1 //===-- ThreadSanitizer.cpp - race detector -------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of ThreadSanitizer, a race detector.
12 // The tool is under development, for the details about previous versions see
13 // http://code.google.com/p/data-race-test
15 // The instrumentation phase is quite simple:
16 // - Insert calls to run-time library before every memory access.
17 // - Optimizations may apply to avoid instrumenting some of the accesses.
18 // - Insert calls at function entry/exit.
19 // The rest is handled by the run-time library.
20 //===----------------------------------------------------------------------===//
22 #define DEBUG_TYPE "tsan"
24 #include "BlackList.h"
25 #include "llvm/Function.h"
26 #include "llvm/IRBuilder.h"
27 #include "llvm/Intrinsics.h"
28 #include "llvm/LLVMContext.h"
29 #include "llvm/Metadata.h"
30 #include "llvm/Module.h"
31 #include "llvm/Type.h"
32 #include "llvm/ADT/SmallSet.h"
33 #include "llvm/ADT/SmallString.h"
34 #include "llvm/ADT/SmallVector.h"
35 #include "llvm/ADT/Statistic.h"
36 #include "llvm/ADT/StringExtras.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/Debug.h"
39 #include "llvm/Support/MathExtras.h"
40 #include "llvm/Support/raw_ostream.h"
41 #include "llvm/DataLayout.h"
42 #include "llvm/Transforms/Instrumentation.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/ModuleUtils.h"
48 static cl::opt<std::string> ClBlackListFile("tsan-blacklist",
49 cl::desc("Blacklist file"), cl::Hidden);
50 static cl::opt<bool> ClInstrumentMemoryAccesses(
51 "tsan-instrument-memory-accesses", cl::init(true),
52 cl::desc("Instrument memory accesses"), cl::Hidden);
53 static cl::opt<bool> ClInstrumentFuncEntryExit(
54 "tsan-instrument-func-entry-exit", cl::init(true),
55 cl::desc("Instrument function entry and exit"), cl::Hidden);
56 static cl::opt<bool> ClInstrumentAtomics(
57 "tsan-instrument-atomics", cl::init(true),
58 cl::desc("Instrument atomics"), cl::Hidden);
60 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
61 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
62 STATISTIC(NumOmittedReadsBeforeWrite,
63 "Number of reads ignored due to following writes");
64 STATISTIC(NumAccessesWithBadSize, "Number of accesses with bad size");
65 STATISTIC(NumInstrumentedVtableWrites, "Number of vtable ptr writes");
66 STATISTIC(NumOmittedReadsFromConstantGlobals,
67 "Number of reads from constant globals");
68 STATISTIC(NumOmittedReadsFromVtable, "Number of vtable reads");
72 /// ThreadSanitizer: instrument the code in module to find races.
73 struct ThreadSanitizer : public FunctionPass {
75 const char *getPassName() const;
76 bool runOnFunction(Function &F);
77 bool doInitialization(Module &M);
78 static char ID; // Pass identification, replacement for typeid.
81 bool instrumentLoadOrStore(Instruction *I);
82 bool instrumentAtomic(Instruction *I);
83 void chooseInstructionsToInstrument(SmallVectorImpl<Instruction*> &Local,
84 SmallVectorImpl<Instruction*> &All);
85 bool addrPointsToConstantData(Value *Addr);
86 int getMemoryAccessFuncIndex(Value *Addr);
89 OwningPtr<BlackList> BL;
91 // Callbacks to run-time library are computed in doInitialization.
92 Function *TsanFuncEntry;
93 Function *TsanFuncExit;
94 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
95 static const size_t kNumberOfAccessSizes = 5;
96 Function *TsanRead[kNumberOfAccessSizes];
97 Function *TsanWrite[kNumberOfAccessSizes];
98 Function *TsanAtomicLoad[kNumberOfAccessSizes];
99 Function *TsanAtomicStore[kNumberOfAccessSizes];
100 Function *TsanVptrUpdate;
104 char ThreadSanitizer::ID = 0;
105 INITIALIZE_PASS(ThreadSanitizer, "tsan",
106 "ThreadSanitizer: detects data races.",
109 const char *ThreadSanitizer::getPassName() const {
110 return "ThreadSanitizer";
113 ThreadSanitizer::ThreadSanitizer()
118 FunctionPass *llvm::createThreadSanitizerPass() {
119 return new ThreadSanitizer();
122 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
123 if (Function *F = dyn_cast<Function>(FuncOrBitcast))
125 FuncOrBitcast->dump();
126 report_fatal_error("ThreadSanitizer interface function redefined");
129 bool ThreadSanitizer::doInitialization(Module &M) {
130 TD = getAnalysisIfAvailable<DataLayout>();
133 BL.reset(new BlackList(ClBlackListFile));
135 // Always insert a call to __tsan_init into the module's CTORs.
136 IRBuilder<> IRB(M.getContext());
137 Value *TsanInit = M.getOrInsertFunction("__tsan_init",
138 IRB.getVoidTy(), NULL);
139 appendToGlobalCtors(M, cast<Function>(TsanInit), 0);
141 // Initialize the callbacks.
142 TsanFuncEntry = checkInterfaceFunction(M.getOrInsertFunction(
143 "__tsan_func_entry", IRB.getVoidTy(), IRB.getInt8PtrTy(), NULL));
144 TsanFuncExit = checkInterfaceFunction(M.getOrInsertFunction(
145 "__tsan_func_exit", IRB.getVoidTy(), NULL));
146 OrdTy = IRB.getInt32Ty();
147 for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
148 const size_t ByteSize = 1 << i;
149 const size_t BitSize = ByteSize * 8;
150 SmallString<32> ReadName("__tsan_read" + itostr(ByteSize));
151 TsanRead[i] = checkInterfaceFunction(M.getOrInsertFunction(
152 ReadName, IRB.getVoidTy(), IRB.getInt8PtrTy(), NULL));
154 SmallString<32> WriteName("__tsan_write" + itostr(ByteSize));
155 TsanWrite[i] = checkInterfaceFunction(M.getOrInsertFunction(
156 WriteName, IRB.getVoidTy(), IRB.getInt8PtrTy(), NULL));
158 Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
159 Type *PtrTy = Ty->getPointerTo();
160 SmallString<32> AtomicLoadName("__tsan_atomic" + itostr(BitSize) +
162 TsanAtomicLoad[i] = checkInterfaceFunction(M.getOrInsertFunction(
163 AtomicLoadName, Ty, PtrTy, OrdTy, NULL));
165 SmallString<32> AtomicStoreName("__tsan_atomic" + itostr(BitSize) +
167 TsanAtomicStore[i] = checkInterfaceFunction(M.getOrInsertFunction(
168 AtomicStoreName, IRB.getVoidTy(), PtrTy, Ty, OrdTy,
171 TsanVptrUpdate = checkInterfaceFunction(M.getOrInsertFunction(
172 "__tsan_vptr_update", IRB.getVoidTy(), IRB.getInt8PtrTy(),
173 IRB.getInt8PtrTy(), NULL));
177 static bool isVtableAccess(Instruction *I) {
178 if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa)) {
179 if (Tag->getNumOperands() < 1) return false;
180 if (MDString *Tag1 = dyn_cast<MDString>(Tag->getOperand(0))) {
181 if (Tag1->getString() == "vtable pointer") return true;
187 bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) {
188 // If this is a GEP, just analyze its pointer operand.
189 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
190 Addr = GEP->getPointerOperand();
192 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
193 if (GV->isConstant()) {
194 // Reads from constant globals can not race with any writes.
195 NumOmittedReadsFromConstantGlobals++;
198 } else if (LoadInst *L = dyn_cast<LoadInst>(Addr)) {
199 if (isVtableAccess(L)) {
200 // Reads from a vtable pointer can not race with any writes.
201 NumOmittedReadsFromVtable++;
208 // Instrumenting some of the accesses may be proven redundant.
209 // Currently handled:
210 // - read-before-write (within same BB, no calls between)
212 // We do not handle some of the patterns that should not survive
213 // after the classic compiler optimizations.
214 // E.g. two reads from the same temp should be eliminated by CSE,
215 // two writes should be eliminated by DSE, etc.
217 // 'Local' is a vector of insns within the same BB (no calls between).
218 // 'All' is a vector of insns that will be instrumented.
219 void ThreadSanitizer::chooseInstructionsToInstrument(
220 SmallVectorImpl<Instruction*> &Local,
221 SmallVectorImpl<Instruction*> &All) {
222 SmallSet<Value*, 8> WriteTargets;
223 // Iterate from the end.
224 for (SmallVectorImpl<Instruction*>::reverse_iterator It = Local.rbegin(),
225 E = Local.rend(); It != E; ++It) {
226 Instruction *I = *It;
227 if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
228 WriteTargets.insert(Store->getPointerOperand());
230 LoadInst *Load = cast<LoadInst>(I);
231 Value *Addr = Load->getPointerOperand();
232 if (WriteTargets.count(Addr)) {
233 // We will write to this temp, so no reason to analyze the read.
234 NumOmittedReadsBeforeWrite++;
237 if (addrPointsToConstantData(Addr)) {
238 // Addr points to some constant data -- it can not race with any writes.
247 static bool isAtomic(Instruction *I) {
248 if (LoadInst *LI = dyn_cast<LoadInst>(I))
249 return LI->isAtomic() && LI->getSynchScope() == CrossThread;
250 if (StoreInst *SI = dyn_cast<StoreInst>(I))
251 return SI->isAtomic() && SI->getSynchScope() == CrossThread;
252 if (isa<AtomicRMWInst>(I))
254 if (isa<AtomicCmpXchgInst>(I))
256 if (FenceInst *FI = dyn_cast<FenceInst>(I))
257 return FI->getSynchScope() == CrossThread;
261 bool ThreadSanitizer::runOnFunction(Function &F) {
262 if (!TD) return false;
263 if (BL->isIn(F)) return false;
264 SmallVector<Instruction*, 8> RetVec;
265 SmallVector<Instruction*, 8> AllLoadsAndStores;
266 SmallVector<Instruction*, 8> LocalLoadsAndStores;
267 SmallVector<Instruction*, 8> AtomicAccesses;
269 bool HasCalls = false;
271 // Traverse all instructions, collect loads/stores/returns, check for calls.
272 for (Function::iterator FI = F.begin(), FE = F.end();
274 BasicBlock &BB = *FI;
275 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
278 AtomicAccesses.push_back(BI);
279 else if (isa<LoadInst>(BI) || isa<StoreInst>(BI))
280 LocalLoadsAndStores.push_back(BI);
281 else if (isa<ReturnInst>(BI))
282 RetVec.push_back(BI);
283 else if (isa<CallInst>(BI) || isa<InvokeInst>(BI)) {
285 chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores);
288 chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores);
291 // We have collected all loads and stores.
292 // FIXME: many of these accesses do not need to be checked for races
293 // (e.g. variables that do not escape, etc).
295 // Instrument memory accesses.
296 if (ClInstrumentMemoryAccesses)
297 for (size_t i = 0, n = AllLoadsAndStores.size(); i < n; ++i) {
298 Res |= instrumentLoadOrStore(AllLoadsAndStores[i]);
301 // Instrument atomic memory accesses.
302 if (ClInstrumentAtomics)
303 for (size_t i = 0, n = AtomicAccesses.size(); i < n; ++i) {
304 Res |= instrumentAtomic(AtomicAccesses[i]);
307 // Instrument function entry/exit points if there were instrumented accesses.
308 if ((Res || HasCalls) && ClInstrumentFuncEntryExit) {
309 IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
310 Value *ReturnAddress = IRB.CreateCall(
311 Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
313 IRB.CreateCall(TsanFuncEntry, ReturnAddress);
314 for (size_t i = 0, n = RetVec.size(); i < n; ++i) {
315 IRBuilder<> IRBRet(RetVec[i]);
316 IRBRet.CreateCall(TsanFuncExit);
323 bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I) {
325 bool IsWrite = isa<StoreInst>(*I);
326 Value *Addr = IsWrite
327 ? cast<StoreInst>(I)->getPointerOperand()
328 : cast<LoadInst>(I)->getPointerOperand();
329 int Idx = getMemoryAccessFuncIndex(Addr);
332 if (IsWrite && isVtableAccess(I)) {
333 DEBUG(dbgs() << " VPTR : " << *I << "\n");
334 Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
335 // StoredValue does not necessary have a pointer type.
336 if (isa<IntegerType>(StoredValue->getType()))
337 StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
338 // Call TsanVptrUpdate.
339 IRB.CreateCall2(TsanVptrUpdate,
340 IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
341 IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy()));
342 NumInstrumentedVtableWrites++;
345 Value *OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
346 IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
347 if (IsWrite) NumInstrumentedWrites++;
348 else NumInstrumentedReads++;
352 static ConstantInt *createOrdering(IRBuilder<> *IRB, AtomicOrdering ord) {
355 case NotAtomic: assert(false);
356 case Unordered: // Fall-through.
357 case Monotonic: v = 1 << 0; break;
358 // case Consume: v = 1 << 1; break; // Not specified yet.
359 case Acquire: v = 1 << 2; break;
360 case Release: v = 1 << 3; break;
361 case AcquireRelease: v = 1 << 4; break;
362 case SequentiallyConsistent: v = 1 << 5; break;
364 // +100500 is temporal to migrate to new enum values.
365 return IRB->getInt32(v + 100500);
368 bool ThreadSanitizer::instrumentAtomic(Instruction *I) {
370 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
371 Value *Addr = LI->getPointerOperand();
372 int Idx = getMemoryAccessFuncIndex(Addr);
375 const size_t ByteSize = 1 << Idx;
376 const size_t BitSize = ByteSize * 8;
377 Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
378 Type *PtrTy = Ty->getPointerTo();
379 Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
380 createOrdering(&IRB, LI->getOrdering())};
381 CallInst *C = CallInst::Create(TsanAtomicLoad[Idx],
382 ArrayRef<Value*>(Args));
383 ReplaceInstWithInst(I, C);
385 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
386 Value *Addr = SI->getPointerOperand();
387 int Idx = getMemoryAccessFuncIndex(Addr);
390 const size_t ByteSize = 1 << Idx;
391 const size_t BitSize = ByteSize * 8;
392 Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
393 Type *PtrTy = Ty->getPointerTo();
394 Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
395 IRB.CreateIntCast(SI->getValueOperand(), Ty, false),
396 createOrdering(&IRB, SI->getOrdering())};
397 CallInst *C = CallInst::Create(TsanAtomicStore[Idx],
398 ArrayRef<Value*>(Args));
399 ReplaceInstWithInst(I, C);
400 } else if (isa<AtomicRMWInst>(I)) {
401 // FIXME: Not yet supported.
402 } else if (isa<AtomicCmpXchgInst>(I)) {
403 // FIXME: Not yet supported.
404 } else if (isa<FenceInst>(I)) {
405 // FIXME: Not yet supported.
410 int ThreadSanitizer::getMemoryAccessFuncIndex(Value *Addr) {
411 Type *OrigPtrTy = Addr->getType();
412 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
413 assert(OrigTy->isSized());
414 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
415 if (TypeSize != 8 && TypeSize != 16 &&
416 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
417 NumAccessesWithBadSize++;
418 // Ignore all unusual sizes.
421 size_t Idx = CountTrailingZeros_32(TypeSize / 8);
422 assert(Idx < kNumberOfAccessSizes);