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LibJS: Add specialized fast paths for 8/16/32-bit integer TypedArrays

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By checking a few conditions up front, we can do a very specialized
direct access into the underlying byte storage for 8/16/32-bit typed
arrays. This relies on the fact that typed arrays are guaranteed to
be type-appropriately aligned within the underlying array buffer.
This commit is contained in:
Andreas Kling 2023-11-26 15:31:14 +01:00
parent 4cce181ece
commit cb46a7fd65
1 changed files with 91 additions and 8 deletions
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99
Userland/Libraries/LibJS/Bytecode/CommonImplementations.cpp
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@ -20,6 +20,42 @@
namespace JS::Bytecode {
// NOTE: This function assumes that the index is valid within the TypedArray,
// and that the TypedArray is not detached.
template<typename T>
inline Value fast_integer_indexed_element_get(TypedArrayBase& typed_array, u32 index)
{
Checked<u32> offset_into_array_buffer = index;
offset_into_array_buffer *= sizeof(T);
offset_into_array_buffer += typed_array.byte_offset();
if (offset_into_array_buffer.has_overflow()) [[unlikely]] {
return js_undefined();
}
auto const& array_buffer = *typed_array.viewed_array_buffer();
auto const* slot = reinterpret_cast<T const*>(array_buffer.buffer().offset_pointer(offset_into_array_buffer.value()));
return Value { *slot };
}
// NOTE: This function assumes that the index is valid within the TypedArray,
// and that the TypedArray is not detached.
template<typename T>
inline void fast_integer_indexed_element_set(TypedArrayBase& typed_array, u32 index, T value)
{
Checked<u32> offset_into_array_buffer = index;
offset_into_array_buffer *= sizeof(T);
offset_into_array_buffer += typed_array.byte_offset();
if (offset_into_array_buffer.has_overflow()) [[unlikely]] {
return;
}
auto& array_buffer = *typed_array.viewed_array_buffer();
auto* slot = reinterpret_cast<T*>(array_buffer.buffer().offset_pointer(offset_into_array_buffer.value()));
*slot = value;
}
ThrowCompletionOr<NonnullGCPtr<Object>> base_object_for_get(VM& vm, Value base_value)
{
if (base_value.is_object())
@ -68,23 +104,43 @@ ThrowCompletionOr<Value> get_by_id(VM& vm, DeprecatedFlyString const& property,
ThrowCompletionOr<Value> get_by_value(VM& vm, Value base_value, Value property_key_value)
{
auto object = TRY(base_object_for_get(vm, base_value));
// OPTIMIZATION: Fast path for simple Int32 indexes in array-like objects.
if (property_key_value.is_int32() && property_key_value.as_i32() >= 0) {
if (base_value.is_object() && property_key_value.is_int32() && property_key_value.as_i32() >= 0) {
auto& object = base_value.as_object();
auto index = static_cast<u32>(property_key_value.as_i32());
// For "non-typed arrays":
if (!object->may_interfere_with_indexed_property_access()
&& object->indexed_properties().has_index(index)) {
auto value = object->indexed_properties().get(index)->value;
if (!object.may_interfere_with_indexed_property_access()
&& object.indexed_properties().has_index(index)) {
auto value = object.indexed_properties().get(index)->value;
if (!value.is_accessor())
return value;
}
// For typed arrays:
if (object->is_typed_array()) {
auto& typed_array = static_cast<TypedArrayBase&>(*object);
if (object.is_typed_array()) {
auto& typed_array = static_cast<TypedArrayBase&>(object);
if (!typed_array.viewed_array_buffer()->is_detached() && index < typed_array.array_length()) {
switch (typed_array.kind()) {
case TypedArrayBase::Kind::Uint8Array:
return fast_integer_indexed_element_get<u8>(typed_array, index);
case TypedArrayBase::Kind::Uint16Array:
return fast_integer_indexed_element_get<u16>(typed_array, index);
case TypedArrayBase::Kind::Uint32Array:
return fast_integer_indexed_element_get<u32>(typed_array, index);
case TypedArrayBase::Kind::Int8Array:
return fast_integer_indexed_element_get<i8>(typed_array, index);
case TypedArrayBase::Kind::Int16Array:
return fast_integer_indexed_element_get<i16>(typed_array, index);
case TypedArrayBase::Kind::Int32Array:
return fast_integer_indexed_element_get<i32>(typed_array, index);
default:
// FIXME: Support more TypedArray kinds.
break;
}
}
auto canonical_index = CanonicalIndex { CanonicalIndex::Type::Index, index };
switch (typed_array.kind()) {
#define __JS_ENUMERATE(ClassName, snake_name, PrototypeName, ConstructorName, Type) \
@ -96,6 +152,8 @@ ThrowCompletionOr<Value> get_by_value(VM& vm, Value base_value, Value property_k
}
}
auto object = TRY(base_object_for_get(vm, base_value));
auto property_key = TRY(property_key_value.to_property_key(vm));
if (base_value.is_string()) {
@ -345,6 +403,31 @@ ThrowCompletionOr<void> put_by_value(VM& vm, Value base, Value property_key_valu
// For typed arrays:
if (object.is_typed_array()) {
auto& typed_array = static_cast<TypedArrayBase&>(object);
if (!typed_array.viewed_array_buffer()->is_detached() && index < typed_array.array_length() && value.is_int32()) {
switch (typed_array.kind()) {
case TypedArrayBase::Kind::Uint8Array:
fast_integer_indexed_element_set<u8>(typed_array, index, static_cast<u8>(value.as_i32()));
return {};
case TypedArrayBase::Kind::Uint16Array:
fast_integer_indexed_element_set<u16>(typed_array, index, static_cast<u16>(value.as_i32()));
return {};
case TypedArrayBase::Kind::Uint32Array:
fast_integer_indexed_element_set<u32>(typed_array, index, static_cast<u32>(value.as_i32()));
return {};
case TypedArrayBase::Kind::Int8Array:
fast_integer_indexed_element_set<i8>(typed_array, index, static_cast<i8>(value.as_i32()));
return {};
case TypedArrayBase::Kind::Int16Array:
fast_integer_indexed_element_set<i16>(typed_array, index, static_cast<i16>(value.as_i32()));
return {};
case TypedArrayBase::Kind::Int32Array:
fast_integer_indexed_element_set<i32>(typed_array, index, value.as_i32());
return {};
default:
// FIXME: Support more TypedArray kinds.
break;
}
}
auto canonical_index = CanonicalIndex { CanonicalIndex::Type::Index, index };
switch (typed_array.kind()) {
#define __JS_ENUMERATE(ClassName, snake_name, PrototypeName, ConstructorName, Type) \