dfg/DFGPrePostNumbering.h

   1 /*
   2  * Copyright (C) 2014 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef DFGPrePostNumbering_h
  27 #define DFGPrePostNumbering_h
  28
  29 #if ENABLE(DFG_JIT)
  30
  31 #include "DFGAnalysis.h"
  32 #include "DFGBasicBlock.h"
  33 #include "DFGBlockMap.h"
  34
  35 namespace JSC { namespace DFG {
  36
  37 enum EdgeKind {
  38     ForwardEdge,
  39     CrossEdge,
  40     BackEdge
  41 };
  42
  43 class PrePostNumbering : public Analysis<PrePostNumbering> {
  44 public:
  45     PrePostNumbering();
  46     ~PrePostNumbering();
  47
  48     void compute(Graph&);
  49
  50     unsigned preNumber(BasicBlock* block) const { return m_map[block].m_preNumber; }
  51     unsigned postNumber(BasicBlock* block) const { return m_map[block].m_postNumber; }
  52
  53     // Is from a strict ancestor of to?
  54     bool isStrictAncestorOf(BasicBlock* from, BasicBlock* to) const
  55     {
  56         return preNumber(from) < preNumber(to)
  57             && postNumber(from) > postNumber(to);
  58     }
  59
  60     bool isAncestorOf(BasicBlock* from, BasicBlock* to) const
  61     {
  62         return from == to || isStrictAncestorOf(from, to);
  63     }
  64
  65     bool isStrictDescendantOf(BasicBlock* from, BasicBlock* to) const
  66     {
  67         return isStrictAncestorOf(to, from);
  68     }
  69
  70     bool isDescendantOf(BasicBlock* from, BasicBlock* to) const
  71     {
  72         return isAncestorOf(to, from);
  73     }
  74
  75     // This will give a bogus answer if there is actually no such edge. If you want to determine
  76     // if there is any such edge, you have to do it yourself.
  77     EdgeKind edgeKind(BasicBlock* from, BasicBlock* to) const
  78     {
  79         if (isStrictDescendantOf(to, from))
  80             return ForwardEdge;
  81
  82         if (isAncestorOf(to, from))
  83             return BackEdge;
  84
  85         return CrossEdge;
  86     }
  87
  88 private:
  89     struct Numbering {
  90         unsigned m_preNumber;
  91         unsigned m_postNumber;
  92     };
  93
  94     BlockMap<Numbering> m_map;
  95 };
  96
  97 } } // namespace JSC::DFG
  98
  99 namespace WTF {
 100
 101 void printInternal(PrintStream&, JSC::DFG::EdgeKind);
 102
 103 } // namespace WTF
 104
 105 #endif // ENABLE(DFG_JIT)
 106
 107 #endif // DFGPrePostNumbering_h
 108