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      1 /*
      2  * Copyright (C) 2008 Apple Inc. All rights reserved.
      3  * Copyright (C) 2008 Cameron Zwarich <cwzwarich (at) 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 "MacroAssembler.h"
     34 #include "UString.h"
     35 #include <wtf/HashMap.h>
     36 #include <wtf/Vector.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->second.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->second.ctiOffset;
     71         }
     72 #endif
     73     };
     74 
     75     struct SimpleJumpTable {
     76         // FIXME: The two Vectors can be combind into one Vector<OffsetLocation>
     77         Vector<int32_t> branchOffsets;
     78         int32_t min;
     79 #if ENABLE(JIT)
     80         Vector<CodeLocationLabel> ctiOffsets;
     81         CodeLocationLabel ctiDefault;
     82 #endif
     83 
     84         int32_t offsetForValue(int32_t value, int32_t defaultOffset);
     85         void add(int32_t key, int32_t offset)
     86         {
     87             if (!branchOffsets[key])
     88                 branchOffsets[key] = offset;
     89         }
     90 
     91 #if ENABLE(JIT)
     92         inline CodeLocationLabel ctiForValue(int32_t value)
     93         {
     94             if (value >= min && static_cast<uint32_t>(value - min) < ctiOffsets.size())
     95                 return ctiOffsets[value - min];
     96             return ctiDefault;
     97         }
     98 #endif
     99     };
    100 
    101 } // namespace JSC
    102 
    103 #endif // JumpTable_h
    104