//===-- IGNode.h - Represent a node in an interference graph ----*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file was developed by the LLVM research group and is distributed under // the University of Illinois Open Source License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file represents a node in an interference graph. // // For efficiency, the AdjList is updated only once - ie. we can add but not // remove nodes from AdjList. // // The removal of nodes from IG is simulated by decrementing the CurDegree. // If this node is put on stack (that is removed from IG), the CurDegree of all // the neighbors are decremented and this node is marked OnStack. Hence // the effective neighbors in the AdjList are the ones that do not have the // OnStack flag set (therefore, they are in the IG). // // The methods that modify/use the CurDegree must be called only // after all modifications to the IG are over (i.e., all neighbors are fixed). // // The vector representation is the most efficient one for adj list. // Though nodes are removed when coalescing is done, we access it in sequence // for far many times when coloring (colorNode()). // //===----------------------------------------------------------------------===// #ifndef IGNODE_H #define IGNODE_H #include "LiveRange.h" #include <vector> namespace llvm { class RegClass; //---------------------------------------------------------------------------- // Class IGNode // // Represents a node in an interference graph. //---------------------------------------------------------------------------- class IGNode { const unsigned Index; // index within IGNodeList bool OnStack; // this has been pushed on to stack for coloring std::vector<IGNode *> AdjList;// adjacency list for this live range int CurDegree; // // set by InterferenceGraph::setCurDegreeOfIGNodes() after calculating // all adjacency lists. // Decremented when a neighbor is pushed on to the stack. // After that, never incremented/set again nor used. LiveRange *const ParentLR; public: IGNode(LiveRange *LR, unsigned index) : Index(index), ParentLR(LR) { OnStack = false; CurDegree = -1; ParentLR->setUserIGNode(this); } inline unsigned int getIndex() const { return Index; } // adjLists must be updated only once. However, the CurDegree can be changed // inline void addAdjIGNode(IGNode *AdjNode) { AdjList.push_back(AdjNode); } inline IGNode *getAdjIGNode(unsigned ind) const { assert ( ind < AdjList.size()); return AdjList[ind]; } // delete a node in AdjList - node must be in the list // should not be called often // void delAdjIGNode(const IGNode *Node); inline unsigned getNumOfNeighbors() const { return AdjList.size(); } // Get the number of unique neighbors if these two nodes are merged unsigned getCombinedDegree(const IGNode* otherNode) const; inline bool isOnStack() const { return OnStack; } // remove form IG and pushes on to stack (reduce the degree of neighbors) // void pushOnStack(); // CurDegree is the effective number of neighbors when neighbors are // pushed on to the stack during the coloring phase. Must be called // after all modifications to the IG are over (i.e., all neighbors are // fixed). // inline void setCurDegree() { assert(CurDegree == -1); CurDegree = AdjList.size(); } inline int getCurDegree() const { return CurDegree; } // called when a neigh is pushed on to stack // inline void decCurDegree() { assert(CurDegree > 0); --CurDegree; } // The following methods call the methods in ParentLR // They are added to this class for convenience // If many of these are called within a single scope, // consider calling the methods directly on LR inline bool hasColor() const { return ParentLR->hasColor(); } inline unsigned int getColor() const { return ParentLR->getColor(); } inline void setColor(unsigned Col) { ParentLR->setColor(Col); } inline LiveRange *getParentLR() const { return ParentLR; } }; } // End llvm namespace #endif