On Tue, 20 Dec 2022 19:52:34 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> src/java.base/share/classes/java/lang/StringUTF16.java line 418:
>>
>>> 416: return 0;
>>> 417: } else {
>>> 418: return ArraysSupport.vectorizedHashCode(value,
>>> ArraysSupport.UTF16);
>>
>> Special case for 1 missing here.
>
> Intentionally left out. Array length is always even for `UTF16` arrays, but
> we could add a case for `2` that'd return `getChar(bytes, 0)` but I didn't
> see much of a win when I tested this.
I do see a 1.5x gain with this special case added:
return switch (value.length) {
case 0 -> 0;
case 2 -> getChar(value, 0);
default -> ArraysSupport.vectorizedHashCode(value,
ArraysSupport.UTF16);
};
before: 0.987 ns/op
after: 0.640 ns/op
-------------
PR: https://git.openjdk.org/jdk/pull/10847
