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.
56 lines
1.6 KiB
C++
56 lines
1.6 KiB
C++
/*
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* Copyright (c) 2021, David Tuin <davidot@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/PrivateEnvironment.h>
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namespace JS {
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JS_DEFINE_ALLOCATOR(PrivateEnvironment);
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PrivateEnvironment::PrivateEnvironment(PrivateEnvironment* parent)
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: m_outer_environment(parent)
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, m_unique_id(s_next_id++)
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{
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// FIXME: We might want to delay getting the next unique id until required.
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VERIFY(s_next_id != 0);
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}
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// Note: we start at one such that 0 can be invalid / default initialized.
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u64 PrivateEnvironment::s_next_id = 1u;
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PrivateName PrivateEnvironment::resolve_private_identifier(DeprecatedFlyString const& identifier) const
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{
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auto name_or_end = find_private_name(identifier);
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if (!name_or_end.is_end())
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return *name_or_end;
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// Note: This verify ensures that we must either have a private name with a matching description
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// or have an outer environment. Combined this means that we assert that we always return a PrivateName.
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VERIFY(m_outer_environment);
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return m_outer_environment->resolve_private_identifier(identifier);
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}
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void PrivateEnvironment::add_private_name(Badge<ClassExpression>, DeprecatedFlyString description)
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{
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if (!find_private_name(description).is_end())
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return;
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m_private_names.empend(m_unique_id, move(description));
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}
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bool PrivateName::operator==(PrivateName const& rhs) const
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{
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return unique_id == rhs.unique_id && description == rhs.description;
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}
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void PrivateEnvironment::visit_edges(Visitor& visitor)
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{
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Base::visit_edges(visitor);
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visitor.visit(m_outer_environment);
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}
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}
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