bytecode/PutByIdStatus.h

   1 /*
   2  * Copyright (C) 2012 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 PutByIdStatus_h
  27 #define PutByIdStatus_h
  28
  29 #include <wtf/NotFound.h>
  30
  31 namespace JSC {
  32
  33 class CodeBlock;
  34 class Identifier;
  35 class Structure;
  36 class StructureChain;
  37
  38 class PutByIdStatus {
  39 public:
  40     enum State {
  41         // It's uncached so we have no information.
  42         NoInformation,
  43         // It's cached as a direct store into an object property for cases where the object
  44         // already has the property.
  45         SimpleReplace,
  46         // It's cached as a transition from one structure that lacks the property to one that
  47         // includes the property, and a direct store to this new property.
  48         SimpleTransition,
  49         // It's known to often take slow path.
  50         TakesSlowPath
  51     };
  52
  53     PutByIdStatus()
  54         : m_state(NoInformation)
  55         , m_oldStructure(0)
  56         , m_newStructure(0)
  57         , m_structureChain(0)
  58         , m_offset(notFound)
  59     {
  60     }
  61
  62     PutByIdStatus(
  63         State state,
  64         Structure* oldStructure,
  65         Structure* newStructure,
  66         StructureChain* structureChain,
  67         size_t offset)
  68         : m_state(state)
  69         , m_oldStructure(oldStructure)
  70         , m_newStructure(newStructure)
  71         , m_structureChain(structureChain)
  72         , m_offset(offset)
  73     {
  74         ASSERT((m_state == NoInformation || m_state == TakesSlowPath) == !m_oldStructure);
  75         ASSERT((m_state != SimpleTransition) == !m_newStructure);
  76         ASSERT((m_state != SimpleTransition) == !m_structureChain);
  77         ASSERT((m_state == NoInformation || m_state == TakesSlowPath) == (m_offset == notFound));
  78     }
  79
  80     static PutByIdStatus computeFor(CodeBlock*, unsigned bytecodeIndex, Identifier&);
  81
  82     State state() const { return m_state; }
  83
  84     bool isSet() const { return m_state != NoInformation; }
  85     bool operator!() const { return m_state == NoInformation; }
  86     bool isSimpleReplace() const { return m_state == SimpleReplace; }
  87     bool isSimpleTransition() const { return m_state == SimpleTransition; }
  88     bool takesSlowPath() const { return m_state == TakesSlowPath; }
  89
  90     Structure* oldStructure() const { return m_oldStructure; }
  91     Structure* newStructure() const { return m_newStructure; }
  92     StructureChain* structureChain() const { return m_structureChain; }
  93     size_t offset() const { return m_offset; }
  94
  95 private:
  96     static PutByIdStatus computeFromLLInt(CodeBlock*, unsigned bytecodeIndex, Identifier&);
  97
  98     State m_state;
  99     Structure* m_oldStructure;
 100     Structure* m_newStructure;
 101     StructureChain* m_structureChain;
 102     size_t m_offset;
 103 };
 104
 105 } // namespace JSC
 106
 107 #endif // PutByIdStatus_h
 108