src/llvm/lib/Transforms/Instrumentation/ThreadSanitizer.cpp

   1 //===-- ThreadSanitizer.cpp - race detector -------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file is a part of ThreadSanitizer, a race detector.
  11 //
  12 // The tool is under development, for the details about previous versions see
  13 // http://code.google.com/p/data-race-test
  14 //
  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 //===----------------------------------------------------------------------===//
  21
  22 #include "llvm/Transforms/Instrumentation.h"
  23 #include "llvm/ADT/SmallSet.h"
  24 #include "llvm/ADT/SmallString.h"
  25 #include "llvm/ADT/SmallVector.h"
  26 #include "llvm/ADT/Statistic.h"
  27 #include "llvm/ADT/StringExtras.h"
  28 #include "llvm/IR/DataLayout.h"
  29 #include "llvm/IR/Function.h"
  30 #include "llvm/IR/IRBuilder.h"
  31 #include "llvm/IR/IntrinsicInst.h"
  32 #include "llvm/IR/Intrinsics.h"
  33 #include "llvm/IR/LLVMContext.h"
  34 #include "llvm/IR/Metadata.h"
  35 #include "llvm/IR/Module.h"
  36 #include "llvm/IR/Type.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/Transforms/Utils/BasicBlockUtils.h"
  42 #include "llvm/Transforms/Utils/ModuleUtils.h"
  43
  44 using namespace llvm;
  45
  46 #define DEBUG_TYPE "tsan"
  47
  48 static cl::opt<bool>  ClInstrumentMemoryAccesses(
  49     "tsan-instrument-memory-accesses", cl::init(true),
  50     cl::desc("Instrument memory accesses"), cl::Hidden);
  51 static cl::opt<bool>  ClInstrumentFuncEntryExit(
  52     "tsan-instrument-func-entry-exit", cl::init(true),
  53     cl::desc("Instrument function entry and exit"), cl::Hidden);
  54 static cl::opt<bool>  ClInstrumentAtomics(
  55     "tsan-instrument-atomics", cl::init(true),
  56     cl::desc("Instrument atomics"), cl::Hidden);
  57 static cl::opt<bool>  ClInstrumentMemIntrinsics(
  58     "tsan-instrument-memintrinsics", cl::init(true),
  59     cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden);
  60
  61 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
  62 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
  63 STATISTIC(NumOmittedReadsBeforeWrite,
  64           "Number of reads ignored due to following writes");
  65 STATISTIC(NumAccessesWithBadSize, "Number of accesses with bad size");
  66 STATISTIC(NumInstrumentedVtableWrites, "Number of vtable ptr writes");
  67 STATISTIC(NumInstrumentedVtableReads, "Number of vtable ptr reads");
  68 STATISTIC(NumOmittedReadsFromConstantGlobals,
  69           "Number of reads from constant globals");
  70 STATISTIC(NumOmittedReadsFromVtable, "Number of vtable reads");
  71
  72 namespace {
  73
  74 /// ThreadSanitizer: instrument the code in module to find races.
  75 struct ThreadSanitizer : public FunctionPass {
  76   ThreadSanitizer() : FunctionPass(ID), DL(nullptr) {}
  77   const char *getPassName() const override;
  78   bool runOnFunction(Function &F) override;
  79   bool doInitialization(Module &M) override;
  80   static char ID;  // Pass identification, replacement for typeid.
  81
  82  private:
  83   void initializeCallbacks(Module &M);
  84   bool instrumentLoadOrStore(Instruction *I);
  85   bool instrumentAtomic(Instruction *I);
  86   bool instrumentMemIntrinsic(Instruction *I);
  87   void chooseInstructionsToInstrument(SmallVectorImpl<Instruction*> &Local,
  88                                       SmallVectorImpl<Instruction*> &All);
  89   bool addrPointsToConstantData(Value *Addr);
  90   int getMemoryAccessFuncIndex(Value *Addr);
  91
  92   const DataLayout *DL;
  93   Type *IntptrTy;
  94   IntegerType *OrdTy;
  95   // Callbacks to run-time library are computed in doInitialization.
  96   Function *TsanFuncEntry;
  97   Function *TsanFuncExit;
  98   // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
  99   static const size_t kNumberOfAccessSizes = 5;
 100   Function *TsanRead[kNumberOfAccessSizes];
 101   Function *TsanWrite[kNumberOfAccessSizes];
 102   Function *TsanAtomicLoad[kNumberOfAccessSizes];
 103   Function *TsanAtomicStore[kNumberOfAccessSizes];
 104   Function *TsanAtomicRMW[AtomicRMWInst::LAST_BINOP + 1][kNumberOfAccessSizes];
 105   Function *TsanAtomicCAS[kNumberOfAccessSizes];
 106   Function *TsanAtomicThreadFence;
 107   Function *TsanAtomicSignalFence;
 108   Function *TsanVptrUpdate;
 109   Function *TsanVptrLoad;
 110   Function *MemmoveFn, *MemcpyFn, *MemsetFn;
 111 };
 112 }  // namespace
 113
 114 char ThreadSanitizer::ID = 0;
 115 INITIALIZE_PASS(ThreadSanitizer, "tsan",
 116     "ThreadSanitizer: detects data races.",
 117     false, false)
 118
 119 const char *ThreadSanitizer::getPassName() const {
 120   return "ThreadSanitizer";
 121 }
 122
 123 FunctionPass *llvm::createThreadSanitizerPass() {
 124   return new ThreadSanitizer();
 125 }
 126
 127 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
 128   if (Function *F = dyn_cast<Function>(FuncOrBitcast))
 129      return F;
 130   FuncOrBitcast->dump();
 131   report_fatal_error("ThreadSanitizer interface function redefined");
 132 }
 133
 134 void ThreadSanitizer::initializeCallbacks(Module &M) {
 135   IRBuilder<> IRB(M.getContext());
 136   // Initialize the callbacks.
 137   TsanFuncEntry = checkInterfaceFunction(M.getOrInsertFunction(
 138       "__tsan_func_entry", IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 139   TsanFuncExit = checkInterfaceFunction(M.getOrInsertFunction(
 140       "__tsan_func_exit", IRB.getVoidTy(), nullptr));
 141   OrdTy = IRB.getInt32Ty();
 142   for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
 143     const size_t ByteSize = 1 << i;
 144     const size_t BitSize = ByteSize * 8;
 145     SmallString<32> ReadName("__tsan_read" + itostr(ByteSize));
 146     TsanRead[i] = checkInterfaceFunction(M.getOrInsertFunction(
 147         ReadName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 148
 149     SmallString<32> WriteName("__tsan_write" + itostr(ByteSize));
 150     TsanWrite[i] = checkInterfaceFunction(M.getOrInsertFunction(
 151         WriteName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 152
 153     Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
 154     Type *PtrTy = Ty->getPointerTo();
 155     SmallString<32> AtomicLoadName("__tsan_atomic" + itostr(BitSize) +
 156                                    "_load");
 157     TsanAtomicLoad[i] = checkInterfaceFunction(M.getOrInsertFunction(
 158         AtomicLoadName, Ty, PtrTy, OrdTy, nullptr));
 159
 160     SmallString<32> AtomicStoreName("__tsan_atomic" + itostr(BitSize) +
 161                                     "_store");
 162     TsanAtomicStore[i] = checkInterfaceFunction(M.getOrInsertFunction(
 163         AtomicStoreName, IRB.getVoidTy(), PtrTy, Ty, OrdTy,
 164         nullptr));
 165
 166     for (int op = AtomicRMWInst::FIRST_BINOP;
 167         op <= AtomicRMWInst::LAST_BINOP; ++op) {
 168       TsanAtomicRMW[op][i] = nullptr;
 169       const char *NamePart = nullptr;
 170       if (op == AtomicRMWInst::Xchg)
 171         NamePart = "_exchange";
 172       else if (op == AtomicRMWInst::Add)
 173         NamePart = "_fetch_add";
 174       else if (op == AtomicRMWInst::Sub)
 175         NamePart = "_fetch_sub";
 176       else if (op == AtomicRMWInst::And)
 177         NamePart = "_fetch_and";
 178       else if (op == AtomicRMWInst::Or)
 179         NamePart = "_fetch_or";
 180       else if (op == AtomicRMWInst::Xor)
 181         NamePart = "_fetch_xor";
 182       else if (op == AtomicRMWInst::Nand)
 183         NamePart = "_fetch_nand";
 184       else
 185         continue;
 186       SmallString<32> RMWName("__tsan_atomic" + itostr(BitSize) + NamePart);
 187       TsanAtomicRMW[op][i] = checkInterfaceFunction(M.getOrInsertFunction(
 188           RMWName, Ty, PtrTy, Ty, OrdTy, nullptr));
 189     }
 190
 191     SmallString<32> AtomicCASName("__tsan_atomic" + itostr(BitSize) +
 192                                   "_compare_exchange_val");
 193     TsanAtomicCAS[i] = checkInterfaceFunction(M.getOrInsertFunction(
 194         AtomicCASName, Ty, PtrTy, Ty, Ty, OrdTy, OrdTy, nullptr));
 195   }
 196   TsanVptrUpdate = checkInterfaceFunction(M.getOrInsertFunction(
 197       "__tsan_vptr_update", IRB.getVoidTy(), IRB.getInt8PtrTy(),
 198       IRB.getInt8PtrTy(), nullptr));
 199   TsanVptrLoad = checkInterfaceFunction(M.getOrInsertFunction(
 200       "__tsan_vptr_read", IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 201   TsanAtomicThreadFence = checkInterfaceFunction(M.getOrInsertFunction(
 202       "__tsan_atomic_thread_fence", IRB.getVoidTy(), OrdTy, nullptr));
 203   TsanAtomicSignalFence = checkInterfaceFunction(M.getOrInsertFunction(
 204       "__tsan_atomic_signal_fence", IRB.getVoidTy(), OrdTy, nullptr));
 205
 206   MemmoveFn = checkInterfaceFunction(M.getOrInsertFunction(
 207     "memmove", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
 208     IRB.getInt8PtrTy(), IntptrTy, nullptr));
 209   MemcpyFn = checkInterfaceFunction(M.getOrInsertFunction(
 210     "memcpy", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
 211     IntptrTy, nullptr));
 212   MemsetFn = checkInterfaceFunction(M.getOrInsertFunction(
 213     "memset", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt32Ty(),
 214     IntptrTy, nullptr));
 215 }
 216
 217 bool ThreadSanitizer::doInitialization(Module &M) {
 218   DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
 219   if (!DLP)
 220     report_fatal_error("data layout missing");
 221   DL = &DLP->getDataLayout();
 222
 223   // Always insert a call to __tsan_init into the module's CTORs.
 224   IRBuilder<> IRB(M.getContext());
 225   IntptrTy = IRB.getIntPtrTy(DL);
 226   Value *TsanInit = M.getOrInsertFunction("__tsan_init",
 227                                           IRB.getVoidTy(), nullptr);
 228   appendToGlobalCtors(M, cast<Function>(TsanInit), 0);
 229
 230   return true;
 231 }
 232
 233 static bool isVtableAccess(Instruction *I) {
 234   if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa))
 235     return Tag->isTBAAVtableAccess();
 236   return false;
 237 }
 238
 239 bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) {
 240   // If this is a GEP, just analyze its pointer operand.
 241   if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
 242     Addr = GEP->getPointerOperand();
 243
 244   if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
 245     if (GV->isConstant()) {
 246       // Reads from constant globals can not race with any writes.
 247       NumOmittedReadsFromConstantGlobals++;
 248       return true;
 249     }
 250   } else if (LoadInst *L = dyn_cast<LoadInst>(Addr)) {
 251     if (isVtableAccess(L)) {
 252       // Reads from a vtable pointer can not race with any writes.
 253       NumOmittedReadsFromVtable++;
 254       return true;
 255     }
 256   }
 257   return false;
 258 }
 259
 260 // Instrumenting some of the accesses may be proven redundant.
 261 // Currently handled:
 262 //  - read-before-write (within same BB, no calls between)
 263 //
 264 // We do not handle some of the patterns that should not survive
 265 // after the classic compiler optimizations.
 266 // E.g. two reads from the same temp should be eliminated by CSE,
 267 // two writes should be eliminated by DSE, etc.
 268 //
 269 // 'Local' is a vector of insns within the same BB (no calls between).
 270 // 'All' is a vector of insns that will be instrumented.
 271 void ThreadSanitizer::chooseInstructionsToInstrument(
 272     SmallVectorImpl<Instruction*> &Local,
 273     SmallVectorImpl<Instruction*> &All) {
 274   SmallSet<Value*, 8> WriteTargets;
 275   // Iterate from the end.
 276   for (SmallVectorImpl<Instruction*>::reverse_iterator It = Local.rbegin(),
 277        E = Local.rend(); It != E; ++It) {
 278     Instruction *I = *It;
 279     if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
 280       WriteTargets.insert(Store->getPointerOperand());
 281     } else {
 282       LoadInst *Load = cast<LoadInst>(I);
 283       Value *Addr = Load->getPointerOperand();
 284       if (WriteTargets.count(Addr)) {
 285         // We will write to this temp, so no reason to analyze the read.
 286         NumOmittedReadsBeforeWrite++;
 287         continue;
 288       }
 289       if (addrPointsToConstantData(Addr)) {
 290         // Addr points to some constant data -- it can not race with any writes.
 291         continue;
 292       }
 293     }
 294     All.push_back(I);
 295   }
 296   Local.clear();
 297 }
 298
 299 static bool isAtomic(Instruction *I) {
 300   if (LoadInst *LI = dyn_cast<LoadInst>(I))
 301     return LI->isAtomic() && LI->getSynchScope() == CrossThread;
 302   if (StoreInst *SI = dyn_cast<StoreInst>(I))
 303     return SI->isAtomic() && SI->getSynchScope() == CrossThread;
 304   if (isa<AtomicRMWInst>(I))
 305     return true;
 306   if (isa<AtomicCmpXchgInst>(I))
 307     return true;
 308   if (isa<FenceInst>(I))
 309     return true;
 310   return false;
 311 }
 312
 313 bool ThreadSanitizer::runOnFunction(Function &F) {
 314   if (!DL) return false;
 315   initializeCallbacks(*F.getParent());
 316   SmallVector<Instruction*, 8> RetVec;
 317   SmallVector<Instruction*, 8> AllLoadsAndStores;
 318   SmallVector<Instruction*, 8> LocalLoadsAndStores;
 319   SmallVector<Instruction*, 8> AtomicAccesses;
 320   SmallVector<Instruction*, 8> MemIntrinCalls;
 321   bool Res = false;
 322   bool HasCalls = false;
 323   bool SanitizeFunction = F.hasFnAttribute(Attribute::SanitizeThread);
 324
 325   // Traverse all instructions, collect loads/stores/returns, check for calls.
 326   for (auto &BB : F) {
 327     for (auto &Inst : BB) {
 328       if (isAtomic(&Inst))
 329         AtomicAccesses.push_back(&Inst);
 330       else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
 331         LocalLoadsAndStores.push_back(&Inst);
 332       else if (isa<ReturnInst>(Inst))
 333         RetVec.push_back(&Inst);
 334       else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
 335         if (isa<MemIntrinsic>(Inst))
 336           MemIntrinCalls.push_back(&Inst);
 337         HasCalls = true;
 338         chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores);
 339       }
 340     }
 341     chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores);
 342   }
 343
 344   // We have collected all loads and stores.
 345   // FIXME: many of these accesses do not need to be checked for races
 346   // (e.g. variables that do not escape, etc).
 347
 348   // Instrument memory accesses only if we want to report bugs in the function.
 349   if (ClInstrumentMemoryAccesses && SanitizeFunction)
 350     for (auto Inst : AllLoadsAndStores) {
 351       Res |= instrumentLoadOrStore(Inst);
 352     }
 353
 354   // Instrument atomic memory accesses in any case (they can be used to
 355   // implement synchronization).
 356   if (ClInstrumentAtomics)
 357     for (auto Inst : AtomicAccesses) {
 358       Res |= instrumentAtomic(Inst);
 359     }
 360
 361   if (ClInstrumentMemIntrinsics && SanitizeFunction)
 362     for (auto Inst : MemIntrinCalls) {
 363       Res |= instrumentMemIntrinsic(Inst);
 364     }
 365
 366   // Instrument function entry/exit points if there were instrumented accesses.
 367   if ((Res || HasCalls) && ClInstrumentFuncEntryExit) {
 368     IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
 369     Value *ReturnAddress = IRB.CreateCall(
 370         Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
 371         IRB.getInt32(0));
 372     IRB.CreateCall(TsanFuncEntry, ReturnAddress);
 373     for (auto RetInst : RetVec) {
 374       IRBuilder<> IRBRet(RetInst);
 375       IRBRet.CreateCall(TsanFuncExit);
 376     }
 377     Res = true;
 378   }
 379   return Res;
 380 }
 381
 382 bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I) {
 383   IRBuilder<> IRB(I);
 384   bool IsWrite = isa<StoreInst>(*I);
 385   Value *Addr = IsWrite
 386       ? cast<StoreInst>(I)->getPointerOperand()
 387       : cast<LoadInst>(I)->getPointerOperand();
 388   int Idx = getMemoryAccessFuncIndex(Addr);
 389   if (Idx < 0)
 390     return false;
 391   if (IsWrite && isVtableAccess(I)) {
 392     DEBUG(dbgs() << "  VPTR : " << *I << "\n");
 393     Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
 394     // StoredValue may be a vector type if we are storing several vptrs at once.
 395     // In this case, just take the first element of the vector since this is
 396     // enough to find vptr races.
 397     if (isa<VectorType>(StoredValue->getType()))
 398       StoredValue = IRB.CreateExtractElement(
 399           StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0));
 400     if (StoredValue->getType()->isIntegerTy())
 401       StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
 402     // Call TsanVptrUpdate.
 403     IRB.CreateCall2(TsanVptrUpdate,
 404                     IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
 405                     IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy()));
 406     NumInstrumentedVtableWrites++;
 407     return true;
 408   }
 409   if (!IsWrite && isVtableAccess(I)) {
 410     IRB.CreateCall(TsanVptrLoad,
 411                    IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
 412     NumInstrumentedVtableReads++;
 413     return true;
 414   }
 415   Value *OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
 416   IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
 417   if (IsWrite) NumInstrumentedWrites++;
 418   else         NumInstrumentedReads++;
 419   return true;
 420 }
 421
 422 static ConstantInt *createOrdering(IRBuilder<> *IRB, AtomicOrdering ord) {
 423   uint32_t v = 0;
 424   switch (ord) {
 425     case NotAtomic: llvm_unreachable("unexpected atomic ordering!");
 426     case Unordered:              // Fall-through.
 427     case Monotonic:              v = 0; break;
 428     // case Consume:                v = 1; break;  // Not specified yet.
 429     case Acquire:                v = 2; break;
 430     case Release:                v = 3; break;
 431     case AcquireRelease:         v = 4; break;
 432     case SequentiallyConsistent: v = 5; break;
 433   }
 434   return IRB->getInt32(v);
 435 }
 436
 437 // If a memset intrinsic gets inlined by the code gen, we will miss races on it.
 438 // So, we either need to ensure the intrinsic is not inlined, or instrument it.
 439 // We do not instrument memset/memmove/memcpy intrinsics (too complicated),
 440 // instead we simply replace them with regular function calls, which are then
 441 // intercepted by the run-time.
 442 // Since tsan is running after everyone else, the calls should not be
 443 // replaced back with intrinsics. If that becomes wrong at some point,
 444 // we will need to call e.g. __tsan_memset to avoid the intrinsics.
 445 bool ThreadSanitizer::instrumentMemIntrinsic(Instruction *I) {
 446   IRBuilder<> IRB(I);
 447   if (MemSetInst *M = dyn_cast<MemSetInst>(I)) {
 448     IRB.CreateCall3(MemsetFn,
 449       IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
 450       IRB.CreateIntCast(M->getArgOperand(1), IRB.getInt32Ty(), false),
 451       IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false));
 452     I->eraseFromParent();
 453   } else if (MemTransferInst *M = dyn_cast<MemTransferInst>(I)) {
 454     IRB.CreateCall3(isa<MemCpyInst>(M) ? MemcpyFn : MemmoveFn,
 455       IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
 456       IRB.CreatePointerCast(M->getArgOperand(1), IRB.getInt8PtrTy()),
 457       IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false));
 458     I->eraseFromParent();
 459   }
 460   return false;
 461 }
 462
 463 // Both llvm and ThreadSanitizer atomic operations are based on C++11/C1x
 464 // standards.  For background see C++11 standard.  A slightly older, publicly
 465 // available draft of the standard (not entirely up-to-date, but close enough
 466 // for casual browsing) is available here:
 467 // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf
 468 // The following page contains more background information:
 469 // http://www.hpl.hp.com/personal/Hans_Boehm/c++mm/
 470
 471 bool ThreadSanitizer::instrumentAtomic(Instruction *I) {
 472   IRBuilder<> IRB(I);
 473   if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
 474     Value *Addr = LI->getPointerOperand();
 475     int Idx = getMemoryAccessFuncIndex(Addr);
 476     if (Idx < 0)
 477       return false;
 478     const size_t ByteSize = 1 << Idx;
 479     const size_t BitSize = ByteSize * 8;
 480     Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
 481     Type *PtrTy = Ty->getPointerTo();
 482     Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
 483                      createOrdering(&IRB, LI->getOrdering())};
 484     CallInst *C = CallInst::Create(TsanAtomicLoad[Idx], Args);
 485     ReplaceInstWithInst(I, C);
 486
 487   } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
 488     Value *Addr = SI->getPointerOperand();
 489     int Idx = getMemoryAccessFuncIndex(Addr);
 490     if (Idx < 0)
 491       return false;
 492     const size_t ByteSize = 1 << Idx;
 493     const size_t BitSize = ByteSize * 8;
 494     Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
 495     Type *PtrTy = Ty->getPointerTo();
 496     Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
 497                      IRB.CreateIntCast(SI->getValueOperand(), Ty, false),
 498                      createOrdering(&IRB, SI->getOrdering())};
 499     CallInst *C = CallInst::Create(TsanAtomicStore[Idx], Args);
 500     ReplaceInstWithInst(I, C);
 501   } else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I)) {
 502     Value *Addr = RMWI->getPointerOperand();
 503     int Idx = getMemoryAccessFuncIndex(Addr);
 504     if (Idx < 0)
 505       return false;
 506     Function *F = TsanAtomicRMW[RMWI->getOperation()][Idx];
 507     if (!F)
 508       return false;
 509     const size_t ByteSize = 1 << Idx;
 510     const size_t BitSize = ByteSize * 8;
 511     Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
 512     Type *PtrTy = Ty->getPointerTo();
 513     Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
 514                      IRB.CreateIntCast(RMWI->getValOperand(), Ty, false),
 515                      createOrdering(&IRB, RMWI->getOrdering())};
 516     CallInst *C = CallInst::Create(F, Args);
 517     ReplaceInstWithInst(I, C);
 518   } else if (AtomicCmpXchgInst *CASI = dyn_cast<AtomicCmpXchgInst>(I)) {
 519     Value *Addr = CASI->getPointerOperand();
 520     int Idx = getMemoryAccessFuncIndex(Addr);
 521     if (Idx < 0)
 522       return false;
 523     const size_t ByteSize = 1 << Idx;
 524     const size_t BitSize = ByteSize * 8;
 525     Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
 526     Type *PtrTy = Ty->getPointerTo();
 527     Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
 528                      IRB.CreateIntCast(CASI->getCompareOperand(), Ty, false),
 529                      IRB.CreateIntCast(CASI->getNewValOperand(), Ty, false),
 530                      createOrdering(&IRB, CASI->getSuccessOrdering()),
 531                      createOrdering(&IRB, CASI->getFailureOrdering())};
 532     CallInst *C = IRB.CreateCall(TsanAtomicCAS[Idx], Args);
 533     Value *Success = IRB.CreateICmpEQ(C, CASI->getCompareOperand());
 534
 535     Value *Res = IRB.CreateInsertValue(UndefValue::get(CASI->getType()), C, 0);
 536     Res = IRB.CreateInsertValue(Res, Success, 1);
 537
 538     I->replaceAllUsesWith(Res);
 539     I->eraseFromParent();
 540   } else if (FenceInst *FI = dyn_cast<FenceInst>(I)) {
 541     Value *Args[] = {createOrdering(&IRB, FI->getOrdering())};
 542     Function *F = FI->getSynchScope() == SingleThread ?
 543         TsanAtomicSignalFence : TsanAtomicThreadFence;
 544     CallInst *C = CallInst::Create(F, Args);
 545     ReplaceInstWithInst(I, C);
 546   }
 547   return true;
 548 }
 549
 550 int ThreadSanitizer::getMemoryAccessFuncIndex(Value *Addr) {
 551   Type *OrigPtrTy = Addr->getType();
 552   Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
 553   assert(OrigTy->isSized());
 554   uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
 555   if (TypeSize != 8  && TypeSize != 16 &&
 556       TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
 557     NumAccessesWithBadSize++;
 558     // Ignore all unusual sizes.
 559     return -1;
 560   }
 561   size_t Idx = countTrailingZeros(TypeSize / 8);
 562   assert(Idx < kNumberOfAccessSizes);
 563   return Idx;
 564 }