CBAccessPath.h

/*
 * This file defines a full access path used in cb-check
 *
 *  Created on: May 26, 2016
 *      Author: Zhou Jinguo
 */
 
#ifndef IR_SEG_CBAccessPath_H
#define IR_SEG_CBAccessPath_H
 
#include <llvm/IR/Value.h>
 
#include "Platform/Arch/CBTypes.h"
#include "Utils/ADT/kvec.h"
 
using namespace llvm;
 
// This class defines the access path for SEG Nodes
// Currently used for pseudo-inputs and pseudo outputs of function
// Note: Offsets are stored in a reverse way for better efficiency
// For example arg2->4->8->0 is abstracted as base_ptr=arg2, offsets=[0,8,4]
class CBAccessPath {
private:
  kvec<pp_offset_t> offsets;
  Value *base_ptr;
 
  bool is_base_ptr_from_return;
 
public:
  CBAccessPath() {
    base_ptr = nullptr;
    is_base_ptr_from_return = false;
  }
  ~CBAccessPath() {}
 
  // Adding one level to the Access Path
  // e.g. arg->8 => base_ptr->offset->8 where arg is base_ptr->offset
  void add_level(Value *base_ptr, pp_offset_t offset,
                 bool is_from_return = false) {
    this->base_ptr = base_ptr;
    offsets.push_back(offset);
    this->is_base_ptr_from_return = is_from_return;
  }
 
  // Adding one level to the Access Path
  // e.g. arg->8 => base_ptr->(8-offset) where arg points to base_ptr->offset
  void reset_cur_level(Value *base_ptr, pp_offset_t offset,
                       bool is_from_return = false) {
    if (!offsets.empty()) {
      this->base_ptr = base_ptr;
      offsets.back() -= offset;
      this->is_base_ptr_from_return = is_from_return;
    }
  }
 
  // reset the Assess Path as a direct access to base_ptr
  void reset(Value *base_ptr, bool is_from_return = false) {
    offsets.clear();
    this->base_ptr = base_ptr;
    this->is_base_ptr_from_return = is_from_return;
  }
 
  // reset the Assess Path as to the argument access path
  void reset(const CBAccessPath &ap) {
    offsets.clear();
    offsets.push_back(ap.offsets);
    this->base_ptr = ap.base_ptr;
    this->is_base_ptr_from_return = ap.is_base_ptr_from_return;
  }
 
  int get_depth() const { return offsets.size(); }
 
  pp_offset_t get_offset(int idx) const {
    // The offset is added in a reversed way, i.e. arg->0->4->8 is stored as
    // [8,4,0] This is because that push_back() is much faster than push_frount
    return offsets[get_depth() - idx - 1];
  }
 
  Value *get_base_ptr() const { return base_ptr; }
 
  // return true if the ap roots from function return
  bool is_from_return() const { return is_base_ptr_from_return; }
};
 
#endif /* IR_SEG_CBAccessPath_H */