1 // Copyright 2011 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are
6 // * Redistributions of source code must retain the above copyright
7 // notice, this list of conditions and the following disclaimer.
8 // * Redistributions in binary form must reproduce the above
9 // copyright notice, this list of conditions and the following
10 // disclaimer in the documentation and/or other materials provided
11 // with the distribution.
12 // * Neither the name of Google Inc. nor the names of its
13 // contributors may be used to endorse or promote products derived
14 // from this software without specific prior written permission.
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #ifndef V8_SCOPEINFO_H_
29 #define V8_SCOPEINFO_H_
31 #include "allocation.h"
32 #include "variables.h"
38 // Cache for mapping (data, property name) into context slot index.
39 // The cache contains both positive and negative results.
40 // Slot index equals -1 means the property is absent.
41 // Cleared at startup and prior to mark sweep collection.
42 class ContextSlotCache {
44 // Lookup context slot index for (data, name).
45 // If absent, kNotFound is returned.
46 int Lookup(Object* data,
49 InitializationFlag* init_flag);
51 // Update an element in the cache.
52 void Update(Object* data,
55 InitializationFlag init_flag,
61 static const int kNotFound = -2;
65 for (int i = 0; i < kLength; ++i) {
68 values_[i] = kNotFound;
72 inline static int Hash(Object* data, String* name);
75 void ValidateEntry(Object* data,
78 InitializationFlag init_flag,
82 static const int kLength = 256;
89 Value(VariableMode mode,
90 InitializationFlag init_flag,
92 ASSERT(ModeField::is_valid(mode));
93 ASSERT(InitField::is_valid(init_flag));
94 ASSERT(IndexField::is_valid(index));
95 value_ = ModeField::encode(mode) |
96 IndexField::encode(index) |
97 InitField::encode(init_flag);
98 ASSERT(mode == this->mode());
99 ASSERT(init_flag == this->initialization_flag());
100 ASSERT(index == this->index());
103 explicit inline Value(uint32_t value) : value_(value) {}
105 uint32_t raw() { return value_; }
107 VariableMode mode() { return ModeField::decode(value_); }
109 InitializationFlag initialization_flag() {
110 return InitField::decode(value_);
113 int index() { return IndexField::decode(value_); }
115 // Bit fields in value_ (type, shift, size). Must be public so the
116 // constants can be embedded in generated code.
117 class ModeField: public BitField<VariableMode, 0, 3> {};
118 class InitField: public BitField<InitializationFlag, 3, 1> {};
119 class IndexField: public BitField<int, 4, 32-4> {};
126 uint32_t values_[kLength];
128 friend class Isolate;
129 DISALLOW_COPY_AND_ASSIGN(ContextSlotCache);
133 } } // namespace v8::internal
135 #endif // V8_SCOPEINFO_H_