Line data Source code
1 : // Copyright 2016 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_CONTEXT_SLOT_CACHE_H_
6 : #define V8_AST_CONTEXT_SLOT_CACHE_H_
7 :
8 : #include "src/allocation.h"
9 : #include "src/ast/modules.h"
10 :
11 : namespace v8 {
12 : namespace internal {
13 :
14 : // Cache for mapping (data, property name) into context slot index.
15 : // The cache contains both positive and negative results.
16 : // Slot index equals -1 means the property is absent.
17 : // Cleared at startup and prior to mark sweep collection.
18 : class ContextSlotCache {
19 : public:
20 : // Lookup context slot index for (data, name).
21 : // If absent, kNotFound is returned.
22 : int Lookup(Object* data, String* name, VariableMode* mode,
23 : InitializationFlag* init_flag,
24 : MaybeAssignedFlag* maybe_assigned_flag);
25 :
26 : // Update an element in the cache.
27 : void Update(Handle<Object> data, Handle<String> name, VariableMode mode,
28 : InitializationFlag init_flag,
29 : MaybeAssignedFlag maybe_assigned_flag, int slot_index);
30 :
31 : // Clear the cache.
32 : void Clear();
33 :
34 : static const int kNotFound = -2;
35 :
36 : private:
37 : ContextSlotCache() {
38 15560192 : for (int i = 0; i < kLength; ++i) {
39 15560192 : keys_[i].data = NULL;
40 15560192 : keys_[i].name = NULL;
41 15560192 : values_[i] = static_cast<uint32_t>(kNotFound);
42 : }
43 : }
44 :
45 : inline static int Hash(Object* data, String* name);
46 :
47 : #ifdef DEBUG
48 : void ValidateEntry(Handle<Object> data, Handle<String> name,
49 : VariableMode mode, InitializationFlag init_flag,
50 : MaybeAssignedFlag maybe_assigned_flag, int slot_index);
51 : #endif
52 :
53 : static const int kLength = 256;
54 : struct Key {
55 : Object* data;
56 : String* name;
57 : };
58 :
59 : struct Value {
60 : Value(VariableMode mode, InitializationFlag init_flag,
61 : MaybeAssignedFlag maybe_assigned_flag, int index) {
62 : DCHECK(ModeField::is_valid(mode));
63 : DCHECK(InitField::is_valid(init_flag));
64 : DCHECK(MaybeAssignedField::is_valid(maybe_assigned_flag));
65 : DCHECK(IndexField::is_valid(index));
66 8525638 : value_ = ModeField::encode(mode) | IndexField::encode(index) |
67 4262819 : InitField::encode(init_flag) |
68 : MaybeAssignedField::encode(maybe_assigned_flag);
69 : DCHECK(mode == this->mode());
70 : DCHECK(init_flag == this->initialization_flag());
71 : DCHECK(maybe_assigned_flag == this->maybe_assigned_flag());
72 : DCHECK(index == this->index());
73 : }
74 :
75 : explicit inline Value(uint32_t value) : value_(value) {}
76 :
77 : uint32_t raw() { return value_; }
78 :
79 : VariableMode mode() { return ModeField::decode(value_); }
80 :
81 : InitializationFlag initialization_flag() {
82 : return InitField::decode(value_);
83 : }
84 :
85 : MaybeAssignedFlag maybe_assigned_flag() {
86 : return MaybeAssignedField::decode(value_);
87 : }
88 :
89 : int index() { return IndexField::decode(value_); }
90 :
91 : // Bit fields in value_ (type, shift, size). Must be public so the
92 : // constants can be embedded in generated code.
93 : class ModeField : public BitField<VariableMode, 0, 4> {};
94 : class InitField : public BitField<InitializationFlag, 4, 1> {};
95 : class MaybeAssignedField : public BitField<MaybeAssignedFlag, 5, 1> {};
96 : class IndexField : public BitField<int, 6, 32 - 6> {};
97 :
98 : private:
99 : uint32_t value_;
100 : };
101 :
102 : Key keys_[kLength];
103 : uint32_t values_[kLength];
104 :
105 : friend class Isolate;
106 : DISALLOW_COPY_AND_ASSIGN(ContextSlotCache);
107 : };
108 :
109 : } // namespace internal
110 : } // namespace v8
111 :
112 : #endif // V8_AST_CONTEXT_SLOT_CACHE_H_
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