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// 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_SCOPEINFO_H_
#define V8_SCOPEINFO_H_
#include "src/allocation.h"
#include "src/modules.h"
#include "src/variables.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,
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);
};
//---------------------------------------------------------------------------
// Auxiliary class used for the description of module instances.
// Used by Runtime_DeclareModules.
class ModuleInfo: public FixedArray {
public:
static ModuleInfo* cast(Object* description) {
return static_cast<ModuleInfo*>(FixedArray::cast(description));
}
static Handle<ModuleInfo> Create(Isolate* isolate,
ModuleDescriptor* descriptor, Scope* scope);
// Index of module's context in host context.
int host_index() { return Smi::cast(get(HOST_OFFSET))->value(); }
// Name, mode, and index of the i-th export, respectively.
// For value exports, the index is the slot of the value in the module
// context, for exported modules it is the slot index of the
// referred module's context in the host context.
// TODO(rossberg): This format cannot yet handle exports of modules declared
// in earlier scripts.
String* name(int i) { return String::cast(get(name_offset(i))); }
VariableMode mode(int i) {
return static_cast<VariableMode>(Smi::cast(get(mode_offset(i)))->value());
}
int index(int i) { return Smi::cast(get(index_offset(i)))->value(); }
int length() { return (FixedArray::length() - HEADER_SIZE) / ITEM_SIZE; }
private:
// The internal format is: Index, (Name, VariableMode, Index)*
enum {
HOST_OFFSET,
NAME_OFFSET,
MODE_OFFSET,
INDEX_OFFSET,
HEADER_SIZE = NAME_OFFSET,
ITEM_SIZE = INDEX_OFFSET - NAME_OFFSET + 1
};
inline int name_offset(int i) { return NAME_OFFSET + i * ITEM_SIZE; }
inline int mode_offset(int i) { return MODE_OFFSET + i * ITEM_SIZE; }
inline int index_offset(int i) { return INDEX_OFFSET + i * ITEM_SIZE; }
static Handle<ModuleInfo> Allocate(Isolate* isolate, int length) {
return Handle<ModuleInfo>::cast(
isolate->factory()->NewFixedArray(HEADER_SIZE + ITEM_SIZE * length));
}
void set_host_index(int index) { set(HOST_OFFSET, Smi::FromInt(index)); }
void set_name(int i, String* name) { set(name_offset(i), name); }
void set_mode(int i, VariableMode mode) {
set(mode_offset(i), Smi::FromInt(mode));
}
void set_index(int i, int index) {
set(index_offset(i), Smi::FromInt(index));
}
};
} // namespace internal
} // namespace v8
#endif // V8_SCOPEINFO_H_
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