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ThreadSanitizer.cpp
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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/ADT/SmallSet.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/Statistic.h"
26 #include "llvm/ADT/StringExtras.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"
41 #include "llvm/Support/Debug.h"
49 
50 using namespace llvm;
51 
52 #define DEBUG_TYPE "tsan"
53 
55  "tsan-instrument-memory-accesses", cl::init(true),
56  cl::desc("Instrument memory accesses"), cl::Hidden);
58  "tsan-instrument-func-entry-exit", cl::init(true),
59  cl::desc("Instrument function entry and exit"), cl::Hidden);
61  "tsan-handle-cxx-exceptions", cl::init(true),
62  cl::desc("Handle C++ exceptions (insert cleanup blocks for unwinding)"),
63  cl::Hidden);
65  "tsan-instrument-atomics", cl::init(true),
66  cl::desc("Instrument atomics"), cl::Hidden);
68  "tsan-instrument-memintrinsics", cl::init(true),
69  cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden);
70 
71 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
72 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
73 STATISTIC(NumOmittedReadsBeforeWrite,
74  "Number of reads ignored due to following writes");
75 STATISTIC(NumAccessesWithBadSize, "Number of accesses with bad size");
76 STATISTIC(NumInstrumentedVtableWrites, "Number of vtable ptr writes");
77 STATISTIC(NumInstrumentedVtableReads, "Number of vtable ptr reads");
78 STATISTIC(NumOmittedReadsFromConstantGlobals,
79  "Number of reads from constant globals");
80 STATISTIC(NumOmittedReadsFromVtable, "Number of vtable reads");
81 STATISTIC(NumOmittedNonCaptured, "Number of accesses ignored due to capturing");
82 
83 static const char *const kTsanModuleCtorName = "tsan.module_ctor";
84 static const char *const kTsanInitName = "__tsan_init";
85 
86 namespace {
87 
88 /// ThreadSanitizer: instrument the code in module to find races.
89 struct ThreadSanitizer : public FunctionPass {
90  ThreadSanitizer() : FunctionPass(ID) {}
91  StringRef getPassName() const override;
92  void getAnalysisUsage(AnalysisUsage &AU) const override;
93  bool runOnFunction(Function &F) override;
94  bool doInitialization(Module &M) override;
95  static char ID; // Pass identification, replacement for typeid.
96 
97  private:
98  void initializeCallbacks(Module &M);
99  bool instrumentLoadOrStore(Instruction *I, const DataLayout &DL);
100  bool instrumentAtomic(Instruction *I, const DataLayout &DL);
101  bool instrumentMemIntrinsic(Instruction *I);
102  void chooseInstructionsToInstrument(SmallVectorImpl<Instruction *> &Local,
104  const DataLayout &DL);
105  bool addrPointsToConstantData(Value *Addr);
106  int getMemoryAccessFuncIndex(Value *Addr, const DataLayout &DL);
107  void InsertRuntimeIgnores(Function &F);
108 
109  Type *IntptrTy;
110  IntegerType *OrdTy;
111  // Callbacks to run-time library are computed in doInitialization.
112  Function *TsanFuncEntry;
113  Function *TsanFuncExit;
114  Function *TsanIgnoreBegin;
115  Function *TsanIgnoreEnd;
116  // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
117  static const size_t kNumberOfAccessSizes = 5;
118  Function *TsanRead[kNumberOfAccessSizes];
119  Function *TsanWrite[kNumberOfAccessSizes];
120  Function *TsanUnalignedRead[kNumberOfAccessSizes];
121  Function *TsanUnalignedWrite[kNumberOfAccessSizes];
122  Function *TsanAtomicLoad[kNumberOfAccessSizes];
123  Function *TsanAtomicStore[kNumberOfAccessSizes];
125  Function *TsanAtomicCAS[kNumberOfAccessSizes];
126  Function *TsanAtomicThreadFence;
127  Function *TsanAtomicSignalFence;
128  Function *TsanVptrUpdate;
129  Function *TsanVptrLoad;
130  Function *MemmoveFn, *MemcpyFn, *MemsetFn;
131  Function *TsanCtorFunction;
132 };
133 } // namespace
134 
135 char ThreadSanitizer::ID = 0;
137  ThreadSanitizer, "tsan",
138  "ThreadSanitizer: detects data races.",
139  false, false)
142  ThreadSanitizer, "tsan",
143  "ThreadSanitizer: detects data races.",
144  false, false)
145 
146 StringRef ThreadSanitizer::getPassName() const { return "ThreadSanitizer"; }
147 
148 void ThreadSanitizer::getAnalysisUsage(AnalysisUsage &AU) const {
150 }
151 
153  return new ThreadSanitizer();
154 }
155 
156 void ThreadSanitizer::initializeCallbacks(Module &M) {
157  IRBuilder<> IRB(M.getContext());
158  AttributeList Attr;
159  Attr = Attr.addAttribute(M.getContext(), AttributeList::FunctionIndex,
160  Attribute::NoUnwind);
161  // Initialize the callbacks.
163  "__tsan_func_entry", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
164  TsanFuncExit = checkSanitizerInterfaceFunction(
165  M.getOrInsertFunction("__tsan_func_exit", Attr, IRB.getVoidTy()));
167  "__tsan_ignore_thread_begin", Attr, IRB.getVoidTy()));
169  "__tsan_ignore_thread_end", Attr, IRB.getVoidTy()));
170  OrdTy = IRB.getInt32Ty();
171  for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
172  const unsigned ByteSize = 1U << i;
173  const unsigned BitSize = ByteSize * 8;
174  std::string ByteSizeStr = utostr(ByteSize);
175  std::string BitSizeStr = utostr(BitSize);
176  SmallString<32> ReadName("__tsan_read" + ByteSizeStr);
178  ReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
179 
180  SmallString<32> WriteName("__tsan_write" + ByteSizeStr);
182  WriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
183 
184  SmallString<64> UnalignedReadName("__tsan_unaligned_read" + ByteSizeStr);
185  TsanUnalignedRead[i] =
187  UnalignedReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
188 
189  SmallString<64> UnalignedWriteName("__tsan_unaligned_write" + ByteSizeStr);
190  TsanUnalignedWrite[i] =
192  UnalignedWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
193 
194  Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
195  Type *PtrTy = Ty->getPointerTo();
196  SmallString<32> AtomicLoadName("__tsan_atomic" + BitSizeStr + "_load");
197  TsanAtomicLoad[i] = checkSanitizerInterfaceFunction(
198  M.getOrInsertFunction(AtomicLoadName, Attr, Ty, PtrTy, OrdTy));
199 
200  SmallString<32> AtomicStoreName("__tsan_atomic" + BitSizeStr + "_store");
202  AtomicStoreName, Attr, IRB.getVoidTy(), PtrTy, Ty, OrdTy));
203 
204  for (int op = AtomicRMWInst::FIRST_BINOP;
206  TsanAtomicRMW[op][i] = nullptr;
207  const char *NamePart = nullptr;
208  if (op == AtomicRMWInst::Xchg)
209  NamePart = "_exchange";
210  else if (op == AtomicRMWInst::Add)
211  NamePart = "_fetch_add";
212  else if (op == AtomicRMWInst::Sub)
213  NamePart = "_fetch_sub";
214  else if (op == AtomicRMWInst::And)
215  NamePart = "_fetch_and";
216  else if (op == AtomicRMWInst::Or)
217  NamePart = "_fetch_or";
218  else if (op == AtomicRMWInst::Xor)
219  NamePart = "_fetch_xor";
220  else if (op == AtomicRMWInst::Nand)
221  NamePart = "_fetch_nand";
222  else
223  continue;
224  SmallString<32> RMWName("__tsan_atomic" + itostr(BitSize) + NamePart);
225  TsanAtomicRMW[op][i] = checkSanitizerInterfaceFunction(
226  M.getOrInsertFunction(RMWName, Attr, Ty, PtrTy, Ty, OrdTy));
227  }
228 
229  SmallString<32> AtomicCASName("__tsan_atomic" + BitSizeStr +
230  "_compare_exchange_val");
232  AtomicCASName, Attr, Ty, PtrTy, Ty, Ty, OrdTy, OrdTy));
233  }
234  TsanVptrUpdate = checkSanitizerInterfaceFunction(
235  M.getOrInsertFunction("__tsan_vptr_update", Attr, IRB.getVoidTy(),
236  IRB.getInt8PtrTy(), IRB.getInt8PtrTy()));
238  "__tsan_vptr_read", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
239  TsanAtomicThreadFence = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
240  "__tsan_atomic_thread_fence", Attr, IRB.getVoidTy(), OrdTy));
241  TsanAtomicSignalFence = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
242  "__tsan_atomic_signal_fence", Attr, IRB.getVoidTy(), OrdTy));
243 
245  M.getOrInsertFunction("memmove", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
246  IRB.getInt8PtrTy(), IntptrTy));
248  M.getOrInsertFunction("memcpy", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
249  IRB.getInt8PtrTy(), IntptrTy));
251  M.getOrInsertFunction("memset", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
252  IRB.getInt32Ty(), IntptrTy));
253 }
254 
255 bool ThreadSanitizer::doInitialization(Module &M) {
256  const DataLayout &DL = M.getDataLayout();
257  IntptrTy = DL.getIntPtrType(M.getContext());
258  std::tie(TsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
259  M, kTsanModuleCtorName, kTsanInitName, /*InitArgTypes=*/{},
260  /*InitArgs=*/{});
261 
262  appendToGlobalCtors(M, TsanCtorFunction, 0);
263 
264  return true;
265 }
266 
267 static bool isVtableAccess(Instruction *I) {
269  return Tag->isTBAAVtableAccess();
270  return false;
271 }
272 
273 // Do not instrument known races/"benign races" that come from compiler
274 // instrumentatin. The user has no way of suppressing them.
275 static bool shouldInstrumentReadWriteFromAddress(const Module *M, Value *Addr) {
276  // Peel off GEPs and BitCasts.
277  Addr = Addr->stripInBoundsOffsets();
278 
279  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
280  if (GV->hasSection()) {
281  StringRef SectionName = GV->getSection();
282  // Check if the global is in the PGO counters section.
283  auto OF = Triple(M->getTargetTriple()).getObjectFormat();
284  if (SectionName.endswith(
285  getInstrProfSectionName(IPSK_cnts, OF, /*AddSegmentInfo=*/false)))
286  return false;
287  }
288 
289  // Check if the global is private gcov data.
290  if (GV->getName().startswith("__llvm_gcov") ||
291  GV->getName().startswith("__llvm_gcda"))
292  return false;
293  }
294 
295  // Do not instrument acesses from different address spaces; we cannot deal
296  // with them.
297  if (Addr) {
298  Type *PtrTy = cast<PointerType>(Addr->getType()->getScalarType());
299  if (PtrTy->getPointerAddressSpace() != 0)
300  return false;
301  }
302 
303  return true;
304 }
305 
306 bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) {
307  // If this is a GEP, just analyze its pointer operand.
308  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
309  Addr = GEP->getPointerOperand();
310 
311  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
312  if (GV->isConstant()) {
313  // Reads from constant globals can not race with any writes.
314  NumOmittedReadsFromConstantGlobals++;
315  return true;
316  }
317  } else if (LoadInst *L = dyn_cast<LoadInst>(Addr)) {
318  if (isVtableAccess(L)) {
319  // Reads from a vtable pointer can not race with any writes.
320  NumOmittedReadsFromVtable++;
321  return true;
322  }
323  }
324  return false;
325 }
326 
327 // Instrumenting some of the accesses may be proven redundant.
328 // Currently handled:
329 // - read-before-write (within same BB, no calls between)
330 // - not captured variables
331 //
332 // We do not handle some of the patterns that should not survive
333 // after the classic compiler optimizations.
334 // E.g. two reads from the same temp should be eliminated by CSE,
335 // two writes should be eliminated by DSE, etc.
336 //
337 // 'Local' is a vector of insns within the same BB (no calls between).
338 // 'All' is a vector of insns that will be instrumented.
339 void ThreadSanitizer::chooseInstructionsToInstrument(
341  const DataLayout &DL) {
342  SmallSet<Value*, 8> WriteTargets;
343  // Iterate from the end.
344  for (Instruction *I : reverse(Local)) {
345  if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
346  Value *Addr = Store->getPointerOperand();
347  if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
348  continue;
349  WriteTargets.insert(Addr);
350  } else {
351  LoadInst *Load = cast<LoadInst>(I);
352  Value *Addr = Load->getPointerOperand();
353  if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
354  continue;
355  if (WriteTargets.count(Addr)) {
356  // We will write to this temp, so no reason to analyze the read.
357  NumOmittedReadsBeforeWrite++;
358  continue;
359  }
360  if (addrPointsToConstantData(Addr)) {
361  // Addr points to some constant data -- it can not race with any writes.
362  continue;
363  }
364  }
365  Value *Addr = isa<StoreInst>(*I)
366  ? cast<StoreInst>(I)->getPointerOperand()
367  : cast<LoadInst>(I)->getPointerOperand();
368  if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
369  !PointerMayBeCaptured(Addr, true, true)) {
370  // The variable is addressable but not captured, so it cannot be
371  // referenced from a different thread and participate in a data race
372  // (see llvm/Analysis/CaptureTracking.h for details).
373  NumOmittedNonCaptured++;
374  continue;
375  }
376  All.push_back(I);
377  }
378  Local.clear();
379 }
380 
381 static bool isAtomic(Instruction *I) {
382  // TODO: Ask TTI whether synchronization scope is between threads.
383  if (LoadInst *LI = dyn_cast<LoadInst>(I))
384  return LI->isAtomic() && LI->getSyncScopeID() != SyncScope::SingleThread;
385  if (StoreInst *SI = dyn_cast<StoreInst>(I))
386  return SI->isAtomic() && SI->getSyncScopeID() != SyncScope::SingleThread;
387  if (isa<AtomicRMWInst>(I))
388  return true;
389  if (isa<AtomicCmpXchgInst>(I))
390  return true;
391  if (isa<FenceInst>(I))
392  return true;
393  return false;
394 }
395 
396 void ThreadSanitizer::InsertRuntimeIgnores(Function &F) {
398  IRB.CreateCall(TsanIgnoreBegin);
399  EscapeEnumerator EE(F, "tsan_ignore_cleanup", ClHandleCxxExceptions);
400  while (IRBuilder<> *AtExit = EE.Next()) {
401  AtExit->CreateCall(TsanIgnoreEnd);
402  }
403 }
404 
406  // This is required to prevent instrumenting call to __tsan_init from within
407  // the module constructor.
408  if (&F == TsanCtorFunction)
409  return false;
410  initializeCallbacks(*F.getParent());
411  SmallVector<Instruction*, 8> AllLoadsAndStores;
412  SmallVector<Instruction*, 8> LocalLoadsAndStores;
413  SmallVector<Instruction*, 8> AtomicAccesses;
414  SmallVector<Instruction*, 8> MemIntrinCalls;
415  bool Res = false;
416  bool HasCalls = false;
417  bool SanitizeFunction = F.hasFnAttribute(Attribute::SanitizeThread);
418  const DataLayout &DL = F.getParent()->getDataLayout();
419  const TargetLibraryInfo *TLI =
420  &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
421 
422  // Traverse all instructions, collect loads/stores/returns, check for calls.
423  for (auto &BB : F) {
424  for (auto &Inst : BB) {
425  if (isAtomic(&Inst))
426  AtomicAccesses.push_back(&Inst);
427  else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
428  LocalLoadsAndStores.push_back(&Inst);
429  else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
430  if (CallInst *CI = dyn_cast<CallInst>(&Inst))
432  if (isa<MemIntrinsic>(Inst))
433  MemIntrinCalls.push_back(&Inst);
434  HasCalls = true;
435  chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores,
436  DL);
437  }
438  }
439  chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores, DL);
440  }
441 
442  // We have collected all loads and stores.
443  // FIXME: many of these accesses do not need to be checked for races
444  // (e.g. variables that do not escape, etc).
445 
446  // Instrument memory accesses only if we want to report bugs in the function.
447  if (ClInstrumentMemoryAccesses && SanitizeFunction)
448  for (auto Inst : AllLoadsAndStores) {
449  Res |= instrumentLoadOrStore(Inst, DL);
450  }
451 
452  // Instrument atomic memory accesses in any case (they can be used to
453  // implement synchronization).
455  for (auto Inst : AtomicAccesses) {
456  Res |= instrumentAtomic(Inst, DL);
457  }
458 
459  if (ClInstrumentMemIntrinsics && SanitizeFunction)
460  for (auto Inst : MemIntrinCalls) {
461  Res |= instrumentMemIntrinsic(Inst);
462  }
463 
464  if (F.hasFnAttribute("sanitize_thread_no_checking_at_run_time")) {
465  assert(!F.hasFnAttribute(Attribute::SanitizeThread));
466  if (HasCalls)
467  InsertRuntimeIgnores(F);
468  }
469 
470  // Instrument function entry/exit points if there were instrumented accesses.
471  if ((Res || HasCalls) && ClInstrumentFuncEntryExit) {
472  IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
473  Value *ReturnAddress = IRB.CreateCall(
474  Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
475  IRB.getInt32(0));
476  IRB.CreateCall(TsanFuncEntry, ReturnAddress);
477 
478  EscapeEnumerator EE(F, "tsan_cleanup", ClHandleCxxExceptions);
479  while (IRBuilder<> *AtExit = EE.Next()) {
480  AtExit->CreateCall(TsanFuncExit, {});
481  }
482  Res = true;
483  }
484  return Res;
485 }
486 
487 bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I,
488  const DataLayout &DL) {
489  IRBuilder<> IRB(I);
490  bool IsWrite = isa<StoreInst>(*I);
491  Value *Addr = IsWrite
492  ? cast<StoreInst>(I)->getPointerOperand()
493  : cast<LoadInst>(I)->getPointerOperand();
494 
495  // swifterror memory addresses are mem2reg promoted by instruction selection.
496  // As such they cannot have regular uses like an instrumentation function and
497  // it makes no sense to track them as memory.
498  if (Addr->isSwiftError())
499  return false;
500 
501  int Idx = getMemoryAccessFuncIndex(Addr, DL);
502  if (Idx < 0)
503  return false;
504  if (IsWrite && isVtableAccess(I)) {
505  DEBUG(dbgs() << " VPTR : " << *I << "\n");
506  Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
507  // StoredValue may be a vector type if we are storing several vptrs at once.
508  // In this case, just take the first element of the vector since this is
509  // enough to find vptr races.
510  if (isa<VectorType>(StoredValue->getType()))
511  StoredValue = IRB.CreateExtractElement(
512  StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0));
513  if (StoredValue->getType()->isIntegerTy())
514  StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
515  // Call TsanVptrUpdate.
516  IRB.CreateCall(TsanVptrUpdate,
517  {IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
518  IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy())});
519  NumInstrumentedVtableWrites++;
520  return true;
521  }
522  if (!IsWrite && isVtableAccess(I)) {
523  IRB.CreateCall(TsanVptrLoad,
524  IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
525  NumInstrumentedVtableReads++;
526  return true;
527  }
528  const unsigned Alignment = IsWrite
529  ? cast<StoreInst>(I)->getAlignment()
530  : cast<LoadInst>(I)->getAlignment();
531  Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
532  const uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
533  Value *OnAccessFunc = nullptr;
534  if (Alignment == 0 || Alignment >= 8 || (Alignment % (TypeSize / 8)) == 0)
535  OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
536  else
537  OnAccessFunc = IsWrite ? TsanUnalignedWrite[Idx] : TsanUnalignedRead[Idx];
538  IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
539  if (IsWrite) NumInstrumentedWrites++;
540  else NumInstrumentedReads++;
541  return true;
542 }
543 
545  uint32_t v = 0;
546  switch (ord) {
548  llvm_unreachable("unexpected atomic ordering!");
550  case AtomicOrdering::Monotonic: v = 0; break;
551  // Not specified yet:
552  // case AtomicOrdering::Consume: v = 1; break;
553  case AtomicOrdering::Acquire: v = 2; break;
554  case AtomicOrdering::Release: v = 3; break;
555  case AtomicOrdering::AcquireRelease: v = 4; break;
556  case AtomicOrdering::SequentiallyConsistent: v = 5; break;
557  }
558  return IRB->getInt32(v);
559 }
560 
561 // If a memset intrinsic gets inlined by the code gen, we will miss races on it.
562 // So, we either need to ensure the intrinsic is not inlined, or instrument it.
563 // We do not instrument memset/memmove/memcpy intrinsics (too complicated),
564 // instead we simply replace them with regular function calls, which are then
565 // intercepted by the run-time.
566 // Since tsan is running after everyone else, the calls should not be
567 // replaced back with intrinsics. If that becomes wrong at some point,
568 // we will need to call e.g. __tsan_memset to avoid the intrinsics.
569 bool ThreadSanitizer::instrumentMemIntrinsic(Instruction *I) {
570  IRBuilder<> IRB(I);
571  if (MemSetInst *M = dyn_cast<MemSetInst>(I)) {
572  IRB.CreateCall(
573  MemsetFn,
574  {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
575  IRB.CreateIntCast(M->getArgOperand(1), IRB.getInt32Ty(), false),
576  IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
577  I->eraseFromParent();
578  } else if (MemTransferInst *M = dyn_cast<MemTransferInst>(I)) {
579  IRB.CreateCall(
580  isa<MemCpyInst>(M) ? MemcpyFn : MemmoveFn,
581  {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
582  IRB.CreatePointerCast(M->getArgOperand(1), IRB.getInt8PtrTy()),
583  IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
584  I->eraseFromParent();
585  }
586  return false;
587 }
588 
589 // Both llvm and ThreadSanitizer atomic operations are based on C++11/C1x
590 // standards. For background see C++11 standard. A slightly older, publicly
591 // available draft of the standard (not entirely up-to-date, but close enough
592 // for casual browsing) is available here:
593 // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf
594 // The following page contains more background information:
595 // http://www.hpl.hp.com/personal/Hans_Boehm/c++mm/
596 
597 bool ThreadSanitizer::instrumentAtomic(Instruction *I, const DataLayout &DL) {
598  IRBuilder<> IRB(I);
599  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
600  Value *Addr = LI->getPointerOperand();
601  int Idx = getMemoryAccessFuncIndex(Addr, DL);
602  if (Idx < 0)
603  return false;
604  const unsigned ByteSize = 1U << Idx;
605  const unsigned BitSize = ByteSize * 8;
606  Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
607  Type *PtrTy = Ty->getPointerTo();
608  Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
609  createOrdering(&IRB, LI->getOrdering())};
610  Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
611  Value *C = IRB.CreateCall(TsanAtomicLoad[Idx], Args);
612  Value *Cast = IRB.CreateBitOrPointerCast(C, OrigTy);
613  I->replaceAllUsesWith(Cast);
614  } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
615  Value *Addr = SI->getPointerOperand();
616  int Idx = getMemoryAccessFuncIndex(Addr, DL);
617  if (Idx < 0)
618  return false;
619  const unsigned ByteSize = 1U << Idx;
620  const unsigned BitSize = ByteSize * 8;
621  Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
622  Type *PtrTy = Ty->getPointerTo();
623  Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
624  IRB.CreateBitOrPointerCast(SI->getValueOperand(), Ty),
625  createOrdering(&IRB, SI->getOrdering())};
626  CallInst *C = CallInst::Create(TsanAtomicStore[Idx], Args);
627  ReplaceInstWithInst(I, C);
628  } else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I)) {
629  Value *Addr = RMWI->getPointerOperand();
630  int Idx = getMemoryAccessFuncIndex(Addr, DL);
631  if (Idx < 0)
632  return false;
633  Function *F = TsanAtomicRMW[RMWI->getOperation()][Idx];
634  if (!F)
635  return false;
636  const unsigned ByteSize = 1U << Idx;
637  const unsigned BitSize = ByteSize * 8;
638  Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
639  Type *PtrTy = Ty->getPointerTo();
640  Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
641  IRB.CreateIntCast(RMWI->getValOperand(), Ty, false),
642  createOrdering(&IRB, RMWI->getOrdering())};
643  CallInst *C = CallInst::Create(F, Args);
644  ReplaceInstWithInst(I, C);
645  } else if (AtomicCmpXchgInst *CASI = dyn_cast<AtomicCmpXchgInst>(I)) {
646  Value *Addr = CASI->getPointerOperand();
647  int Idx = getMemoryAccessFuncIndex(Addr, DL);
648  if (Idx < 0)
649  return false;
650  const unsigned ByteSize = 1U << Idx;
651  const unsigned BitSize = ByteSize * 8;
652  Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
653  Type *PtrTy = Ty->getPointerTo();
654  Value *CmpOperand =
655  IRB.CreateBitOrPointerCast(CASI->getCompareOperand(), Ty);
656  Value *NewOperand =
657  IRB.CreateBitOrPointerCast(CASI->getNewValOperand(), Ty);
658  Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
659  CmpOperand,
660  NewOperand,
661  createOrdering(&IRB, CASI->getSuccessOrdering()),
662  createOrdering(&IRB, CASI->getFailureOrdering())};
663  CallInst *C = IRB.CreateCall(TsanAtomicCAS[Idx], Args);
664  Value *Success = IRB.CreateICmpEQ(C, CmpOperand);
665  Value *OldVal = C;
666  Type *OrigOldValTy = CASI->getNewValOperand()->getType();
667  if (Ty != OrigOldValTy) {
668  // The value is a pointer, so we need to cast the return value.
669  OldVal = IRB.CreateIntToPtr(C, OrigOldValTy);
670  }
671 
672  Value *Res =
673  IRB.CreateInsertValue(UndefValue::get(CASI->getType()), OldVal, 0);
674  Res = IRB.CreateInsertValue(Res, Success, 1);
675 
676  I->replaceAllUsesWith(Res);
677  I->eraseFromParent();
678  } else if (FenceInst *FI = dyn_cast<FenceInst>(I)) {
679  Value *Args[] = {createOrdering(&IRB, FI->getOrdering())};
680  Function *F = FI->getSyncScopeID() == SyncScope::SingleThread ?
681  TsanAtomicSignalFence : TsanAtomicThreadFence;
682  CallInst *C = CallInst::Create(F, Args);
683  ReplaceInstWithInst(I, C);
684  }
685  return true;
686 }
687 
688 int ThreadSanitizer::getMemoryAccessFuncIndex(Value *Addr,
689  const DataLayout &DL) {
690  Type *OrigPtrTy = Addr->getType();
691  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
692  assert(OrigTy->isSized());
693  uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
694  if (TypeSize != 8 && TypeSize != 16 &&
695  TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
696  NumAccessesWithBadSize++;
697  // Ignore all unusual sizes.
698  return -1;
699  }
700  size_t Idx = countTrailingZeros(TypeSize / 8);
702  return Idx;
703 }
uint64_t CallInst * C
SymbolTableList< Instruction >::iterator eraseFromParent()
This method unlinks &#39;this&#39; from the containing basic block and deletes it.
Definition: Instruction.cpp:69
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:109
uint64_t getTypeStoreSizeInBits(Type *Ty) const
Returns the maximum number of bits that may be overwritten by storing the specified type; always a mu...
Definition: DataLayout.h:394
const std::string & getTargetTriple() const
Get the target triple which is a string describing the target host.
Definition: Module.h:233
void ReplaceInstWithInst(BasicBlock::InstListType &BIL, BasicBlock::iterator &BI, Instruction *I)
Replace the instruction specified by BI with the instruction specified by I.
LLVMContext & getContext() const
Definition: IRBuilder.h:124
Function * checkSanitizerInterfaceFunction(Constant *FuncOrBitcast)
const Value * stripInBoundsOffsets() const
Strip off pointer casts and inbounds GEPs.
Definition: Value.cpp:618
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
Constant * getOrInsertFunction(StringRef Name, FunctionType *T, AttributeList AttributeList)
Look up the specified function in the module symbol table.
Definition: Module.cpp:142
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:63
bool isSized(SmallPtrSetImpl< Type *> *Visited=nullptr) const
Return true if it makes sense to take the size of this type.
Definition: Type.h:262
An instruction for ordering other memory operations.
Definition: Instructions.h:440
an instruction that atomically checks whether a specified value is in a memory location, and, if it is, stores a new value there.
Definition: Instructions.h:514
This class represents a function call, abstracting a target machine&#39;s calling convention.
This file contains the declarations for metadata subclasses.
bool hasFnAttribute(Attribute::AttrKind Kind) const
Return true if the function has the attribute.
Definition: Function.h:262
This class wraps the llvm.memset intrinsic.
static bool shouldInstrumentReadWriteFromAddress(const Module *M, Value *Addr)
STATISTIC(NumFunctions, "Total number of functions")
Metadata node.
Definition: Metadata.h:862
std::string getInstrProfSectionName(InstrProfSectKind IPSK, Triple::ObjectFormatType OF, bool AddSegmentInfo=true)
Return the name of the profile section corresponding to IPSK.
Definition: InstrProf.cpp:165
F(f)
static CallInst * Create(Value *Func, ArrayRef< Value *> Args, ArrayRef< OperandBundleDef > Bundles=None, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
unsigned getPointerAddressSpace() const
Get the address space of this pointer or pointer vector type.
Definition: DerivedTypes.h:503
An instruction for reading from memory.
Definition: Instructions.h:164
an instruction that atomically reads a memory location, combines it with another value, and then stores the result back.
Definition: Instructions.h:677
Hexagon Common GEP
#define op(i)
IntegerType * getInt32Ty()
Fetch the type representing a 32-bit integer.
Definition: IRBuilder.h:348
static cl::opt< bool > ClInstrumentAtomics("tsan-instrument-atomics", cl::init(true), cl::desc("Instrument atomics"), cl::Hidden)
EscapeEnumerator - This is a little algorithm to find all escape points from a function so that "fina...
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE bool endswith(StringRef Suffix) const
Check if this string ends with the given Suffix.
Definition: StringRef.h:279
AnalysisUsage & addRequired()
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:51
static uint32_t getAlignment(const MCSectionCOFF &Sec)
static Value * getPointerOperand(Instruction &Inst)
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:361
LLVMContext & getContext() const
Get the global data context.
Definition: Module.h:237
PointerType * getPointerTo(unsigned AddrSpace=0) const
Return a pointer to the current type.
Definition: Type.cpp:639
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:42
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:197
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:668
Type * getVoidTy()
Fetch the type representing void.
Definition: IRBuilder.h:381
AtomicOrdering
Atomic ordering for LLVM&#39;s memory model.
auto reverse(ContainerTy &&C, typename std::enable_if< has_rbegin< ContainerTy >::value >::type *=nullptr) -> decltype(make_range(C.rbegin(), C.rend()))
Definition: STLExtras.h:186
Value * CreateIntToPtr(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1444
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
std::string itostr(int64_t X)
Definition: StringExtras.h:189
bool isSwiftError() const
Return true if this value is a swifterror value.
Definition: Value.cpp:749
MDNode * getMetadata(unsigned KindID) const
Get the metadata of given kind attached to this Instruction.
Definition: Instruction.h:194
An instruction for storing to memory.
Definition: Instructions.h:306
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:430
Function * getDeclaration(Module *M, ID id, ArrayRef< Type *> Tys=None)
Create or insert an LLVM Function declaration for an intrinsic, and return it.
Definition: Function.cpp:980
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:301
const BasicBlock & getEntryBlock() const
Definition: Function.h:572
an instruction for type-safe pointer arithmetic to access elements of arrays and structs ...
Definition: Instructions.h:837
IntegerType * getIntPtrType(LLVMContext &C, unsigned AddressSpace=0) const
Returns an integer type with size at least as big as that of a pointer in the given address space...
Definition: DataLayout.cpp:702
static const size_t kNumberOfAccessSizes
static bool runOnFunction(Function &F, bool PostInlining)
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:406
const Instruction * getFirstNonPHI() const
Returns a pointer to the first instruction in this block that is not a PHINode instruction.
Definition: BasicBlock.cpp:171
std::size_t countTrailingZeros(T Val, ZeroBehavior ZB=ZB_Width)
Count number of 0&#39;s from the least significant bit to the most stopping at the first 1...
Definition: MathExtras.h:112
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
std::pair< Function *, Function * > createSanitizerCtorAndInitFunctions(Module &M, StringRef CtorName, StringRef InitName, ArrayRef< Type *> InitArgTypes, ArrayRef< Value *> InitArgs, StringRef VersionCheckName=StringRef())
Creates sanitizer constructor function, and calls sanitizer&#39;s init function from it.
static const char *const kTsanModuleCtorName
SmallSet - This maintains a set of unique values, optimizing for the case when the set is small (less...
Definition: SmallSet.h:36
Represent the analysis usage information of a pass.
FunctionPass * createThreadSanitizerPass()
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:285
Value * getPointerOperand()
Definition: Instructions.h:270
Value * CreateICmpEQ(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1550
Class to represent integer types.
Definition: DerivedTypes.h:40
std::pair< NoneType, bool > insert(const T &V)
insert - Insert an element into the set if it isn&#39;t already there.
Definition: SmallSet.h:81
Value * CreateExtractElement(Value *Vec, Value *Idx, const Twine &Name="")
Definition: IRBuilder.h:1713
static UndefValue * get(Type *T)
Static factory methods - Return an &#39;undef&#39; object of the specified type.
Definition: Constants.cpp:1320
static cl::opt< bool > ClInstrumentFuncEntryExit("tsan-instrument-func-entry-exit", cl::init(true), cl::desc("Instrument function entry and exit"), cl::Hidden)
bool PointerMayBeCaptured(const Value *V, bool ReturnCaptures, bool StoreCaptures)
PointerMayBeCaptured - Return true if this pointer value may be captured by the enclosing function (w...
static bool isAtomic(Instruction *I)
PointerType * getInt8PtrTy(unsigned AddrSpace=0)
Fetch the type representing a pointer to an 8-bit integer value.
Definition: IRBuilder.h:386
static PointerType * getInt8PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:220
Value * GetUnderlyingObject(Value *V, const DataLayout &DL, unsigned MaxLookup=6)
This method strips off any GEP address adjustments and pointer casts from the specified value...
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:44
This is the shared class of boolean and integer constants.
Definition: Constants.h:84
Value * CreateIntCast(Value *V, Type *DestTy, bool isSigned, const Twine &Name="")
Definition: IRBuilder.h:1511
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:864
Module.h This file contains the declarations for the Module class.
Provides information about what library functions are available for the current target.
ConstantInt * getInt32(uint32_t C)
Get a constant 32-bit value.
Definition: IRBuilder.h:308
static IntegerType * getIntNTy(LLVMContext &C, unsigned N)
Definition: Type.cpp:180
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:560
static ConstantInt * createOrdering(IRBuilder<> *IRB, AtomicOrdering ord)
void appendToGlobalCtors(Module &M, Function *F, int Priority, Constant *Data=nullptr)
Append F to the list of global ctors of module M with the given Priority.
Definition: ModuleUtils.cpp:84
std::string utostr(uint64_t X, bool isNeg=false)
Definition: StringExtras.h:174
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
static cl::opt< bool > ClHandleCxxExceptions("tsan-handle-cxx-exceptions", cl::init(true), cl::desc("Handle C++ exceptions (insert cleanup blocks for unwinding)"), cl::Hidden)
Value * CreatePointerCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1488
#define Success
Value * CreateBitOrPointerCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1520
This class wraps the llvm.memcpy/memmove intrinsics.
Synchronized with respect to signal handlers executing in the same thread.
Definition: LLVMContext.h:56
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:176
#define I(x, y, z)
Definition: MD5.cpp:58
static cl::opt< bool > ClInstrumentMemoryAccesses("tsan-instrument-memory-accesses", cl::init(true), cl::desc("Instrument memory accesses"), cl::Hidden)
void maybeMarkSanitizerLibraryCallNoBuiltin(CallInst *CI, const TargetLibraryInfo *TLI)
Given a CallInst, check if it calls a string function known to CodeGen, and mark it with NoBuiltin if...
Definition: Local.cpp:2220
static cl::opt< bool > ClInstrumentMemIntrinsics("tsan-instrument-memintrinsics", cl::init(true), cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden)
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
static const char *const kTsanInitName
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:556
LLVM Value Representation.
Definition: Value.h:73
#define LLVM_FALLTHROUGH
LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
Definition: Compiler.h:235
#define DEBUG(X)
Definition: Debug.h:118
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
INITIALIZE_PASS_BEGIN(ThreadSanitizer, "tsan", "ThreadSanitizer: detects data races.", false, false) INITIALIZE_PASS_END(ThreadSanitizer
Value * CreateInsertValue(Value *Agg, Value *Val, ArrayRef< unsigned > Idxs, const Twine &Name="")
Definition: IRBuilder.h:1763
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
static bool isVtableAccess(Instruction *I)
CallInst * CreateCall(Value *Callee, ArrayRef< Value *> Args=None, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:1663
size_type count(const T &V) const
count - Return 1 if the element is in the set, 0 otherwise.
Definition: SmallSet.h:65