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// Copyright 2018 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_BUILTINS_CONSTANTS_TABLE_BUILDER_H_
#define V8_BUILTINS_CONSTANTS_TABLE_BUILDER_H_
#include "src/base/macros.h"
#include "src/utils/allocation.h"
#include "src/utils/identity-map.h"
#include "src/handles/handles.h"
namespace v8 {
namespace internal {
class Isolate;
class Object;
// Utility class to build the builtins constants table and store it on the root
// list. The constants table contains constants used by builtins, and is there
// to avoid directly embedding them into code objects, which would not be
// possible for off-heap (and thus immutable) code objects.
class BuiltinsConstantsTableBuilder final {
public:
explicit BuiltinsConstantsTableBuilder(Isolate* isolate);
// Returns the index within the builtins constants table for the given
// object, possibly adding the object to the table. Objects are deduplicated.
uint32_t AddObject(Handle<Object> object);
// Self-references during code generation start out by referencing a handle
// with a temporary dummy object. Once the final Code object exists, such
// entries in the constants map must be patched up.
void PatchSelfReference(Handle<Object> self_reference,
Handle<Code> code_object);
// Should be called after all affected code (e.g. builtins and bytecode
// handlers) has been generated.
void Finalize();
private:
Isolate* isolate_;
// Maps objects to corresponding indices within the constants list.
using ConstantsMap = IdentityMap<uint32_t, FreeStoreAllocationPolicy>;
ConstantsMap map_;
DISALLOW_COPY_AND_ASSIGN(BuiltinsConstantsTableBuilder);
};
} // namespace internal
} // namespace v8
#endif // V8_BUILTINS_CONSTANTS_TABLE_BUILDER_H_
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