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.
63 lines
2.2 KiB
C++
63 lines
2.2 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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#pragma once
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#include <LibJS/Runtime/Completion.h>
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#include <LibJS/Runtime/DeclarativeEnvironment.h>
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namespace JS {
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class FunctionEnvironment final : public DeclarativeEnvironment {
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JS_ENVIRONMENT(FunctionEnvironment, DeclarativeEnvironment);
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JS_DECLARE_ALLOCATOR(FunctionEnvironment);
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public:
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enum class ThisBindingStatus : u8 {
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Lexical,
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Initialized,
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Uninitialized,
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};
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virtual ~FunctionEnvironment() override = default;
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ThisBindingStatus this_binding_status() const { return m_this_binding_status; }
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void set_this_binding_status(ThisBindingStatus status) { m_this_binding_status = status; }
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ECMAScriptFunctionObject& function_object() { return *m_function_object; }
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ECMAScriptFunctionObject const& function_object() const { return *m_function_object; }
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void set_function_object(ECMAScriptFunctionObject& function) { m_function_object = &function; }
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Value new_target() const { return m_new_target; }
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void set_new_target(Value new_target)
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{
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VERIFY(!new_target.is_empty());
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m_new_target = new_target;
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}
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// Abstract operations
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ThrowCompletionOr<Value> get_super_base() const;
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bool has_super_binding() const;
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virtual bool has_this_binding() const override;
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virtual ThrowCompletionOr<Value> get_this_binding(VM&) const override;
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ThrowCompletionOr<Value> bind_this_value(VM&, Value);
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private:
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explicit FunctionEnvironment(Environment* parent_environment);
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virtual bool is_function_environment() const override { return true; }
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virtual void visit_edges(Visitor&) override;
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Value m_this_value; // [[ThisValue]]
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ThisBindingStatus m_this_binding_status { ThisBindingStatus::Uninitialized }; // [[ThisBindingStatus]]
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GCPtr<ECMAScriptFunctionObject> m_function_object; // [[FunctionObject]]
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Value m_new_target { js_undefined() }; // [[NewTarget]]
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};
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template<>
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inline bool Environment::fast_is<FunctionEnvironment>() const { return is_function_environment(); }
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}
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