3c74dc9f4d
This patch adds two macros to declare per-type allocators: - JS_DECLARE_ALLOCATOR(TypeName) - JS_DEFINE_ALLOCATOR(TypeName) When used, they add a type-specific CellAllocator that the Heap will delegate allocation requests to. The result of this is that GC objects of the same type always end up within the same HeapBlock, drastically reducing the ability to perform type confusion attacks. It also improves HeapBlock utilization, since each block now has cells sized exactly to the type used within that block. (Previously we only had a handful of block sizes available, and most GC allocations ended up with a large amount of slack in their tails.) There is a small performance hit from this, but I'm sure we can make up for it elsewhere. Note that the old size-based allocators still exist, and we fall back to them for any type that doesn't have its own CellAllocator.
101 lines
3.2 KiB
C++
101 lines
3.2 KiB
C++
/*
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* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibJS/Runtime/Completion.h>
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#include <LibJS/Runtime/ECMAScriptFunctionObject.h>
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#include <LibJS/Runtime/FunctionEnvironment.h>
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#include <LibJS/Runtime/GlobalObject.h>
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namespace JS {
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JS_DEFINE_ALLOCATOR(FunctionEnvironment);
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FunctionEnvironment::FunctionEnvironment(Environment* parent_environment)
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: DeclarativeEnvironment(parent_environment)
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{
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}
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void FunctionEnvironment::visit_edges(Visitor& visitor)
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{
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Base::visit_edges(visitor);
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visitor.visit(m_this_value);
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visitor.visit(m_new_target);
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visitor.visit(m_function_object);
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}
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// 9.1.1.3.5 GetSuperBase ( ), https://tc39.es/ecma262/#sec-getsuperbase
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ThrowCompletionOr<Value> FunctionEnvironment::get_super_base() const
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{
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VERIFY(m_function_object);
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// 1. Let home be envRec.[[FunctionObject]].[[HomeObject]].
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auto home_object = m_function_object->home_object();
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// 2. If home is undefined, return undefined.
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if (!home_object)
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return js_undefined();
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// 3. Assert: Type(home) is Object.
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// 4. Return ? home.[[GetPrototypeOf]]().
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return TRY(home_object->internal_get_prototype_of());
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}
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// 9.1.1.3.2 HasThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hasthisbinding
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bool FunctionEnvironment::has_this_binding() const
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{
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if (this_binding_status() == ThisBindingStatus::Lexical)
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return false;
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return true;
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}
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// 9.1.1.3.3 HasSuperBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hassuperbinding
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bool FunctionEnvironment::has_super_binding() const
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{
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if (this_binding_status() == ThisBindingStatus::Lexical)
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return false;
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if (!function_object().home_object())
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return false;
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return true;
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}
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// 9.1.1.3.4 GetThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-getthisbinding
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ThrowCompletionOr<Value> FunctionEnvironment::get_this_binding(VM& vm) const
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{
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// 1. Assert: envRec.[[ThisBindingStatus]] is not lexical.
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VERIFY(m_this_binding_status != ThisBindingStatus::Lexical);
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// 2. If envRec.[[ThisBindingStatus]] is uninitialized, throw a ReferenceError exception.
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if (m_this_binding_status == ThisBindingStatus::Uninitialized)
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return vm.throw_completion<ReferenceError>(ErrorType::ThisHasNotBeenInitialized);
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// 3. Return envRec.[[ThisValue]].
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return m_this_value;
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}
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// 9.1.1.3.1 BindThisValue ( V ), https://tc39.es/ecma262/#sec-bindthisvalue
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ThrowCompletionOr<Value> FunctionEnvironment::bind_this_value(VM& vm, Value this_value)
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{
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VERIFY(!this_value.is_empty());
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// 1. Assert: envRec.[[ThisBindingStatus]] is not lexical.
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VERIFY(m_this_binding_status != ThisBindingStatus::Lexical);
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// 2. If envRec.[[ThisBindingStatus]] is initialized, throw a ReferenceError exception.
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if (m_this_binding_status == ThisBindingStatus::Initialized)
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return vm.throw_completion<ReferenceError>(ErrorType::ThisIsAlreadyInitialized);
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// 3. Set envRec.[[ThisValue]] to V.
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m_this_value = this_value;
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// 4. Set envRec.[[ThisBindingStatus]] to initialized.
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m_this_binding_status = ThisBindingStatus::Initialized;
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// 5. Return V.
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return this_value;
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}
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}
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