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 "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 
offsetForValueStringJumpTable54         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)
ctiForValueStringJumpTable64         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);
addSimpleJumpTable85         void add(int32_t key, int32_t offset)
86         {
87             if (!branchOffsets[key])
88                 branchOffsets[key] = offset;
89         }
90 
91 #if ENABLE(JIT)
ctiForValueSimpleJumpTable92         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