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+//===-- ThreadSanitizer.cpp - race detector -------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// 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.
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "tsan"
+
+#include "FunctionBlackList.h"
+#include "llvm/Function.h"
+#include "llvm/IRBuilder.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Metadata.h"
+#include "llvm/Module.h"
+#include "llvm/Type.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Instrumentation.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
+
+using namespace llvm;
+
+static cl::opt<std::string> ClBlackListFile("tsan-blacklist",
+ cl::desc("Blacklist file"), 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(NumOmittedReadsFromConstantGlobals,
+ "Number of reads from constant globals");
+STATISTIC(NumOmittedReadsFromVtable, "Number of vtable reads");
+
+namespace {
+
+/// ThreadSanitizer: instrument the code in module to find races.
+struct ThreadSanitizer : public FunctionPass {
+ ThreadSanitizer();
+ const char *getPassName() const;
+ bool runOnFunction(Function &F);
+ bool doInitialization(Module &M);
+ static char ID; // Pass identification, replacement for typeid.
+
+ private:
+ bool instrumentLoadOrStore(Instruction *I);
+ bool instrumentAtomic(Instruction *I);
+ void chooseInstructionsToInstrument(SmallVectorImpl<Instruction*> &Local,
+ SmallVectorImpl<Instruction*> &All);
+ bool addrPointsToConstantData(Value *Addr);
+ int getMemoryAccessFuncIndex(Value *Addr);
+
+ TargetData *TD;
+ OwningPtr<FunctionBlackList> BL;
+ IntegerType *OrdTy;
+ // Callbacks to run-time library are computed in doInitialization.
+ Function *TsanFuncEntry;
+ Function *TsanFuncExit;
+ // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
+ static const size_t kNumberOfAccessSizes = 5;
+ Function *TsanRead[kNumberOfAccessSizes];
+ Function *TsanWrite[kNumberOfAccessSizes];
+ Function *TsanAtomicLoad[kNumberOfAccessSizes];
+ Function *TsanAtomicStore[kNumberOfAccessSizes];
+ Function *TsanVptrUpdate;
+};
+} // namespace
+
+char ThreadSanitizer::ID = 0;
+INITIALIZE_PASS(ThreadSanitizer, "tsan",
+ "ThreadSanitizer: detects data races.",
+ false, false)
+
+const char *ThreadSanitizer::getPassName() const {
+ return "ThreadSanitizer";
+}
+
+ThreadSanitizer::ThreadSanitizer()
+ : FunctionPass(ID),
+ TD(NULL) {
+}
+
+FunctionPass *llvm::createThreadSanitizerPass() {
+ return new ThreadSanitizer();
+}
+
+static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
+ if (Function *F = dyn_cast<Function>(FuncOrBitcast))
+ return F;
+ FuncOrBitcast->dump();
+ report_fatal_error("ThreadSanitizer interface function redefined");
+}
+
+bool ThreadSanitizer::doInitialization(Module &M) {
+ TD = getAnalysisIfAvailable<TargetData>();
+ if (!TD)
+ return false;
+ BL.reset(new FunctionBlackList(ClBlackListFile));
+
+ // Always insert a call to __tsan_init into the module's CTORs.
+ IRBuilder<> IRB(M.getContext());
+ Value *TsanInit = M.getOrInsertFunction("__tsan_init",
+ IRB.getVoidTy(), NULL);
+ appendToGlobalCtors(M, cast<Function>(TsanInit), 0);
+
+ // Initialize the callbacks.
+ TsanFuncEntry = checkInterfaceFunction(M.getOrInsertFunction(
+ "__tsan_func_entry", IRB.getVoidTy(), IRB.getInt8PtrTy(), NULL));
+ TsanFuncExit = checkInterfaceFunction(M.getOrInsertFunction(
+ "__tsan_func_exit", IRB.getVoidTy(), NULL));
+ OrdTy = IRB.getInt32Ty();
+ for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
+ const size_t ByteSize = 1 << i;
+ const size_t BitSize = ByteSize * 8;
+ SmallString<32> ReadName("__tsan_read" + itostr(ByteSize));
+ TsanRead[i] = checkInterfaceFunction(M.getOrInsertFunction(
+ ReadName, IRB.getVoidTy(), IRB.getInt8PtrTy(), NULL));
+
+ SmallString<32> WriteName("__tsan_write" + itostr(ByteSize));
+ TsanWrite[i] = checkInterfaceFunction(M.getOrInsertFunction(
+ WriteName, IRB.getVoidTy(), IRB.getInt8PtrTy(), NULL));
+
+ Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
+ Type *PtrTy = Ty->getPointerTo();
+ SmallString<32> AtomicLoadName("__tsan_atomic" + itostr(BitSize) +
+ "_load");
+ TsanAtomicLoad[i] = checkInterfaceFunction(M.getOrInsertFunction(
+ AtomicLoadName, Ty, PtrTy, OrdTy, NULL));
+
+ SmallString<32> AtomicStoreName("__tsan_atomic" + itostr(BitSize) +
+ "_store");
+ TsanAtomicStore[i] = checkInterfaceFunction(M.getOrInsertFunction(
+ AtomicStoreName, IRB.getVoidTy(), PtrTy, Ty, OrdTy,
+ NULL));
+ }
+ TsanVptrUpdate = checkInterfaceFunction(M.getOrInsertFunction(
+ "__tsan_vptr_update", IRB.getVoidTy(), IRB.getInt8PtrTy(),
+ IRB.getInt8PtrTy(), NULL));
+ return true;
+}
+
+static bool isVtableAccess(Instruction *I) {
+ if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa)) {
+ if (Tag->getNumOperands() < 1) return false;
+ if (MDString *Tag1 = dyn_cast<MDString>(Tag->getOperand(0))) {
+ if (Tag1->getString() == "vtable pointer") return true;
+ }
+ }
+ return false;
+}
+
+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)
+//
+// 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) {
+ SmallSet<Value*, 8> WriteTargets;
+ // Iterate from the end.
+ for (SmallVectorImpl<Instruction*>::reverse_iterator It = Local.rbegin(),
+ E = Local.rend(); It != E; ++It) {
+ Instruction *I = *It;
+ if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
+ WriteTargets.insert(Store->getPointerOperand());
+ } else {
+ LoadInst *Load = cast<LoadInst>(I);
+ Value *Addr = Load->getPointerOperand();
+ 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;
+ }
+ }
+ All.push_back(I);
+ }
+ Local.clear();
+}
+
+static bool isAtomic(Instruction *I) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I))
+ return LI->isAtomic() && LI->getSynchScope() == CrossThread;
+ if (StoreInst *SI = dyn_cast<StoreInst>(I))
+ return SI->isAtomic() && SI->getSynchScope() == CrossThread;
+ if (isa<AtomicRMWInst>(I))
+ return true;
+ if (isa<AtomicCmpXchgInst>(I))
+ return true;
+ if (FenceInst *FI = dyn_cast<FenceInst>(I))
+ return FI->getSynchScope() == CrossThread;
+ return false;
+}
+
+bool ThreadSanitizer::runOnFunction(Function &F) {
+ if (!TD) return false;
+ if (BL->isIn(F)) return false;
+ SmallVector<Instruction*, 8> RetVec;
+ SmallVector<Instruction*, 8> AllLoadsAndStores;
+ SmallVector<Instruction*, 8> LocalLoadsAndStores;
+ SmallVector<Instruction*, 8> AtomicAccesses;
+ bool Res = false;
+ bool HasCalls = false;
+
+ // Traverse all instructions, collect loads/stores/returns, check for calls.
+ for (Function::iterator FI = F.begin(), FE = F.end();
+ FI != FE; ++FI) {
+ BasicBlock &BB = *FI;
+ for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
+ BI != BE; ++BI) {
+ if (isAtomic(BI))
+ AtomicAccesses.push_back(BI);
+ else if (isa<LoadInst>(BI) || isa<StoreInst>(BI))
+ LocalLoadsAndStores.push_back(BI);
+ else if (isa<ReturnInst>(BI))
+ RetVec.push_back(BI);
+ else if (isa<CallInst>(BI) || isa<InvokeInst>(BI)) {
+ HasCalls = true;
+ chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores);
+ }
+ }
+ chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores);
+ }
+
+ // 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.
+ for (size_t i = 0, n = AllLoadsAndStores.size(); i < n; ++i) {
+ Res |= instrumentLoadOrStore(AllLoadsAndStores[i]);
+ }
+
+ // Instrument atomic memory accesses.
+ for (size_t i = 0, n = AtomicAccesses.size(); i < n; ++i) {
+ Res |= instrumentAtomic(AtomicAccesses[i]);
+ }
+
+ // Instrument function entry/exit points if there were instrumented accesses.
+ if (Res || HasCalls) {
+ IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
+ Value *ReturnAddress = IRB.CreateCall(
+ Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
+ IRB.getInt32(0));
+ IRB.CreateCall(TsanFuncEntry, ReturnAddress);
+ for (size_t i = 0, n = RetVec.size(); i < n; ++i) {
+ IRBuilder<> IRBRet(RetVec[i]);
+ IRBRet.CreateCall(TsanFuncExit);
+ }
+ Res = true;
+ }
+ return Res;
+}
+
+bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I) {
+ IRBuilder<> IRB(I);
+ bool IsWrite = isa<StoreInst>(*I);
+ Value *Addr = IsWrite
+ ? cast<StoreInst>(I)->getPointerOperand()
+ : cast<LoadInst>(I)->getPointerOperand();
+ int Idx = getMemoryAccessFuncIndex(Addr);
+ if (Idx < 0)
+ return false;
+ if (IsWrite && isVtableAccess(I)) {
+ DEBUG(dbgs() << " VPTR : " << *I << "\n");
+ Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
+ // StoredValue does not necessary have a pointer type.
+ if (isa<IntegerType>(StoredValue->getType()))
+ StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
+ // Call TsanVptrUpdate.
+ IRB.CreateCall2(TsanVptrUpdate,
+ IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
+ IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy()));
+ NumInstrumentedVtableWrites++;
+ return true;
+ }
+ Value *OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[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 NotAtomic: assert(false);
+ case Unordered: // Fall-through.
+ case Monotonic: v = 1 << 0; break;
+ // case Consume: v = 1 << 1; break; // Not specified yet.
+ case Acquire: v = 1 << 2; break;
+ case Release: v = 1 << 3; break;
+ case AcquireRelease: v = 1 << 4; break;
+ case SequentiallyConsistent: v = 1 << 5; break;
+ }
+ return IRB->getInt32(v);
+}
+
+bool ThreadSanitizer::instrumentAtomic(Instruction *I) {
+ IRBuilder<> IRB(I);
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ Value *Addr = LI->getPointerOperand();
+ int Idx = getMemoryAccessFuncIndex(Addr);
+ if (Idx < 0)
+ return false;
+ const size_t ByteSize = 1 << Idx;
+ const size_t BitSize = ByteSize * 8;
+ Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
+ Type *PtrTy = Ty->getPointerTo();
+ Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
+ createOrdering(&IRB, LI->getOrdering())};
+ CallInst *C = CallInst::Create(TsanAtomicLoad[Idx],
+ ArrayRef<Value*>(Args));
+ ReplaceInstWithInst(I, C);
+
+ } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
+ Value *Addr = SI->getPointerOperand();
+ int Idx = getMemoryAccessFuncIndex(Addr);
+ if (Idx < 0)
+ return false;
+ const size_t ByteSize = 1 << Idx;
+ const size_t BitSize = ByteSize * 8;
+ Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
+ Type *PtrTy = Ty->getPointerTo();
+ Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
+ IRB.CreateIntCast(SI->getValueOperand(), Ty, false),
+ createOrdering(&IRB, SI->getOrdering())};
+ CallInst *C = CallInst::Create(TsanAtomicStore[Idx],
+ ArrayRef<Value*>(Args));
+ ReplaceInstWithInst(I, C);
+ } else if (isa<AtomicRMWInst>(I)) {
+ // FIXME: Not yet supported.
+ } else if (isa<AtomicCmpXchgInst>(I)) {
+ // FIXME: Not yet supported.
+ } else if (isa<FenceInst>(I)) {
+ // FIXME: Not yet supported.
+ }
+ return true;
+}
+
+int ThreadSanitizer::getMemoryAccessFuncIndex(Value *Addr) {
+ Type *OrigPtrTy = Addr->getType();
+ Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
+ assert(OrigTy->isSized());
+ uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
+ if (TypeSize != 8 && TypeSize != 16 &&
+ TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
+ NumAccessesWithBadSize++;
+ // Ignore all unusual sizes.
+ return -1;
+ }
+ size_t Idx = CountTrailingZeros_32(TypeSize / 8);
+ assert(Idx < kNumberOfAccessSizes);
+ return Idx;
+}
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