bytecode/PolymorphicAccessStructureList.h

   1 /*
   2  * Copyright (C) 2013 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 PolymorphicAccessStructureList_h
  27 #define PolymorphicAccessStructureList_h
  28
  29 #include "JITStubRoutine.h"
  30 #include "Structure.h"
  31 #include "StructureChain.h"
  32
  33 #define POLYMORPHIC_LIST_CACHE_SIZE 8
  34
  35 namespace JSC {
  36
  37 // *Sigh*, If the JIT is enabled we need to track the stubRountine (of type CodeLocationLabel),
  38 // If the JIT is not in use we don't actually need the variable (that said, if the JIT is not in use we don't
  39 // curently actually use PolymorphicAccessStructureLists, which we should).  Anyway, this seems like the best
  40 // solution for now - will need to something smarter if/when we actually want mixed-mode operation.
  41
  42 #if ENABLE(JIT)
  43 // Structure used by op_get_by_id_self_list and op_get_by_id_proto_list instruction to hold data off the main opcode stream.
  44 struct PolymorphicAccessStructureList {
  45     WTF_MAKE_FAST_ALLOCATED;
  46 public:
  47     struct PolymorphicStubInfo {
  48         bool isDirect : 1;
  49         unsigned count : 31;
  50         RefPtr<JITStubRoutine> stubRoutine;
  51         WriteBarrier<Structure> base;
  52         WriteBarrier<StructureChain> chain;
  53
  54         PolymorphicStubInfo()
  55         {
  56         }
  57
  58         void set(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> _stubRoutine, Structure* _base, bool _isDirect)
  59         {
  60             stubRoutine = _stubRoutine;
  61             base.set(vm, owner, _base);
  62             isDirect = _isDirect;
  63             count = 0;
  64         }
  65
  66         void set(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> _stubRoutine, Structure* _base, StructureChain* _chain, bool _isDirect, unsigned _count)
  67         {
  68             stubRoutine = _stubRoutine;
  69             base.set(vm, owner, _base);
  70             chain.set(vm, owner, _chain);
  71             isDirect = _isDirect;
  72             count = _count;
  73         }
  74     } list[POLYMORPHIC_LIST_CACHE_SIZE];
  75
  76     PolymorphicAccessStructureList()
  77     {
  78     }
  79
  80     PolymorphicAccessStructureList(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> stubRoutine, Structure* firstBase, bool isDirect)
  81     {
  82         list[0].set(vm, owner, stubRoutine, firstBase, isDirect);
  83     }
  84
  85     PolymorphicAccessStructureList(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> stubRoutine, Structure* firstBase, StructureChain* firstChain, bool isDirect, unsigned count)
  86     {
  87         list[0].set(vm, owner, stubRoutine, firstBase, firstChain, isDirect, count);
  88     }
  89
  90     bool visitWeak(int count)
  91     {
  92         for (int i = 0; i < count; ++i) {
  93             PolymorphicStubInfo& info = list[i];
  94             if (!info.base)
  95                 continue;
  96
  97             if (!Heap::isMarked(info.base.get()))
  98                 return false;
  99             if (info.chain && !Heap::isMarked(info.chain.get()))
 100                 return false;
 101         }
 102
 103         return true;
 104     }
 105 };
 106
 107 #endif // ENABLE(JIT)
 108
 109 } // namespace JSC
 110
 111 #endif // PolymorphicAccessStructureList_h
 112