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  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.   /// 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. ///
  99. inline Interval::succ_iterator succ_begin(Interval *I) {
  100.   return I->Successors.begin();
  101. }
  102. inline 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. ///
  109. inline Interval::pred_iterator pred_begin(Interval *I) {
  110.   return I->Predecessors.begin();
  111. }
  112. inline Interval::pred_iterator pred_end(Interval *I)   {
  113.   return I->Predecessors.end();
  114. }
  115.  
  116. template <> 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.  
  127. template <> 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.