1  /*
 2   * Copyright (C) 2018-2019 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 "ConcurrentJSLock.h"
29  #include "IsoSubspace.h"
30  #include "JSCast.h"
31  #include "VM.h"
32  
33  namespace JSC {
34  
35  class CodeBlock;
36  class LLIntOffsetsExtractor;
37  
38  class ExecutableToCodeBlockEdge final : public JSCell {
39  public:
40      typedef JSCell Base;
41      static constexpr unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;
42  
43      template<typename CellType, SubspaceAccess>
44      static IsoSubspace* subspaceFor(VM& vm)
45      {
46          return &vm.executableToCodeBlockEdgeSpace;
47      }
48  
49      static Structure* createStructure(VM&, JSGlobalObject*, JSValue prototype);
50  
51      static ExecutableToCodeBlockEdge* create(VM&, CodeBlock*);
52      
53      DECLARE_INFO;
54  
55      CodeBlock* codeBlock() const { return m_codeBlock.get(); }
56      
57      static void visitChildren(JSCell*, SlotVisitor&);
58      static void visitOutputConstraints(JSCell*, SlotVisitor&);
59      void finalizeUnconditionally(VM&);
60      
61      static CodeBlock* unwrap(ExecutableToCodeBlockEdge* edge)
62      {
63          if (!edge)
64              return nullptr;
65          return edge->codeBlock();
66      }
67      
68      static CodeBlock* deactivateAndUnwrap(ExecutableToCodeBlockEdge* edge);
69      
70      static ExecutableToCodeBlockEdge* wrap(CodeBlock* codeBlock);
71      
72      static ExecutableToCodeBlockEdge* wrapAndActivate(CodeBlock* codeBlock);
73      
74  private:
75      friend class LLIntOffsetsExtractor;
76  
77      ExecutableToCodeBlockEdge(VM&, CodeBlock*);
78  
79      void finishCreation(VM&);
80  
81      void activate();
82      void deactivate();
83      bool isActive() const;
84      
85      void runConstraint(const ConcurrentJSLocker&, VM&, SlotVisitor&);
86      
87      WriteBarrier<CodeBlock> m_codeBlock;
88  };
89  
90  } // namespace JSC
91