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LibJS: Avoid ByteBuffer copying in RawBytesToNumeric

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4% speed-up on Octane/gbemu.js :^)
This commit is contained in:
Andreas Kling 2023-10-05 11:53:56 +02:00
parent 03be26317f
commit 285484874d
1 changed files with 7 additions and 7 deletions
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14
Userland/Libraries/LibJS/Runtime/ArrayBuffer.h
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@ -135,7 +135,7 @@ ThrowCompletionOr<NonnullGCPtr<ArrayBuffer>> allocate_shared_array_buffer(VM&, F
// 25.1.2.9 RawBytesToNumeric ( type, rawBytes, isLittleEndian ), https://tc39.es/ecma262/#sec-rawbytestonumeric
template<typename T>
static Value raw_bytes_to_numeric(VM& vm, ByteBuffer raw_value, bool is_little_endian)
static Value raw_bytes_to_numeric(VM& vm, Bytes raw_value, bool is_little_endian)
{
// 1. Let elementSize be the Element Size value specified in Table 70 for Element Type type.
// NOTE: Used in step 6, but not needed with our implementation of that step.
@ -152,7 +152,7 @@ static Value raw_bytes_to_numeric(VM& vm, ByteBuffer raw_value, bool is_little_e
if constexpr (IsSame<UnderlyingBufferDataType, float>) {
// a. Let value be the byte elements of rawBytes concatenated and interpreted as a little-endian bit string encoding of an IEEE 754-2019 binary32 value.
float value;
raw_value.span().copy_to({ &value, sizeof(float) });
raw_value.copy_to({ &value, sizeof(float) });
// b. If value is an IEEE 754-2019 binary32 NaN value, return the NaN Number value.
if (isnan(value))
@ -166,7 +166,7 @@ static Value raw_bytes_to_numeric(VM& vm, ByteBuffer raw_value, bool is_little_e
if constexpr (IsSame<UnderlyingBufferDataType, double>) {
// a. Let value be the byte elements of rawBytes concatenated and interpreted as a little-endian bit string encoding of an IEEE 754-2019 binary64 value.
double value;
raw_value.span().copy_to({ &value, sizeof(double) });
raw_value.copy_to({ &value, sizeof(double) });
// b. If value is an IEEE 754-2019 binary64 NaN value, return the NaN Number value.
if (isnan(value))
@ -187,7 +187,7 @@ static Value raw_bytes_to_numeric(VM& vm, ByteBuffer raw_value, bool is_little_e
//
// NOTE: The signed/unsigned logic above is implemented in step 7 by the IsSigned<> check, and in step 8 by JS::Value constructor overloads.
UnderlyingBufferDataType int_value = 0;
raw_value.span().copy_to({ &int_value, sizeof(UnderlyingBufferDataType) });
raw_value.copy_to({ &int_value, sizeof(UnderlyingBufferDataType) });
// 7. If IsBigIntElementType(type) is true, return the BigInt value that corresponds to intValue.
if constexpr (sizeof(UnderlyingBufferDataType) == 8) {
@ -222,7 +222,7 @@ ThrowCompletionOr<Value> ArrayBuffer::get_value(size_t byte_index, [[maybe_unuse
// 4. Let elementSize be the Element Size value specified in Table 70 for Element Type type.
auto element_size = sizeof(T);
ByteBuffer raw_value;
AK::Array<u8, sizeof(T)> raw_value {};
// FIXME: 5. If IsSharedArrayBuffer(arrayBuffer) is true, then
if (false) {
@ -238,7 +238,7 @@ ThrowCompletionOr<Value> ArrayBuffer::get_value(size_t byte_index, [[maybe_unuse
// 6. Else,
else {
// a. Let rawValue be a List whose elements are bytes from block at indices in the interval from byteIndex (inclusive) to byteIndex + elementSize (exclusive).
raw_value = TRY_OR_THROW_OOM(vm, block.slice(byte_index, element_size));
block.bytes().slice(byte_index, element_size).copy_to(raw_value);
}
// 7. Assert: The number of elements in rawValue is elementSize.
@ -248,7 +248,7 @@ ThrowCompletionOr<Value> ArrayBuffer::get_value(size_t byte_index, [[maybe_unuse
// NOTE: Done by default parameter at declaration of this function.
// 9. Return RawBytesToNumeric(type, rawValue, isLittleEndian).
return raw_bytes_to_numeric<T>(vm, move(raw_value), is_little_endian);
return raw_bytes_to_numeric<T>(vm, raw_value, is_little_endian);
}
// 25.1.2.11 NumericToRawBytes ( type, value, isLittleEndian ), https://tc39.es/ecma262/#sec-numerictorawbytes