bool LLPE::runOnModule(Module &M) { vector<int> argv = readInputFile(); for (Module::iterator F = M.begin(), F_end = M.end(); F != F_end; ++F) { for (Function::arg_iterator A = F->arg_begin(), A_end = F->arg_end(); A != A_end; ++A) { //Search for variables referencing argv if (A->getName() == "argv") { //Iterate through uses of argv for (Value::use_iterator U = A->use_begin(), U_end = A->use_end(); U != U_end; ++U) { Instruction *User = dyn_cast<Instruction>(*U); StoreInst *SI = dyn_cast<StoreInst>(User); AllocaInst *OrigAlloca = dyn_cast<AllocaInst>(SI->getOperand(1)); for (Value::use_iterator U2 = OrigAlloca->use_begin(), U2_end = OrigAlloca->use_end(); U2 != U2_end; ++U2) { Instruction *User2 = dyn_cast<Instruction>(*U2); for (Value::use_iterator U3 = User2->use_begin(), U3_end = OrigAlloca->use_end(); U3 != U3_end; ++U3) { searchForStoreInstruction(dyn_cast<Instruction>(*U3)->getParent(), argv); } } } } } } return true; }
AllocaInst* Variables::changeLocal(Value* value, ArrayType* newType) { AllocaInst* oldTarget = dyn_cast<AllocaInst>(value); PointerType* oldPointerType = dyn_cast<PointerType>(oldTarget->getType()); ArrayType* oldType = dyn_cast<ArrayType>(oldPointerType->getElementType()); AllocaInst* newTarget = NULL; errs() << "Changing the precision of variable \"" << oldTarget->getName() << "\" from " << *oldType << " to " << *newType << ".\n"; if (newType->getElementType()->getTypeID() != oldType->getElementType()->getTypeID()) { newTarget = new AllocaInst(newType, getInt32(1), "", oldTarget); // we are not calling getAlignment because in this case double requires 16. Investigate further. unsigned alignment; switch(newType->getElementType()->getTypeID()) { case Type::FloatTyID: alignment = 4; break; case Type::DoubleTyID: alignment = 16; break; case Type::X86_FP80TyID: alignment = 16; break; default: alignment = 0; } newTarget->setAlignment(alignment); // depends on type? 8 for float? 16 for double? newTarget->takeName(oldTarget); // iterating through instructions using old AllocaInst vector<Instruction*> erase; Value::use_iterator it = oldTarget->use_begin(); for(; it != oldTarget->use_end(); it++) { bool is_erased = Transformer::transform(it, newTarget, oldTarget, newType, oldType, alignment); if (!is_erased) erase.push_back(dyn_cast<Instruction>(*it)); } // erasing uses of old instructions for(unsigned int i = 0; i < erase.size(); i++) { erase[i]->eraseFromParent(); } // erase old instruction //oldTarget->eraseFromParent(); } else { errs() << "\tNo changes required.\n"; } return newTarget; }
/// performCallSlotOptzn - takes a memcpy and a call that it depends on, /// and checks for the possibility of a call slot optimization by having /// the call write its result directly into the destination of the memcpy. bool MemCpyOpt::performCallSlotOptzn(Instruction *cpy, Value *cpyDest, Value *cpySrc, uint64_t cpyLen, unsigned cpyAlign, CallInst *C) { // The general transformation to keep in mind is // // call @func(..., src, ...) // memcpy(dest, src, ...) // // -> // // memcpy(dest, src, ...) // call @func(..., dest, ...) // // Since moving the memcpy is technically awkward, we additionally check that // src only holds uninitialized values at the moment of the call, meaning that // the memcpy can be discarded rather than moved. // Deliberately get the source and destination with bitcasts stripped away, // because we'll need to do type comparisons based on the underlying type. CallSite CS(C); // Require that src be an alloca. This simplifies the reasoning considerably. AllocaInst *srcAlloca = dyn_cast<AllocaInst>(cpySrc); if (!srcAlloca) return false; // Check that all of src is copied to dest. if (TD == 0) return false; ConstantInt *srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize()); if (!srcArraySize) return false; uint64_t srcSize = TD->getTypeAllocSize(srcAlloca->getAllocatedType()) * srcArraySize->getZExtValue(); if (cpyLen < srcSize) return false; // Check that dest points to memory that is at least as aligned as src. unsigned srcAlign = srcAlloca->getAlignment(); if (!srcAlign) srcAlign = TD->getABITypeAlignment(srcAlloca->getAllocatedType()); bool isDestSufficientlyAligned = srcAlign <= cpyAlign; // If dest is not aligned enough and we can't increase its alignment then // bail out. if (!isDestSufficientlyAligned && !isa<AllocaInst>(cpyDest)) return false; // Check that accessing the first srcSize bytes of dest will not cause a // trap. Otherwise the transform is invalid since it might cause a trap // to occur earlier than it otherwise would. if (AllocaInst *A = dyn_cast<AllocaInst>(cpyDest)) { // The destination is an alloca. Check it is larger than srcSize. ConstantInt *destArraySize = dyn_cast<ConstantInt>(A->getArraySize()); if (!destArraySize) return false; uint64_t destSize = TD->getTypeAllocSize(A->getAllocatedType()) * destArraySize->getZExtValue(); if (destSize < srcSize) return false; } else if (Argument *A = dyn_cast<Argument>(cpyDest)) { // If the destination is an sret parameter then only accesses that are // outside of the returned struct type can trap. if (!A->hasStructRetAttr()) return false; Type *StructTy = cast<PointerType>(A->getType())->getElementType(); uint64_t destSize = TD->getTypeAllocSize(StructTy); if (destSize < srcSize) return false; } else { return false; } // Check that src is not accessed except via the call and the memcpy. This // guarantees that it holds only undefined values when passed in (so the final // memcpy can be dropped), that it is not read or written between the call and // the memcpy, and that writing beyond the end of it is undefined. SmallVector<User*, 8> srcUseList(srcAlloca->use_begin(), srcAlloca->use_end()); while (!srcUseList.empty()) { User *UI = srcUseList.pop_back_val(); if (isa<BitCastInst>(UI)) { for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); I != E; ++I) srcUseList.push_back(*I); } else if (GetElementPtrInst *G = dyn_cast<GetElementPtrInst>(UI)) { if (G->hasAllZeroIndices()) for (User::use_iterator I = UI->use_begin(), E = UI->use_end(); I != E; ++I) srcUseList.push_back(*I); else return false; } else if (UI != C && UI != cpy) { return false; } } // Since we're changing the parameter to the callsite, we need to make sure // that what would be the new parameter dominates the callsite. DominatorTree &DT = getAnalysis<DominatorTree>(); if (Instruction *cpyDestInst = dyn_cast<Instruction>(cpyDest)) if (!DT.dominates(cpyDestInst, C)) return false; // In addition to knowing that the call does not access src in some // unexpected manner, for example via a global, which we deduce from // the use analysis, we also need to know that it does not sneakily // access dest. We rely on AA to figure this out for us. AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); AliasAnalysis::ModRefResult MR = AA.getModRefInfo(C, cpyDest, srcSize); // If necessary, perform additional analysis. if (MR != AliasAnalysis::NoModRef) MR = AA.callCapturesBefore(C, cpyDest, srcSize, &DT); if (MR != AliasAnalysis::NoModRef) return false; // All the checks have passed, so do the transformation. bool changedArgument = false; for (unsigned i = 0; i < CS.arg_size(); ++i) if (CS.getArgument(i)->stripPointerCasts() == cpySrc) { Value *Dest = cpySrc->getType() == cpyDest->getType() ? cpyDest : CastInst::CreatePointerCast(cpyDest, cpySrc->getType(), cpyDest->getName(), C); changedArgument = true; if (CS.getArgument(i)->getType() == Dest->getType()) CS.setArgument(i, Dest); else CS.setArgument(i, CastInst::CreatePointerCast(Dest, CS.getArgument(i)->getType(), Dest->getName(), C)); } if (!changedArgument) return false; // If the destination wasn't sufficiently aligned then increase its alignment. if (!isDestSufficientlyAligned) { assert(isa<AllocaInst>(cpyDest) && "Can only increase alloca alignment!"); cast<AllocaInst>(cpyDest)->setAlignment(srcAlign); } // Drop any cached information about the call, because we may have changed // its dependence information by changing its parameter. MD->removeInstruction(C); // Remove the memcpy. MD->removeInstruction(cpy); ++NumMemCpyInstr; return true; }
bool SpDefUseInstrumenter::runOnModule(Module &M) { cerr << "instrument: --- Def-Use pair Spectrum ---\n"; Function *Main = M.getFunction("main"); LLVMContext &C = M.getContext(); if (Main == 0) { cerr << "WARNING: cannot insert def-use instrumentation into a module" << " with no main function!\n"; return false; // No main, no instrumentation! } // Add library function prototype Constant *SpFn = M.getOrInsertFunction("_updateSpectrum", Type::getVoidTy(C), Type::getInt32Ty(C), // spectrum index Type::getInt32Ty(C), // component index NULL); unsigned spectrumIndex = IndexManager::getSpectrumIndex(); unsigned nDefs = 0; unsigned nUses = 0; // Loop through all functions within module for (Module::iterator F = M.begin(), ME = M.end(); F != ME; ++F) { // skip function declarations if(F->isDeclaration()) continue; // skip the _registerAll function if(F->getName()=="_registerAll") continue; // Loop through all basic blocks within function for (Function::iterator B = F->begin(), FE = F->end(); B != FE; ++B) { //skip dead blocks //is this really safe?? BasicBlock *bb = B; if (B!=F->begin() && (pred_begin(bb)==pred_end(bb))) continue; //skip dead blocks // Loop through all instructions within basic block for (BasicBlock::iterator I = B->begin(), BE = B->end(); I != BE; I++) { if(isa<DbgDeclareInst>(*I)) { // extract source file information from debug intrinsic DbgDeclareInst &DDI = cast<DbgDeclareInst>(*I); std::string file, dir; std::string name; GlobalVariable *gv = cast<GlobalVariable>(DDI.getVariable()); if(!gv->hasInitializer()) continue; ConstantStruct *cs = cast<ConstantStruct>(gv->getInitializer()); llvm::GetConstantStringInfo(cs->getOperand(2), name); unsigned int line = unsigned(cast<ConstantInt>(cs->getOperand(4))->getZExtValue()); Value *V = cast<Value>(cs->getOperand(3)); GlobalVariable *gv2 = cast<GlobalVariable>(cast<ConstantExpr>(V)->getOperand(0)); if(!gv2->hasInitializer()) continue; ConstantStruct *cs2 = cast<ConstantStruct>(gv2->getInitializer()); llvm::GetConstantStringInfo(cs2->getOperand(3), file); llvm::GetConstantStringInfo(cs2->getOperand(4), dir); // get the allocation instruction of the variable definition AllocaInst *AI; if(isa<AllocaInst>(DDI.getAddress())) { AI = cast<AllocaInst>(DDI.getAddress()); } else if (isa<BitCastInst>(DDI.getAddress())) { AI = cast<AllocaInst>(cast<BitCastInst>(DDI.getAddress())->getOperand(0)); } else { continue; } nDefs++; // add calls to lib function for each use of the variable int currUses = 0; for(AllocaInst::use_iterator U = AI->use_begin(), UE = AI->use_end(); U != UE; ++U) { if(isa<Instruction>(*U)) { User *user = *U; Instruction *insertInst = (Instruction*)user; // find most likely context location of use int useline = line; std::string usefile = file, usedir = dir; BasicBlock *parent = insertInst->getParent(); BasicBlock::iterator inst = parent->begin(); while(((Instruction *)inst) != insertInst && inst != parent->end()) { /*TODO: solve DbgStopPointInst problem*/ /*if(isa<DbgStopPointInst>(*inst)) { DbgStopPointInst &DSPI = cast<DbgStopPointInst>(*inst); llvm::GetConstantStringInfo(DSPI.getDirectory(), usedir); llvm::GetConstantStringInfo(DSPI.getFileName(), usefile); useline = DSPI.getLine(); }*/ inst++; } std::stringstream usename; usename << name << "(use_" << currUses << ")"; // add source context of this invariant to context file ContextManager::addSpectrumContext( spectrumIndex, // spectrumIndex nUses, // componentIndex usedir, // path usefile, // file useline, // line usename.str()); // name currUses++; std::vector<Value*> Args(2); Args[0] = ConstantInt::get(Type::getInt32Ty(C), spectrumIndex); Args[1] = ConstantInt::get(Type::getInt32Ty(C), nUses++); CallInst::Create(SpFn, Args.begin(), Args.end(), "", insertInst); } } } } } } // add the registration of the instrumented spectrum points in the _registerAll() function addSpectrumRegistration(M, spectrumIndex, nUses, "Def-Use_Pairs"); std::cerr << "instrument: " << nDefs << " defines with a total number of " << nUses << " uses instrumented\n"; // notify change of program return true; }