LLVM  10.0.0svn
ThreadSanitizer.cpp
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1 //===-- ThreadSanitizer.cpp - race detector -------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is a part of ThreadSanitizer, a race detector.
10 //
11 // The tool is under development, for the details about previous versions see
12 // http://code.google.com/p/data-race-test
13 //
14 // The instrumentation phase is quite simple:
15 // - Insert calls to run-time library before every memory access.
16 // - Optimizations may apply to avoid instrumenting some of the accesses.
17 // - Insert calls at function entry/exit.
18 // The rest is handled by the run-time library.
19 //===----------------------------------------------------------------------===//
20 
22 #include "llvm/ADT/SmallPtrSet.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"
31 #include "llvm/IR/DataLayout.h"
32 #include "llvm/IR/Function.h"
33 #include "llvm/IR/IRBuilder.h"
34 #include "llvm/IR/IntrinsicInst.h"
35 #include "llvm/IR/Intrinsics.h"
36 #include "llvm/IR/LLVMContext.h"
37 #include "llvm/IR/Metadata.h"
38 #include "llvm/IR/Module.h"
39 #include "llvm/IR/Type.h"
42 #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 ///
90 /// Instantiating ThreadSanitizer inserts the tsan runtime library API function
91 /// declarations into the module if they don't exist already. Instantiating
92 /// ensures the __tsan_init function is in the list of global constructors for
93 /// the module.
94 struct ThreadSanitizer {
95  ThreadSanitizer(Module &M);
96  bool sanitizeFunction(Function &F, const TargetLibraryInfo &TLI);
97 
98 private:
99  void initializeCallbacks(Module &M);
100  bool instrumentLoadOrStore(Instruction *I, const DataLayout &DL);
101  bool instrumentAtomic(Instruction *I, const DataLayout &DL);
102  bool instrumentMemIntrinsic(Instruction *I);
103  void chooseInstructionsToInstrument(SmallVectorImpl<Instruction *> &Local,
105  const DataLayout &DL);
106  bool addrPointsToConstantData(Value *Addr);
107  int getMemoryAccessFuncIndex(Value *Addr, const DataLayout &DL);
108  void InsertRuntimeIgnores(Function &F);
109 
110  Type *IntptrTy;
111  IntegerType *OrdTy;
112  // Callbacks to run-time library are computed in doInitialization.
113  FunctionCallee TsanFuncEntry;
114  FunctionCallee TsanFuncExit;
115  FunctionCallee TsanIgnoreBegin;
116  FunctionCallee TsanIgnoreEnd;
117  // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
118  static const size_t kNumberOfAccessSizes = 5;
121  FunctionCallee TsanUnalignedRead[kNumberOfAccessSizes];
122  FunctionCallee TsanUnalignedWrite[kNumberOfAccessSizes];
123  FunctionCallee TsanAtomicLoad[kNumberOfAccessSizes];
124  FunctionCallee TsanAtomicStore[kNumberOfAccessSizes];
125  FunctionCallee TsanAtomicRMW[AtomicRMWInst::LAST_BINOP + 1]
127  FunctionCallee TsanAtomicCAS[kNumberOfAccessSizes];
128  FunctionCallee TsanAtomicThreadFence;
129  FunctionCallee TsanAtomicSignalFence;
130  FunctionCallee TsanVptrUpdate;
131  FunctionCallee TsanVptrLoad;
132  FunctionCallee MemmoveFn, MemcpyFn, MemsetFn;
133  Function *TsanCtorFunction;
134 };
135 
136 struct ThreadSanitizerLegacyPass : FunctionPass {
137  ThreadSanitizerLegacyPass() : FunctionPass(ID) {}
138  StringRef getPassName() const override;
139  void getAnalysisUsage(AnalysisUsage &AU) const override;
140  bool runOnFunction(Function &F) override;
141  bool doInitialization(Module &M) override;
142  static char ID; // Pass identification, replacement for typeid.
143 private:
145 };
146 } // namespace
147 
150  ThreadSanitizer TSan(*F.getParent());
151  if (TSan.sanitizeFunction(F, FAM.getResult<TargetLibraryAnalysis>(F)))
152  return PreservedAnalyses::none();
153  return PreservedAnalyses::all();
154 }
155 
157 INITIALIZE_PASS_BEGIN(ThreadSanitizerLegacyPass, "tsan",
158  "ThreadSanitizer: detects data races.", false, false)
160 INITIALIZE_PASS_END(ThreadSanitizerLegacyPass, "tsan",
161  "ThreadSanitizer: detects data races.", false, false)
162 
163 StringRef ThreadSanitizerLegacyPass::getPassName() const {
164  return "ThreadSanitizerLegacyPass";
165 }
166 
167 void ThreadSanitizerLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const {
169 }
170 
171 bool ThreadSanitizerLegacyPass::doInitialization(Module &M) {
172  TSan.emplace(M);
173  return true;
174 }
175 
177  auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
178  TSan->sanitizeFunction(F, TLI);
179  return true;
180 }
181 
183  return new ThreadSanitizerLegacyPass();
184 }
185 
186 void ThreadSanitizer::initializeCallbacks(Module &M) {
187  IRBuilder<> IRB(M.getContext());
188  AttributeList Attr;
189  Attr = Attr.addAttribute(M.getContext(), AttributeList::FunctionIndex,
190  Attribute::NoUnwind);
191  // Initialize the callbacks.
192  TsanFuncEntry = M.getOrInsertFunction("__tsan_func_entry", Attr,
193  IRB.getVoidTy(), IRB.getInt8PtrTy());
194  TsanFuncExit =
195  M.getOrInsertFunction("__tsan_func_exit", Attr, IRB.getVoidTy());
196  TsanIgnoreBegin = M.getOrInsertFunction("__tsan_ignore_thread_begin", Attr,
197  IRB.getVoidTy());
198  TsanIgnoreEnd =
199  M.getOrInsertFunction("__tsan_ignore_thread_end", Attr, IRB.getVoidTy());
200  OrdTy = IRB.getInt32Ty();
201  for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
202  const unsigned ByteSize = 1U << i;
203  const unsigned BitSize = ByteSize * 8;
204  std::string ByteSizeStr = utostr(ByteSize);
205  std::string BitSizeStr = utostr(BitSize);
206  SmallString<32> ReadName("__tsan_read" + ByteSizeStr);
207  TsanRead[i] = M.getOrInsertFunction(ReadName, Attr, IRB.getVoidTy(),
208  IRB.getInt8PtrTy());
209 
210  SmallString<32> WriteName("__tsan_write" + ByteSizeStr);
211  TsanWrite[i] = M.getOrInsertFunction(WriteName, Attr, IRB.getVoidTy(),
212  IRB.getInt8PtrTy());
213 
214  SmallString<64> UnalignedReadName("__tsan_unaligned_read" + ByteSizeStr);
215  TsanUnalignedRead[i] = M.getOrInsertFunction(
216  UnalignedReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());
217 
218  SmallString<64> UnalignedWriteName("__tsan_unaligned_write" + ByteSizeStr);
219  TsanUnalignedWrite[i] = M.getOrInsertFunction(
220  UnalignedWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());
221 
222  Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
223  Type *PtrTy = Ty->getPointerTo();
224  SmallString<32> AtomicLoadName("__tsan_atomic" + BitSizeStr + "_load");
225  TsanAtomicLoad[i] =
226  M.getOrInsertFunction(AtomicLoadName, Attr, Ty, PtrTy, OrdTy);
227 
228  SmallString<32> AtomicStoreName("__tsan_atomic" + BitSizeStr + "_store");
229  TsanAtomicStore[i] = M.getOrInsertFunction(
230  AtomicStoreName, Attr, IRB.getVoidTy(), PtrTy, Ty, OrdTy);
231 
232  for (int op = AtomicRMWInst::FIRST_BINOP;
234  TsanAtomicRMW[op][i] = nullptr;
235  const char *NamePart = nullptr;
236  if (op == AtomicRMWInst::Xchg)
237  NamePart = "_exchange";
238  else if (op == AtomicRMWInst::Add)
239  NamePart = "_fetch_add";
240  else if (op == AtomicRMWInst::Sub)
241  NamePart = "_fetch_sub";
242  else if (op == AtomicRMWInst::And)
243  NamePart = "_fetch_and";
244  else if (op == AtomicRMWInst::Or)
245  NamePart = "_fetch_or";
246  else if (op == AtomicRMWInst::Xor)
247  NamePart = "_fetch_xor";
248  else if (op == AtomicRMWInst::Nand)
249  NamePart = "_fetch_nand";
250  else
251  continue;
252  SmallString<32> RMWName("__tsan_atomic" + itostr(BitSize) + NamePart);
253  TsanAtomicRMW[op][i] =
254  M.getOrInsertFunction(RMWName, Attr, Ty, PtrTy, Ty, OrdTy);
255  }
256 
257  SmallString<32> AtomicCASName("__tsan_atomic" + BitSizeStr +
258  "_compare_exchange_val");
259  TsanAtomicCAS[i] = M.getOrInsertFunction(AtomicCASName, Attr, Ty, PtrTy, Ty,
260  Ty, OrdTy, OrdTy);
261  }
262  TsanVptrUpdate =
263  M.getOrInsertFunction("__tsan_vptr_update", Attr, IRB.getVoidTy(),
264  IRB.getInt8PtrTy(), IRB.getInt8PtrTy());
265  TsanVptrLoad = M.getOrInsertFunction("__tsan_vptr_read", Attr,
266  IRB.getVoidTy(), IRB.getInt8PtrTy());
267  TsanAtomicThreadFence = M.getOrInsertFunction("__tsan_atomic_thread_fence",
268  Attr, IRB.getVoidTy(), OrdTy);
269  TsanAtomicSignalFence = M.getOrInsertFunction("__tsan_atomic_signal_fence",
270  Attr, IRB.getVoidTy(), OrdTy);
271 
272  MemmoveFn =
273  M.getOrInsertFunction("memmove", Attr, IRB.getInt8PtrTy(),
274  IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy);
275  MemcpyFn =
276  M.getOrInsertFunction("memcpy", Attr, IRB.getInt8PtrTy(),
277  IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy);
278  MemsetFn =
279  M.getOrInsertFunction("memset", Attr, IRB.getInt8PtrTy(),
280  IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy);
281 }
282 
283 ThreadSanitizer::ThreadSanitizer(Module &M) {
284  const DataLayout &DL = M.getDataLayout();
285  IntptrTy = DL.getIntPtrType(M.getContext());
286  std::tie(TsanCtorFunction, std::ignore) =
288  M, kTsanModuleCtorName, kTsanInitName, /*InitArgTypes=*/{},
289  /*InitArgs=*/{},
290  // This callback is invoked when the functions are created the first
291  // time. Hook them into the global ctors list in that case:
292  [&](Function *Ctor, FunctionCallee) {
293  appendToGlobalCtors(M, Ctor, 0);
294  });
295 }
296 
297 static bool isVtableAccess(Instruction *I) {
298  if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa))
299  return Tag->isTBAAVtableAccess();
300  return false;
301 }
302 
303 // Do not instrument known races/"benign races" that come from compiler
304 // instrumentatin. The user has no way of suppressing them.
305 static bool shouldInstrumentReadWriteFromAddress(const Module *M, Value *Addr) {
306  // Peel off GEPs and BitCasts.
307  Addr = Addr->stripInBoundsOffsets();
308 
309  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
310  if (GV->hasSection()) {
311  StringRef SectionName = GV->getSection();
312  // Check if the global is in the PGO counters section.
313  auto OF = Triple(M->getTargetTriple()).getObjectFormat();
314  if (SectionName.endswith(
315  getInstrProfSectionName(IPSK_cnts, OF, /*AddSegmentInfo=*/false)))
316  return false;
317  }
318 
319  // Check if the global is private gcov data.
320  if (GV->getName().startswith("__llvm_gcov") ||
321  GV->getName().startswith("__llvm_gcda"))
322  return false;
323  }
324 
325  // Do not instrument acesses from different address spaces; we cannot deal
326  // with them.
327  if (Addr) {
328  Type *PtrTy = cast<PointerType>(Addr->getType()->getScalarType());
329  if (PtrTy->getPointerAddressSpace() != 0)
330  return false;
331  }
332 
333  return true;
334 }
335 
336 bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) {
337  // If this is a GEP, just analyze its pointer operand.
338  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
339  Addr = GEP->getPointerOperand();
340 
341  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
342  if (GV->isConstant()) {
343  // Reads from constant globals can not race with any writes.
344  NumOmittedReadsFromConstantGlobals++;
345  return true;
346  }
347  } else if (LoadInst *L = dyn_cast<LoadInst>(Addr)) {
348  if (isVtableAccess(L)) {
349  // Reads from a vtable pointer can not race with any writes.
350  NumOmittedReadsFromVtable++;
351  return true;
352  }
353  }
354  return false;
355 }
356 
357 // Instrumenting some of the accesses may be proven redundant.
358 // Currently handled:
359 // - read-before-write (within same BB, no calls between)
360 // - not captured variables
361 //
362 // We do not handle some of the patterns that should not survive
363 // after the classic compiler optimizations.
364 // E.g. two reads from the same temp should be eliminated by CSE,
365 // two writes should be eliminated by DSE, etc.
366 //
367 // 'Local' is a vector of insns within the same BB (no calls between).
368 // 'All' is a vector of insns that will be instrumented.
369 void ThreadSanitizer::chooseInstructionsToInstrument(
371  const DataLayout &DL) {
372  SmallPtrSet<Value*, 8> WriteTargets;
373  // Iterate from the end.
374  for (Instruction *I : reverse(Local)) {
375  if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
376  Value *Addr = Store->getPointerOperand();
377  if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
378  continue;
379  WriteTargets.insert(Addr);
380  } else {
381  LoadInst *Load = cast<LoadInst>(I);
382  Value *Addr = Load->getPointerOperand();
383  if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
384  continue;
385  if (WriteTargets.count(Addr)) {
386  // We will write to this temp, so no reason to analyze the read.
387  NumOmittedReadsBeforeWrite++;
388  continue;
389  }
390  if (addrPointsToConstantData(Addr)) {
391  // Addr points to some constant data -- it can not race with any writes.
392  continue;
393  }
394  }
395  Value *Addr = isa<StoreInst>(*I)
396  ? cast<StoreInst>(I)->getPointerOperand()
397  : cast<LoadInst>(I)->getPointerOperand();
398  if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
399  !PointerMayBeCaptured(Addr, true, true)) {
400  // The variable is addressable but not captured, so it cannot be
401  // referenced from a different thread and participate in a data race
402  // (see llvm/Analysis/CaptureTracking.h for details).
403  NumOmittedNonCaptured++;
404  continue;
405  }
406  All.push_back(I);
407  }
408  Local.clear();
409 }
410 
411 static bool isAtomic(Instruction *I) {
412  // TODO: Ask TTI whether synchronization scope is between threads.
413  if (LoadInst *LI = dyn_cast<LoadInst>(I))
414  return LI->isAtomic() && LI->getSyncScopeID() != SyncScope::SingleThread;
415  if (StoreInst *SI = dyn_cast<StoreInst>(I))
416  return SI->isAtomic() && SI->getSyncScopeID() != SyncScope::SingleThread;
417  if (isa<AtomicRMWInst>(I))
418  return true;
419  if (isa<AtomicCmpXchgInst>(I))
420  return true;
421  if (isa<FenceInst>(I))
422  return true;
423  return false;
424 }
425 
426 void ThreadSanitizer::InsertRuntimeIgnores(Function &F) {
428  IRB.CreateCall(TsanIgnoreBegin);
429  EscapeEnumerator EE(F, "tsan_ignore_cleanup", ClHandleCxxExceptions);
430  while (IRBuilder<> *AtExit = EE.Next()) {
431  AtExit->CreateCall(TsanIgnoreEnd);
432  }
433 }
434 
435 bool ThreadSanitizer::sanitizeFunction(Function &F,
436  const TargetLibraryInfo &TLI) {
437  // This is required to prevent instrumenting call to __tsan_init from within
438  // the module constructor.
439  if (&F == TsanCtorFunction)
440  return false;
441  initializeCallbacks(*F.getParent());
442  SmallVector<Instruction*, 8> AllLoadsAndStores;
443  SmallVector<Instruction*, 8> LocalLoadsAndStores;
444  SmallVector<Instruction*, 8> AtomicAccesses;
445  SmallVector<Instruction*, 8> MemIntrinCalls;
446  bool Res = false;
447  bool HasCalls = false;
448  bool SanitizeFunction = F.hasFnAttribute(Attribute::SanitizeThread);
449  const DataLayout &DL = F.getParent()->getDataLayout();
450 
451  // Traverse all instructions, collect loads/stores/returns, check for calls.
452  for (auto &BB : F) {
453  for (auto &Inst : BB) {
454  if (isAtomic(&Inst))
455  AtomicAccesses.push_back(&Inst);
456  else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
457  LocalLoadsAndStores.push_back(&Inst);
458  else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
459  if (CallInst *CI = dyn_cast<CallInst>(&Inst))
461  if (isa<MemIntrinsic>(Inst))
462  MemIntrinCalls.push_back(&Inst);
463  HasCalls = true;
464  chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores,
465  DL);
466  }
467  }
468  chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores, DL);
469  }
470 
471  // We have collected all loads and stores.
472  // FIXME: many of these accesses do not need to be checked for races
473  // (e.g. variables that do not escape, etc).
474 
475  // Instrument memory accesses only if we want to report bugs in the function.
476  if (ClInstrumentMemoryAccesses && SanitizeFunction)
477  for (auto Inst : AllLoadsAndStores) {
478  Res |= instrumentLoadOrStore(Inst, DL);
479  }
480 
481  // Instrument atomic memory accesses in any case (they can be used to
482  // implement synchronization).
484  for (auto Inst : AtomicAccesses) {
485  Res |= instrumentAtomic(Inst, DL);
486  }
487 
488  if (ClInstrumentMemIntrinsics && SanitizeFunction)
489  for (auto Inst : MemIntrinCalls) {
490  Res |= instrumentMemIntrinsic(Inst);
491  }
492 
493  if (F.hasFnAttribute("sanitize_thread_no_checking_at_run_time")) {
494  assert(!F.hasFnAttribute(Attribute::SanitizeThread));
495  if (HasCalls)
496  InsertRuntimeIgnores(F);
497  }
498 
499  // Instrument function entry/exit points if there were instrumented accesses.
500  if ((Res || HasCalls) && ClInstrumentFuncEntryExit) {
501  IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
502  Value *ReturnAddress = IRB.CreateCall(
503  Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
504  IRB.getInt32(0));
505  IRB.CreateCall(TsanFuncEntry, ReturnAddress);
506 
507  EscapeEnumerator EE(F, "tsan_cleanup", ClHandleCxxExceptions);
508  while (IRBuilder<> *AtExit = EE.Next()) {
509  AtExit->CreateCall(TsanFuncExit, {});
510  }
511  Res = true;
512  }
513  return Res;
514 }
515 
516 bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I,
517  const DataLayout &DL) {
518  IRBuilder<> IRB(I);
519  bool IsWrite = isa<StoreInst>(*I);
520  Value *Addr = IsWrite
521  ? cast<StoreInst>(I)->getPointerOperand()
522  : cast<LoadInst>(I)->getPointerOperand();
523 
524  // swifterror memory addresses are mem2reg promoted by instruction selection.
525  // As such they cannot have regular uses like an instrumentation function and
526  // it makes no sense to track them as memory.
527  if (Addr->isSwiftError())
528  return false;
529 
530  int Idx = getMemoryAccessFuncIndex(Addr, DL);
531  if (Idx < 0)
532  return false;
533  if (IsWrite && isVtableAccess(I)) {
534  LLVM_DEBUG(dbgs() << " VPTR : " << *I << "\n");
535  Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
536  // StoredValue may be a vector type if we are storing several vptrs at once.
537  // In this case, just take the first element of the vector since this is
538  // enough to find vptr races.
539  if (isa<VectorType>(StoredValue->getType()))
540  StoredValue = IRB.CreateExtractElement(
541  StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0));
542  if (StoredValue->getType()->isIntegerTy())
543  StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
544  // Call TsanVptrUpdate.
545  IRB.CreateCall(TsanVptrUpdate,
546  {IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
547  IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy())});
548  NumInstrumentedVtableWrites++;
549  return true;
550  }
551  if (!IsWrite && isVtableAccess(I)) {
552  IRB.CreateCall(TsanVptrLoad,
553  IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
554  NumInstrumentedVtableReads++;
555  return true;
556  }
557  const unsigned Alignment = IsWrite
558  ? cast<StoreInst>(I)->getAlignment()
559  : cast<LoadInst>(I)->getAlignment();
560  Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
561  const uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
562  FunctionCallee OnAccessFunc = nullptr;
563  if (Alignment == 0 || Alignment >= 8 || (Alignment % (TypeSize / 8)) == 0)
564  OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
565  else
566  OnAccessFunc = IsWrite ? TsanUnalignedWrite[Idx] : TsanUnalignedRead[Idx];
567  IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
568  if (IsWrite) NumInstrumentedWrites++;
569  else NumInstrumentedReads++;
570  return true;
571 }
572 
574  uint32_t v = 0;
575  switch (ord) {
577  llvm_unreachable("unexpected atomic ordering!");
579  case AtomicOrdering::Monotonic: v = 0; break;
580  // Not specified yet:
581  // case AtomicOrdering::Consume: v = 1; break;
582  case AtomicOrdering::Acquire: v = 2; break;
583  case AtomicOrdering::Release: v = 3; break;
584  case AtomicOrdering::AcquireRelease: v = 4; break;
585  case AtomicOrdering::SequentiallyConsistent: v = 5; break;
586  }
587  return IRB->getInt32(v);
588 }
589 
590 // If a memset intrinsic gets inlined by the code gen, we will miss races on it.
591 // So, we either need to ensure the intrinsic is not inlined, or instrument it.
592 // We do not instrument memset/memmove/memcpy intrinsics (too complicated),
593 // instead we simply replace them with regular function calls, which are then
594 // intercepted by the run-time.
595 // Since tsan is running after everyone else, the calls should not be
596 // replaced back with intrinsics. If that becomes wrong at some point,
597 // we will need to call e.g. __tsan_memset to avoid the intrinsics.
598 bool ThreadSanitizer::instrumentMemIntrinsic(Instruction *I) {
599  IRBuilder<> IRB(I);
600  if (MemSetInst *M = dyn_cast<MemSetInst>(I)) {
601  IRB.CreateCall(
602  MemsetFn,
603  {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
604  IRB.CreateIntCast(M->getArgOperand(1), IRB.getInt32Ty(), false),
605  IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
606  I->eraseFromParent();
607  } else if (MemTransferInst *M = dyn_cast<MemTransferInst>(I)) {
608  IRB.CreateCall(
609  isa<MemCpyInst>(M) ? MemcpyFn : MemmoveFn,
610  {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
611  IRB.CreatePointerCast(M->getArgOperand(1), IRB.getInt8PtrTy()),
612  IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
613  I->eraseFromParent();
614  }
615  return false;
616 }
617 
618 // Both llvm and ThreadSanitizer atomic operations are based on C++11/C1x
619 // standards. For background see C++11 standard. A slightly older, publicly
620 // available draft of the standard (not entirely up-to-date, but close enough
621 // for casual browsing) is available here:
622 // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf
623 // The following page contains more background information:
624 // http://www.hpl.hp.com/personal/Hans_Boehm/c++mm/
625 
626 bool ThreadSanitizer::instrumentAtomic(Instruction *I, const DataLayout &DL) {
627  IRBuilder<> IRB(I);
628  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
629  Value *Addr = LI->getPointerOperand();
630  int Idx = getMemoryAccessFuncIndex(Addr, DL);
631  if (Idx < 0)
632  return false;
633  const unsigned ByteSize = 1U << Idx;
634  const unsigned BitSize = ByteSize * 8;
635  Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
636  Type *PtrTy = Ty->getPointerTo();
637  Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
638  createOrdering(&IRB, LI->getOrdering())};
639  Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
640  Value *C = IRB.CreateCall(TsanAtomicLoad[Idx], Args);
641  Value *Cast = IRB.CreateBitOrPointerCast(C, OrigTy);
642  I->replaceAllUsesWith(Cast);
643  } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
644  Value *Addr = SI->getPointerOperand();
645  int Idx = getMemoryAccessFuncIndex(Addr, DL);
646  if (Idx < 0)
647  return false;
648  const unsigned ByteSize = 1U << Idx;
649  const unsigned BitSize = ByteSize * 8;
650  Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
651  Type *PtrTy = Ty->getPointerTo();
652  Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
653  IRB.CreateBitOrPointerCast(SI->getValueOperand(), Ty),
654  createOrdering(&IRB, SI->getOrdering())};
655  CallInst *C = CallInst::Create(TsanAtomicStore[Idx], Args);
656  ReplaceInstWithInst(I, C);
657  } else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I)) {
658  Value *Addr = RMWI->getPointerOperand();
659  int Idx = getMemoryAccessFuncIndex(Addr, DL);
660  if (Idx < 0)
661  return false;
662  FunctionCallee F = TsanAtomicRMW[RMWI->getOperation()][Idx];
663  if (!F)
664  return false;
665  const unsigned ByteSize = 1U << Idx;
666  const unsigned BitSize = ByteSize * 8;
667  Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
668  Type *PtrTy = Ty->getPointerTo();
669  Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
670  IRB.CreateIntCast(RMWI->getValOperand(), Ty, false),
671  createOrdering(&IRB, RMWI->getOrdering())};
672  CallInst *C = CallInst::Create(F, Args);
673  ReplaceInstWithInst(I, C);
674  } else if (AtomicCmpXchgInst *CASI = dyn_cast<AtomicCmpXchgInst>(I)) {
675  Value *Addr = CASI->getPointerOperand();
676  int Idx = getMemoryAccessFuncIndex(Addr, DL);
677  if (Idx < 0)
678  return false;
679  const unsigned ByteSize = 1U << Idx;
680  const unsigned BitSize = ByteSize * 8;
681  Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
682  Type *PtrTy = Ty->getPointerTo();
683  Value *CmpOperand =
684  IRB.CreateBitOrPointerCast(CASI->getCompareOperand(), Ty);
685  Value *NewOperand =
686  IRB.CreateBitOrPointerCast(CASI->getNewValOperand(), Ty);
687  Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
688  CmpOperand,
689  NewOperand,
690  createOrdering(&IRB, CASI->getSuccessOrdering()),
691  createOrdering(&IRB, CASI->getFailureOrdering())};
692  CallInst *C = IRB.CreateCall(TsanAtomicCAS[Idx], Args);
693  Value *Success = IRB.CreateICmpEQ(C, CmpOperand);
694  Value *OldVal = C;
695  Type *OrigOldValTy = CASI->getNewValOperand()->getType();
696  if (Ty != OrigOldValTy) {
697  // The value is a pointer, so we need to cast the return value.
698  OldVal = IRB.CreateIntToPtr(C, OrigOldValTy);
699  }
700 
701  Value *Res =
702  IRB.CreateInsertValue(UndefValue::get(CASI->getType()), OldVal, 0);
703  Res = IRB.CreateInsertValue(Res, Success, 1);
704 
705  I->replaceAllUsesWith(Res);
706  I->eraseFromParent();
707  } else if (FenceInst *FI = dyn_cast<FenceInst>(I)) {
708  Value *Args[] = {createOrdering(&IRB, FI->getOrdering())};
709  FunctionCallee F = FI->getSyncScopeID() == SyncScope::SingleThread
710  ? TsanAtomicSignalFence
711  : TsanAtomicThreadFence;
712  CallInst *C = CallInst::Create(F, Args);
713  ReplaceInstWithInst(I, C);
714  }
715  return true;
716 }
717 
718 int ThreadSanitizer::getMemoryAccessFuncIndex(Value *Addr,
719  const DataLayout &DL) {
720  Type *OrigPtrTy = Addr->getType();
721  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
722  assert(OrigTy->isSized());
723  uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
724  if (TypeSize != 8 && TypeSize != 16 &&
725  TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
726  NumAccessesWithBadSize++;
727  // Ignore all unusual sizes.
728  return -1;
729  }
730  size_t Idx = countTrailingZeros(TypeSize / 8);
732  return Idx;
733 }
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:67
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
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:453
const std::string & getTargetTriple() const
Get the target triple which is a string describing the target host.
Definition: Module.h:240
void ReplaceInstWithInst(BasicBlock::InstListType &BIL, BasicBlock::iterator &BI, Instruction *I)
Replace the instruction specified by BI with the instruction specified by I.
Value * getPointerOperand(Value *V)
A helper function that returns the pointer operand of a load, store or GEP instruction.
LLVMContext & getContext() const
Definition: IRBuilder.h:128
const Value * stripInBoundsOffsets() const
Strip off pointer casts and inbounds GEPs.
Definition: Value.cpp:608
LLVM_NODISCARD bool endswith(StringRef Suffix) const
Check if this string ends with the given Suffix.
Definition: StringRef.h:267
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:776
This class represents lattice values for constants.
Definition: AllocatorList.h:23
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:65
bool isSized(SmallPtrSetImpl< Type *> *Visited=nullptr) const
Return true if it makes sense to take the size of this type.
Definition: Type.h:264
An instruction for ordering other memory operations.
Definition: Instructions.h:454
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:530
static CallInst * Create(FunctionType *Ty, Value *F, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
A handy container for a FunctionType+Callee-pointer pair, which can be passed around as a single enti...
Definition: DerivedTypes.h:165
void push_back(const T &Elt)
Definition: SmallVector.h:211
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:323
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:863
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)
unsigned getPointerAddressSpace() const
Get the address space of this pointer or pointer vector type.
Definition: DerivedTypes.h:580
An instruction for reading from memory.
Definition: Instructions.h:167
an instruction that atomically reads a memory location, combines it with another value, and then stores the result back.
Definition: Instructions.h:693
Hexagon Common GEP
#define op(i)
IntegerType * getInt32Ty()
Fetch the type representing a 32-bit integer.
Definition: IRBuilder.h:383
static cl::opt< bool > ClInstrumentAtomics("tsan-instrument-atomics", cl::init(true), cl::desc("Instrument atomics"), cl::Hidden)
unsigned 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:119
EscapeEnumerator - This is a little algorithm to find all escape points from a function so that "fina...
AnalysisUsage & addRequired()
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:50
static uint32_t getAlignment(const MCSectionCOFF &Sec)
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:369
LLVMContext & getContext() const
Get the global data context.
Definition: Module.h:244
PointerType * getPointerTo(unsigned AddrSpace=0) const
Return a pointer to the current type.
Definition: Type.cpp:654
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:196
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:779
Type * getVoidTy()
Fetch the type representing void.
Definition: IRBuilder.h:416
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:273
Value * CreateIntToPtr(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1953
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:238
bool isSwiftError() const
Return true if this value is a swifterror value.
Definition: Value.cpp:766
std::pair< Function *, FunctionCallee > getOrCreateSanitizerCtorAndInitFunctions(Module &M, StringRef CtorName, StringRef InitName, ArrayRef< Type *> InitArgTypes, ArrayRef< Value *> InitArgs, function_ref< void(Function *, FunctionCallee)> FunctionsCreatedCallback, StringRef VersionCheckName=StringRef())
Creates sanitizer constructor function lazily.
MDNode * getMetadata(unsigned KindID) const
Get the metadata of given kind attached to this Instruction.
Definition: Instruction.h:234
An instruction for storing to memory.
Definition: Instructions.h:320
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:429
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:1043
static PreservedAnalyses none()
Convenience factory function for the empty preserved set.
Definition: PassManager.h:156
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:303
const BasicBlock & getEntryBlock() const
Definition: Function.h:664
an instruction for type-safe pointer arithmetic to access elements of arrays and structs ...
Definition: Instructions.h:875
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:772
static const size_t kNumberOfAccessSizes
static bool runOnFunction(Function &F, bool PostInlining)
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:432
const Instruction * getFirstNonPHI() const
Returns a pointer to the first instruction in this block that is not a PHINode instruction.
Definition: BasicBlock.cpp:189
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
static const char *const kTsanModuleCtorName
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:370
Represent the analysis usage information of a pass.
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:284
Value * getPointerOperand()
Definition: Instructions.h:284
Value * CreateICmpEQ(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2088
size_type count(ConstPtrType Ptr) const
count - Return 1 if the specified pointer is in the set, 0 otherwise.
Definition: SmallPtrSet.h:381
Class to represent integer types.
Definition: DerivedTypes.h:40
Value * CreateExtractElement(Value *Vec, Value *Idx, const Twine &Name="")
Definition: IRBuilder.h:2293
static UndefValue * get(Type *T)
Static factory methods - Return an &#39;undef&#39; object of the specified type.
Definition: Constants.cpp:1433
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:159
static cl::opt< bool > ClInstrumentFuncEntryExit("tsan-instrument-func-entry-exit", cl::init(true), cl::desc("Instrument function entry and exit"), cl::Hidden)
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:421
static PointerType * getInt8PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:219
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:43
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements...
Definition: SmallPtrSet.h:417
This is the shared class of boolean and integer constants.
Definition: Constants.h:83
Value * CreateIntCast(Value *V, Type *DestTy, bool isSigned, const Twine &Name="")
Definition: IRBuilder.h:2027
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
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:343
static IntegerType * getIntNTy(LLVMContext &C, unsigned N)
Definition: Type.cpp:179
INITIALIZE_PASS_BEGIN(ThreadSanitizerLegacyPass, "tsan", "ThreadSanitizer: detects data races.", false, false) INITIALIZE_PASS_END(ThreadSanitizerLegacyPass
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:640
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:63
FunctionCallee getOrInsertFunction(StringRef Name, FunctionType *T, AttributeList AttributeList)
Look up the specified function in the module symbol table.
Definition: Module.cpp:143
std::string utostr(uint64_t X, bool isNeg=false)
Definition: StringExtras.h:223
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:2004
#define Success
Value * CreateBitOrPointerCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:2036
PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM)
This class wraps the llvm.memcpy/memmove intrinsics.
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:175
#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:2892
CallInst * CreateCall(FunctionType *FTy, Value *Callee, ArrayRef< Value *> Args=None, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:2223
static cl::opt< bool > ClInstrumentMemIntrinsics("tsan-instrument-memintrinsics", cl::init(true), cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden)
Analysis pass providing the TargetLibraryInfo.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
static const char *const kTsanInitName
FunctionPass * createThreadSanitizerLegacyPassPass()
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:575
LLVM Value Representation.
Definition: Value.h:73
Synchronized with respect to signal handlers executing in the same thread.
Definition: LLVMContext.h:51
#define LLVM_FALLTHROUGH
LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
Definition: Compiler.h:258
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
Value * CreateInsertValue(Value *Agg, Value *Val, ArrayRef< unsigned > Idxs, const Twine &Name="")
Definition: IRBuilder.h:2343
#define LLVM_DEBUG(X)
Definition: Debug.h:122
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
static bool isVtableAccess(Instruction *I)
bool PointerMayBeCaptured(const Value *V, bool ReturnCaptures, bool StoreCaptures, unsigned MaxUsesToExplore=DefaultMaxUsesToExplore)
PointerMayBeCaptured - Return true if this pointer value may be captured by the enclosing function (w...