RFR: 8331264: Reduce java.lang.constant initialization overhead [v3]

[Mandy Chung]

On Mon, 29 Apr 2024 12:39:17 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> I'm looking at ways at reducing/eliminating startup overheads the classfile API in preparation of #17108, and have pushed a series of enhancements to that effect already. This PR is a collection of minor improvements which add up to a 1.5% reduction in retired instructions - or a 5% reduction in executed bytecode - on a simple lambda startup test.
>
> Claes Redestad has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Simplified void check

The changes look good to me but I wonder if the non-zero length check before calling `arraycopy` really needed?  That seems to add some noise to the code.

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PR Review: https://git.openjdk.org/jdk/pull/18991#pullrequestreview-2029162828