bytecode/JumpTable.h

   1 /*
   2  * Copyright (C) 2008 Apple Inc. All rights reserved.
   3  * Copyright (C) 2008 Cameron Zwarich <cwzwarich@uwaterloo.ca>
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1.  Redistributions of source code must retain the above copyright
  10  *     notice, this list of conditions and the following disclaimer.
  11  * 2.  Redistributions in binary form must reproduce the above copyright
  12  *     notice, this list of conditions and the following disclaimer in the
  13  *     documentation and/or other materials provided with the distribution.
  14  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  15  *     its contributors may be used to endorse or promote products derived
  16  *     from this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  19  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  20  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  21  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  22  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  23  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  24  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  25  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #ifndef JumpTable_h
  31 #define JumpTable_h
  32
  33 #include "UString.h"
  34 #include <wtf/HashMap.h>
  35 #include <wtf/Vector.h>
  36
  37 namespace JSC {
  38
  39     struct OffsetLocation {
  40         int32_t branchOffset;
  41 #if ENABLE(JIT)
  42         void* ctiOffset;
  43 #endif
  44     };
  45
  46     struct StringJumpTable {
  47         typedef HashMap<RefPtr<UString::Rep>, OffsetLocation> StringOffsetTable;
  48         StringOffsetTable offsetTable;
  49 #if ENABLE(JIT)
  50         void* ctiDefault; // FIXME: it should not be necessary to store this.
  51 #endif
  52
  53         inline int32_t offsetForValue(UString::Rep* value, int32_t defaultOffset)
  54         {
  55             StringOffsetTable::const_iterator end = offsetTable.end();
  56             StringOffsetTable::const_iterator loc = offsetTable.find(value);
  57             if (loc == end)
  58                 return defaultOffset;
  59             return loc->second.branchOffset;
  60         }
  61
  62 #if ENABLE(JIT)
  63         inline void* ctiForValue(UString::Rep* value)
  64         {
  65             StringOffsetTable::const_iterator end = offsetTable.end();
  66             StringOffsetTable::const_iterator loc = offsetTable.find(value);
  67             if (loc == end)
  68                 return ctiDefault;
  69             return loc->second.ctiOffset;
  70         }
  71 #endif
  72     };
  73
  74     struct SimpleJumpTable {
  75         // FIXME: The two Vectors can be combind into one Vector<OffsetLocation>
  76         Vector<int32_t> branchOffsets;
  77         int32_t min;
  78 #if ENABLE(JIT)
  79         Vector<void*> ctiOffsets;
  80         void* ctiDefault;
  81 #endif
  82
  83         int32_t offsetForValue(int32_t value, int32_t defaultOffset);
  84         void add(int32_t key, int32_t offset)
  85         {
  86             if (!branchOffsets[key])
  87                 branchOffsets[key] = offset;
  88         }
  89
  90 #if ENABLE(JIT)
  91         inline void* ctiForValue(int32_t value)
  92         {
  93             if (value >= min && static_cast<uint32_t>(value - min) < ctiOffsets.size())
  94                 return ctiOffsets[value - min];
  95             return ctiDefault;
  96         }
  97 #endif
  98     };
  99
 100 } // namespace JSC
 101
 102 #endif // JumpTable_h