312 lines
11 KiB
C++
312 lines
11 KiB
C++
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//===-- ThreadSanitizer.cpp - race detector -------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of ThreadSanitizer, a race detector.
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//
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// The tool is under development, for the details about previous versions see
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// http://code.google.com/p/data-race-test
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//
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// The instrumentation phase is quite simple:
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// - Insert calls to run-time library before every memory access.
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// - Optimizations may apply to avoid instrumenting some of the accesses.
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// - Insert calls at function entry/exit.
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// The rest is handled by the run-time library.
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "tsan"
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#include "FunctionBlackList.h"
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#include "llvm/ADT/SmallSet.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Intrinsics.h"
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#include "llvm/Function.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Metadata.h"
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#include "llvm/Module.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/IRBuilder.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Transforms/Instrumentation.h"
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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#include "llvm/Type.h"
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using namespace llvm;
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static cl::opt<std::string> ClBlackListFile("tsan-blacklist",
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cl::desc("Blacklist file"), cl::Hidden);
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static cl::opt<bool> ClPrintStats("tsan-print-stats",
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cl::desc("Print ThreadSanitizer instrumentation stats"), cl::Hidden);
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namespace {
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// Stats counters for ThreadSanitizer instrumentation.
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struct ThreadSanitizerStats {
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size_t NumInstrumentedReads;
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size_t NumInstrumentedWrites;
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size_t NumOmittedReadsBeforeWrite;
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size_t NumAccessesWithBadSize;
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size_t NumInstrumentedVtableWrites;
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size_t NumOmittedReadsFromConstantGlobals;
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size_t NumOmittedReadsFromVtable;
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};
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/// ThreadSanitizer: instrument the code in module to find races.
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struct ThreadSanitizer : public FunctionPass {
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ThreadSanitizer();
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bool runOnFunction(Function &F);
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bool doInitialization(Module &M);
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bool doFinalization(Module &M);
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bool instrumentLoadOrStore(Instruction *I);
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static char ID; // Pass identification, replacement for typeid.
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private:
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void choseInstructionsToInstrument(SmallVectorImpl<Instruction*> &Local,
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SmallVectorImpl<Instruction*> &All);
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bool addrPointsToConstantData(Value *Addr);
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TargetData *TD;
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OwningPtr<FunctionBlackList> BL;
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// Callbacks to run-time library are computed in doInitialization.
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Value *TsanFuncEntry;
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Value *TsanFuncExit;
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// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
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static const size_t kNumberOfAccessSizes = 5;
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Value *TsanRead[kNumberOfAccessSizes];
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Value *TsanWrite[kNumberOfAccessSizes];
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Value *TsanVptrUpdate;
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// Stats are modified w/o synchronization.
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ThreadSanitizerStats stats;
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};
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} // namespace
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char ThreadSanitizer::ID = 0;
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INITIALIZE_PASS(ThreadSanitizer, "tsan",
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"ThreadSanitizer: detects data races.",
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false, false)
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ThreadSanitizer::ThreadSanitizer()
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: FunctionPass(ID),
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TD(NULL) {
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}
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FunctionPass *llvm::createThreadSanitizerPass() {
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return new ThreadSanitizer();
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}
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bool ThreadSanitizer::doInitialization(Module &M) {
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TD = getAnalysisIfAvailable<TargetData>();
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if (!TD)
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return false;
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BL.reset(new FunctionBlackList(ClBlackListFile));
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memset(&stats, 0, sizeof(stats));
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// Always insert a call to __tsan_init into the module's CTORs.
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IRBuilder<> IRB(M.getContext());
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Value *TsanInit = M.getOrInsertFunction("__tsan_init",
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IRB.getVoidTy(), NULL);
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appendToGlobalCtors(M, cast<Function>(TsanInit), 0);
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// Initialize the callbacks.
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TsanFuncEntry = M.getOrInsertFunction("__tsan_func_entry", IRB.getVoidTy(),
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IRB.getInt8PtrTy(), NULL);
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TsanFuncExit = M.getOrInsertFunction("__tsan_func_exit", IRB.getVoidTy(),
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NULL);
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for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
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SmallString<32> ReadName("__tsan_read");
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ReadName += itostr(1 << i);
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TsanRead[i] = M.getOrInsertFunction(ReadName, IRB.getVoidTy(),
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IRB.getInt8PtrTy(), NULL);
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SmallString<32> WriteName("__tsan_write");
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WriteName += itostr(1 << i);
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TsanWrite[i] = M.getOrInsertFunction(WriteName, IRB.getVoidTy(),
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IRB.getInt8PtrTy(), NULL);
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}
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TsanVptrUpdate = M.getOrInsertFunction("__tsan_vptr_update", IRB.getVoidTy(),
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IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
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NULL);
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return true;
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}
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bool ThreadSanitizer::doFinalization(Module &M) {
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if (ClPrintStats) {
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errs() << "ThreadSanitizerStats " << M.getModuleIdentifier()
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<< ": wr " << stats.NumInstrumentedWrites
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<< "; rd " << stats.NumInstrumentedReads
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<< "; vt " << stats.NumInstrumentedVtableWrites
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<< "; bs " << stats.NumAccessesWithBadSize
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<< "; rbw " << stats.NumOmittedReadsBeforeWrite
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<< "; rcg " << stats.NumOmittedReadsFromConstantGlobals
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<< "; rvt " << stats.NumOmittedReadsFromVtable
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<< "\n";
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}
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return true;
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}
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static bool isVtableAccess(Instruction *I) {
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if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa)) {
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if (Tag->getNumOperands() < 1) return false;
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if (MDString *Tag1 = dyn_cast<MDString>(Tag->getOperand(0))) {
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if (Tag1->getString() == "vtable pointer") return true;
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}
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}
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return false;
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}
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bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) {
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// If this is a GEP, just analyze its pointer operand.
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if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
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Addr = GEP->getPointerOperand();
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if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
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if (GV->isConstant()) {
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// Reads from constant globals can not race with any writes.
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stats.NumOmittedReadsFromConstantGlobals++;
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return true;
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}
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} else if(LoadInst *L = dyn_cast<LoadInst>(Addr)) {
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if (isVtableAccess(L)) {
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// Reads from a vtable pointer can not race with any writes.
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stats.NumOmittedReadsFromVtable++;
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return true;
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}
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}
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return false;
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}
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// Instrumenting some of the accesses may be proven redundant.
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// Currently handled:
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// - read-before-write (within same BB, no calls between)
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//
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// We do not handle some of the patterns that should not survive
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// after the classic compiler optimizations.
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// E.g. two reads from the same temp should be eliminated by CSE,
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// two writes should be eliminated by DSE, etc.
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//
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// 'Local' is a vector of insns within the same BB (no calls between).
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// 'All' is a vector of insns that will be instrumented.
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void ThreadSanitizer::choseInstructionsToInstrument(
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SmallVectorImpl<Instruction*> &Local,
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SmallVectorImpl<Instruction*> &All) {
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SmallSet<Value*, 8> WriteTargets;
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// Iterate from the end.
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for (SmallVectorImpl<Instruction*>::reverse_iterator It = Local.rbegin(),
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E = Local.rend(); It != E; ++It) {
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Instruction *I = *It;
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if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
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WriteTargets.insert(Store->getPointerOperand());
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} else {
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LoadInst *Load = cast<LoadInst>(I);
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Value *Addr = Load->getPointerOperand();
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if (WriteTargets.count(Addr)) {
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// We will write to this temp, so no reason to analyze the read.
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stats.NumOmittedReadsBeforeWrite++;
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continue;
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}
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if (addrPointsToConstantData(Addr)) {
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// Addr points to some constant data -- it can not race with any writes.
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continue;
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}
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}
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All.push_back(I);
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}
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Local.clear();
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}
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bool ThreadSanitizer::runOnFunction(Function &F) {
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if (!TD) return false;
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if (BL->isIn(F)) return false;
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SmallVector<Instruction*, 8> RetVec;
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SmallVector<Instruction*, 8> AllLoadsAndStores;
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SmallVector<Instruction*, 8> LocalLoadsAndStores;
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bool Res = false;
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bool HasCalls = false;
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// Traverse all instructions, collect loads/stores/returns, check for calls.
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for (Function::iterator FI = F.begin(), FE = F.end();
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FI != FE; ++FI) {
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BasicBlock &BB = *FI;
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for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
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BI != BE; ++BI) {
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if (isa<LoadInst>(BI) || isa<StoreInst>(BI))
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LocalLoadsAndStores.push_back(BI);
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else if (isa<ReturnInst>(BI))
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RetVec.push_back(BI);
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else if (isa<CallInst>(BI) || isa<InvokeInst>(BI)) {
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HasCalls = true;
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choseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores);
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}
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}
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choseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores);
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}
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// We have collected all loads and stores.
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// FIXME: many of these accesses do not need to be checked for races
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// (e.g. variables that do not escape, etc).
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// Instrument memory accesses.
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for (size_t i = 0, n = AllLoadsAndStores.size(); i < n; ++i) {
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Res |= instrumentLoadOrStore(AllLoadsAndStores[i]);
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}
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// Instrument function entry/exit points if there were instrumented accesses.
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if (Res || HasCalls) {
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IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
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Value *ReturnAddress = IRB.CreateCall(
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Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
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IRB.getInt32(0));
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IRB.CreateCall(TsanFuncEntry, ReturnAddress);
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for (size_t i = 0, n = RetVec.size(); i < n; ++i) {
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IRBuilder<> IRBRet(RetVec[i]);
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IRBRet.CreateCall(TsanFuncExit);
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}
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Res = true;
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}
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return Res;
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}
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bool ThreadSanitizer::instrumentLoadOrStore(Instruction *I) {
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IRBuilder<> IRB(I);
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bool IsWrite = isa<StoreInst>(*I);
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Value *Addr = IsWrite
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? cast<StoreInst>(I)->getPointerOperand()
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: cast<LoadInst>(I)->getPointerOperand();
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Type *OrigPtrTy = Addr->getType();
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Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
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assert(OrigTy->isSized());
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uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
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if (TypeSize != 8 && TypeSize != 16 &&
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TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
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stats.NumAccessesWithBadSize++;
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// Ignore all unusual sizes.
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return false;
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}
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if (IsWrite && isVtableAccess(I)) {
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Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
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IRB.CreateCall2(TsanVptrUpdate,
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IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
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IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy()));
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stats.NumInstrumentedVtableWrites++;
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return true;
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}
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size_t Idx = CountTrailingZeros_32(TypeSize / 8);
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assert(Idx < kNumberOfAccessSizes);
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Value *OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
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IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
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if (IsWrite) stats.NumInstrumentedWrites++;
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else stats.NumInstrumentedReads++;
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return true;
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}
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