[llvm-dev] Difficulty in understanding loop analysis code (original) (raw)
Fatima Ahmed via llvm-dev llvm-dev at lists.llvm.org
Wed Dec 19 09:47:24 PST 2018
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Hey all! I'm new to LLVM and advance C++. I came across this piece of code and found it difficult to understand.
Can anyone please explain how is it working ? I want to get loop count, sub loop count etc printed as output.Thanks. //Iteration on loops for (LoopInfo::iterator i = LI.begin(), e = LI.end(); i != e; ++i) { Loop *L = *i; int subloop = 1; countLoop++; static LLVMContext Context; BasicBlock *parentLoopPred = L->getLoopPredecessor(); BasicBlock *parentLoopHead = L->getHeader(); std::vector<Loop*> subLoopAll = L->getSubLoops(); Loop::iterator j, f; //Parent Loop Calculation //Counter = 0 instruction insertion // You must declare a constant Int like so instead of using it directly in a AllocaInst instantiation. ConstantInt *IntVal4 = ConstantInt::get(Type::getInt32Ty(Context), 4); // counter = 4 Value *one1 = ConstantInt::get(Type::getInt32Ty(Context), -1, true); Instruction *ACounter1 = new AllocaInst(Type::getInt32Ty(Context), 0, IntVal4, "counter"); //(IntegerType::get(mContext, 32), one, "counter", loopPredecessor); //(IntegerType::get(mContext, 32), IR.getInt32(0), "counter"); parentLoopPred->getInstList().insert(parentLoopPred->getFirstInsertionPt(), ACounter1);
Instruction *SCounter1 = new StoreInst(one1, ACounter1); SCounter1->insertAfter(ACounter1); //Counter++ instruction insertion Value *IValue1 = ConstantInt::get(Type::getInt32Ty(Context), 1, true); Instruction *CValue1 = new LoadInst(ACounter1, "midCount"); parentLoopHead->getInstList().insert(parentLoopHead->getFirstInsertionPt(), CValue1); Instruction *NValue1 = BinaryOperator::CreateNSWAdd(CValue1, IValue1, "incremented");// Instruction::Add, CValue, IValue, ""); NValue1->insertAfter(CValue1); Instruction *SNValue1 = new StoreInst(NValue1, ACounter1); SNValue1->insertAfter(NValue1); Value *PValue1 = SNValue1->getOperand(0); std::vector<Value *> printArrayRef1; Value *PValue12 = ConstantInt::get(Type::getInt32Ty(Context), subLoopAll.size(), true); std::vector<Value *> printArrayRef12; -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20181219/3d5e1aee/attachment.html>
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