11aead3df7dafcdc8e86ce22c0041f6a06c57dc4
[WebKit-https.git] / Source / JavaScriptCore / bytecode / GetByIdStatus.cpp
1 /*
2  * Copyright (C) 2012 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  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
24  */
25
26 #include "config.h"
27 #include "GetByIdStatus.h"
28
29 #include "CodeBlock.h"
30 #include "LowLevelInterpreter.h"
31
32 namespace JSC {
33
34 GetByIdStatus GetByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned bytecodeIndex, Identifier& ident)
35 {
36     UNUSED_PARAM(profiledBlock);
37     UNUSED_PARAM(bytecodeIndex);
38     UNUSED_PARAM(ident);
39 #if ENABLE(LLINT)
40     Instruction* instruction = profiledBlock->instructions().begin() + bytecodeIndex;
41     
42     if (instruction[0].u.opcode == llint_op_method_check)
43         instruction++;
44
45     Structure* structure = instruction[4].u.structure.get();
46     if (!structure)
47         return GetByIdStatus(NoInformation, StructureSet(), notFound, false);
48     
49     size_t offset = structure->get(*profiledBlock->globalData(), ident);
50     if (offset == notFound)
51         return GetByIdStatus(NoInformation, StructureSet(), notFound, false);
52     
53     return GetByIdStatus(SimpleDirect, StructureSet(structure), offset, false);
54 #else
55     return GetByIdStatus(NoInformation, StructureSet(), notFound, false);
56 #endif
57 }
58
59 GetByIdStatus GetByIdStatus::computeFor(CodeBlock* profiledBlock, unsigned bytecodeIndex, Identifier& ident)
60 {
61     UNUSED_PARAM(profiledBlock);
62     UNUSED_PARAM(bytecodeIndex);
63     UNUSED_PARAM(ident);
64 #if ENABLE(JIT) && ENABLE(VALUE_PROFILER)
65     if (!profiledBlock->numberOfStructureStubInfos())
66         return computeFromLLInt(profiledBlock, bytecodeIndex, ident);
67     
68     // First check if it makes either calls, in which case we want to be super careful, or
69     // if it's not set at all, in which case we punt.
70     StructureStubInfo& stubInfo = profiledBlock->getStubInfo(bytecodeIndex);
71     if (!stubInfo.seen)
72         return computeFromLLInt(profiledBlock, bytecodeIndex, ident);
73     
74     PolymorphicAccessStructureList* list;
75     int listSize;
76     switch (stubInfo.accessType) {
77     case access_get_by_id_self_list:
78         list = stubInfo.u.getByIdSelfList.structureList;
79         listSize = stubInfo.u.getByIdSelfList.listSize;
80         break;
81     case access_get_by_id_proto_list:
82         list = stubInfo.u.getByIdProtoList.structureList;
83         listSize = stubInfo.u.getByIdProtoList.listSize;
84         break;
85     default:
86         list = 0;
87         listSize = 0;
88         break;
89     }
90     for (int i = 0; i < listSize; ++i) {
91         if (!list->list[i].isDirect)
92             return GetByIdStatus(MakesCalls, StructureSet(), notFound, true);
93     }
94     
95     // Next check if it takes slow case, in which case we want to be kind of careful.
96     if (profiledBlock->likelyToTakeSlowCase(bytecodeIndex))
97         return GetByIdStatus(TakesSlowPath, StructureSet(), notFound, true);
98     
99     // Finally figure out if we can derive an access strategy.
100     GetByIdStatus result;
101     result.m_wasSeenInJIT = true;
102     switch (stubInfo.accessType) {
103     case access_unset:
104         return computeFromLLInt(profiledBlock, bytecodeIndex, ident);
105         
106     case access_get_by_id_self: {
107         Structure* structure = stubInfo.u.getByIdSelf.baseObjectStructure.get();
108         result.m_offset = structure->get(*profiledBlock->globalData(), ident);
109         
110         if (result.m_offset != notFound)
111             result.m_structureSet.add(structure);
112         
113         if (result.m_offset != notFound)
114             ASSERT(result.m_structureSet.size());
115         break;
116     }
117         
118     case access_get_by_id_self_list: {
119         PolymorphicAccessStructureList* list = stubInfo.u.getByIdProtoList.structureList;
120         unsigned size = stubInfo.u.getByIdProtoList.listSize;
121         for (unsigned i = 0; i < size; ++i) {
122             ASSERT(list->list[i].isDirect);
123             
124             Structure* structure = list->list[i].base.get();
125             if (result.m_structureSet.contains(structure))
126                 continue;
127             
128             size_t myOffset = structure->get(*profiledBlock->globalData(), ident);
129             
130             if (myOffset == notFound) {
131                 result.m_offset = notFound;
132                 break;
133             }
134                     
135             if (!i)
136                 result.m_offset = myOffset;
137             else if (result.m_offset != myOffset) {
138                 result.m_offset = notFound;
139                 break;
140             }
141                     
142             result.m_structureSet.add(structure);
143         }
144                     
145         if (result.m_offset != notFound)
146             ASSERT(result.m_structureSet.size());
147         break;
148     }
149         
150     default:
151         ASSERT(result.m_offset == notFound);
152         break;
153     }
154     
155     if (result.m_offset == notFound) {
156         result.m_state = TakesSlowPath;
157         result.m_structureSet.clear();
158     } else
159         result.m_state = SimpleDirect;
160     
161     return result;
162 #else // ENABLE(JIT)
163     return GetByIdStatus(NoInformation, StructureSet(), notFound, false);
164 #endif // ENABLE(JIT)
165 }
166
167 } // namespace JSC
168