On Wed, 8 Feb 2023 01:10:59 GMT, David Schlosnagle <d...@openjdk.org> wrote:
>> Claes Redestad has updated the pull request incrementally with one
>> additional commit since the last revision:
>>
>> Minimize, force inline, generalize
>
> src/java.base/share/classes/java/util/Arrays.java line 3594:
>
>> 3592: public static int[] copyOf(int[] original, int newLength) {
>> 3593: if (newLength == original.length) {
>> 3594: return original.clone();
>
> I am curious about the use of `clone` for some primitive array types
> (`short[]`, `int[]`, `long[]`, `char[]`, `float[]`) and `copyOf` using
> `System.arraycopy` in other types (`byte[]`, `double[]`). Do these types
> optimize differently or hit different intrinsics depending on primitive type?
> Is there difference in array zeroing?
>
> From a quick [JMH
> benchmark](https://gist.github.com/schlosna/975e26965ec822ad42034b3ea2b08676)
> `System.arraycopy` seems slightly better.
I went back and forth on this and also saw a small win using `arraycopy`, but
the PR ended up in an inconsistent state with some using one and some using the
other. While this discrepancy seem like something we should treat as a bug,
I've arranged to use `copyOf` helper consistently for now.
-------------
PR: https://git.openjdk.org/jdk/pull/12453
