1  /*
 2   * Copyright (C) 2016-2017 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  #pragma once
27  
28  #include "JSGlobalObject.h"
29  #include "SlotVisitor.h"
30  #include "WriteBarrier.h"
31  
32  namespace JSC {
33  
34  class InternalFunctionAllocationProfile {
35  public:
36      static inline ptrdiff_t offsetOfStructure() { return OBJECT_OFFSETOF(InternalFunctionAllocationProfile, m_structure); }
37  
38      Structure* structure() { return m_structure.get(); }
39      Structure* createAllocationStructureFromBase(VM&, JSGlobalObject*, JSCell* owner, JSObject* prototype, Structure* base);
40  
41      void clear() { m_structure.clear(); }
42      void visitAggregate(SlotVisitor& visitor) { visitor.append(m_structure); }
43  
44  private:
45      WriteBarrier<Structure> m_structure;
46  };
47  
48  inline Structure* InternalFunctionAllocationProfile::createAllocationStructureFromBase(VM& vm, JSGlobalObject* baseGlobalObject, JSCell* owner, JSObject* prototype, Structure* baseStructure)
49  {
50      ASSERT(!m_structure || m_structure.get()->classInfo() != baseStructure->classInfo() || m_structure->globalObject() != baseGlobalObject);
51      ASSERT(baseStructure->hasMonoProto());
52  
53      Structure* structure;
54      // FIXME: Implement polymorphic prototypes for subclasses of builtin types:
55      // https://bugs.webkit.org/show_bug.cgi?id=177318
56      if (prototype == baseStructure->storedPrototype())
57          structure = baseStructure;
58      else
59          structure = vm.structureCache.emptyStructureForPrototypeFromBaseStructure(baseGlobalObject, prototype, baseStructure);
60  
61      // Ensure that if another thread sees the structure, it will see it properly created.
62      WTF::storeStoreFence();
63  
64      m_structure.set(vm, owner, structure);
65      return m_structure.get();
66  }
67  
68  } // namespace JSC