get_const_value_from_store.cpp

//===- Hello.cpp - Example code from "Writing an LLVM Pass" ---------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements two versions of the LLVM "Hello World" pass described
// in docs/WritingAnLLVMPass.html
//
//===----------------------------------------------------------------------===//

#include "llvm/ADT/Statistic.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Support/raw_ostream.h"
#include <vector>
using namespace llvm;

#define DEBUG_TYPE "demo"

STATISTIC(HelloCounter, "Counts number of functions greeted");

namespace {
// Hello - The first implementation, without getAnalysisUsage.
struct Demo : public FunctionPass {
  static char ID; // Pass identification, replacement for typeid
  Demo() : FunctionPass(ID) {}

  bool runOnFunction(Function &F) override {
    // int number_of_ins = 0;

    ++HelloCounter;
    errs() << "Demo: ";
    errs().write_escaped(F.getName()) << '\n';
    for (BasicBlock &BB : F) {
      for (Instruction &I : BB) {
        errs() << " opcode of the instruction is : " << I.getOpcodeName()<< " ";
        errs() << "Variable name : "<< I.getName()<<"\n"; // This gets the variable name
        if (StoreInst *Store = dyn_cast<StoreInst>(&I))  // Checks if the instruction is a store inst
        {
          Value *StoredValue = Store->getValueOperand();  // gets the Operand value 
          if (ConstantInt *ConstantValue = dyn_cast<ConstantInt>(StoredValue)) {  // Initially, the operand value was in hex, but we need to change in integer
            errs() << "Constant value in store instruction: "<< ConstantValue->getValue() << "\n"; // This gives the constant Integer value
          }}
      }
      
    }

    return false;
  }
};
} // namespace

char Demo::ID = 0;
static RegisterPass<Demo> X("demo", "This is a Demo pass");