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.
75 lines
2.7 KiB
C++
75 lines
2.7 KiB
C++
/*
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* Copyright (c) 2023, Shannon Booth <shannon@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 <AK/TypeCasts.h>
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#include <LibJS/Forward.h>
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#include <LibJS/Runtime/ArrayBuffer.h>
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#include <LibJS/Runtime/Error.h>
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#include <LibJS/Runtime/GlobalObject.h>
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#include <LibJS/Runtime/SharedArrayBufferConstructor.h>
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#include <LibJS/Runtime/TypedArray.h>
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namespace JS {
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JS_DEFINE_ALLOCATOR(SharedArrayBufferConstructor);
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SharedArrayBufferConstructor::SharedArrayBufferConstructor(Realm& realm)
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: NativeFunction(realm.vm().names.SharedArrayBuffer.as_string(), realm.intrinsics().function_prototype())
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{
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}
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void SharedArrayBufferConstructor::initialize(Realm& realm)
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{
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auto& vm = this->vm();
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Base::initialize(realm);
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// 25.2.4.2 SharedArrayBuffer.prototype, https://tc39.es/ecma262/#sec-sharedarraybuffer.prototype
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define_direct_property(vm.names.prototype, realm.intrinsics().shared_array_buffer_prototype(), 0);
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// 25.2.4.4 SharedArrayBuffer.prototype [ @@toStringTag ], https://tc39.es/ecma262/#sec-sharedarraybuffer.prototype.toString
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define_native_accessor(realm, vm.well_known_symbol_species(), symbol_species_getter, {}, Attribute::Configurable);
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define_direct_property(vm.names.length, Value(1), Attribute::Configurable);
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}
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// 25.2.2.1 SharedArrayBuffer ( length ), https://tc39.es/ecma262/#sec-sharedarraybuffer-length
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ThrowCompletionOr<Value> SharedArrayBufferConstructor::call()
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{
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auto& vm = this->vm();
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// 1. If NewTarget is undefined, throw a TypeError exception.
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return vm.throw_completion<TypeError>(ErrorType::ConstructorWithoutNew, vm.names.SharedArrayBuffer);
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}
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// 25.2.2.1 SharedArrayBuffer ( length ), https://tc39.es/ecma262/#sec-sharedarraybuffer-length
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ThrowCompletionOr<NonnullGCPtr<Object>> SharedArrayBufferConstructor::construct(FunctionObject& new_target)
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{
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auto& vm = this->vm();
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// 2. Let byteLength be ? ToIndex(length).
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auto byte_length_or_error = vm.argument(0).to_index(vm);
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if (byte_length_or_error.is_error()) {
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auto error = byte_length_or_error.release_error();
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if (error.value()->is_object() && is<RangeError>(error.value()->as_object())) {
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// Re-throw more specific RangeError
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return vm.throw_completion<RangeError>(ErrorType::InvalidLength, "shared array buffer");
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}
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return error;
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}
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// 3. Return ? AllocateSharedArrayBuffer(NewTarget, byteLength).
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return *TRY(allocate_shared_array_buffer(vm, new_target, byte_length_or_error.release_value()));
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}
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// 25.2.3.2 get SharedArrayBuffer [ @@species ], https://tc39.es/ecma262/#sec-sharedarraybuffer-@@species
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JS_DEFINE_NATIVE_FUNCTION(SharedArrayBufferConstructor::symbol_species_getter)
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{
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// 1. Return the this value.
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return vm.this_value();
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}
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}
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