bytecode/JumpTable.h

   1 /*
   2  * Copyright (C) 2008, 2013 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 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 "MacroAssembler.h"
  34 #include <wtf/HashMap.h>
  35 #include <wtf/Vector.h>
  36 #include <wtf/text/StringImpl.h>
  37
  38 namespace JSC {
  39
  40     struct OffsetLocation {
  41         int32_t branchOffset;
  42 #if ENABLE(JIT)
  43         CodeLocationLabel ctiOffset;
  44 #endif
  45     };
  46
  47     struct StringJumpTable {
  48         typedef HashMap<RefPtr<StringImpl>, OffsetLocation> StringOffsetTable;
  49         StringOffsetTable offsetTable;
  50 #if ENABLE(JIT)
  51         CodeLocationLabel ctiDefault; // FIXME: it should not be necessary to store this.
  52 #endif
  53
  54         inline int32_t offsetForValue(StringImpl* value, int32_t defaultOffset)
  55         {
  56             StringOffsetTable::const_iterator end = offsetTable.end();
  57             StringOffsetTable::const_iterator loc = offsetTable.find(value);
  58             if (loc == end)
  59                 return defaultOffset;
  60             return loc->value.branchOffset;
  61         }
  62
  63 #if ENABLE(JIT)
  64         inline CodeLocationLabel ctiForValue(StringImpl* value)
  65         {
  66             StringOffsetTable::const_iterator end = offsetTable.end();
  67             StringOffsetTable::const_iterator loc = offsetTable.find(value);
  68             if (loc == end)
  69                 return ctiDefault;
  70             return loc->value.ctiOffset;
  71         }
  72 #endif
  73
  74         void clear()
  75         {
  76             offsetTable.clear();
  77         }
  78     };
  79
  80     struct SimpleJumpTable {
  81         // FIXME: The two Vectors can be combind into one Vector<OffsetLocation>
  82         Vector<int32_t> branchOffsets;
  83         int32_t min;
  84 #if ENABLE(JIT)
  85         Vector<CodeLocationLabel> ctiOffsets;
  86         CodeLocationLabel ctiDefault;
  87 #endif
  88
  89         int32_t offsetForValue(int32_t value, int32_t defaultOffset);
  90         void add(int32_t key, int32_t offset)
  91         {
  92             if (!branchOffsets[key])
  93                 branchOffsets[key] = offset;
  94         }
  95
  96 #if ENABLE(JIT)
  97         void ensureCTITable()
  98         {
  99             ASSERT(ctiOffsets.isEmpty() || ctiOffsets.size() == branchOffsets.size());
 100             ctiOffsets.grow(branchOffsets.size());
 101         }
 102
 103         inline CodeLocationLabel ctiForValue(int32_t value)
 104         {
 105             if (value >= min && static_cast<uint32_t>(value - min) < ctiOffsets.size())
 106                 return ctiOffsets[value - min];
 107             return ctiDefault;
 108         }
 109 #endif
 110
 111         void clear()
 112         {
 113             branchOffsets.clear();
 114 #if ENABLE(JIT)
 115             ctiOffsets.clear();
 116 #endif
 117         }
 118     };
 119
 120 } // namespace JSC
 121
 122 #endif // JumpTable_h