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/Analysis/CaptureTracking.h"
29#include "llvm/Analysis/ValueTracking.h"
30#include "llvm/IR/DataLayout.h"
31#include "llvm/IR/Function.h"
32#include "llvm/IR/IRBuilder.h"
33#include "llvm/IR/IntrinsicInst.h"
34#include "llvm/IR/Intrinsics.h"
35#include "llvm/IR/LLVMContext.h"
36#include "llvm/IR/Metadata.h"
37#include "llvm/IR/Module.h"
38#include "llvm/IR/Type.h"
39#include "llvm/Support/CommandLine.h"
40#include "llvm/Support/Debug.h"
41#include "llvm/Support/MathExtras.h"
42#include "llvm/Support/raw_ostream.h"
43#include "llvm/Transforms/Utils/BasicBlockUtils.h"
44#include "llvm/Transforms/Utils/ModuleUtils.h"
45
46using namespace llvm;
47
48#define DEBUG_TYPE "tsan"
49
50static cl::opt<bool>  ClInstrumentMemoryAccesses(
51    "tsan-instrument-memory-accesses", cl::init(true),
52    cl::desc("Instrument memory accesses"), cl::Hidden);
53static cl::opt<bool>  ClInstrumentFuncEntryExit(
54    "tsan-instrument-func-entry-exit", cl::init(true),
55    cl::desc("Instrument function entry and exit"), cl::Hidden);
56static cl::opt<bool>  ClInstrumentAtomics(
57    "tsan-instrument-atomics", cl::init(true),
58    cl::desc("Instrument atomics"), cl::Hidden);
59static cl::opt<bool>  ClInstrumentMemIntrinsics(
60    "tsan-instrument-memintrinsics", cl::init(true),
61    cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden);
62
63STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
64STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
65STATISTIC(NumOmittedReadsBeforeWrite,
66          "Number of reads ignored due to following writes");
67STATISTIC(NumAccessesWithBadSize, "Number of accesses with bad size");
68STATISTIC(NumInstrumentedVtableWrites, "Number of vtable ptr writes");
69STATISTIC(NumInstrumentedVtableReads, "Number of vtable ptr reads");
70STATISTIC(NumOmittedReadsFromConstantGlobals,
71          "Number of reads from constant globals");
72STATISTIC(NumOmittedReadsFromVtable, "Number of vtable reads");
73STATISTIC(NumOmittedNonCaptured, "Number of accesses ignored due to capturing");
74
75static const char *const kTsanModuleCtorName = "tsan.module_ctor";
76static const char *const kTsanInitName = "__tsan_init";
77
78namespace {
79
80/// ThreadSanitizer: instrument the code in module to find races.
81struct ThreadSanitizer : public FunctionPass {
82  ThreadSanitizer() : FunctionPass(ID) {}
83  const char *getPassName() const override;
84  bool runOnFunction(Function &F) override;
85  bool doInitialization(Module &M) override;
86  static char ID;  // Pass identification, replacement for typeid.
87
88 private:
89  void initializeCallbacks(Module &M);
90  bool instrumentLoadOrStore(Instruction *I, const DataLayout &DL);
91  bool instrumentAtomic(Instruction *I, const DataLayout &DL);
92  bool instrumentMemIntrinsic(Instruction *I);
93  void chooseInstructionsToInstrument(SmallVectorImpl<Instruction *> &Local,
94                                      SmallVectorImpl<Instruction *> &All,
95                                      const DataLayout &DL);
96  bool addrPointsToConstantData(Value *Addr);
97  int getMemoryAccessFuncIndex(Value *Addr, const DataLayout &DL);
98
99  Type *IntptrTy;
100  IntegerType *OrdTy;
101  // Callbacks to run-time library are computed in doInitialization.
102  Function *TsanFuncEntry;
103  Function *TsanFuncExit;
104  // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
105  static const size_t kNumberOfAccessSizes = 5;
106  Function *TsanRead[kNumberOfAccessSizes];
107  Function *TsanWrite[kNumberOfAccessSizes];
108  Function *TsanUnalignedRead[kNumberOfAccessSizes];
109  Function *TsanUnalignedWrite[kNumberOfAccessSizes];
110  Function *TsanAtomicLoad[kNumberOfAccessSizes];
111  Function *TsanAtomicStore[kNumberOfAccessSizes];
112  Function *TsanAtomicRMW[AtomicRMWInst::LAST_BINOP + 1][kNumberOfAccessSizes];
113  Function *TsanAtomicCAS[kNumberOfAccessSizes];
114  Function *TsanAtomicThreadFence;
115  Function *TsanAtomicSignalFence;
116  Function *TsanVptrUpdate;
117  Function *TsanVptrLoad;
118  Function *MemmoveFn, *MemcpyFn, *MemsetFn;
119  Function *TsanCtorFunction;
120};
121}  // namespace
122
123char ThreadSanitizer::ID = 0;
124INITIALIZE_PASS(ThreadSanitizer, "tsan",
125    "ThreadSanitizer: detects data races.",
126    false, false)
127
128const char *ThreadSanitizer::getPassName() const {
129  return "ThreadSanitizer";
130}
131
132FunctionPass *llvm::createThreadSanitizerPass() {
133  return new ThreadSanitizer();
134}
135
136void ThreadSanitizer::initializeCallbacks(Module &M) {
137  IRBuilder<> IRB(M.getContext());
138  // Initialize the callbacks.
139  TsanFuncEntry = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
140      "__tsan_func_entry", IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
141  TsanFuncExit = checkSanitizerInterfaceFunction(
142      M.getOrInsertFunction("__tsan_func_exit", IRB.getVoidTy(), nullptr));
143  OrdTy = IRB.getInt32Ty();
144  for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
145    const unsigned ByteSize = 1U << i;
146    const unsigned BitSize = ByteSize * 8;
147    std::string ByteSizeStr = utostr(ByteSize);
148    std::string BitSizeStr = utostr(BitSize);
149    SmallString<32> ReadName("__tsan_read" + ByteSizeStr);
150    TsanRead[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
151        ReadName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
152
153    SmallString<32> WriteName("__tsan_write" + ByteSizeStr);
154    TsanWrite[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
155        WriteName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
156
157    SmallString<64> UnalignedReadName("__tsan_unaligned_read" + ByteSizeStr);
158    TsanUnalignedRead[i] =
159        checkSanitizerInterfaceFunction(M.getOrInsertFunction(
160            UnalignedReadName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
161
162    SmallString<64> UnalignedWriteName("__tsan_unaligned_write" + ByteSizeStr);
163    TsanUnalignedWrite[i] =
164        checkSanitizerInterfaceFunction(M.getOrInsertFunction(
165            UnalignedWriteName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
166
167    Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
168    Type *PtrTy = Ty->getPointerTo();
169    SmallString<32> AtomicLoadName("__tsan_atomic" + BitSizeStr + "_load");
170    TsanAtomicLoad[i] = checkSanitizerInterfaceFunction(
171        M.getOrInsertFunction(AtomicLoadName, Ty, PtrTy, OrdTy, nullptr));
172
173    SmallString<32> AtomicStoreName("__tsan_atomic" + BitSizeStr + "_store");
174    TsanAtomicStore[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
175        AtomicStoreName, IRB.getVoidTy(), PtrTy, Ty, OrdTy, nullptr));
176
177    for (int op = AtomicRMWInst::FIRST_BINOP;
178        op <= AtomicRMWInst::LAST_BINOP; ++op) {
179      TsanAtomicRMW[op][i] = nullptr;
180      const char *NamePart = nullptr;
181      if (op == AtomicRMWInst::Xchg)
182        NamePart = "_exchange";
183      else if (op == AtomicRMWInst::Add)
184        NamePart = "_fetch_add";
185      else if (op == AtomicRMWInst::Sub)
186        NamePart = "_fetch_sub";
187      else if (op == AtomicRMWInst::And)
188        NamePart = "_fetch_and";
189      else if (op == AtomicRMWInst::Or)
190        NamePart = "_fetch_or";
191      else if (op == AtomicRMWInst::Xor)
192        NamePart = "_fetch_xor";
193      else if (op == AtomicRMWInst::Nand)
194        NamePart = "_fetch_nand";
195      else
196        continue;
197      SmallString<32> RMWName("__tsan_atomic" + itostr(BitSize) + NamePart);
198      TsanAtomicRMW[op][i] = checkSanitizerInterfaceFunction(
199          M.getOrInsertFunction(RMWName, Ty, PtrTy, Ty, OrdTy, nullptr));
200    }
201
202    SmallString<32> AtomicCASName("__tsan_atomic" + BitSizeStr +
203                                  "_compare_exchange_val");
204    TsanAtomicCAS[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
205        AtomicCASName, Ty, PtrTy, Ty, Ty, OrdTy, OrdTy, nullptr));
206  }
207  TsanVptrUpdate = checkSanitizerInterfaceFunction(
208      M.getOrInsertFunction("__tsan_vptr_update", IRB.getVoidTy(),
209                            IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), nullptr));
210  TsanVptrLoad = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
211      "__tsan_vptr_read", IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
212  TsanAtomicThreadFence = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
213      "__tsan_atomic_thread_fence", IRB.getVoidTy(), OrdTy, nullptr));
214  TsanAtomicSignalFence = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
215      "__tsan_atomic_signal_fence", IRB.getVoidTy(), OrdTy, nullptr));
216
217  MemmoveFn = checkSanitizerInterfaceFunction(
218      M.getOrInsertFunction("memmove", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
219                            IRB.getInt8PtrTy(), IntptrTy, nullptr));
220  MemcpyFn = checkSanitizerInterfaceFunction(
221      M.getOrInsertFunction("memcpy", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
222                            IRB.getInt8PtrTy(), IntptrTy, nullptr));
223  MemsetFn = checkSanitizerInterfaceFunction(
224      M.getOrInsertFunction("memset", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
225                            IRB.getInt32Ty(), IntptrTy, nullptr));
226}
227
228bool ThreadSanitizer::doInitialization(Module &M) {
229  const DataLayout &DL = M.getDataLayout();
230  IntptrTy = DL.getIntPtrType(M.getContext());
231  std::tie(TsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
232      M, kTsanModuleCtorName, kTsanInitName, /*InitArgTypes=*/{},
233      /*InitArgs=*/{});
234
235  appendToGlobalCtors(M, TsanCtorFunction, 0);
236
237  return true;
238}
239
240static bool isVtableAccess(Instruction *I) {
241  if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa))
242    return Tag->isTBAAVtableAccess();
243  return false;
244}
245
246bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) {
247  // If this is a GEP, just analyze its pointer operand.
248  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
249    Addr = GEP->getPointerOperand();
250
251  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
252    if (GV->isConstant()) {
253      // Reads from constant globals can not race with any writes.
254      NumOmittedReadsFromConstantGlobals++;
255      return true;
256    }
257  } else if (LoadInst *L = dyn_cast<LoadInst>(Addr)) {
258    if (isVtableAccess(L)) {
259      // Reads from a vtable pointer can not race with any writes.
260      NumOmittedReadsFromVtable++;
261      return true;
262    }
263  }
264  return false;
265}
266
267// Instrumenting some of the accesses may be proven redundant.
268// Currently handled:
269//  - read-before-write (within same BB, no calls between)
270//  - not captured variables
271//
272// We do not handle some of the patterns that should not survive
273// after the classic compiler optimizations.
274// E.g. two reads from the same temp should be eliminated by CSE,
275// two writes should be eliminated by DSE, etc.
276//
277// 'Local' is a vector of insns within the same BB (no calls between).
278// 'All' is a vector of insns that will be instrumented.
279void ThreadSanitizer::chooseInstructionsToInstrument(
280    SmallVectorImpl<Instruction *> &Local, SmallVectorImpl<Instruction *> &All,
281    const DataLayout &DL) {
282  SmallSet<Value*, 8> WriteTargets;
283  // Iterate from the end.
284  for (SmallVectorImpl<Instruction*>::reverse_iterator It = Local.rbegin(),
285       E = Local.rend(); It != E; ++It) {
286    Instruction *I = *It;
287    if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
288      WriteTargets.insert(Store->getPointerOperand());
289    } else {
290      LoadInst *Load = cast<LoadInst>(I);
291      Value *Addr = Load->getPointerOperand();
292      if (WriteTargets.count(Addr)) {
293        // We will write to this temp, so no reason to analyze the read.
294        NumOmittedReadsBeforeWrite++;
295        continue;
296      }
297      if (addrPointsToConstantData(Addr)) {
298        // Addr points to some constant data -- it can not race with any writes.
299        continue;
300      }
301    }
302    Value *Addr = isa<StoreInst>(*I)
303        ? cast<StoreInst>(I)->getPointerOperand()
304        : cast<LoadInst>(I)->getPointerOperand();
305    if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
306        !PointerMayBeCaptured(Addr, true, true)) {
307      // The variable is addressable but not captured, so it cannot be
308      // referenced from a different thread and participate in a data race
309      // (see llvm/Analysis/CaptureTracking.h for details).
310      NumOmittedNonCaptured++;
311      continue;
312    }
313    All.push_back(I);
314  }
315  Local.clear();
316}
317
318static bool isAtomic(Instruction *I) {
319  if (LoadInst *LI = dyn_cast<LoadInst>(I))
320    return LI->isAtomic() && LI->getSynchScope() == CrossThread;
321  if (StoreInst *SI = dyn_cast<StoreInst>(I))
322    return SI->isAtomic() && SI->getSynchScope() == CrossThread;
323  if (isa<AtomicRMWInst>(I))
324    return true;
325  if (isa<AtomicCmpXchgInst>(I))
326    return true;
327  if (isa<FenceInst>(I))
328    return true;
329  return false;
330}
331
332bool ThreadSanitizer::runOnFunction(Function &F) {
333  // This is required to prevent instrumenting call to __tsan_init from within
334  // the module constructor.
335  if (&F == TsanCtorFunction)
336    return false;
337  initializeCallbacks(*F.getParent());
338  SmallVector<Instruction*, 8> RetVec;
339  SmallVector<Instruction*, 8> AllLoadsAndStores;
340  SmallVector<Instruction*, 8> LocalLoadsAndStores;
341  SmallVector<Instruction*, 8> AtomicAccesses;
342  SmallVector<Instruction*, 8> MemIntrinCalls;
343  bool Res = false;
344  bool HasCalls = false;
345  bool SanitizeFunction = F.hasFnAttribute(Attribute::SanitizeThread);
346  const DataLayout &DL = F.getParent()->getDataLayout();
347
348  // Traverse all instructions, collect loads/stores/returns, check for calls.
349  for (auto &BB : F) {
350    for (auto &Inst : BB) {
351      if (isAtomic(&Inst))
352        AtomicAccesses.push_back(&Inst);
353      else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
354        LocalLoadsAndStores.push_back(&Inst);
355      else if (isa<ReturnInst>(Inst))
356        RetVec.push_back(&Inst);
357      else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
358        if (isa<MemIntrinsic>(Inst))
359          MemIntrinCalls.push_back(&Inst);
360        HasCalls = true;
361        chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores,
362                                       DL);
363      }
364    }
365    chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores, DL);
366  }
367
368  // We have collected all loads and stores.
369  // FIXME: many of these accesses do not need to be checked for races
370  // (e.g. variables that do not escape, etc).
371
372  // Instrument memory accesses only if we want to report bugs in the function.
373  if (ClInstrumentMemoryAccesses && SanitizeFunction)
374    for (auto Inst : AllLoadsAndStores) {
375      Res |= instrumentLoadOrStore(Inst, DL);
376    }
377
378  // Instrument atomic memory accesses in any case (they can be used to
379  // implement synchronization).
380  if (ClInstrumentAtomics)
381    for (auto Inst : AtomicAccesses) {
382      Res |= instrumentAtomic(Inst, DL);
383    }
384
385  if (ClInstrumentMemIntrinsics && SanitizeFunction)
386    for (auto Inst : MemIntrinCalls) {
387      Res |= instrumentMemIntrinsic(Inst);
388    }
389
390  // Instrument function entry/exit points if there were instrumented accesses.
391  if ((Res || HasCalls) && ClInstrumentFuncEntryExit) {
392    IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
393    Value *ReturnAddress = IRB.CreateCall(
394        Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
395        IRB.getInt32(0));
396    IRB.CreateCall(TsanFuncEntry, ReturnAddress);
397    for (auto RetInst : RetVec) {
398      IRBuilder<> IRBRet(RetInst);
399      IRBRet.CreateCall(TsanFuncExit, {});
400    }
401    Res = true;
402  }
403  return Res;
404}
405
406bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I,
407                                            const DataLayout &DL) {
408  IRBuilder<> IRB(I);
409  bool IsWrite = isa<StoreInst>(*I);
410  Value *Addr = IsWrite
411      ? cast<StoreInst>(I)->getPointerOperand()
412      : cast<LoadInst>(I)->getPointerOperand();
413  int Idx = getMemoryAccessFuncIndex(Addr, DL);
414  if (Idx < 0)
415    return false;
416  if (IsWrite && isVtableAccess(I)) {
417    DEBUG(dbgs() << "  VPTR : " << *I << "\n");
418    Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
419    // StoredValue may be a vector type if we are storing several vptrs at once.
420    // In this case, just take the first element of the vector since this is
421    // enough to find vptr races.
422    if (isa<VectorType>(StoredValue->getType()))
423      StoredValue = IRB.CreateExtractElement(
424          StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0));
425    if (StoredValue->getType()->isIntegerTy())
426      StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
427    // Call TsanVptrUpdate.
428    IRB.CreateCall(TsanVptrUpdate,
429                   {IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
430                    IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy())});
431    NumInstrumentedVtableWrites++;
432    return true;
433  }
434  if (!IsWrite && isVtableAccess(I)) {
435    IRB.CreateCall(TsanVptrLoad,
436                   IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
437    NumInstrumentedVtableReads++;
438    return true;
439  }
440  const unsigned Alignment = IsWrite
441      ? cast<StoreInst>(I)->getAlignment()
442      : cast<LoadInst>(I)->getAlignment();
443  Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
444  const uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
445  Value *OnAccessFunc = nullptr;
446  if (Alignment == 0 || Alignment >= 8 || (Alignment % (TypeSize / 8)) == 0)
447    OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
448  else
449    OnAccessFunc = IsWrite ? TsanUnalignedWrite[Idx] : TsanUnalignedRead[Idx];
450  IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
451  if (IsWrite) NumInstrumentedWrites++;
452  else         NumInstrumentedReads++;
453  return true;
454}
455
456static ConstantInt *createOrdering(IRBuilder<> *IRB, AtomicOrdering ord) {
457  uint32_t v = 0;
458  switch (ord) {
459    case NotAtomic: llvm_unreachable("unexpected atomic ordering!");
460    case Unordered:              // Fall-through.
461    case Monotonic:              v = 0; break;
462    // case Consume:                v = 1; break;  // Not specified yet.
463    case Acquire:                v = 2; break;
464    case Release:                v = 3; break;
465    case AcquireRelease:         v = 4; break;
466    case SequentiallyConsistent: v = 5; break;
467  }
468  return IRB->getInt32(v);
469}
470
471// If a memset intrinsic gets inlined by the code gen, we will miss races on it.
472// So, we either need to ensure the intrinsic is not inlined, or instrument it.
473// We do not instrument memset/memmove/memcpy intrinsics (too complicated),
474// instead we simply replace them with regular function calls, which are then
475// intercepted by the run-time.
476// Since tsan is running after everyone else, the calls should not be
477// replaced back with intrinsics. If that becomes wrong at some point,
478// we will need to call e.g. __tsan_memset to avoid the intrinsics.
479bool ThreadSanitizer::instrumentMemIntrinsic(Instruction *I) {
480  IRBuilder<> IRB(I);
481  if (MemSetInst *M = dyn_cast<MemSetInst>(I)) {
482    IRB.CreateCall(
483        MemsetFn,
484        {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
485         IRB.CreateIntCast(M->getArgOperand(1), IRB.getInt32Ty(), false),
486         IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
487    I->eraseFromParent();
488  } else if (MemTransferInst *M = dyn_cast<MemTransferInst>(I)) {
489    IRB.CreateCall(
490        isa<MemCpyInst>(M) ? MemcpyFn : MemmoveFn,
491        {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
492         IRB.CreatePointerCast(M->getArgOperand(1), IRB.getInt8PtrTy()),
493         IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
494    I->eraseFromParent();
495  }
496  return false;
497}
498
499// Both llvm and ThreadSanitizer atomic operations are based on C++11/C1x
500// standards.  For background see C++11 standard.  A slightly older, publicly
501// available draft of the standard (not entirely up-to-date, but close enough
502// for casual browsing) is available here:
503// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf
504// The following page contains more background information:
505// http://www.hpl.hp.com/personal/Hans_Boehm/c++mm/
506
507bool ThreadSanitizer::instrumentAtomic(Instruction *I, const DataLayout &DL) {
508  IRBuilder<> IRB(I);
509  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
510    Value *Addr = LI->getPointerOperand();
511    int Idx = getMemoryAccessFuncIndex(Addr, DL);
512    if (Idx < 0)
513      return false;
514    const unsigned ByteSize = 1U << Idx;
515    const unsigned BitSize = ByteSize * 8;
516    Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
517    Type *PtrTy = Ty->getPointerTo();
518    Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
519                     createOrdering(&IRB, LI->getOrdering())};
520    CallInst *C = CallInst::Create(TsanAtomicLoad[Idx], Args);
521    ReplaceInstWithInst(I, C);
522
523  } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
524    Value *Addr = SI->getPointerOperand();
525    int Idx = getMemoryAccessFuncIndex(Addr, DL);
526    if (Idx < 0)
527      return false;
528    const unsigned ByteSize = 1U << Idx;
529    const unsigned BitSize = ByteSize * 8;
530    Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
531    Type *PtrTy = Ty->getPointerTo();
532    Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
533                     IRB.CreateIntCast(SI->getValueOperand(), Ty, false),
534                     createOrdering(&IRB, SI->getOrdering())};
535    CallInst *C = CallInst::Create(TsanAtomicStore[Idx], Args);
536    ReplaceInstWithInst(I, C);
537  } else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I)) {
538    Value *Addr = RMWI->getPointerOperand();
539    int Idx = getMemoryAccessFuncIndex(Addr, DL);
540    if (Idx < 0)
541      return false;
542    Function *F = TsanAtomicRMW[RMWI->getOperation()][Idx];
543    if (!F)
544      return false;
545    const unsigned ByteSize = 1U << Idx;
546    const unsigned BitSize = ByteSize * 8;
547    Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
548    Type *PtrTy = Ty->getPointerTo();
549    Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
550                     IRB.CreateIntCast(RMWI->getValOperand(), Ty, false),
551                     createOrdering(&IRB, RMWI->getOrdering())};
552    CallInst *C = CallInst::Create(F, Args);
553    ReplaceInstWithInst(I, C);
554  } else if (AtomicCmpXchgInst *CASI = dyn_cast<AtomicCmpXchgInst>(I)) {
555    Value *Addr = CASI->getPointerOperand();
556    int Idx = getMemoryAccessFuncIndex(Addr, DL);
557    if (Idx < 0)
558      return false;
559    const unsigned ByteSize = 1U << Idx;
560    const unsigned BitSize = ByteSize * 8;
561    Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
562    Type *PtrTy = Ty->getPointerTo();
563    Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
564                     IRB.CreateIntCast(CASI->getCompareOperand(), Ty, false),
565                     IRB.CreateIntCast(CASI->getNewValOperand(), Ty, false),
566                     createOrdering(&IRB, CASI->getSuccessOrdering()),
567                     createOrdering(&IRB, CASI->getFailureOrdering())};
568    CallInst *C = IRB.CreateCall(TsanAtomicCAS[Idx], Args);
569    Value *Success = IRB.CreateICmpEQ(C, CASI->getCompareOperand());
570
571    Value *Res = IRB.CreateInsertValue(UndefValue::get(CASI->getType()), C, 0);
572    Res = IRB.CreateInsertValue(Res, Success, 1);
573
574    I->replaceAllUsesWith(Res);
575    I->eraseFromParent();
576  } else if (FenceInst *FI = dyn_cast<FenceInst>(I)) {
577    Value *Args[] = {createOrdering(&IRB, FI->getOrdering())};
578    Function *F = FI->getSynchScope() == SingleThread ?
579        TsanAtomicSignalFence : TsanAtomicThreadFence;
580    CallInst *C = CallInst::Create(F, Args);
581    ReplaceInstWithInst(I, C);
582  }
583  return true;
584}
585
586int ThreadSanitizer::getMemoryAccessFuncIndex(Value *Addr,
587                                              const DataLayout &DL) {
588  Type *OrigPtrTy = Addr->getType();
589  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
590  assert(OrigTy->isSized());
591  uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
592  if (TypeSize != 8  && TypeSize != 16 &&
593      TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
594    NumAccessesWithBadSize++;
595    // Ignore all unusual sizes.
596    return -1;
597  }
598  size_t Idx = countTrailingZeros(TypeSize / 8);
599  assert(Idx < kNumberOfAccessSizes);
600  return Idx;
601}
602