text: /*
   * Copyright (C) 2013 Apple Inc. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
   */
  
  #ifndef PolymorphicAccessStructureList_h
  #define PolymorphicAccessStructureList_h
  
  #include "JITStubRoutine.h"
  #include "Structure.h"
  #include "StructureChain.h"
  #include <wtf/Platform.h>
  
  #define POLYMORPHIC_LIST_CACHE_SIZE 8
  
  namespace JSC {
  
  // *Sigh*, If the JIT is enabled we need to track the stubRountine (of type CodeLocationLabel),
  // 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
  // curently actually use PolymorphicAccessStructureLists, which we should).  Anyway, this seems like the best
  // solution for now - will need to something smarter if/when we actually want mixed-mode operation.
  
  #if ENABLE(JIT)
  // 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.
  struct PolymorphicAccessStructureList {
      WTF_MAKE_FAST_ALLOCATED;
  public:
      struct PolymorphicStubInfo {
          bool isChain;
          bool isDirect;
          RefPtr<JITStubRoutine> stubRoutine;
          WriteBarrier<Structure> base;
          union {
              WriteBarrierBase<Structure> proto;
              WriteBarrierBase<StructureChain> chain;
          } u;
  
          PolymorphicStubInfo()
          {
              u.proto.clear();
          }
  
          void set(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> _stubRoutine, Structure* _base, bool isDirect)
          {
              stubRoutine = _stubRoutine;
              base.set(vm, owner, _base);
              u.proto.clear();
              isChain = false;
              this->isDirect = isDirect;
          }
              
          void set(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> _stubRoutine, Structure* _base, Structure* _proto, bool isDirect)
          {
              stubRoutine = _stubRoutine;
              base.set(vm, owner, _base);
              u.proto.set(vm, owner, _proto);
              isChain = false;
              this->isDirect = isDirect;
          }
              
          void set(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> _stubRoutine, Structure* _base, StructureChain* _chain, bool isDirect)
          {
              stubRoutine = _stubRoutine;
              base.set(vm, owner, _base);
              u.chain.set(vm, owner, _chain);
              isChain = true;
              this->isDirect = isDirect;
          }
      } list[POLYMORPHIC_LIST_CACHE_SIZE];
          
      PolymorphicAccessStructureList()
      {
      }
          
      PolymorphicAccessStructureList(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> stubRoutine, Structure* firstBase, bool isDirect)
      {
          list[0].set(vm, owner, stubRoutine, firstBase, isDirect);
      }
  
      PolymorphicAccessStructureList(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> stubRoutine, Structure* firstBase, Structure* firstProto, bool isDirect)
      {
          list[0].set(vm, owner, stubRoutine, firstBase, firstProto, isDirect);
      }
  
      PolymorphicAccessStructureList(VM& vm, JSCell* owner, PassRefPtr<JITStubRoutine> stubRoutine, Structure* firstBase, StructureChain* firstChain, bool isDirect)
      {
          list[0].set(vm, owner, stubRoutine, firstBase, firstChain, isDirect);
      }
  
      bool visitWeak(int count)
      {
          for (int i = 0; i < count; ++i) {
              PolymorphicStubInfo& info = list[i];
              if (!info.base) {
                  // We're being marked during initialisation of an entry
                  ASSERT(!info.u.proto);
                  continue;
              }
                  
              if (!Heap::isMarked(info.base.get()))
                  return false;
              if (info.u.proto && !info.isChain
                  && !Heap::isMarked(info.u.proto.get()))
                  return false;
              if (info.u.chain && info.isChain
                  && !Heap::isMarked(info.u.chain.get()))
                  return false;
          }
              
          return true;
      }
  };
  
  #endif // ENABLE(JIT)
  
  } // namespace JSC
  
  #endif // PolymorphicAccessStructureList_h
  
  