Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 1 | // Copyright 2011 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #ifndef V8_AST_SCOPEINFO_H_ |
| 6 | #define V8_AST_SCOPEINFO_H_ |
| 7 | |
| 8 | #include "src/allocation.h" |
| 9 | #include "src/ast/modules.h" |
| 10 | #include "src/ast/variables.h" |
| 11 | |
| 12 | namespace v8 { |
| 13 | namespace internal { |
| 14 | |
| 15 | // Cache for mapping (data, property name) into context slot index. |
| 16 | // The cache contains both positive and negative results. |
| 17 | // Slot index equals -1 means the property is absent. |
| 18 | // Cleared at startup and prior to mark sweep collection. |
| 19 | class ContextSlotCache { |
| 20 | public: |
| 21 | // Lookup context slot index for (data, name). |
| 22 | // If absent, kNotFound is returned. |
| 23 | int Lookup(Object* data, String* name, VariableMode* mode, |
| 24 | InitializationFlag* init_flag, |
| 25 | MaybeAssignedFlag* maybe_assigned_flag); |
| 26 | |
| 27 | // Update an element in the cache. |
| 28 | void Update(Handle<Object> data, Handle<String> name, VariableMode mode, |
| 29 | InitializationFlag init_flag, |
| 30 | MaybeAssignedFlag maybe_assigned_flag, int slot_index); |
| 31 | |
| 32 | // Clear the cache. |
| 33 | void Clear(); |
| 34 | |
| 35 | static const int kNotFound = -2; |
| 36 | |
| 37 | private: |
| 38 | ContextSlotCache() { |
| 39 | for (int i = 0; i < kLength; ++i) { |
| 40 | keys_[i].data = NULL; |
| 41 | keys_[i].name = NULL; |
| 42 | values_[i] = kNotFound; |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | inline static int Hash(Object* data, String* name); |
| 47 | |
| 48 | #ifdef DEBUG |
| 49 | void ValidateEntry(Handle<Object> data, Handle<String> name, |
| 50 | VariableMode mode, InitializationFlag init_flag, |
| 51 | MaybeAssignedFlag maybe_assigned_flag, int slot_index); |
| 52 | #endif |
| 53 | |
| 54 | static const int kLength = 256; |
| 55 | struct Key { |
| 56 | Object* data; |
| 57 | String* name; |
| 58 | }; |
| 59 | |
| 60 | struct Value { |
| 61 | Value(VariableMode mode, InitializationFlag init_flag, |
| 62 | MaybeAssignedFlag maybe_assigned_flag, int index) { |
| 63 | DCHECK(ModeField::is_valid(mode)); |
| 64 | DCHECK(InitField::is_valid(init_flag)); |
| 65 | DCHECK(MaybeAssignedField::is_valid(maybe_assigned_flag)); |
| 66 | DCHECK(IndexField::is_valid(index)); |
| 67 | value_ = ModeField::encode(mode) | IndexField::encode(index) | |
| 68 | InitField::encode(init_flag) | |
| 69 | MaybeAssignedField::encode(maybe_assigned_flag); |
| 70 | DCHECK(mode == this->mode()); |
| 71 | DCHECK(init_flag == this->initialization_flag()); |
| 72 | DCHECK(maybe_assigned_flag == this->maybe_assigned_flag()); |
| 73 | DCHECK(index == this->index()); |
| 74 | } |
| 75 | |
| 76 | explicit inline Value(uint32_t value) : value_(value) {} |
| 77 | |
| 78 | uint32_t raw() { return value_; } |
| 79 | |
| 80 | VariableMode mode() { return ModeField::decode(value_); } |
| 81 | |
| 82 | InitializationFlag initialization_flag() { |
| 83 | return InitField::decode(value_); |
| 84 | } |
| 85 | |
| 86 | MaybeAssignedFlag maybe_assigned_flag() { |
| 87 | return MaybeAssignedField::decode(value_); |
| 88 | } |
| 89 | |
| 90 | int index() { return IndexField::decode(value_); } |
| 91 | |
| 92 | // Bit fields in value_ (type, shift, size). Must be public so the |
| 93 | // constants can be embedded in generated code. |
| 94 | class ModeField : public BitField<VariableMode, 0, 4> {}; |
| 95 | class InitField : public BitField<InitializationFlag, 4, 1> {}; |
| 96 | class MaybeAssignedField : public BitField<MaybeAssignedFlag, 5, 1> {}; |
| 97 | class IndexField : public BitField<int, 6, 32 - 6> {}; |
| 98 | |
| 99 | private: |
| 100 | uint32_t value_; |
| 101 | }; |
| 102 | |
| 103 | Key keys_[kLength]; |
| 104 | uint32_t values_[kLength]; |
| 105 | |
| 106 | friend class Isolate; |
| 107 | DISALLOW_COPY_AND_ASSIGN(ContextSlotCache); |
| 108 | }; |
| 109 | |
| 110 | |
| 111 | |
| 112 | |
| 113 | //--------------------------------------------------------------------------- |
| 114 | // Auxiliary class used for the description of module instances. |
| 115 | // Used by Runtime_DeclareModules. |
| 116 | |
| 117 | class ModuleInfo: public FixedArray { |
| 118 | public: |
| 119 | static ModuleInfo* cast(Object* description) { |
| 120 | return static_cast<ModuleInfo*>(FixedArray::cast(description)); |
| 121 | } |
| 122 | |
| 123 | static Handle<ModuleInfo> Create(Isolate* isolate, |
| 124 | ModuleDescriptor* descriptor, Scope* scope); |
| 125 | |
| 126 | // Index of module's context in host context. |
| 127 | int host_index() { return Smi::cast(get(HOST_OFFSET))->value(); } |
| 128 | |
| 129 | // Name, mode, and index of the i-th export, respectively. |
| 130 | // For value exports, the index is the slot of the value in the module |
| 131 | // context, for exported modules it is the slot index of the |
| 132 | // referred module's context in the host context. |
| 133 | // TODO(rossberg): This format cannot yet handle exports of modules declared |
| 134 | // in earlier scripts. |
| 135 | String* name(int i) { return String::cast(get(name_offset(i))); } |
| 136 | VariableMode mode(int i) { |
| 137 | return static_cast<VariableMode>(Smi::cast(get(mode_offset(i)))->value()); |
| 138 | } |
| 139 | int index(int i) { return Smi::cast(get(index_offset(i)))->value(); } |
| 140 | |
| 141 | int length() { return (FixedArray::length() - HEADER_SIZE) / ITEM_SIZE; } |
| 142 | |
| 143 | private: |
| 144 | // The internal format is: Index, (Name, VariableMode, Index)* |
| 145 | enum { |
| 146 | HOST_OFFSET, |
| 147 | NAME_OFFSET, |
| 148 | MODE_OFFSET, |
| 149 | INDEX_OFFSET, |
| 150 | HEADER_SIZE = NAME_OFFSET, |
| 151 | ITEM_SIZE = INDEX_OFFSET - NAME_OFFSET + 1 |
| 152 | }; |
| 153 | inline int name_offset(int i) { return NAME_OFFSET + i * ITEM_SIZE; } |
| 154 | inline int mode_offset(int i) { return MODE_OFFSET + i * ITEM_SIZE; } |
| 155 | inline int index_offset(int i) { return INDEX_OFFSET + i * ITEM_SIZE; } |
| 156 | |
| 157 | static Handle<ModuleInfo> Allocate(Isolate* isolate, int length) { |
| 158 | return Handle<ModuleInfo>::cast( |
| 159 | isolate->factory()->NewFixedArray(HEADER_SIZE + ITEM_SIZE * length)); |
| 160 | } |
| 161 | void set_host_index(int index) { set(HOST_OFFSET, Smi::FromInt(index)); } |
| 162 | void set_name(int i, String* name) { set(name_offset(i), name); } |
| 163 | void set_mode(int i, VariableMode mode) { |
| 164 | set(mode_offset(i), Smi::FromInt(mode)); |
| 165 | } |
| 166 | void set_index(int i, int index) { |
| 167 | set(index_offset(i), Smi::FromInt(index)); |
| 168 | } |
| 169 | }; |
| 170 | |
| 171 | |
| 172 | } // namespace internal |
| 173 | } // namespace v8 |
| 174 | |
| 175 | #endif // V8_AST_SCOPEINFO_H_ |