interpreter/RegisterFile.h

   1 /*
   2  * Copyright (C) 2008, 2009 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  *
   8  * 1.  Redistributions of source code must retain the above copyright
   9  *     notice, this list of conditions and the following disclaimer.
  10  * 2.  Redistributions in binary form must reproduce the above copyright
  11  *     notice, this list of conditions and the following disclaimer in the
  12  *     documentation and/or other materials provided with the distribution.
  13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  14  *     its contributors may be used to endorse or promote products derived
  15  *     from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 #ifndef RegisterFile_h
  30 #define RegisterFile_h
  31
  32 #include "ExecutableAllocator.h"
  33 #include "Register.h"
  34 #include <wtf/Noncopyable.h>
  35 #include <wtf/PageReservation.h>
  36 #include <wtf/VMTags.h>
  37
  38 namespace JSC {
  39
  40     class ConservativeRoots;
  41     class DFGCodeBlocks;
  42     class LLIntOffsetsExtractor;
  43
  44     class RegisterFile {
  45         WTF_MAKE_NONCOPYABLE(RegisterFile);
  46     public:
  47         enum CallFrameHeaderEntry {
  48             CallFrameHeaderSize = 6,
  49
  50             ArgumentCount = -6,
  51             CallerFrame = -5,
  52             Callee = -4,
  53             ScopeChain = -3,
  54             ReturnPC = -2, // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*.
  55             CodeBlock = -1,
  56         };
  57
  58         static const size_t defaultCapacity = 512 * 1024;
  59         static const size_t commitSize = 16 * 1024;
  60         // Allow 8k of excess registers before we start trying to reap the registerfile
  61         static const ptrdiff_t maxExcessCapacity = 8 * 1024;
  62
  63         RegisterFile(size_t capacity = defaultCapacity);
  64         ~RegisterFile();
  65
  66         void gatherConservativeRoots(ConservativeRoots&);
  67         void gatherConservativeRoots(ConservativeRoots&, DFGCodeBlocks&);
  68
  69         Register* begin() const { return static_cast<Register*>(m_reservation.base()); }
  70         Register* end() const { return m_end; }
  71         size_t size() const { return end() - begin(); }
  72
  73         bool grow(Register*);
  74         void shrink(Register*);
  75
  76         static size_t committedByteCount();
  77         static void initializeThreading();
  78
  79         Register* const * addressOfEnd() const
  80         {
  81             return &m_end;
  82         }
  83
  84     private:
  85         friend class LLIntOffsetsExtractor;
  86
  87         bool growSlowCase(Register*);
  88         void releaseExcessCapacity();
  89         void addToCommittedByteCount(long);
  90         Register* m_end;
  91         Register* m_commitEnd;
  92         PageReservation m_reservation;
  93     };
  94
  95     inline RegisterFile::RegisterFile(size_t capacity)
  96         : m_end(0)
  97     {
  98         ASSERT(capacity && isPageAligned(capacity));
  99
 100         m_reservation = PageReservation::reserve(roundUpAllocationSize(capacity * sizeof(Register), commitSize), OSAllocator::JSVMStackPages);
 101         m_end = static_cast<Register*>(m_reservation.base());
 102         m_commitEnd = static_cast<Register*>(m_reservation.base());
 103     }
 104
 105     inline void RegisterFile::shrink(Register* newEnd)
 106     {
 107         if (newEnd >= m_end)
 108             return;
 109         m_end = newEnd;
 110         if (m_end == m_reservation.base() && (m_commitEnd - begin()) >= maxExcessCapacity)
 111             releaseExcessCapacity();
 112     }
 113
 114     inline bool RegisterFile::grow(Register* newEnd)
 115     {
 116         if (newEnd <= m_end)
 117             return true;
 118         return growSlowCase(newEnd);
 119     }
 120
 121 } // namespace JSC
 122
 123 #endif // RegisterFile_h