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 "PropertyOffset.h"
  30 #include <wtf/NotFound.h>
  31
  32 namespace JSC {
  33
  34 class CodeBlock;
  35 class Identifier;
  36 class VM;
  37 class JSGlobalObject;
  38 class Structure;
  39 class StructureChain;
  40
  41 class PutByIdStatus {
  42 public:
  43     enum State {
  44         // It's uncached so we have no information.
  45         NoInformation,
  46         // It's cached as a direct store into an object property for cases where the object
  47         // already has the property.
  48         SimpleReplace,
  49         // It's cached as a transition from one structure that lacks the property to one that
  50         // includes the property, and a direct store to this new property.
  51         SimpleTransition,
  52         // It's known to often take slow path.
  53         TakesSlowPath
  54     };
  55
  56     PutByIdStatus()
  57         : m_state(NoInformation)
  58         , m_oldStructure(0)
  59         , m_newStructure(0)
  60         , m_structureChain(0)
  61         , m_offset(invalidOffset)
  62     {
  63     }
  64
  65     explicit PutByIdStatus(State state)
  66         : m_state(state)
  67         , m_oldStructure(0)
  68         , m_newStructure(0)
  69         , m_structureChain(0)
  70         , m_offset(invalidOffset)
  71     {
  72         ASSERT(m_state == NoInformation || m_state == TakesSlowPath);
  73     }
  74
  75     PutByIdStatus(
  76         State state,
  77         Structure* oldStructure,
  78         Structure* newStructure,
  79         StructureChain* structureChain,
  80         PropertyOffset offset)
  81         : m_state(state)
  82         , m_oldStructure(oldStructure)
  83         , m_newStructure(newStructure)
  84         , m_structureChain(structureChain)
  85         , m_offset(offset)
  86     {
  87         ASSERT((m_state == NoInformation || m_state == TakesSlowPath) == !m_oldStructure);
  88         ASSERT((m_state != SimpleTransition) == !m_newStructure);
  89         ASSERT((m_state != SimpleTransition) == !m_structureChain);
  90         ASSERT((m_state == NoInformation || m_state == TakesSlowPath) == (m_offset == invalidOffset));
  91     }
  92
  93     static PutByIdStatus computeFor(CodeBlock*, unsigned bytecodeIndex, Identifier&);
  94     static PutByIdStatus computeFor(VM&, JSGlobalObject*, Structure*, Identifier&, bool isDirect);
  95
  96     State state() const { return m_state; }
  97
  98     bool isSet() const { return m_state != NoInformation; }
  99     bool operator!() const { return m_state == NoInformation; }
 100     bool isSimpleReplace() const { return m_state == SimpleReplace; }
 101     bool isSimpleTransition() const { return m_state == SimpleTransition; }
 102     bool takesSlowPath() const { return m_state == TakesSlowPath; }
 103
 104     Structure* oldStructure() const { return m_oldStructure; }
 105     Structure* newStructure() const { return m_newStructure; }
 106     StructureChain* structureChain() const { return m_structureChain; }
 107     PropertyOffset offset() const { return m_offset; }
 108
 109 private:
 110     static PutByIdStatus computeFromLLInt(CodeBlock*, unsigned bytecodeIndex, Identifier&);
 111
 112     State m_state;
 113     Structure* m_oldStructure;
 114     Structure* m_newStructure;
 115     StructureChain* m_structureChain;
 116     PropertyOffset m_offset;
 117 };
 118
 119 } // namespace JSC
 120
 121 #endif // PutByIdStatus_h
 122