CycleLookBackSoftwareBypasser.hh

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/*
    Copyright (c) 2002-2009 Tampere University.
 
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/**
 * @file CycleLookBackSoftwareBypasser.hh
 *
 * Declaration of CycleLookBackSoftwareBypasser interface.
 *
 * @author Pekka Jääskeläinen 2007 (pjaaskel-no.spam-cs.tut.fi)
 * @note rating: red
 */
 
#ifndef TTA_CYCLE_LOOK_BACK_SOFTWARE_BYPASSER_HH
#define TTA_CYCLE_LOOK_BACK_SOFTWARE_BYPASSER_HH
 
#include <map>
#include <set>
 
#include "SoftwareBypasser.hh"
#include "DataDependenceGraph.hh"
 
namespace TTAMachine {
    class Bus;
}
class MoveNodeSelector;
class MoveNode;
/**
 * A simple implementation of software bypassing that reschedules operand
 * writes as bypassed moves in case the result has been produced in n
 * previous cycles.
 */
class CycleLookBackSoftwareBypasser : public SoftwareBypasser {
public:
    CycleLookBackSoftwareBypasser();
    virtual ~CycleLookBackSoftwareBypasser();
 
    virtual int bypass(
        MoveNodeGroup& candidates,
        DataDependenceGraph& ddg,
        ResourceManager& rm, bool bypassTrigger);
 
    virtual void removeBypass(
        MoveNodeGroup& candidates,
        DataDependenceGraph& ddg,
        ResourceManager& rm);
 
    virtual void removeBypass(
        MoveNode& moveNode,
        DataDependenceGraph& ddg,
        ResourceManager& rm, bool restoreSource=true);
 
    virtual int removeDeadResults(
        MoveNodeGroup& candidates,
        DataDependenceGraph& ddg,
        ResourceManager& rm,
        std::set<std::pair<TTAProgram::Move*, int> >& removedMoves);
 
    void setSelector(MoveNodeSelector* selector);
    
    virtual void clearCaches(DataDependenceGraph& ddg, bool removeDeadResults);
 
    static void printStats();
private:
    /// count of cycles before the operand write to look for the producer
    /// of the read value
    int cyclesToLookBack_;
 
    /// count of cycles before the operand write to look for the producer
    /// of the read value when cannot kill result
    int cyclesToLookBackNoDRE_;
    
    // whether dead results should be killed.
    bool killDeadResults_;
 
    // whether to bypass from register-to-register moves
    bool bypassFromRegs_;
 
    // whether to bypass to register-to-register moves
    bool bypassToRegs_;
 
    int bypassNode(
        MoveNode& nodeToBypass,
        int& lastOperandCycle,
        DataDependenceGraph& ddg,
        ResourceManager& rm);
 
    /// Stores sources and bypassed moves in case they
    /// have to be unassigned (case when operands are scheduled
    /// and bypassed but result can not be scheduled with such operands
    // First is bypassed node, second is original source
    std::map<MoveNode*, MoveNode*, MoveNode::Comparator> storedSources_;
    
    // cycles and buses of source nodes so that they can be reassigned.
    std::map<MoveNode*, int> sourceCycles_;
    std::map<MoveNode*, const TTAMachine::Bus*> sourceBuses_;
 
    std::map<MoveNode*, MoveNode*, MoveNode::Comparator> removedStoredSources_;
 
    // these are alreayd removed from the dubgraph. remove also from the
    // big ddg.
    DataDependenceGraph::NodeSet removedNodes_;
 
    MoveNodeSelector* selector_;
 
    static int bypassCount_;
    static int deadResultCount_;
    static int triggerAbortCount_;
};
 
#endif