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// Copyright 2011 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_SCOPEINFO_H_
#define V8_SCOPEINFO_H_
#include "allocation.h"
#include "variables.h"
#include "zone-inl.h"
namespace v8 {
namespace internal {
// 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);
// Update an element in the cache.
void Update(Object* data,
String* name,
VariableMode mode,
InitializationFlag init_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(Object* data,
String* name,
VariableMode mode,
InitializationFlag init_flag,
int slot_index);
#endif
static const int kLength = 256;
struct Key {
Object* data;
String* name;
};
struct Value {
Value(VariableMode mode,
InitializationFlag init_flag,
int index) {
ASSERT(ModeField::is_valid(mode));
ASSERT(InitField::is_valid(init_flag));
ASSERT(IndexField::is_valid(index));
value_ = ModeField::encode(mode) |
IndexField::encode(index) |
InitField::encode(init_flag);
ASSERT(mode == this->mode());
ASSERT(init_flag == this->initialization_flag());
ASSERT(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_);
}
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, 3> {};
class InitField: public BitField<InitializationFlag, 3, 1> {};
class IndexField: public BitField<int, 4, 32-4> {};
private:
uint32_t value_;
};
Key keys_[kLength];
uint32_t values_[kLength];
friend class Isolate;
DISALLOW_COPY_AND_ASSIGN(ContextSlotCache);
};
} } // namespace v8::internal
#endif // V8_SCOPEINFO_H_
|
