On Wed, 8 Feb 2023 10:53:22 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> This patch adds special-cases to `Arrays.copyOf` and `Arrays.copyOfRange` to
>> copy arrays more efficiently when exactly the whole input array is to be
>> copied. This helps eliminate range checks and has been verified to help
>> various String operations. Example:
>>
>> Baseline
>>
>> Benchmark (size) Mode Cnt
>> Score Error Units
>> StringConstructor.newStringFromArray 7 avgt 15
>> 16.817 ± 0.369 ns/op
>> StringConstructor.newStringFromArrayWithCharset 7 avgt 15
>> 16.866 ± 0.449 ns/op
>> StringConstructor.newStringFromArrayWithCharsetName 7 avgt 15
>> 22.198 ± 0.396 ns/op
>>
>> Patch:
>>
>> Benchmark (size) Mode Cnt
>> Score Error Units
>> StringConstructor.newStringFromArray 7 avgt 15
>> 14.666 ± 0.336 ns/op
>> StringConstructor.newStringFromArrayWithCharset 7 avgt 15
>> 14.582 ± 0.288 ns/op
>> StringConstructor.newStringFromArrayWithCharsetName 7 avgt 15
>> 20.339 ± 0.328 ns/op
>
> Claes Redestad has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Add offset param to micro, reduce number of configurations and variants
The nudge from John and others to move this to Arrays.copyOf is much better. It
looks good.
We may have to come back to the SB::toLength issue from the original proposal.
src/java.base/share/classes/java/util/Arrays.java line 29:
> 27:
> 28: import jdk.internal.util.ArraysSupport;
> 29: import jdk.internal.util.Preconditions;
I don't think Preconditions is needed now.
src/java.base/share/classes/java/util/Arrays.java line 3909:
> 3907:
> 3908: @ForceInline
> 3909: private static byte[] copyOfRangeGeneric(byte[] original, int from,
> int to) {
Maybe copyOfRange{Short,Int,Long,...} might be better than a "Generic" suffix.
-------------
Marked as reviewed by alanb (Reviewer).
PR: https://git.openjdk.org/jdk/pull/12453
