bytecode/ArrayAllocationProfile.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 ArrayAllocationProfile_h
  27 #define ArrayAllocationProfile_h
  28
  29 #include "IndexingType.h"
  30 #include "JSArray.h"
  31
  32 namespace JSC {
  33
  34 class ArrayAllocationProfile {
  35 public:
  36     ArrayAllocationProfile()
  37         : m_currentIndexingType(ArrayWithUndecided)
  38         , m_lastArray(0)
  39     {
  40     }
  41
  42     IndexingType selectIndexingType()
  43     {
  44         if (m_lastArray && UNLIKELY(m_lastArray->structure()->indexingType() != m_currentIndexingType))
  45             updateIndexingType();
  46         return m_currentIndexingType;
  47     }
  48
  49     JSArray* updateLastAllocation(JSArray* lastArray)
  50     {
  51         m_lastArray = lastArray;
  52         return lastArray;
  53     }
  54
  55     JS_EXPORT_PRIVATE void updateIndexingType();
  56
  57     static IndexingType selectIndexingTypeFor(ArrayAllocationProfile* profile)
  58     {
  59         if (!profile)
  60             return ArrayWithUndecided;
  61         return profile->selectIndexingType();
  62     }
  63
  64     static JSArray* updateLastAllocationFor(ArrayAllocationProfile* profile, JSArray* lastArray)
  65     {
  66         if (profile)
  67             profile->updateLastAllocation(lastArray);
  68         return lastArray;
  69     }
  70
  71 private:
  72
  73     IndexingType m_currentIndexingType;
  74     JSArray* m_lastArray;
  75 };
  76
  77 } // namespace JSC
  78
  79 #endif // ArrayAllocationProfile_h
  80