1//===- llvm/Analysis/Interval.h - Interval Class Declaration ----*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains the declaration of the Interval class, which
10// represents a set of CFG nodes and is a portion of an interval partition.
11//
12// Intervals have some interesting and useful properties, including the
13// following:
14//    1. The header node of an interval dominates all of the elements of the
15//       interval
16//
17//===----------------------------------------------------------------------===//
18
19#ifndef LLVM_ANALYSIS_INTERVAL_H
20#define LLVM_ANALYSIS_INTERVAL_H
21
22#include "llvm/ADT/GraphTraits.h"
23#include <vector>
24
25namespace llvm {
26
27class BasicBlock;
28class raw_ostream;
29
30//===----------------------------------------------------------------------===//
31//
32/// Interval Class - An Interval is a set of nodes defined such that every node
33/// in the interval has all of its predecessors in the interval (except for the
34/// header)
35///
36class Interval {
37  /// HeaderNode - The header BasicBlock, which dominates all BasicBlocks in this
38  /// interval.  Also, any loops in this interval must go through the HeaderNode.
39  ///
40  BasicBlock *HeaderNode;
41
42public:
43  using succ_iterator = std::vector<BasicBlock*>::iterator;
44  using pred_iterator = std::vector<BasicBlock*>::iterator;
45  using node_iterator = std::vector<BasicBlock*>::iterator;
46
47  inline Interval(BasicBlock *Header) : HeaderNode(Header) {
48    Nodes.push_back(Header);
49  }
50
51  inline BasicBlock *getHeaderNode() const { return HeaderNode; }
52
53  /// Nodes - The basic blocks in this interval.
54  std::vector<BasicBlock*> Nodes;
55
56  /// Successors - List of BasicBlocks that are reachable directly from nodes in
57  /// this interval, but are not in the interval themselves.
58  /// These nodes necessarily must be header nodes for other intervals.
59  std::vector<BasicBlock*> Successors;
60
61  /// Predecessors - List of BasicBlocks that have this Interval's header block
62  /// as one of their successors.
63  std::vector<BasicBlock*> Predecessors;
64
65  /// contains - Find out if a basic block is in this interval
66  inline bool contains(BasicBlock *BB) const {
67    for (BasicBlock *Node : Nodes)
68      if (Node == BB)
69        return true;
70    return false;
71    // I don't want the dependency on <algorithm>
72    //return find(Nodes.begin(), Nodes.end(), BB) != Nodes.end();
73  }
74
75  /// isSuccessor - find out if a basic block is a successor of this Interval
76  inline bool isSuccessor(BasicBlock *BB) const {
77    for (BasicBlock *Successor : Successors)
78      if (Successor == BB)
79        return true;
80    return false;
81    // I don't want the dependency on <algorithm>
82    //return find(Successors.begin(), Successors.end(), BB) != Successors.end();
83  }
84
85  /// Equality operator.  It is only valid to compare two intervals from the
86  /// same partition, because of this, all we have to check is the header node
87  /// for equality.
88  inline bool operator==(const Interval &I) const {
89    return HeaderNode == I.HeaderNode;
90  }
91
92  /// print - Show contents in human readable format...
93  void print(raw_ostream &O) const;
94};
95
96/// succ_begin/succ_end - define methods so that Intervals may be used
97/// just like BasicBlocks can with the succ_* functions, and *::succ_iterator.
98///
99inline Interval::succ_iterator succ_begin(Interval *I) {
100  return I->Successors.begin();
101}
102inline Interval::succ_iterator succ_end(Interval *I)   {
103  return I->Successors.end();
104}
105
106/// pred_begin/pred_end - define methods so that Intervals may be used
107/// just like BasicBlocks can with the pred_* functions, and *::pred_iterator.
108///
109inline Interval::pred_iterator pred_begin(Interval *I) {
110  return I->Predecessors.begin();
111}
112inline Interval::pred_iterator pred_end(Interval *I)   {
113  return I->Predecessors.end();
114}
115
116template <> struct GraphTraits<Interval*> {
117  using NodeRef = Interval *;
118  using ChildIteratorType = Interval::succ_iterator;
119
120  static NodeRef getEntryNode(Interval *I) { return I; }
121
122  /// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
123  static ChildIteratorType child_begin(NodeRef N) { return succ_begin(N); }
124  static ChildIteratorType child_end(NodeRef N) { return succ_end(N); }
125};
126
127template <> struct GraphTraits<Inverse<Interval*>> {
128  using NodeRef = Interval *;
129  using ChildIteratorType = Interval::pred_iterator;
130
131  static NodeRef getEntryNode(Inverse<Interval *> G) { return G.Graph; }
132  static ChildIteratorType child_begin(NodeRef N) { return pred_begin(N); }
133  static ChildIteratorType child_end(NodeRef N) { return pred_end(N); }
134};
135
136} // end namespace llvm
137
138#endif // LLVM_ANALYSIS_INTERVAL_H
139