stack_dist_calc.hh

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/*
 * Copyright (c) 2014-2015 ARM Limited
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 * Authors: Kanishk Sugand
 *          Andreas Hansson
 */

#ifndef __MEM_STACK_DIST_CALC_HH__
#define __MEM_STACK_DIST_CALC_HH__

#include <limits>
#include <map>
#include <vector>

#include "base/types.hh"

class StackDistCalc
{

  private:

    struct Node;

    typedef std::map<uint64_t, Node*> IndexNodeMap;
    typedef std::map<Addr, uint64_t> AddressIndexMap;
    typedef std::vector<IndexNodeMap> TreeType;

    uint64_t getSum(Node* node, bool from_left, uint64_t sum_from_below,
                    uint64_t stack_dist, uint64_t level) const;

    uint64_t getSumsLeavesToRoot(Node* node) const;

    uint64_t updateSum(Node* node,
                       bool from_left, uint64_t sum_from_below, uint64_t level,
                       uint64_t stack_dist, bool discard_node);

    uint64_t updateSumsLeavesToRoot(Node* node, bool is_new_leaf);

    void updateTree();

    void sanityCheckTree(const Node* node, uint64_t level = 0) const;

    uint64_t getIndex() const { return index; }

    uint64_t getTreeDepth() const { return tree.size() - 1; }

    void printStack(int n = 5) const;

    uint64_t verifyStackDist(const Addr r_address,
                             bool update_stack = false);

  public:
    StackDistCalc(bool verify_stack = false);

    ~StackDistCalc();

    static constexpr uint64_t Infinity = std::numeric_limits<uint64_t>::max();


    std::pair<uint64_t, bool> calcStackDist(const Addr r_address,
                                            bool mark = false);

    std::pair<uint64_t, bool> calcStackDistAndUpdate(const Addr r_address,
                                                     bool addNewNode = true);

  private:

    struct Node{
        // Sum of the left children
        uint64_t sumLeft;

        // Sum of the right children
        uint64_t sumRight;

        // Flag to indicate that sumLeft has gone from non-zero value to 0
        bool discardLeft;

        // Flag to indicate that sumRight has gone from non-zero value to 0
        bool discardRight;

        // Index of the current element in the Map
        uint64_t nodeIndex;

        // Pointer to the parent
        Node* parent;

        // Flag to mark the node as the right/left child
        bool isLeftNode;

        bool isMarked;

        Node() : sumLeft(0), sumRight(0), discardLeft(false),
                 discardRight(false), nodeIndex(0),
                 parent(nullptr), isLeftNode(true), isMarked(false)
        { }
    };

    uint64_t index;

    // Binary tree of partial sums
    TreeType tree;

    // Hash map which returns last seen index of each address
    AddressIndexMap aiMap;

    // Keeps count of number of the next unique index for each
    // level in the tree
    std::vector<uint64_t> nextIndex;

    // Dummy Stack for verification
    std::vector<uint64_t> stack;

    // Flag to enable verification of stack. (Slows down the simulation)
    const bool verifyStack;
};


#endif //__STACK_DIST_CALC_HH__