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 4 // met: 5 // 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. 15 // 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 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 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. 27 28 #ifndef V8_SCOPEINFO_H_ 29 #define V8_SCOPEINFO_H_ 30 31 #include "allocation.h" 32 #include "variables.h" 33 #include "zone-inl.h" 34 35 namespace v8 { 36 namespace internal { 37 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 { 43 public: 44 // Lookup context slot index for (data, name). 45 // If absent, kNotFound is returned. 46 int Lookup(Object* data, 47 String* name, 48 VariableMode* mode, 49 InitializationFlag* init_flag); 50 51 // Update an element in the cache. 52 void Update(Object* data, 53 String* name, 54 VariableMode mode, 55 InitializationFlag init_flag, 56 int slot_index); 57 58 // Clear the cache. 59 void Clear(); 60 61 static const int kNotFound = -2; 62 63 private: ContextSlotCache()64 ContextSlotCache() { 65 for (int i = 0; i < kLength; ++i) { 66 keys_[i].data = NULL; 67 keys_[i].name = NULL; 68 values_[i] = kNotFound; 69 } 70 } 71 72 inline static int Hash(Object* data, String* name); 73 74 #ifdef DEBUG 75 void ValidateEntry(Object* data, 76 String* name, 77 VariableMode mode, 78 InitializationFlag init_flag, 79 int slot_index); 80 #endif 81 82 static const int kLength = 256; 83 struct Key { 84 Object* data; 85 String* name; 86 }; 87 88 struct Value { ValueValue89 Value(VariableMode mode, 90 InitializationFlag init_flag, 91 int index) { 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()); 101 } 102 ValueValue103 explicit inline Value(uint32_t value) : value_(value) {} 104 rawValue105 uint32_t raw() { return value_; } 106 modeValue107 VariableMode mode() { return ModeField::decode(value_); } 108 initialization_flagValue109 InitializationFlag initialization_flag() { 110 return InitField::decode(value_); 111 } 112 indexValue113 int index() { return IndexField::decode(value_); } 114 115 // 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> {}; 120 121 private: 122 uint32_t value_; 123 }; 124 125 Key keys_[kLength]; 126 uint32_t values_[kLength]; 127 128 friend class Isolate; 129 DISALLOW_COPY_AND_ASSIGN(ContextSlotCache); 130 }; 131 132 133 } } // namespace v8::internal 134 135 #endif // V8_SCOPEINFO_H_ 136