include/llvm/Analysis/Interval.h

   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
  25 namespace llvm {
  26
  27 class BasicBlock;
  28 class 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 ///
  36 class 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
  42 public:
  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   /// isLoop - Find out if there is a back edge in this interval...
  93   bool isLoop() const;
  94
  95   /// print - Show contents in human readable format...
  96   void print(raw_ostream &O) const;
  97 };
  98
  99 /// succ_begin/succ_end - define methods so that Intervals may be used
 100 /// just like BasicBlocks can with the succ_* functions, and *::succ_iterator.
 101 ///
 102 inline Interval::succ_iterator succ_begin(Interval *I) {
 103   return I->Successors.begin();
 104 }
 105 inline Interval::succ_iterator succ_end(Interval *I)   {
 106   return I->Successors.end();
 107 }
 108
 109 /// pred_begin/pred_end - define methods so that Intervals may be used
 110 /// just like BasicBlocks can with the pred_* functions, and *::pred_iterator.
 111 ///
 112 inline Interval::pred_iterator pred_begin(Interval *I) {
 113   return I->Predecessors.begin();
 114 }
 115 inline Interval::pred_iterator pred_end(Interval *I)   {
 116   return I->Predecessors.end();
 117 }
 118
 119 template <> struct GraphTraits<Interval*> {
 120   using NodeRef = Interval *;
 121   using ChildIteratorType = Interval::succ_iterator;
 122
 123   static NodeRef getEntryNode(Interval *I) { return I; }
 124
 125   /// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
 126   static ChildIteratorType child_begin(NodeRef N) { return succ_begin(N); }
 127   static ChildIteratorType child_end(NodeRef N) { return succ_end(N); }
 128 };
 129
 130 template <> struct GraphTraits<Inverse<Interval*>> {
 131   using NodeRef = Interval *;
 132   using ChildIteratorType = Interval::pred_iterator;
 133
 134   static NodeRef getEntryNode(Inverse<Interval *> G) { return G.Graph; }
 135   static ChildIteratorType child_begin(NodeRef N) { return pred_begin(N); }
 136   static ChildIteratorType child_end(NodeRef N) { return pred_end(N); }
 137 };
 138
 139 } // end namespace llvm
 140
 141 #endif // LLVM_ANALYSIS_INTERVAL_H