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+//===-- 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/SmallPtrSet.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/Transforms/Utils/Local.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.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/ModuleUtils.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "tsan"
+
+static cl::opt<bool> ClInstrumentMemoryAccesses(
+ "tsan-instrument-memory-accesses", cl::init(true),
+ cl::desc("Instrument memory accesses"), cl::Hidden);
+static cl::opt<bool> ClInstrumentFuncEntryExit(
+ "tsan-instrument-func-entry-exit", cl::init(true),
+ cl::desc("Instrument function entry and exit"), cl::Hidden);
+static cl::opt<bool> ClHandleCxxExceptions(
+ "tsan-handle-cxx-exceptions", cl::init(true),
+ cl::desc("Handle C++ exceptions (insert cleanup blocks for unwinding)"),
+ cl::Hidden);
+static cl::opt<bool> ClInstrumentAtomics(
+ "tsan-instrument-atomics", cl::init(true),
+ cl::desc("Instrument atomics"), cl::Hidden);
+static cl::opt<bool> ClInstrumentMemIntrinsics(
+ "tsan-instrument-memintrinsics", cl::init(true),
+ cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), 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");
+
+static const char *const kTsanModuleCtorName = "tsan.module_ctor";
+static const char *const 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 {
+ bool sanitizeFunction(Function &F, const TargetLibraryInfo &TLI);
+
+private:
+ void initialize(Module &M);
+ bool instrumentLoadOrStore(Instruction *I, const DataLayout &DL);
+ bool instrumentAtomic(Instruction *I, const DataLayout &DL);
+ bool instrumentMemIntrinsic(Instruction *I);
+ void chooseInstructionsToInstrument(SmallVectorImpl<Instruction *> &Local,
+ SmallVectorImpl<Instruction *> &All,
+ const DataLayout &DL);
+ bool addrPointsToConstantData(Value *Addr);
+ int getMemoryAccessFuncIndex(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 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;
+};
+
+struct ThreadSanitizerLegacyPass : FunctionPass {
+ ThreadSanitizerLegacyPass() : FunctionPass(ID) {}
+ StringRef getPassName() const override;
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+ bool runOnFunction(Function &F) override;
+ bool doInitialization(Module &M) override;
+ static char ID; // Pass identification, replacement for typeid.
+private:
+ Optional<ThreadSanitizer> TSan;
+};
+
+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<TargetLibraryAnalysis>(F)))
+ return PreservedAnalyses::none();
+ return PreservedAnalyses::all();
+}
+
+PreservedAnalyses ThreadSanitizerPass::run(Module &M,
+ ModuleAnalysisManager &MAM) {
+ insertModuleCtor(M);
+ return PreservedAnalyses::none();
+}
+
+char ThreadSanitizerLegacyPass::ID = 0;
+INITIALIZE_PASS_BEGIN(ThreadSanitizerLegacyPass, "tsan",
+ "ThreadSanitizer: detects data races.", false, false)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_END(ThreadSanitizerLegacyPass, "tsan",
+ "ThreadSanitizer: detects data races.", false, false)
+
+StringRef ThreadSanitizerLegacyPass::getPassName() const {
+ return "ThreadSanitizerLegacyPass";
+}
+
+void ThreadSanitizerLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
+}
+
+bool ThreadSanitizerLegacyPass::doInitialization(Module &M) {
+ insertModuleCtor(M);
+ TSan.emplace();
+ return true;
+}
+
+bool ThreadSanitizerLegacyPass::runOnFunction(Function &F) {
+ auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
+ TSan->sanitizeFunction(F, TLI);
+ return true;
+}
+
+FunctionPass *llvm::createThreadSanitizerLegacyPassPass() {
+ return new ThreadSanitizerLegacyPass();
+}
+
+void ThreadSanitizer::initialize(Module &M) {
+ const DataLayout &DL = M.getDataLayout();
+ IntptrTy = DL.getIntPtrType(M.getContext());
+
+ IRBuilder<> IRB(M.getContext());
+ AttributeList Attr;
+ Attr = Attr.addAttribute(M.getContext(), AttributeList::FunctionIndex,
+ 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());
+
+ Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
+ Type *PtrTy = Ty->getPointerTo();
+ SmallString<32> AtomicLoadName("__tsan_atomic" + BitSizeStr + "_load");
+ TsanAtomicLoad[i] =
+ M.getOrInsertFunction(AtomicLoadName, Attr, Ty, PtrTy, OrdTy);
+
+ SmallString<32> AtomicStoreName("__tsan_atomic" + BitSizeStr + "_store");
+ TsanAtomicStore[i] = M.getOrInsertFunction(
+ AtomicStoreName, Attr, IRB.getVoidTy(), PtrTy, Ty, OrdTy);
+
+ for (int 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, Attr, Ty, PtrTy, Ty, OrdTy);
+ }
+
+ SmallString<32> AtomicCASName("__tsan_atomic" + BitSizeStr +
+ "_compare_exchange_val");
+ TsanAtomicCAS[i] = M.getOrInsertFunction(AtomicCASName, 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",
+ Attr, IRB.getVoidTy(), OrdTy);
+ TsanAtomicSignalFence = M.getOrInsertFunction("__tsan_atomic_signal_fence",
+ Attr, IRB.getVoidTy(), OrdTy);
+
+ MemmoveFn =
+ M.getOrInsertFunction("memmove", Attr, IRB.getInt8PtrTy(),
+ IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy);
+ MemcpyFn =
+ M.getOrInsertFunction("memcpy", Attr, IRB.getInt8PtrTy(),
+ IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy);
+ MemsetFn =
+ M.getOrInsertFunction("memset", 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<GlobalVariable>(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 acesses from different address spaces; we cannot deal
+ // with them.
+ if (Addr) {
+ Type *PtrTy = cast<PointerType>(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<GetElementPtrInst>(Addr))
+ Addr = GEP->getPointerOperand();
+
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
+ if (GV->isConstant()) {
+ // Reads from constant globals can not race with any writes.
+ NumOmittedReadsFromConstantGlobals++;
+ return true;
+ }
+ } else if (LoadInst *L = dyn_cast<LoadInst>(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<Instruction *> &Local, SmallVectorImpl<Instruction *> &All,
+ const DataLayout &DL) {
+ SmallPtrSet<Value*, 8> WriteTargets;
+ // Iterate from the end.
+ for (Instruction *I : reverse(Local)) {
+ if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
+ Value *Addr = Store->getPointerOperand();
+ if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
+ continue;
+ WriteTargets.insert(Addr);
+ } else {
+ LoadInst *Load = cast<LoadInst>(I);
+ Value *Addr = Load->getPointerOperand();
+ if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
+ continue;
+ if (WriteTargets.count(Addr)) {
+ // We will write to this temp, so no reason to analyze the read.
+ NumOmittedReadsBeforeWrite++;
+ continue;
+ }
+ if (addrPointsToConstantData(Addr)) {
+ // Addr points to some constant data -- it can not race with any writes.
+ continue;
+ }
+ }
+ Value *Addr = isa<StoreInst>(*I)
+ ? cast<StoreInst>(I)->getPointerOperand()
+ : cast<LoadInst>(I)->getPointerOperand();
+ if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
+ !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;
+ }
+ All.push_back(I);
+ }
+ Local.clear();
+}
+
+static bool isAtomic(Instruction *I) {
+ // TODO: Ask TTI whether synchronization scope is between threads.
+ if (LoadInst *LI = dyn_cast<LoadInst>(I))
+ return LI->isAtomic() && LI->getSyncScopeID() != SyncScope::SingleThread;
+ if (StoreInst *SI = dyn_cast<StoreInst>(I))
+ return SI->isAtomic() && SI->getSyncScopeID() != SyncScope::SingleThread;
+ if (isa<AtomicRMWInst>(I))
+ return true;
+ if (isa<AtomicCmpXchgInst>(I))
+ return true;
+ if (isa<FenceInst>(I))
+ return true;
+ return false;
+}
+
+void ThreadSanitizer::InsertRuntimeIgnores(Function &F) {
+ IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
+ IRB.CreateCall(TsanIgnoreBegin);
+ EscapeEnumerator EE(F, "tsan_ignore_cleanup", ClHandleCxxExceptions);
+ while (IRBuilder<> *AtExit = EE.Next()) {
+ 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;
+ initialize(*F.getParent());
+ SmallVector<Instruction*, 8> AllLoadsAndStores;
+ SmallVector<Instruction*, 8> LocalLoadsAndStores;
+ SmallVector<Instruction*, 8> AtomicAccesses;
+ SmallVector<Instruction*, 8> 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 (isAtomic(&Inst))
+ AtomicAccesses.push_back(&Inst);
+ else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
+ LocalLoadsAndStores.push_back(&Inst);
+ else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
+ if (CallInst *CI = dyn_cast<CallInst>(&Inst))
+ maybeMarkSanitizerLibraryCallNoBuiltin(CI, &TLI);
+ if (isa<MemIntrinsic>(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 (auto Inst : AllLoadsAndStores) {
+ Res |= instrumentLoadOrStore(Inst, 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) {
+ IRBuilder<> 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()) {
+ AtExit->CreateCall(TsanFuncExit, {});
+ }
+ Res = true;
+ }
+ return Res;
+}
+
+bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I,
+ const DataLayout &DL) {
+ IRBuilder<> IRB(I);
+ bool IsWrite = isa<StoreInst>(*I);
+ Value *Addr = IsWrite
+ ? cast<StoreInst>(I)->getPointerOperand()
+ : cast<LoadInst>(I)->getPointerOperand();
+
+ // 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(Addr, DL);
+ if (Idx < 0)
+ return false;
+ if (IsWrite && isVtableAccess(I)) {
+ LLVM_DEBUG(dbgs() << " VPTR : " << *I << "\n");
+ Value *StoredValue = cast<StoreInst>(I)->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<VectorType>(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(I)) {
+ IRB.CreateCall(TsanVptrLoad,
+ IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
+ NumInstrumentedVtableReads++;
+ return true;
+ }
+ const unsigned Alignment = IsWrite
+ ? cast<StoreInst>(I)->getAlignment()
+ : cast<LoadInst>(I)->getAlignment();
+ Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
+ const uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
+ FunctionCallee OnAccessFunc = nullptr;
+ if (Alignment == 0 || Alignment >= 8 || (Alignment % (TypeSize / 8)) == 0)
+ OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
+ else
+ OnAccessFunc = IsWrite ? TsanUnalignedWrite[Idx] : TsanUnalignedRead[Idx];
+ IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
+ if (IsWrite) NumInstrumentedWrites++;
+ else 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: LLVM_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<MemSetInst>(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<MemTransferInst>(I)) {
+ IRB.CreateCall(
+ isa<MemCpyInst>(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) {
+ IRBuilder<> IRB(I);
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ Value *Addr = LI->getPointerOperand();
+ int Idx = getMemoryAccessFuncIndex(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())};
+ Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
+ Value *C = IRB.CreateCall(TsanAtomicLoad[Idx], Args);
+ Value *Cast = IRB.CreateBitOrPointerCast(C, OrigTy);
+ I->replaceAllUsesWith(Cast);
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+ Value *Addr = SI->getPointerOperand();
+ int Idx = getMemoryAccessFuncIndex(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<AtomicRMWInst>(I)) {
+ Value *Addr = RMWI->getPointerOperand();
+ int Idx = getMemoryAccessFuncIndex(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<AtomicCmpXchgInst>(I)) {
+ Value *Addr = CASI->getPointerOperand();
+ int Idx = getMemoryAccessFuncIndex(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;
+ Type *OrigOldValTy = CASI->getNewValOperand()->getType();
+ 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(UndefValue::get(CASI->getType()), OldVal, 0);
+ Res = IRB.CreateInsertValue(Res, Success, 1);
+
+ I->replaceAllUsesWith(Res);
+ I->eraseFromParent();
+ } else if (FenceInst *FI = dyn_cast<FenceInst>(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(Value *Addr,
+ const DataLayout &DL) {
+ Type *OrigPtrTy = Addr->getType();
+ Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
+ assert(OrigTy->isSized());
+ 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;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-17 19:49:15 +0000