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LibJS: Inline the ArrayBufferByteLength implementation

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Note: When we better support SharedArrayBuffer, that part of this AO
might not be inlined, as it looks a bit expensive.

On https://cyxx.github.io/another_js, this reduces the runtime of
IsValidIntegerIndex from 12.5% to 11.5%.
This commit is contained in:
Timothy Flynn 2024-02-27 09:19:58 -05:00 • committed by Andreas Kling
parent 9c943f36ed
commit 84936c9ab6
2 changed files with 16 additions and 17 deletions
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17
Userland/Libraries/LibJS/Runtime/ArrayBuffer.h
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@ -146,13 +146,28 @@ private:
ThrowCompletionOr<DataBlock> create_byte_data_block(VM& vm, size_t size);
void copy_data_block_bytes(ByteBuffer& to_block, u64 to_index, ByteBuffer const& from_block, u64 from_index, u64 count);
ThrowCompletionOr<ArrayBuffer*> allocate_array_buffer(VM&, FunctionObject& constructor, size_t byte_length, Optional<size_t> const& max_byte_length = {});
size_t array_buffer_byte_length(ArrayBuffer const&, ArrayBuffer::Order);
ThrowCompletionOr<void> detach_array_buffer(VM&, ArrayBuffer& array_buffer, Optional<Value> key = {});
ThrowCompletionOr<Optional<size_t>> get_array_buffer_max_byte_length_option(VM&, Value options);
ThrowCompletionOr<ArrayBuffer*> clone_array_buffer(VM&, ArrayBuffer& source_buffer, size_t source_byte_offset, size_t source_length);
ThrowCompletionOr<ArrayBuffer*> array_buffer_copy_and_detach(VM&, ArrayBuffer& array_buffer, Value new_length, PreserveResizability preserve_resizability);
ThrowCompletionOr<NonnullGCPtr<ArrayBuffer>> allocate_shared_array_buffer(VM&, FunctionObject& constructor, size_t byte_length);
// 25.1.3.2 ArrayBufferByteLength ( arrayBuffer, order ), https://tc39.es/ecma262/#sec-arraybufferbytelength
inline size_t array_buffer_byte_length(ArrayBuffer const& array_buffer, ArrayBuffer::Order)
{
// FIXME: 1. If IsSharedArrayBuffer(arrayBuffer) is true and arrayBuffer has an [[ArrayBufferByteLengthData]] internal slot, then
// FIXME: a. Let bufferByteLengthBlock be arrayBuffer.[[ArrayBufferByteLengthData]].
// FIXME: b. Let rawLength be GetRawBytesFromSharedBlock(bufferByteLengthBlock, 0, biguint64, true, order).
// FIXME: c. Let isLittleEndian be the value of the [[LittleEndian]] field of the surrounding agent's Agent Record.
// FIXME: d. Return ℝ(RawBytesToNumeric(biguint64, rawLength, isLittleEndian)).
// 2. Assert: IsDetachedBuffer(arrayBuffer) is false.
VERIFY(!array_buffer.is_detached());
// 3. Return arrayBuffer.[[ArrayBufferByteLength]].
return array_buffer.byte_length();
}
// 25.1.3.13 RawBytesToNumeric ( type, rawBytes, isLittleEndian ), https://tc39.es/ecma262/#sec-rawbytestonumeric
template<typename T>
static Value raw_bytes_to_numeric(VM& vm, Bytes raw_value, bool is_little_endian)