// 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); // References to the array that stores basic block usage counters start out as // references to a unique oddball. Once the actual array has been allocated, // such entries in the constants map must be patched up. void PatchBasicBlockCountersReference(Handle<ByteArray> counters); // 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_