1 //===-- IGNode.h - Represent a node in an interference graph ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 /* Title: IGNode.h -*- C++ -*-
11 Author: Ruchira Sasanka
13 Purpose: Represents a node in an interference graph.
16 For efficiency, the AdjList is updated only once - ie. we can add but not
17 remove nodes from AdjList.
19 The removal of nodes from IG is simulated by decrementing the CurDegree.
20 If this node is put on stack (that is removed from IG), the CurDegree of all
21 the neighbors are decremented and this node is marked OnStack. Hence
22 the effective neighbors in the AdjList are the ones that do not have the
23 OnStack flag set (therefore, they are in the IG).
25 The methods that modify/use the CurDegree must be called only
26 after all modifications to the IG are over (i.e., all neighbors are fixed).
28 The vector representation is the most efficient one for adj list.
29 Though nodes are removed when coalescing is done, we access it in sequence
30 for far many times when coloring (colorNode()).
36 #include "LiveRange.h"
40 //----------------------------------------------------------------------------
43 // Represents a node in an interference graph.
44 //----------------------------------------------------------------------------
47 const unsigned Index; // index within IGNodeList
48 bool OnStack; // this has been pushed on to stack for coloring
49 std::vector<IGNode *> AdjList;// adjacency list for this live range
53 // set by InterferenceGraph::setCurDegreeOfIGNodes() after calculating
54 // all adjacency lists.
55 // Decremented when a neighbor is pushed on to the stack.
56 // After that, never incremented/set again nor used.
58 LiveRange *const ParentLR;
61 IGNode(LiveRange *LR, unsigned index) : Index(index), ParentLR(LR) {
64 ParentLR->setUserIGNode(this);
67 inline unsigned int getIndex() const { return Index; }
69 // adjLists must be updated only once. However, the CurDegree can be changed
71 inline void addAdjIGNode(IGNode *AdjNode) { AdjList.push_back(AdjNode); }
73 inline IGNode *getAdjIGNode(unsigned ind) const
74 { assert ( ind < AdjList.size()); return AdjList[ind]; }
76 // delete a node in AdjList - node must be in the list
77 // should not be called often
79 void delAdjIGNode(const IGNode *Node);
81 inline unsigned getNumOfNeighbors() const { return AdjList.size(); }
83 // Get the number of unique neighbors if these two nodes are merged
84 unsigned getCombinedDegree(const IGNode* otherNode) const;
86 inline bool isOnStack() const { return OnStack; }
88 // remove form IG and pushes on to stack (reduce the degree of neighbors)
92 // CurDegree is the effective number of neighbors when neighbors are
93 // pushed on to the stack during the coloring phase. Must be called
94 // after all modifications to the IG are over (i.e., all neighbors are
97 inline void setCurDegree() {
98 assert(CurDegree == -1);
99 CurDegree = AdjList.size();
102 inline int getCurDegree() const { return CurDegree; }
104 // called when a neigh is pushed on to stack
106 inline void decCurDegree() { assert(CurDegree > 0); --CurDegree; }
108 // The following methods call the methods in ParentLR
109 // They are added to this class for convenience
110 // If many of these are called within a single scope,
111 // consider calling the methods directly on LR
112 inline bool hasColor() const { return ParentLR->hasColor(); }
114 inline unsigned int getColor() const { return ParentLR->getColor(); }
116 inline void setColor(unsigned Col) { ParentLR->setColor(Col); }
118 inline LiveRange *getParentLR() const { return ParentLR; }