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llvm-mirror/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
Konstantin Zhuravlyov d382d6f3fc Enhance synchscope representation 
OpenCL 2.0 introduces the notion of memory scopes in atomic operations to
  global and local memory. These scopes restrict how synchronization is
  achieved, which can result in improved performance.

  This change extends existing notion of synchronization scopes in LLVM to
  support arbitrary scopes expressed as target-specific strings, in addition to
  the already defined scopes (single thread, system).

  The LLVM IR and MIR syntax for expressing synchronization scopes has changed
  to use *syncscope("<scope>")*, where <scope> can be "singlethread" (this
  replaces *singlethread* keyword), or a target-specific name. As before, if
  the scope is not specified, it defaults to CrossThread/System scope.

  Implementation details:
    - Mapping from synchronization scope name/string to synchronization scope id
      is stored in LLVM context;
    - CrossThread/System and SingleThread scopes are pre-defined to efficiently
      check for known scopes without comparing strings;
    - Synchronization scope names are stored in SYNC_SCOPE_NAMES_BLOCK in
      the bitcode.

Differential Revision: https://reviews.llvm.org/D21723

llvm-svn: 307722
2017-07-11 22:23:00 +00:00

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28 KiB
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//===-- ThreadSanitizer.cpp - race detector -------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of ThreadSanitizer, a race detector.
//
// The tool is under development, for the details about previous versions see
// http://code.google.com/p/data-race-test
//
// The instrumentation phase is quite simple:
// - Insert calls to run-time library before every memory access.
// - Optimizations may apply to avoid instrumenting some of the accesses.
// - Insert calls at function entry/exit.
// The rest is handled by the run-time library.
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/EscapeEnumerator.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
using namespace llvm;
#define DEBUG_TYPE "tsan"
static cl::opt<bool> ClInstrumentMemoryAccesses(
"tsan-instrument-memory-accesses", cl::init(true),
cl::desc("Instrument memory accesses"), cl::Hidden);
static cl::opt<bool> ClInstrumentFuncEntryExit(
"tsan-instrument-func-entry-exit", cl::init(true),
cl::desc("Instrument function entry and exit"), cl::Hidden);
static cl::opt<bool> ClHandleCxxExceptions(
"tsan-handle-cxx-exceptions", cl::init(true),
cl::desc("Handle C++ exceptions (insert cleanup blocks for unwinding)"),
cl::Hidden);
static cl::opt<bool> ClInstrumentAtomics(
"tsan-instrument-atomics", cl::init(true),
cl::desc("Instrument atomics"), cl::Hidden);
static cl::opt<bool> ClInstrumentMemIntrinsics(
"tsan-instrument-memintrinsics", cl::init(true),
cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden);
STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
STATISTIC(NumOmittedReadsBeforeWrite,
"Number of reads ignored due to following writes");
STATISTIC(NumAccessesWithBadSize, "Number of accesses with bad size");
STATISTIC(NumInstrumentedVtableWrites, "Number of vtable ptr writes");
STATISTIC(NumInstrumentedVtableReads, "Number of vtable ptr reads");
STATISTIC(NumOmittedReadsFromConstantGlobals,
"Number of reads from constant globals");
STATISTIC(NumOmittedReadsFromVtable, "Number of vtable reads");
STATISTIC(NumOmittedNonCaptured, "Number of accesses ignored due to capturing");
static const char *const kTsanModuleCtorName = "tsan.module_ctor";
static const char *const kTsanInitName = "__tsan_init";
namespace {
/// ThreadSanitizer: instrument the code in module to find races.
struct ThreadSanitizer : public FunctionPass {
ThreadSanitizer() : FunctionPass(ID) {}
StringRef getPassName() const override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
bool runOnFunction(Function &F) override;
bool doInitialization(Module &M) override;
static char ID; // Pass identification, replacement for typeid.
private:
void initializeCallbacks(Module &M);
bool instrumentLoadOrStore(Instruction *I, const DataLayout &DL);
bool instrumentAtomic(Instruction *I, const DataLayout &DL);
bool instrumentMemIntrinsic(Instruction *I);
void chooseInstructionsToInstrument(SmallVectorImpl<Instruction *> &Local,
SmallVectorImpl<Instruction *> &All,
const DataLayout &DL);
bool addrPointsToConstantData(Value *Addr);
int getMemoryAccessFuncIndex(Value *Addr, const DataLayout &DL);
void InsertRuntimeIgnores(Function &F);
Type *IntptrTy;
IntegerType *OrdTy;
// Callbacks to run-time library are computed in doInitialization.
Function *TsanFuncEntry;
Function *TsanFuncExit;
Function *TsanIgnoreBegin;
Function *TsanIgnoreEnd;
// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
static const size_t kNumberOfAccessSizes = 5;
Function *TsanRead[kNumberOfAccessSizes];
Function *TsanWrite[kNumberOfAccessSizes];
Function *TsanUnalignedRead[kNumberOfAccessSizes];
Function *TsanUnalignedWrite[kNumberOfAccessSizes];
Function *TsanAtomicLoad[kNumberOfAccessSizes];
Function *TsanAtomicStore[kNumberOfAccessSizes];
Function *TsanAtomicRMW[AtomicRMWInst::LAST_BINOP + 1][kNumberOfAccessSizes];
Function *TsanAtomicCAS[kNumberOfAccessSizes];
Function *TsanAtomicThreadFence;
Function *TsanAtomicSignalFence;
Function *TsanVptrUpdate;
Function *TsanVptrLoad;
Function *MemmoveFn, *MemcpyFn, *MemsetFn;
Function *TsanCtorFunction;
};
} // namespace
char ThreadSanitizer::ID = 0;
INITIALIZE_PASS_BEGIN(
ThreadSanitizer, "tsan",
"ThreadSanitizer: detects data races.",
false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(
ThreadSanitizer, "tsan",
"ThreadSanitizer: detects data races.",
false, false)
StringRef ThreadSanitizer::getPassName() const { return "ThreadSanitizer"; }
void ThreadSanitizer::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
FunctionPass *llvm::createThreadSanitizerPass() {
return new ThreadSanitizer();
}
void ThreadSanitizer::initializeCallbacks(Module &M) {
IRBuilder<> IRB(M.getContext());
AttributeList Attr;
Attr = Attr.addAttribute(M.getContext(), AttributeList::FunctionIndex,
Attribute::NoUnwind);
// Initialize the callbacks.
TsanFuncEntry = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
"__tsan_func_entry", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
TsanFuncExit = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("__tsan_func_exit", Attr, IRB.getVoidTy()));
TsanIgnoreBegin = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
"__tsan_ignore_thread_begin", Attr, IRB.getVoidTy()));
TsanIgnoreEnd = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
"__tsan_ignore_thread_end", Attr, IRB.getVoidTy()));
OrdTy = IRB.getInt32Ty();
for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
const unsigned ByteSize = 1U << i;
const unsigned BitSize = ByteSize * 8;
std::string ByteSizeStr = utostr(ByteSize);
std::string BitSizeStr = utostr(BitSize);
SmallString<32> ReadName("__tsan_read" + ByteSizeStr);
TsanRead[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
ReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
SmallString<32> WriteName("__tsan_write" + ByteSizeStr);
TsanWrite[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
WriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
SmallString<64> UnalignedReadName("__tsan_unaligned_read" + ByteSizeStr);
TsanUnalignedRead[i] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
UnalignedReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
SmallString<64> UnalignedWriteName("__tsan_unaligned_write" + ByteSizeStr);
TsanUnalignedWrite[i] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
UnalignedWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
Type *PtrTy = Ty->getPointerTo();
SmallString<32> AtomicLoadName("__tsan_atomic" + BitSizeStr + "_load");
TsanAtomicLoad[i] = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(AtomicLoadName, Attr, Ty, PtrTy, OrdTy));
SmallString<32> AtomicStoreName("__tsan_atomic" + BitSizeStr + "_store");
TsanAtomicStore[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
AtomicStoreName, Attr, IRB.getVoidTy(), PtrTy, Ty, OrdTy));
for (int op = AtomicRMWInst::FIRST_BINOP;
op <= AtomicRMWInst::LAST_BINOP; ++op) {
TsanAtomicRMW[op][i] = nullptr;
const char *NamePart = nullptr;
if (op == AtomicRMWInst::Xchg)
NamePart = "_exchange";
else if (op == AtomicRMWInst::Add)
NamePart = "_fetch_add";
else if (op == AtomicRMWInst::Sub)
NamePart = "_fetch_sub";
else if (op == AtomicRMWInst::And)
NamePart = "_fetch_and";
else if (op == AtomicRMWInst::Or)
NamePart = "_fetch_or";
else if (op == AtomicRMWInst::Xor)
NamePart = "_fetch_xor";
else if (op == AtomicRMWInst::Nand)
NamePart = "_fetch_nand";
else
continue;
SmallString<32> RMWName("__tsan_atomic" + itostr(BitSize) + NamePart);
TsanAtomicRMW[op][i] = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(RMWName, Attr, Ty, PtrTy, Ty, OrdTy));
}
SmallString<32> AtomicCASName("__tsan_atomic" + BitSizeStr +
"_compare_exchange_val");
TsanAtomicCAS[i] = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
AtomicCASName, Attr, Ty, PtrTy, Ty, Ty, OrdTy, OrdTy));
}
TsanVptrUpdate = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("__tsan_vptr_update", Attr, IRB.getVoidTy(),
IRB.getInt8PtrTy(), IRB.getInt8PtrTy()));
TsanVptrLoad = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
"__tsan_vptr_read", Attr, IRB.getVoidTy(), IRB.getInt8PtrTy()));
TsanAtomicThreadFence = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
"__tsan_atomic_thread_fence", Attr, IRB.getVoidTy(), OrdTy));
TsanAtomicSignalFence = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
"__tsan_atomic_signal_fence", Attr, IRB.getVoidTy(), OrdTy));
MemmoveFn = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("memmove", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
IRB.getInt8PtrTy(), IntptrTy));
MemcpyFn = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("memcpy", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
IRB.getInt8PtrTy(), IntptrTy));
MemsetFn = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("memset", Attr, IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
IRB.getInt32Ty(), IntptrTy));
}
bool ThreadSanitizer::doInitialization(Module &M) {
const DataLayout &DL = M.getDataLayout();
IntptrTy = DL.getIntPtrType(M.getContext());
std::tie(TsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
M, kTsanModuleCtorName, kTsanInitName, /*InitArgTypes=*/{},
/*InitArgs=*/{});
appendToGlobalCtors(M, TsanCtorFunction, 0);
return true;
}
static bool isVtableAccess(Instruction *I) {
if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa))
return Tag->isTBAAVtableAccess();
return false;
}
// Do not instrument known races/"benign races" that come from compiler
// instrumentatin. The user has no way of suppressing them.
static bool shouldInstrumentReadWriteFromAddress(const Module *M, Value *Addr) {
// Peel off GEPs and BitCasts.
Addr = Addr->stripInBoundsOffsets();
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
if (GV->hasSection()) {
StringRef SectionName = GV->getSection();
// Check if the global is in the PGO counters section.
auto OF = Triple(M->getTargetTriple()).getObjectFormat();
if (SectionName.endswith(
getInstrProfSectionName(IPSK_cnts, OF, /*AddSegmentInfo=*/false)))
return false;
}
// Check if the global is private gcov data.
if (GV->getName().startswith("__llvm_gcov") ||
GV->getName().startswith("__llvm_gcda"))
return false;
}
// Do not instrument acesses from different address spaces; we cannot deal
// with them.
if (Addr) {
Type *PtrTy = cast<PointerType>(Addr->getType()->getScalarType());
if (PtrTy->getPointerAddressSpace() != 0)
return false;
}
return true;
}
bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) {
// If this is a GEP, just analyze its pointer operand.
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
Addr = GEP->getPointerOperand();
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
if (GV->isConstant()) {
// Reads from constant globals can not race with any writes.
NumOmittedReadsFromConstantGlobals++;
return true;
}
} else if (LoadInst *L = dyn_cast<LoadInst>(Addr)) {
if (isVtableAccess(L)) {
// Reads from a vtable pointer can not race with any writes.
NumOmittedReadsFromVtable++;
return true;
}
}
return false;
}
// Instrumenting some of the accesses may be proven redundant.
// Currently handled:
// - read-before-write (within same BB, no calls between)
// - not captured variables
//
// We do not handle some of the patterns that should not survive
// after the classic compiler optimizations.
// E.g. two reads from the same temp should be eliminated by CSE,
// two writes should be eliminated by DSE, etc.
//
// 'Local' is a vector of insns within the same BB (no calls between).
// 'All' is a vector of insns that will be instrumented.
void ThreadSanitizer::chooseInstructionsToInstrument(
SmallVectorImpl<Instruction *> &Local, SmallVectorImpl<Instruction *> &All,
const DataLayout &DL) {
SmallSet<Value*, 8> WriteTargets;
// Iterate from the end.
for (Instruction *I : reverse(Local)) {
if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
Value *Addr = Store->getPointerOperand();
if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
continue;
WriteTargets.insert(Addr);
} else {
LoadInst *Load = cast<LoadInst>(I);
Value *Addr = Load->getPointerOperand();
if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
continue;
if (WriteTargets.count(Addr)) {
// We will write to this temp, so no reason to analyze the read.
NumOmittedReadsBeforeWrite++;
continue;
}
if (addrPointsToConstantData(Addr)) {
// Addr points to some constant data -- it can not race with any writes.
continue;
}
}
Value *Addr = isa<StoreInst>(*I)
? cast<StoreInst>(I)->getPointerOperand()
: cast<LoadInst>(I)->getPointerOperand();
if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
!PointerMayBeCaptured(Addr, true, true)) {
// The variable is addressable but not captured, so it cannot be
// referenced from a different thread and participate in a data race
// (see llvm/Analysis/CaptureTracking.h for details).
NumOmittedNonCaptured++;
continue;
}
All.push_back(I);
}
Local.clear();
}
static bool isAtomic(Instruction *I) {
// TODO: Ask TTI whether synchronization scope is between threads.
if (LoadInst *LI = dyn_cast<LoadInst>(I))
return LI->isAtomic() && LI->getSyncScopeID() != SyncScope::SingleThread;
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return SI->isAtomic() && SI->getSyncScopeID() != SyncScope::SingleThread;
if (isa<AtomicRMWInst>(I))
return true;
if (isa<AtomicCmpXchgInst>(I))
return true;
if (isa<FenceInst>(I))
return true;
return false;
}
void ThreadSanitizer::InsertRuntimeIgnores(Function &F) {
IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
IRB.CreateCall(TsanIgnoreBegin);
EscapeEnumerator EE(F, "tsan_ignore_cleanup", ClHandleCxxExceptions);
while (IRBuilder<> *AtExit = EE.Next()) {
AtExit->CreateCall(TsanIgnoreEnd);
}
}
bool ThreadSanitizer::runOnFunction(Function &F) {
// This is required to prevent instrumenting call to __tsan_init from within
// the module constructor.
if (&F == TsanCtorFunction)
return false;
initializeCallbacks(*F.getParent());
SmallVector<Instruction*, 8> AllLoadsAndStores;
SmallVector<Instruction*, 8> LocalLoadsAndStores;
SmallVector<Instruction*, 8> AtomicAccesses;
SmallVector<Instruction*, 8> MemIntrinCalls;
bool Res = false;
bool HasCalls = false;
bool SanitizeFunction = F.hasFnAttribute(Attribute::SanitizeThread);
const DataLayout &DL = F.getParent()->getDataLayout();
const TargetLibraryInfo *TLI =
&getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
// Traverse all instructions, collect loads/stores/returns, check for calls.
for (auto &BB : F) {
for (auto &Inst : BB) {
if (isAtomic(&Inst))
AtomicAccesses.push_back(&Inst);
else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
LocalLoadsAndStores.push_back(&Inst);
else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
if (CallInst *CI = dyn_cast<CallInst>(&Inst))
maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
if (isa<MemIntrinsic>(Inst))
MemIntrinCalls.push_back(&Inst);
HasCalls = true;
chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores,
DL);
}
}
chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores, DL);
}
// We have collected all loads and stores.
// FIXME: many of these accesses do not need to be checked for races
// (e.g. variables that do not escape, etc).
// Instrument memory accesses only if we want to report bugs in the function.
if (ClInstrumentMemoryAccesses && SanitizeFunction)
for (auto Inst : AllLoadsAndStores) {
Res |= instrumentLoadOrStore(Inst, DL);
}
// Instrument atomic memory accesses in any case (they can be used to
// implement synchronization).
if (ClInstrumentAtomics)
for (auto Inst : AtomicAccesses) {
Res |= instrumentAtomic(Inst, DL);
}
if (ClInstrumentMemIntrinsics && SanitizeFunction)
for (auto Inst : MemIntrinCalls) {
Res |= instrumentMemIntrinsic(Inst);
}
if (F.hasFnAttribute("sanitize_thread_no_checking_at_run_time")) {
assert(!F.hasFnAttribute(Attribute::SanitizeThread));
if (HasCalls)
InsertRuntimeIgnores(F);
}
// Instrument function entry/exit points if there were instrumented accesses.
if ((Res || HasCalls) && ClInstrumentFuncEntryExit) {
IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
Value *ReturnAddress = IRB.CreateCall(
Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
IRB.getInt32(0));
IRB.CreateCall(TsanFuncEntry, ReturnAddress);
EscapeEnumerator EE(F, "tsan_cleanup", ClHandleCxxExceptions);
while (IRBuilder<> *AtExit = EE.Next()) {
AtExit->CreateCall(TsanFuncExit, {});
}
Res = true;
}
return Res;
}
bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I,
const DataLayout &DL) {
IRBuilder<> IRB(I);
bool IsWrite = isa<StoreInst>(*I);
Value *Addr = IsWrite
? cast<StoreInst>(I)->getPointerOperand()
: cast<LoadInst>(I)->getPointerOperand();
// swifterror memory addresses are mem2reg promoted by instruction selection.
// As such they cannot have regular uses like an instrumentation function and
// it makes no sense to track them as memory.
if (Addr->isSwiftError())
return false;
int Idx = getMemoryAccessFuncIndex(Addr, DL);
if (Idx < 0)
return false;
if (IsWrite && isVtableAccess(I)) {
DEBUG(dbgs() << " VPTR : " << *I << "\n");
Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
// StoredValue may be a vector type if we are storing several vptrs at once.
// In this case, just take the first element of the vector since this is
// enough to find vptr races.
if (isa<VectorType>(StoredValue->getType()))
StoredValue = IRB.CreateExtractElement(
StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0));
if (StoredValue->getType()->isIntegerTy())
StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
// Call TsanVptrUpdate.
IRB.CreateCall(TsanVptrUpdate,
{IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy())});
NumInstrumentedVtableWrites++;
return true;
}
if (!IsWrite && isVtableAccess(I)) {
IRB.CreateCall(TsanVptrLoad,
IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
NumInstrumentedVtableReads++;
return true;
}
const unsigned Alignment = IsWrite
? cast<StoreInst>(I)->getAlignment()
: cast<LoadInst>(I)->getAlignment();
Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
const uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
Value *OnAccessFunc = nullptr;
if (Alignment == 0 || Alignment >= 8 || (Alignment % (TypeSize / 8)) == 0)
OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
else
OnAccessFunc = IsWrite ? TsanUnalignedWrite[Idx] : TsanUnalignedRead[Idx];
IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
if (IsWrite) NumInstrumentedWrites++;
else NumInstrumentedReads++;
return true;
}
static ConstantInt *createOrdering(IRBuilder<> *IRB, AtomicOrdering ord) {
uint32_t v = 0;
switch (ord) {
case AtomicOrdering::NotAtomic:
llvm_unreachable("unexpected atomic ordering!");
case AtomicOrdering::Unordered: LLVM_FALLTHROUGH;
case AtomicOrdering::Monotonic: v = 0; break;
// Not specified yet:
// case AtomicOrdering::Consume: v = 1; break;
case AtomicOrdering::Acquire: v = 2; break;
case AtomicOrdering::Release: v = 3; break;
case AtomicOrdering::AcquireRelease: v = 4; break;
case AtomicOrdering::SequentiallyConsistent: v = 5; break;
}
return IRB->getInt32(v);
}
// If a memset intrinsic gets inlined by the code gen, we will miss races on it.
// So, we either need to ensure the intrinsic is not inlined, or instrument it.
// We do not instrument memset/memmove/memcpy intrinsics (too complicated),
// instead we simply replace them with regular function calls, which are then
// intercepted by the run-time.
// Since tsan is running after everyone else, the calls should not be
// replaced back with intrinsics. If that becomes wrong at some point,
// we will need to call e.g. __tsan_memset to avoid the intrinsics.
bool ThreadSanitizer::instrumentMemIntrinsic(Instruction *I) {
IRBuilder<> IRB(I);
if (MemSetInst *M = dyn_cast<MemSetInst>(I)) {
IRB.CreateCall(
MemsetFn,
{IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
IRB.CreateIntCast(M->getArgOperand(1), IRB.getInt32Ty(), false),
IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
I->eraseFromParent();
} else if (MemTransferInst *M = dyn_cast<MemTransferInst>(I)) {
IRB.CreateCall(
isa<MemCpyInst>(M) ? MemcpyFn : MemmoveFn,
{IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
IRB.CreatePointerCast(M->getArgOperand(1), IRB.getInt8PtrTy()),
IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
I->eraseFromParent();
}
return false;
}
// Both llvm and ThreadSanitizer atomic operations are based on C++11/C1x
// standards. For background see C++11 standard. A slightly older, publicly
// available draft of the standard (not entirely up-to-date, but close enough
// for casual browsing) is available here:
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf
// The following page contains more background information:
// http://www.hpl.hp.com/personal/Hans_Boehm/c++mm/
bool ThreadSanitizer::instrumentAtomic(Instruction *I, const DataLayout &DL) {
IRBuilder<> IRB(I);
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
Value *Addr = LI->getPointerOperand();
int Idx = getMemoryAccessFuncIndex(Addr, DL);
if (Idx < 0)
return false;
const unsigned ByteSize = 1U << Idx;
const unsigned BitSize = ByteSize * 8;
Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
Type *PtrTy = Ty->getPointerTo();
Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
createOrdering(&IRB, LI->getOrdering())};
Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
Value *C = IRB.CreateCall(TsanAtomicLoad[Idx], Args);
Value *Cast = IRB.CreateBitOrPointerCast(C, OrigTy);
I->replaceAllUsesWith(Cast);
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
Value *Addr = SI->getPointerOperand();
int Idx = getMemoryAccessFuncIndex(Addr, DL);
if (Idx < 0)
return false;
const unsigned ByteSize = 1U << Idx;
const unsigned BitSize = ByteSize * 8;
Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
Type *PtrTy = Ty->getPointerTo();
Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
IRB.CreateBitOrPointerCast(SI->getValueOperand(), Ty),
createOrdering(&IRB, SI->getOrdering())};
CallInst *C = CallInst::Create(TsanAtomicStore[Idx], Args);
ReplaceInstWithInst(I, C);
} else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I)) {
Value *Addr = RMWI->getPointerOperand();
int Idx = getMemoryAccessFuncIndex(Addr, DL);
if (Idx < 0)
return false;
Function *F = TsanAtomicRMW[RMWI->getOperation()][Idx];
if (!F)
return false;
const unsigned ByteSize = 1U << Idx;
const unsigned BitSize = ByteSize * 8;
Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
Type *PtrTy = Ty->getPointerTo();
Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
IRB.CreateIntCast(RMWI->getValOperand(), Ty, false),
createOrdering(&IRB, RMWI->getOrdering())};
CallInst *C = CallInst::Create(F, Args);
ReplaceInstWithInst(I, C);
} else if (AtomicCmpXchgInst *CASI = dyn_cast<AtomicCmpXchgInst>(I)) {
Value *Addr = CASI->getPointerOperand();
int Idx = getMemoryAccessFuncIndex(Addr, DL);
if (Idx < 0)
return false;
const unsigned ByteSize = 1U << Idx;
const unsigned BitSize = ByteSize * 8;
Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
Type *PtrTy = Ty->getPointerTo();
Value *CmpOperand =
IRB.CreateBitOrPointerCast(CASI->getCompareOperand(), Ty);
Value *NewOperand =
IRB.CreateBitOrPointerCast(CASI->getNewValOperand(), Ty);
Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
CmpOperand,
NewOperand,
createOrdering(&IRB, CASI->getSuccessOrdering()),
createOrdering(&IRB, CASI->getFailureOrdering())};
CallInst *C = IRB.CreateCall(TsanAtomicCAS[Idx], Args);
Value *Success = IRB.CreateICmpEQ(C, CmpOperand);
Value *OldVal = C;
Type *OrigOldValTy = CASI->getNewValOperand()->getType();
if (Ty != OrigOldValTy) {
// The value is a pointer, so we need to cast the return value.
OldVal = IRB.CreateIntToPtr(C, OrigOldValTy);
}
Value *Res =
IRB.CreateInsertValue(UndefValue::get(CASI->getType()), OldVal, 0);
Res = IRB.CreateInsertValue(Res, Success, 1);
I->replaceAllUsesWith(Res);
I->eraseFromParent();
} else if (FenceInst *FI = dyn_cast<FenceInst>(I)) {
Value *Args[] = {createOrdering(&IRB, FI->getOrdering())};
Function *F = FI->getSyncScopeID() == SyncScope::SingleThread ?
TsanAtomicSignalFence : TsanAtomicThreadFence;
CallInst *C = CallInst::Create(F, Args);
ReplaceInstWithInst(I, C);
}
return true;
}
int ThreadSanitizer::getMemoryAccessFuncIndex(Value *Addr,
const DataLayout &DL) {
Type *OrigPtrTy = Addr->getType();
Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
assert(OrigTy->isSized());
uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
if (TypeSize != 8 && TypeSize != 16 &&
TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
NumAccessesWithBadSize++;
// Ignore all unusual sizes.
return -1;
}
size_t Idx = countTrailingZeros(TypeSize / 8);
assert(Idx < kNumberOfAccessSizes);
return Idx;
}
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