if (Idx < 0) return false; FunctionCallee F = TsanAtomicRMW[RMWI->getOperation()][Idx]; if (!F) return false; const unsigned ByteSize = 1U << Idx; const unsigned BitSize = ByteSize * 8; Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize); Type *PtrTy = Ty->getPointerTo(); Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy), IRB.CreateIntCast(RMWI->getValOperand(), Ty, false), createOrdering(&IRB, RMWI->getOrdering())}; CallInst *C = CallInst::Create(F, Args); ReplaceInstWithInst(I, C); } else if (AtomicCmpXchgInst *CASI = dyn_cast(I)) { Value *Addr = CASI->getPointerOperand(); Type *OrigOldValTy = CASI->getNewValOperand()->getType(); int Idx = getMemoryAccessFuncIndex(OrigOldValTy, Addr, DL); if (Idx < 0) return false; const unsigned ByteSize = 1U << Idx; const unsigned BitSize = ByteSize * 8; Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize); Type *PtrTy = Ty->getPointerTo(); Value *CmpOperand = IRB.CreateBitOrPointerCast(CASI->getCompareOperand(), Ty); Value *NewOperand = IRB.CreateBitOrPointerCast(CASI->getNewValOperand(), Ty); Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy), CmpOperand, NewOperand, createOrdering(&IRB, CASI->getSuccessOrdering()), createOrdering(&IRB, CASI->getFailureOrdering())}; CallInst *C = IRB.CreateCall(TsanAtomicCAS[Idx], Args); Value *Success = IRB.CreateICmpEQ(C, CmpOperand); Value *OldVal = C; if (Ty != OrigOldValTy) { // The value is a pointer, so we need to cast the return value. OldVal = IRB.CreateIntToPtr(C, OrigOldValTy); } Value *Res = IRB.CreateInsertValue(PoisonValue::get(CASI->getType()), OldVal, 0); Res = IRB.CreateInsertValue(Res, Success, 1); I->replaceAllUsesWith(Res); I->eraseFromParent(); } else if (FenceInst *FI = dyn_cast(I)) { Value *Args[] = {createOrdering(&IRB, FI->getOrdering())}; FunctionCallee F = FI->getSyncScopeID() == SyncScope::SingleThread ? TsanAtomicSignalFence : TsanAtomicThreadFence; CallInst *C = CallInst::Create(F, Args); ReplaceInstWithInst(I, C); } return true; } int ThreadSanitizer::getMemoryAccessFuncIndex(Type *OrigTy, Value *Addr, const DataLayout &DL) { assert(OrigTy->isSized()); assert( cast(Addr->getType())->isOpaqueOrPointeeTypeMatches(OrigTy)); uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy); if (TypeSize != 8 && TypeSize != 16 && TypeSize != 32 && TypeSize != 64 && TypeSize != 128) { NumAccessesWithBadSize++; // Ignore all unusual sizes. return -1; } size_t Idx = countTrailingZeros(TypeSize / 8); assert(Idx < kNumberOfAccessSizes); return Idx; }