On Thu, 20 Jul 2023 15:16:33 GMT, Jorn Vernee <jver...@openjdk.org> wrote:
>> Mandy Chung has updated the pull request incrementally with one additional
>> commit since the last revision:
>>
>> update copyright header
>
> src/java.base/share/classes/java/lang/invoke/VarHandle.java line 2010:
>
>> 2008: static AccessMode valueFromOrdinal(int mode) {
>> 2009: return VALUES[mode];
>> 2010: }
>
> Also, I'll throw this out there, though I'm not sure how big of an issue it
> is: this array creation might have an effect on startup. But, since it is
> only used on a slow path right before we throw an exception (at least, at the
> moment), calling `values()` every time inside the `valueFromOrdinal` method,
> and avoiding the array creation on startup, might be 'better'.
I think this is a worthy change: see
https://github.com/openjdk/jdk/pull/14943/files#diff-556b309ea2df3f5bfe8229de944183ef19750ce4511d0328cd59af2ce2b61ae2R135
that `VarHandle.AccessMode.values()` is called every time a polymorphic VH call
is linked.
If the startup cost from array allocation is really problematic, we can make it
stable and allocate `VALUES` on demand (at `valueFromOrdinal` calls).
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/14928#discussion_r1269665939
