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

   1 //===-- ThreadSanitizer.cpp - race detector -------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file is a part of ThreadSanitizer, a race detector.
  11 //
  12 // The tool is under development, for the details about previous versions see
  13 // http://code.google.com/p/data-race-test
  14 //
  15 // The instrumentation phase is quite simple:
  16 //   - Insert calls to run-time library before every memory access.
  17 //      - Optimizations may apply to avoid instrumenting some of the accesses.
  18 //   - Insert calls at function entry/exit.
  19 // The rest is handled by the run-time library.
  20 //===----------------------------------------------------------------------===//
  21
  22 #include "llvm/Transforms/Instrumentation.h"
  23 #include "llvm/ADT/SmallSet.h"
  24 #include "llvm/ADT/SmallString.h"
  25 #include "llvm/ADT/SmallVector.h"
  26 #include "llvm/ADT/Statistic.h"
  27 #include "llvm/ADT/StringExtras.h"
  28 #include "llvm/Analysis/CaptureTracking.h"
  29 #include "llvm/Analysis/TargetLibraryInfo.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/Utils/BasicBlockUtils.h"
  46 #include "llvm/Transforms/Utils/EscapeEnumerator.h"
  47 #include "llvm/Transforms/Utils/Local.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   AttributeSet Attr;
 159   Attr = Attr.addAttribute(M.getContext(), AttributeSet::FunctionIndex, Attribute::NoUnwind);
 160   // Initialize the callbacks.
 161   TsanFuncEntry = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 162       "__tsan_func_entry", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 163   TsanFuncExit = checkSanitizerInterfaceFunction(
 164       M.getOrInsertFunction("__tsan_func_exit", Attr, IRB.getVoidTy(), nullptr));
 165   TsanIgnoreBegin = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 166       "__tsan_ignore_thread_begin", Attr, IRB.getVoidTy(), nullptr));
 167   TsanIgnoreEnd = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 168       "__tsan_ignore_thread_end", Attr, IRB.getVoidTy(), nullptr));
 169   OrdTy = IRB.getInt32Ty();
 170   for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
 171     const unsigned ByteSize = 1U << i;
 172     const unsigned BitSize = ByteSize * 8;
 173     std::string ByteSizeStr = utostr(ByteSize);
 174     std::string BitSizeStr = utostr(BitSize);
 175     SmallString<32> ReadName("__tsan_read" + ByteSizeStr);
 176     TsanRead[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 177         ReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 178
 179     SmallString<32> WriteName("__tsan_write" + ByteSizeStr);
 180     TsanWrite[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 181         WriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 182
 183     SmallString<64> UnalignedReadName("__tsan_unaligned_read" + ByteSizeStr);
 184     TsanUnalignedRead[i] =
 185         checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 186             UnalignedReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 187
 188     SmallString<64> UnalignedWriteName("__tsan_unaligned_write" + ByteSizeStr);
 189     TsanUnalignedWrite[i] =
 190         checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 191             UnalignedWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 192
 193     Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
 194     Type *PtrTy = Ty->getPointerTo();
 195     SmallString<32> AtomicLoadName("__tsan_atomic" + BitSizeStr + "_load");
 196     TsanAtomicLoad[i] = checkSanitizerInterfaceFunction(
 197         M.getOrInsertFunction(AtomicLoadName, Attr, Ty, PtrTy, OrdTy, nullptr));
 198
 199     SmallString<32> AtomicStoreName("__tsan_atomic" + BitSizeStr + "_store");
 200     TsanAtomicStore[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 201         AtomicStoreName, Attr, IRB.getVoidTy(), PtrTy, Ty, OrdTy, nullptr));
 202
 203     for (int op = AtomicRMWInst::FIRST_BINOP;
 204         op <= AtomicRMWInst::LAST_BINOP; ++op) {
 205       TsanAtomicRMW[op][i] = nullptr;
 206       const char *NamePart = nullptr;
 207       if (op == AtomicRMWInst::Xchg)
 208         NamePart = "_exchange";
 209       else if (op == AtomicRMWInst::Add)
 210         NamePart = "_fetch_add";
 211       else if (op == AtomicRMWInst::Sub)
 212         NamePart = "_fetch_sub";
 213       else if (op == AtomicRMWInst::And)
 214         NamePart = "_fetch_and";
 215       else if (op == AtomicRMWInst::Or)
 216         NamePart = "_fetch_or";
 217       else if (op == AtomicRMWInst::Xor)
 218         NamePart = "_fetch_xor";
 219       else if (op == AtomicRMWInst::Nand)
 220         NamePart = "_fetch_nand";
 221       else
 222         continue;
 223       SmallString<32> RMWName("__tsan_atomic" + itostr(BitSize) + NamePart);
 224       TsanAtomicRMW[op][i] = checkSanitizerInterfaceFunction(
 225           M.getOrInsertFunction(RMWName, Attr, Ty, PtrTy, Ty, OrdTy, nullptr));
 226     }
 227
 228     SmallString<32> AtomicCASName("__tsan_atomic" + BitSizeStr +
 229                                   "_compare_exchange_val");
 230     TsanAtomicCAS[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 231         AtomicCASName, Attr, Ty, PtrTy, Ty, Ty, OrdTy, OrdTy, nullptr));
 232   }
 233   TsanVptrUpdate = checkSanitizerInterfaceFunction(
 234       M.getOrInsertFunction("__tsan_vptr_update", Attr, IRB.getVoidTy(),
 235                             IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), nullptr));
 236   TsanVptrLoad = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 237       "__tsan_vptr_read", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
 238   TsanAtomicThreadFence = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 239       "__tsan_atomic_thread_fence", Attr, IRB.getVoidTy(), OrdTy, nullptr));
 240   TsanAtomicSignalFence = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 241       "__tsan_atomic_signal_fence", Attr, IRB.getVoidTy(), OrdTy, nullptr));
 242
 243   MemmoveFn = checkSanitizerInterfaceFunction(
 244       M.getOrInsertFunction("memmove", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
 245                             IRB.getInt8PtrTy(), IntptrTy, nullptr));
 246   MemcpyFn = checkSanitizerInterfaceFunction(
 247       M.getOrInsertFunction("memcpy", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
 248                             IRB.getInt8PtrTy(), IntptrTy, nullptr));
 249   MemsetFn = checkSanitizerInterfaceFunction(
 250       M.getOrInsertFunction("memset", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
 251                             IRB.getInt32Ty(), IntptrTy, nullptr));
 252 }
 253
 254 bool ThreadSanitizer::doInitialization(Module &M) {
 255   const DataLayout &DL = M.getDataLayout();
 256   IntptrTy = DL.getIntPtrType(M.getContext());
 257   std::tie(TsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
 258       M, kTsanModuleCtorName, kTsanInitName, /*InitArgTypes=*/{},
 259       /*InitArgs=*/{});
 260
 261   appendToGlobalCtors(M, TsanCtorFunction, 0);
 262
 263   return true;
 264 }
 265
 266 static bool isVtableAccess(Instruction *I) {
 267   if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa))
 268     return Tag->isTBAAVtableAccess();
 269   return false;
 270 }
 271
 272 // Do not instrument known races/"benign races" that come from compiler
 273 // instrumentatin. The user has no way of suppressing them.
 274 static bool shouldInstrumentReadWriteFromAddress(Value *Addr) {
 275   // Peel off GEPs and BitCasts.
 276   Addr = Addr->stripInBoundsOffsets();
 277
 278   if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
 279     if (GV->hasSection()) {
 280       StringRef SectionName = GV->getSection();
 281       // Check if the global is in the PGO counters section.
 282       if (SectionName.endswith(getInstrProfCountersSectionName(
 283             /*AddSegment=*/false)))
 284         return false;
 285     }
 286
 287     // Check if the global is private gcov data.
 288     if (GV->getName().startswith("__llvm_gcov") ||
 289         GV->getName().startswith("__llvm_gcda"))
 290       return false;
 291   }
 292
 293   // Do not instrument acesses from different address spaces; we cannot deal
 294   // with them.
 295   if (Addr) {
 296     Type *PtrTy = cast<PointerType>(Addr->getType()->getScalarType());
 297     if (PtrTy->getPointerAddressSpace() != 0)
 298       return false;
 299   }
 300
 301   return true;
 302 }
 303
 304 bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) {
 305   // If this is a GEP, just analyze its pointer operand.
 306   if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
 307     Addr = GEP->getPointerOperand();
 308
 309   if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
 310     if (GV->isConstant()) {
 311       // Reads from constant globals can not race with any writes.
 312       NumOmittedReadsFromConstantGlobals++;
 313       return true;
 314     }
 315   } else if (LoadInst *L = dyn_cast<LoadInst>(Addr)) {
 316     if (isVtableAccess(L)) {
 317       // Reads from a vtable pointer can not race with any writes.
 318       NumOmittedReadsFromVtable++;
 319       return true;
 320     }
 321   }
 322   return false;
 323 }
 324
 325 // Instrumenting some of the accesses may be proven redundant.
 326 // Currently handled:
 327 //  - read-before-write (within same BB, no calls between)
 328 //  - not captured variables
 329 //
 330 // We do not handle some of the patterns that should not survive
 331 // after the classic compiler optimizations.
 332 // E.g. two reads from the same temp should be eliminated by CSE,
 333 // two writes should be eliminated by DSE, etc.
 334 //
 335 // 'Local' is a vector of insns within the same BB (no calls between).
 336 // 'All' is a vector of insns that will be instrumented.
 337 void ThreadSanitizer::chooseInstructionsToInstrument(
 338     SmallVectorImpl<Instruction *> &Local, SmallVectorImpl<Instruction *> &All,
 339     const DataLayout &DL) {
 340   SmallSet<Value*, 8> WriteTargets;
 341   // Iterate from the end.
 342   for (Instruction *I : reverse(Local)) {
 343     if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
 344       Value *Addr = Store->getPointerOperand();
 345       if (!shouldInstrumentReadWriteFromAddress(Addr))
 346         continue;
 347       WriteTargets.insert(Addr);
 348     } else {
 349       LoadInst *Load = cast<LoadInst>(I);
 350       Value *Addr = Load->getPointerOperand();
 351       if (!shouldInstrumentReadWriteFromAddress(Addr))
 352         continue;
 353       if (WriteTargets.count(Addr)) {
 354         // We will write to this temp, so no reason to analyze the read.
 355         NumOmittedReadsBeforeWrite++;
 356         continue;
 357       }
 358       if (addrPointsToConstantData(Addr)) {
 359         // Addr points to some constant data -- it can not race with any writes.
 360         continue;
 361       }
 362     }
 363     Value *Addr = isa<StoreInst>(*I)
 364         ? cast<StoreInst>(I)->getPointerOperand()
 365         : cast<LoadInst>(I)->getPointerOperand();
 366     if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
 367         !PointerMayBeCaptured(Addr, true, true)) {
 368       // The variable is addressable but not captured, so it cannot be
 369       // referenced from a different thread and participate in a data race
 370       // (see llvm/Analysis/CaptureTracking.h for details).
 371       NumOmittedNonCaptured++;
 372       continue;
 373     }
 374     All.push_back(I);
 375   }
 376   Local.clear();
 377 }
 378
 379 static bool isAtomic(Instruction *I) {
 380   if (LoadInst *LI = dyn_cast<LoadInst>(I))
 381     return LI->isAtomic() && LI->getSynchScope() == CrossThread;
 382   if (StoreInst *SI = dyn_cast<StoreInst>(I))
 383     return SI->isAtomic() && SI->getSynchScope() == CrossThread;
 384   if (isa<AtomicRMWInst>(I))
 385     return true;
 386   if (isa<AtomicCmpXchgInst>(I))
 387     return true;
 388   if (isa<FenceInst>(I))
 389     return true;
 390   return false;
 391 }
 392
 393 void ThreadSanitizer::InsertRuntimeIgnores(Function &F) {
 394   IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
 395   IRB.CreateCall(TsanIgnoreBegin);
 396   EscapeEnumerator EE(F, "tsan_ignore_cleanup", ClHandleCxxExceptions);
 397   while (IRBuilder<> *AtExit = EE.Next()) {
 398     AtExit->CreateCall(TsanIgnoreEnd);
 399   }
 400 }
 401
 402 bool ThreadSanitizer::runOnFunction(Function &F) {
 403   // This is required to prevent instrumenting call to __tsan_init from within
 404   // the module constructor.
 405   if (&F == TsanCtorFunction)
 406     return false;
 407   initializeCallbacks(*F.getParent());
 408   SmallVector<Instruction*, 8> AllLoadsAndStores;
 409   SmallVector<Instruction*, 8> LocalLoadsAndStores;
 410   SmallVector<Instruction*, 8> AtomicAccesses;
 411   SmallVector<Instruction*, 8> MemIntrinCalls;
 412   bool Res = false;
 413   bool HasCalls = false;
 414   bool SanitizeFunction = F.hasFnAttribute(Attribute::SanitizeThread);
 415   const DataLayout &DL = F.getParent()->getDataLayout();
 416   const TargetLibraryInfo *TLI =
 417       &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
 418
 419   // Traverse all instructions, collect loads/stores/returns, check for calls.
 420   for (auto &BB : F) {
 421     for (auto &Inst : BB) {
 422       if (isAtomic(&Inst))
 423         AtomicAccesses.push_back(&Inst);
 424       else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
 425         LocalLoadsAndStores.push_back(&Inst);
 426       else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
 427         if (CallInst *CI = dyn_cast<CallInst>(&Inst))
 428           maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
 429         if (isa<MemIntrinsic>(Inst))
 430           MemIntrinCalls.push_back(&Inst);
 431         HasCalls = true;
 432         chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores,
 433                                        DL);
 434       }
 435     }
 436     chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores, DL);
 437   }
 438
 439   // We have collected all loads and stores.
 440   // FIXME: many of these accesses do not need to be checked for races
 441   // (e.g. variables that do not escape, etc).
 442
 443   // Instrument memory accesses only if we want to report bugs in the function.
 444   if (ClInstrumentMemoryAccesses && SanitizeFunction)
 445     for (auto Inst : AllLoadsAndStores) {
 446       Res |= instrumentLoadOrStore(Inst, DL);
 447     }
 448
 449   // Instrument atomic memory accesses in any case (they can be used to
 450   // implement synchronization).
 451   if (ClInstrumentAtomics)
 452     for (auto Inst : AtomicAccesses) {
 453       Res |= instrumentAtomic(Inst, DL);
 454     }
 455
 456   if (ClInstrumentMemIntrinsics && SanitizeFunction)
 457     for (auto Inst : MemIntrinCalls) {
 458       Res |= instrumentMemIntrinsic(Inst);
 459     }
 460
 461   if (F.hasFnAttribute("sanitize_thread_no_checking_at_run_time")) {
 462     assert(!F.hasFnAttribute(Attribute::SanitizeThread));
 463     if (HasCalls)
 464       InsertRuntimeIgnores(F);
 465   }
 466
 467   // Instrument function entry/exit points if there were instrumented accesses.
 468   if ((Res || HasCalls) && ClInstrumentFuncEntryExit) {
 469     IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
 470     Value *ReturnAddress = IRB.CreateCall(
 471         Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
 472         IRB.getInt32(0));
 473     IRB.CreateCall(TsanFuncEntry, ReturnAddress);
 474
 475     EscapeEnumerator EE(F, "tsan_cleanup", ClHandleCxxExceptions);
 476     while (IRBuilder<> *AtExit = EE.Next()) {
 477       AtExit->CreateCall(TsanFuncExit, {});
 478     }
 479     Res = true;
 480   }
 481   return Res;
 482 }
 483
 484 bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I,
 485                                             const DataLayout &DL) {
 486   IRBuilder<> IRB(I);
 487   bool IsWrite = isa<StoreInst>(*I);
 488   Value *Addr = IsWrite
 489       ? cast<StoreInst>(I)->getPointerOperand()
 490       : cast<LoadInst>(I)->getPointerOperand();
 491
 492   // swifterror memory addresses are mem2reg promoted by instruction selection.
 493   // As such they cannot have regular uses like an instrumentation function and
 494   // it makes no sense to track them as memory.
 495   if (Addr->isSwiftError())
 496     return false;
 497
 498   int Idx = getMemoryAccessFuncIndex(Addr, DL);
 499   if (Idx < 0)
 500     return false;
 501   if (IsWrite && isVtableAccess(I)) {
 502     DEBUG(dbgs() << "  VPTR : " << *I << "\n");
 503     Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
 504     // StoredValue may be a vector type if we are storing several vptrs at once.
 505     // In this case, just take the first element of the vector since this is
 506     // enough to find vptr races.
 507     if (isa<VectorType>(StoredValue->getType()))
 508       StoredValue = IRB.CreateExtractElement(
 509           StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0));
 510     if (StoredValue->getType()->isIntegerTy())
 511       StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
 512     // Call TsanVptrUpdate.
 513     IRB.CreateCall(TsanVptrUpdate,
 514                    {IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
 515                     IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy())});
 516     NumInstrumentedVtableWrites++;
 517     return true;
 518   }
 519   if (!IsWrite && isVtableAccess(I)) {
 520     IRB.CreateCall(TsanVptrLoad,
 521                    IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
 522     NumInstrumentedVtableReads++;
 523     return true;
 524   }
 525   const unsigned Alignment = IsWrite
 526       ? cast<StoreInst>(I)->getAlignment()
 527       : cast<LoadInst>(I)->getAlignment();
 528   Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
 529   const uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
 530   Value *OnAccessFunc = nullptr;
 531   if (Alignment == 0 || Alignment >= 8 || (Alignment % (TypeSize / 8)) == 0)
 532     OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
 533   else
 534     OnAccessFunc = IsWrite ? TsanUnalignedWrite[Idx] : TsanUnalignedRead[Idx];
 535   IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
 536   if (IsWrite) NumInstrumentedWrites++;
 537   else         NumInstrumentedReads++;
 538   return true;
 539 }
 540
 541 static ConstantInt *createOrdering(IRBuilder<> *IRB, AtomicOrdering ord) {
 542   uint32_t v = 0;
 543   switch (ord) {
 544     case AtomicOrdering::NotAtomic:
 545       llvm_unreachable("unexpected atomic ordering!");
 546     case AtomicOrdering::Unordered:              LLVM_FALLTHROUGH;
 547     case AtomicOrdering::Monotonic:              v = 0; break;
 548     // Not specified yet:
 549     // case AtomicOrdering::Consume:                v = 1; break;
 550     case AtomicOrdering::Acquire:                v = 2; break;
 551     case AtomicOrdering::Release:                v = 3; break;
 552     case AtomicOrdering::AcquireRelease:         v = 4; break;
 553     case AtomicOrdering::SequentiallyConsistent: v = 5; break;
 554   }
 555   return IRB->getInt32(v);
 556 }
 557
 558 // If a memset intrinsic gets inlined by the code gen, we will miss races on it.
 559 // So, we either need to ensure the intrinsic is not inlined, or instrument it.
 560 // We do not instrument memset/memmove/memcpy intrinsics (too complicated),
 561 // instead we simply replace them with regular function calls, which are then
 562 // intercepted by the run-time.
 563 // Since tsan is running after everyone else, the calls should not be
 564 // replaced back with intrinsics. If that becomes wrong at some point,
 565 // we will need to call e.g. __tsan_memset to avoid the intrinsics.
 566 bool ThreadSanitizer::instrumentMemIntrinsic(Instruction *I) {
 567   IRBuilder<> IRB(I);
 568   if (MemSetInst *M = dyn_cast<MemSetInst>(I)) {
 569     IRB.CreateCall(
 570         MemsetFn,
 571         {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
 572          IRB.CreateIntCast(M->getArgOperand(1), IRB.getInt32Ty(), false),
 573          IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
 574     I->eraseFromParent();
 575   } else if (MemTransferInst *M = dyn_cast<MemTransferInst>(I)) {
 576     IRB.CreateCall(
 577         isa<MemCpyInst>(M) ? MemcpyFn : MemmoveFn,
 578         {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
 579          IRB.CreatePointerCast(M->getArgOperand(1), IRB.getInt8PtrTy()),
 580          IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
 581     I->eraseFromParent();
 582   }
 583   return false;
 584 }
 585
 586 // Both llvm and ThreadSanitizer atomic operations are based on C++11/C1x
 587 // standards.  For background see C++11 standard.  A slightly older, publicly
 588 // available draft of the standard (not entirely up-to-date, but close enough
 589 // for casual browsing) is available here:
 590 // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf
 591 // The following page contains more background information:
 592 // http://www.hpl.hp.com/personal/Hans_Boehm/c++mm/
 593
 594 bool ThreadSanitizer::instrumentAtomic(Instruction *I, const DataLayout &DL) {
 595   IRBuilder<> IRB(I);
 596   if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
 597     Value *Addr = LI->getPointerOperand();
 598     int Idx = getMemoryAccessFuncIndex(Addr, DL);
 599     if (Idx < 0)
 600       return false;
 601     const unsigned ByteSize = 1U << Idx;
 602     const unsigned BitSize = ByteSize * 8;
 603     Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
 604     Type *PtrTy = Ty->getPointerTo();
 605     Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
 606                      createOrdering(&IRB, LI->getOrdering())};
 607     Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
 608     Value *C = IRB.CreateCall(TsanAtomicLoad[Idx], Args);
 609     Value *Cast = IRB.CreateBitOrPointerCast(C, OrigTy);
 610     I->replaceAllUsesWith(Cast);
 611   } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
 612     Value *Addr = SI->getPointerOperand();
 613     int Idx = getMemoryAccessFuncIndex(Addr, DL);
 614     if (Idx < 0)
 615       return false;
 616     const unsigned ByteSize = 1U << Idx;
 617     const unsigned BitSize = ByteSize * 8;
 618     Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
 619     Type *PtrTy = Ty->getPointerTo();
 620     Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
 621                      IRB.CreateBitOrPointerCast(SI->getValueOperand(), Ty),
 622                      createOrdering(&IRB, SI->getOrdering())};
 623     CallInst *C = CallInst::Create(TsanAtomicStore[Idx], Args);
 624     ReplaceInstWithInst(I, C);
 625   } else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I)) {
 626     Value *Addr = RMWI->getPointerOperand();
 627     int Idx = getMemoryAccessFuncIndex(Addr, DL);
 628     if (Idx < 0)
 629       return false;
 630     Function *F = TsanAtomicRMW[RMWI->getOperation()][Idx];
 631     if (!F)
 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                      IRB.CreateIntCast(RMWI->getValOperand(), Ty, false),
 639                      createOrdering(&IRB, RMWI->getOrdering())};
 640     CallInst *C = CallInst::Create(F, Args);
 641     ReplaceInstWithInst(I, C);
 642   } else if (AtomicCmpXchgInst *CASI = dyn_cast<AtomicCmpXchgInst>(I)) {
 643     Value *Addr = CASI->getPointerOperand();
 644     int Idx = getMemoryAccessFuncIndex(Addr, DL);
 645     if (Idx < 0)
 646       return false;
 647     const unsigned ByteSize = 1U << Idx;
 648     const unsigned BitSize = ByteSize * 8;
 649     Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
 650     Type *PtrTy = Ty->getPointerTo();
 651     Value *CmpOperand =
 652       IRB.CreateBitOrPointerCast(CASI->getCompareOperand(), Ty);
 653     Value *NewOperand =
 654       IRB.CreateBitOrPointerCast(CASI->getNewValOperand(), Ty);
 655     Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
 656                      CmpOperand,
 657                      NewOperand,
 658                      createOrdering(&IRB, CASI->getSuccessOrdering()),
 659                      createOrdering(&IRB, CASI->getFailureOrdering())};
 660     CallInst *C = IRB.CreateCall(TsanAtomicCAS[Idx], Args);
 661     Value *Success = IRB.CreateICmpEQ(C, CmpOperand);
 662     Value *OldVal = C;
 663     Type *OrigOldValTy = CASI->getNewValOperand()->getType();
 664     if (Ty != OrigOldValTy) {
 665       // The value is a pointer, so we need to cast the return value.
 666       OldVal = IRB.CreateIntToPtr(C, OrigOldValTy);
 667     }
 668
 669     Value *Res =
 670       IRB.CreateInsertValue(UndefValue::get(CASI->getType()), OldVal, 0);
 671     Res = IRB.CreateInsertValue(Res, Success, 1);
 672
 673     I->replaceAllUsesWith(Res);
 674     I->eraseFromParent();
 675   } else if (FenceInst *FI = dyn_cast<FenceInst>(I)) {
 676     Value *Args[] = {createOrdering(&IRB, FI->getOrdering())};
 677     Function *F = FI->getSynchScope() == SingleThread ?
 678         TsanAtomicSignalFence : TsanAtomicThreadFence;
 679     CallInst *C = CallInst::Create(F, Args);
 680     ReplaceInstWithInst(I, C);
 681   }
 682   return true;
 683 }
 684
 685 int ThreadSanitizer::getMemoryAccessFuncIndex(Value *Addr,
 686                                               const DataLayout &DL) {
 687   Type *OrigPtrTy = Addr->getType();
 688   Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
 689   assert(OrigTy->isSized());
 690   uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
 691   if (TypeSize != 8  && TypeSize != 16 &&
 692       TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
 693     NumAccessesWithBadSize++;
 694     // Ignore all unusual sizes.
 695     return -1;
 696   }
 697   size_t Idx = countTrailingZeros(TypeSize / 8);
 698   assert(Idx < kNumberOfAccessSizes);
 699   return Idx;
 700 }