lib/Transforms/Instrumentation/ThreadSanitizer.cpp

   1 //===-- ThreadSanitizer.cpp - race detector -------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file is a part of ThreadSanitizer, a race detector.
  11 //
  12 // The tool is under development, for the details about previous versions see
  13 // http://code.google.com/p/data-race-test
  14 //
  15 // The instrumentation phase is quite simple:
  16 //   - Insert calls to run-time library before every memory access.
  17 //      - Optimizations may apply to avoid instrumenting some of the accesses.
  18 //   - Insert calls at function entry/exit.
  19 // The rest is handled by the run-time library.
  20 //===----------------------------------------------------------------------===//
  21
  22 #include "llvm/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"
  27 #include "llvm/Analysis/CaptureTracking.h"
  28 #include "llvm/Analysis/TargetLibraryInfo.h"
  29 #include "llvm/Transforms/Utils/Local.h"
  30 #include "llvm/Analysis/ValueTracking.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"
  40 #include "llvm/ProfileData/InstrProf.h"
  41 #include "llvm/Support/CommandLine.h"
  42 #include "llvm/Support/Debug.h"
  43 #include "llvm/Support/MathExtras.h"
  44 #include "llvm/Support/raw_ostream.h"
  45 #include "llvm/Transforms/Instrumentation.h"
  46 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
  47 #include "llvm/Transforms/Utils/EscapeEnumerator.h"
  48 #include "llvm/Transforms/Utils/ModuleUtils.h"
  49
  50 using namespace llvm;
  51
  52 #define DEBUG_TYPE "tsan"
  53
  54 static cl::opt<bool>  ClInstrumentMemoryAccesses(
  55     "tsan-instrument-memory-accesses", cl::init(true),
  56     cl::desc("Instrument memory accesses"), cl::Hidden);
  57 static cl::opt<bool>  ClInstrumentFuncEntryExit(
  58     "tsan-instrument-func-entry-exit", cl::init(true),
  59     cl::desc("Instrument function entry and exit"), cl::Hidden);
  60 static cl::opt<bool>  ClHandleCxxExceptions(
  61     "tsan-handle-cxx-exceptions", cl::init(true),
  62     cl::desc("Handle C++ exceptions (insert cleanup blocks for unwinding)"),
  63     cl::Hidden);
  64 static cl::opt<bool>  ClInstrumentAtomics(
  65     "tsan-instrument-atomics", cl::init(true),
  66     cl::desc("Instrument atomics"), cl::Hidden);
  67 static cl::opt<bool>  ClInstrumentMemIntrinsics(
  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,
 103                                       SmallVectorImpl<Instruction *> &All,
 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];
 124   Function *TsanAtomicRMW[AtomicRMWInst::LAST_BINOP + 1][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;
 136 INITIALIZE_PASS_BEGIN(
 137     ThreadSanitizer, "tsan",
 138     "ThreadSanitizer: detects data races.",
 139     false, false)
 140 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
 141 INITIALIZE_PASS_END(
 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 {
 149   AU.addRequired<TargetLibraryInfoWrapperPass>();
 150 }
 151
 152 FunctionPass *llvm::createThreadSanitizerPass() {
 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.
 162   TsanFuncEntry = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 163       "__tsan_func_entry", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
 164   TsanFuncExit = checkSanitizerInterfaceFunction(
 165       M.getOrInsertFunction("__tsan_func_exit", Attr, IRB.getVoidTy()));
 166   TsanIgnoreBegin = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 167       "__tsan_ignore_thread_begin", Attr, IRB.getVoidTy()));
 168   TsanIgnoreEnd = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 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);
 177     TsanRead[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 178         ReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
 179
 180     SmallString<32> WriteName("__tsan_write" + ByteSizeStr);
 181     TsanWrite[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 182         WriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
 183
 184     SmallString<64> UnalignedReadName("__tsan_unaligned_read" + ByteSizeStr);
 185     TsanUnalignedRead[i] =
 186         checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 187             UnalignedReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
 188
 189     SmallString<64> UnalignedWriteName("__tsan_unaligned_write" + ByteSizeStr);
 190     TsanUnalignedWrite[i] =
 191         checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 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");
 201     TsanAtomicStore[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 202         AtomicStoreName, Attr, IRB.getVoidTy(), PtrTy, Ty, OrdTy));
 203
 204     for (int op = AtomicRMWInst::FIRST_BINOP;
 205         op <= AtomicRMWInst::LAST_BINOP; ++op) {
 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");
 231     TsanAtomicCAS[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 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()));
 237   TsanVptrLoad = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 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
 244   MemmoveFn = checkSanitizerInterfaceFunction(
 245       M.getOrInsertFunction("memmove", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
 246                             IRB.getInt8PtrTy(), IntptrTy));
 247   MemcpyFn = checkSanitizerInterfaceFunction(
 248       M.getOrInsertFunction("memcpy", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
 249                             IRB.getInt8PtrTy(), IntptrTy));
 250   MemsetFn = checkSanitizerInterfaceFunction(
 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) {
 268   if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa))
 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(
 340     SmallVectorImpl<Instruction *> &Local, SmallVectorImpl<Instruction *> &All,
 341     const DataLayout &DL) {
 342   SmallPtrSet<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) {
 397   IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
 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
 405 bool ThreadSanitizer::runOnFunction(Function &F) {
 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))
 431           maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
 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).
 454   if (ClInstrumentAtomics)
 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     LLVM_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
 544 static ConstantInt *createOrdering(IRBuilder<> *IRB, AtomicOrdering ord) {
 545   uint32_t v = 0;
 546   switch (ord) {
 547     case AtomicOrdering::NotAtomic:
 548       llvm_unreachable("unexpected atomic ordering!");
 549     case AtomicOrdering::Unordered:              LLVM_FALLTHROUGH;
 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);
 701   assert(Idx < kNumberOfAccessSizes);
 702   return Idx;
 703 }