bytecode/GetByIdStatus.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 GetByIdStatus_h
  27 #define GetByIdStatus_h
  28
  29 #include "PropertyOffset.h"
  30 #include "StructureSet.h"
  31 #include <wtf/NotFound.h>
  32
  33 namespace JSC {
  34
  35 class CodeBlock;
  36 class Identifier;
  37
  38 class GetByIdStatus {
  39 public:
  40     enum State {
  41         NoInformation,  // It's uncached so we have no information.
  42         Simple,         // It's cached for a simple access to a known object property with
  43                         // a possible structure chain and a possible specific value.
  44         TakesSlowPath,  // It's known to often take slow path.
  45         MakesCalls      // It's known to take paths that make calls.
  46     };
  47
  48     GetByIdStatus()
  49         : m_state(NoInformation)
  50         , m_offset(invalidOffset)
  51     {
  52     }
  53
  54     explicit GetByIdStatus(State state)
  55         : m_state(state)
  56         , m_offset(invalidOffset)
  57     {
  58         ASSERT(state == NoInformation || state == TakesSlowPath || state == MakesCalls);
  59     }
  60
  61     GetByIdStatus(
  62         State state, bool wasSeenInJIT, const StructureSet& structureSet = StructureSet(),
  63         PropertyOffset offset = invalidOffset, JSValue specificValue = JSValue(), Vector<Structure*> chain = Vector<Structure*>())
  64         : m_state(state)
  65         , m_structureSet(structureSet)
  66         , m_chain(chain)
  67         , m_specificValue(specificValue)
  68         , m_offset(offset)
  69         , m_wasSeenInJIT(wasSeenInJIT)
  70     {
  71         ASSERT((state == Simple) == (offset != invalidOffset));
  72     }
  73
  74     static GetByIdStatus computeFor(CodeBlock*, unsigned bytecodeIndex, Identifier&);
  75     static GetByIdStatus computeFor(VM&, Structure*, Identifier&);
  76
  77     State state() const { return m_state; }
  78
  79     bool isSet() const { return m_state != NoInformation; }
  80     bool operator!() const { return !isSet(); }
  81     bool isSimple() const { return m_state == Simple; }
  82     bool takesSlowPath() const { return m_state == TakesSlowPath || m_state == MakesCalls; }
  83     bool makesCalls() const { return m_state == MakesCalls; }
  84
  85     const StructureSet& structureSet() const { return m_structureSet; }
  86     const Vector<Structure*>& chain() const { return m_chain; } // Returns empty vector if this is a direct access.
  87     JSValue specificValue() const { return m_specificValue; } // Returns JSValue() if there is no specific value.
  88     PropertyOffset offset() const { return m_offset; }
  89
  90     bool wasSeenInJIT() const { return m_wasSeenInJIT; }
  91
  92 private:
  93     static void computeForChain(GetByIdStatus& result, CodeBlock*, Identifier&, Structure*);
  94     static GetByIdStatus computeFromLLInt(CodeBlock*, unsigned bytecodeIndex, Identifier&);
  95
  96     State m_state;
  97     StructureSet m_structureSet;
  98     Vector<Structure*> m_chain;
  99     JSValue m_specificValue;
 100     PropertyOffset m_offset;
 101     bool m_wasSeenInJIT;
 102 };
 103
 104 } // namespace JSC
 105
 106 #endif // PropertyAccessStatus_h
 107