Move ContextSlotCache to its own file

src/ast/scopeinfo.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_AST_SCOPEINFO_H_
 #define V8_AST_SCOPEINFO_H_
 
 #include "src/allocation.h"
 #include "src/ast/modules.h"
 #include "src/ast/variables.h"
 
 namespace v8 {
 namespace internal {

[jochen (gone - plz use gerrit), 2016/08/01 11:00:51]

I kept this file around, because I'll put the actual ScopeInfo class decl here

 
-// Cache for mapping (data, property name) into context slot index.
-// The cache contains both positive and negative results.
-// Slot index equals -1 means the property is absent.
-// Cleared at startup and prior to mark sweep collection.
-class ContextSlotCache {
- public:
-  // Lookup context slot index for (data, name).
-  // If absent, kNotFound is returned.
-  int Lookup(Object* data, String* name, VariableMode* mode,
-             InitializationFlag* init_flag,
-             MaybeAssignedFlag* maybe_assigned_flag);
-
-  // Update an element in the cache.
-  void Update(Handle<Object> data, Handle<String> name, VariableMode mode,
-              InitializationFlag init_flag,
-              MaybeAssignedFlag maybe_assigned_flag, int slot_index);
-
-  // Clear the cache.
-  void Clear();
-
-  static const int kNotFound = -2;
-
- private:
-  ContextSlotCache() {
-    for (int i = 0; i < kLength; ++i) {
-      keys_[i].data = NULL;
-      keys_[i].name = NULL;
-      values_[i] = kNotFound;
-    }
-  }
-
-  inline static int Hash(Object* data, String* name);
-
-#ifdef DEBUG
-  void ValidateEntry(Handle<Object> data, Handle<String> name,
-                     VariableMode mode, InitializationFlag init_flag,
-                     MaybeAssignedFlag maybe_assigned_flag, int slot_index);
-#endif
-
-  static const int kLength = 256;
-  struct Key {
-    Object* data;
-    String* name;
-  };
-
-  struct Value {
-    Value(VariableMode mode, InitializationFlag init_flag,
-          MaybeAssignedFlag maybe_assigned_flag, int index) {
-      DCHECK(ModeField::is_valid(mode));
-      DCHECK(InitField::is_valid(init_flag));
-      DCHECK(MaybeAssignedField::is_valid(maybe_assigned_flag));
-      DCHECK(IndexField::is_valid(index));
-      value_ = ModeField::encode(mode) | IndexField::encode(index) |
-               InitField::encode(init_flag) |
-               MaybeAssignedField::encode(maybe_assigned_flag);
-      DCHECK(mode == this->mode());
-      DCHECK(init_flag == this->initialization_flag());
-      DCHECK(maybe_assigned_flag == this->maybe_assigned_flag());
-      DCHECK(index == this->index());
-    }
-
-    explicit inline Value(uint32_t value) : value_(value) {}
-
-    uint32_t raw() { return value_; }
-
-    VariableMode mode() { return ModeField::decode(value_); }
-
-    InitializationFlag initialization_flag() {
-      return InitField::decode(value_);
-    }
-
-    MaybeAssignedFlag maybe_assigned_flag() {
-      return MaybeAssignedField::decode(value_);
-    }
-
-    int index() { return IndexField::decode(value_); }
-
-    // Bit fields in value_ (type, shift, size). Must be public so the
-    // constants can be embedded in generated code.
-    class ModeField : public BitField<VariableMode, 0, 4> {};
-    class InitField : public BitField<InitializationFlag, 4, 1> {};
-    class MaybeAssignedField : public BitField<MaybeAssignedFlag, 5, 1> {};
-    class IndexField : public BitField<int, 6, 32 - 6> {};
-
-   private:
-    uint32_t value_;
-  };
-
-  Key keys_[kLength];
-  uint32_t values_[kLength];
-
-  friend class Isolate;
-  DISALLOW_COPY_AND_ASSIGN(ContextSlotCache);
-};
-
-
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_SCOPEINFO_H_