Interval.h revision 4dd88f6fbf6dc44ceba03b34aeab458536789b98 
1//===- llvm/Analysis/Interval.h - Interval Class Declaration -----*- C++ -*--=//
2//
3// This file contains the declaration of the cfg::Interval class, which
4// represents a set of CFG nodes and is a portion of an interval partition.
5//
6// Intervals have some interesting and useful properties, including the
7// following:
8//    1. The header node of an interval dominates all of the elements of the
9//       interval
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_INTERVAL_H
14#define LLVM_INTERVAL_H
15
16#include <vector>
17
18class BasicBlock;
19
20namespace cfg {
21
22//===----------------------------------------------------------------------===//
23//
24// Interval Class - An Interval is a set of nodes defined such that every node
25// in the interval has all of its predecessors in the interval (except for the
26// header)
27//
28class Interval {
29  // HeaderNode - The header BasicBlock, which dominates all BasicBlocks in this
30  // interval.  Also, any loops in this interval must go through the HeaderNode.
31  //
32  BasicBlock *HeaderNode;
33public:
34  typedef vector<BasicBlock*>::iterator succ_iterator;
35  typedef vector<BasicBlock*>::iterator pred_iterator;
36  typedef vector<BasicBlock*>::iterator node_iterator;
37
38  inline Interval(BasicBlock *Header) : HeaderNode(Header) {
39    Nodes.push_back(Header);
40  }
41
42  inline Interval(const Interval &I) // copy ctor
43    : HeaderNode(I.HeaderNode), Nodes(I.Nodes), Successors(I.Successors) {}
44
45  inline BasicBlock *getHeaderNode() const { return HeaderNode; }
46
47  // Nodes - The basic blocks in this interval.
48  //
49  vector<BasicBlock*> Nodes;
50
51  // Successors - List of BasicBlocks that are reachable directly from nodes in
52  // this interval, but are not in the interval themselves.
53  // These nodes neccesarily must be header nodes for other intervals.
54  //
55  vector<BasicBlock*> Successors;
56
57  // Predecessors - List of BasicBlocks that have this Interval's header block
58  // as one of their successors.
59  //
60  vector<BasicBlock*> Predecessors;
61
62  // contains - Find out if a basic block is in this interval
63  inline bool contains(BasicBlock *BB) const {
64    for (unsigned i = 0; i < Nodes.size(); ++i)
65      if (Nodes[i] == BB) return true;
66    return false;
67    // I don't want the dependency on <algorithm>
68    //return find(Nodes.begin(), Nodes.end(), BB) != Nodes.end();
69  }
70
71  // isSuccessor - find out if a basic block is a successor of this Interval
72  inline bool isSuccessor(BasicBlock *BB) const {
73    for (unsigned i = 0; i < Successors.size(); ++i)
74      if (Successors[i] == BB) return true;
75    return false;
76    // I don't want the dependency on <algorithm>
77    //return find(Successors.begin(), Successors.end(), BB) != Successors.end();
78  }
79
80  // Equality operator.  It is only valid to compare two intervals from the same
81  // partition, because of this, all we have to check is the header node for
82  // equality.
83  //
84  inline bool operator==(const Interval &I) const {
85    return HeaderNode == I.HeaderNode;
86  }
87
88  // isLoop - Find out if there is a back edge in this interval...
89  bool isLoop() const;
90};
91
92
93// succ_begin/succ_end - define global functions so that Intervals may be used
94// just like BasicBlocks can with the succ_* functions, and *::succ_iterator.
95//
96inline Interval::succ_iterator succ_begin(Interval *I) {
97  return I->Successors.begin();
98}
99inline Interval::succ_iterator succ_end(Interval *I) {
100  return I->Successors.end();
101}
102
103// pred_begin/pred_end - define global functions so that Intervals may be used
104// just like BasicBlocks can with the pred_* functions, and *::pred_iterator.
105//
106inline Interval::pred_iterator pred_begin(Interval *I) {
107  return I->Predecessors.begin();
108}
109inline Interval::pred_iterator pred_end(Interval *I) {
110  return I->Predecessors.end();
111}
112
113}    // End namespace cfg
114
115#endif
116