heap/CodeBlockSet.h

   1 /*
   2  * Copyright (C) 2013, 2014 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 CodeBlockSet_h
  27 #define CodeBlockSet_h
  28
  29 #include "GCSegmentedArray.h"
  30 #include "HeapOperation.h"
  31 #include <wtf/HashSet.h>
  32 #include <wtf/Noncopyable.h>
  33 #include <wtf/PassRefPtr.h>
  34 #include <wtf/PrintStream.h>
  35 #include <wtf/RefPtr.h>
  36
  37 namespace JSC {
  38
  39 class BlockAllocator;
  40 class CodeBlock;
  41 class Heap;
  42 class JSCell;
  43 class SlotVisitor;
  44
  45 // CodeBlockSet tracks all CodeBlocks. Every CodeBlock starts out with one
  46 // reference coming in from GC. The GC is responsible for freeing CodeBlocks
  47 // once they hasOneRef() and nobody is running code from that CodeBlock.
  48
  49 class CodeBlockSet {
  50     WTF_MAKE_NONCOPYABLE(CodeBlockSet);
  51
  52 public:
  53     CodeBlockSet(BlockAllocator&);
  54     ~CodeBlockSet();
  55
  56     // Add a CodeBlock. This is only called by CodeBlock constructors.
  57     void add(PassRefPtr<CodeBlock>);
  58
  59     // Clear mark bits for certain CodeBlocks depending on the type of collection.
  60     void clearMarksForEdenCollection(const Vector<const JSCell*>&);
  61
  62     // Clear all mark bits for all CodeBlocks.
  63     void clearMarksForFullCollection();
  64
  65     // Mark a pointer that may be a CodeBlock that belongs to the set of DFG
  66     // blocks. This is defined in CodeBlock.h.
  67     void mark(CodeBlock* candidateCodeBlock);
  68     void mark(void* candidateCodeBlock);
  69
  70     // Delete all code blocks that are only referenced by this set (i.e. owned
  71     // by this set), and that have not been marked.
  72     void deleteUnmarkedAndUnreferenced(HeapOperation);
  73
  74     void remove(CodeBlock*);
  75
  76     // Trace all marked code blocks. The CodeBlock is free to make use of
  77     // mayBeExecuting.
  78     void traceMarked(SlotVisitor&);
  79
  80     // Add all currently executing CodeBlocks to the remembered set to be
  81     // re-scanned during the next collection.
  82     void rememberCurrentlyExecutingCodeBlocks(Heap*);
  83
  84     // Visits each CodeBlock in the heap until the visitor function returns true
  85     // to indicate that it is done iterating, or until every CodeBlock has been
  86     // visited.
  87     template<typename Functor> void iterate(Functor& functor)
  88     {
  89         for (auto& codeBlock : m_oldCodeBlocks) {
  90             bool done = functor(codeBlock);
  91             if (done)
  92                 return;
  93         }
  94
  95         for (auto& codeBlock : m_newCodeBlocks) {
  96             bool done = functor(codeBlock);
  97             if (done)
  98                 return;
  99         }
 100     }
 101
 102     void dump(PrintStream&) const;
 103
 104 private:
 105     void clearMarksForCodeBlocksInRememberedExecutables(const Vector<const JSCell*>&);
 106     void promoteYoungCodeBlocks();
 107
 108     // This is not a set of RefPtr<CodeBlock> because we need to be able to find
 109     // arbitrary bogus pointers. I could have written a thingy that had peek types
 110     // and all, but that seemed like overkill.
 111     HashSet<CodeBlock*> m_oldCodeBlocks;
 112     HashSet<CodeBlock*> m_newCodeBlocks;
 113     GCSegmentedArray<CodeBlock*> m_currentlyExecuting;
 114 };
 115
 116 } // namespace JSC
 117
 118 #endif // CodeBlockSet_h
 119