On Wed, 15 Dec 2021 23:04:37 GMT, Claes Redestad <redes...@openjdk.org> wrote:
> During TemplatedStrings work Jim has noticed that we could probably profit
> from reusing the lookup tables also for the 1 or 2 leftmost bytes:
>
> // We know there are at most two digits left at this point.
> buf[--charPos] = DigitOnes[-i];
> if (i < -9) {
> buf[--charPos] = DigitTens[-i];
> }
>
> This avoids some arithmetic, and on average achieves a small speed-up since
> the lookup tables are likely cached are likely to be in cache. Small
> improvements on a few affected microbenchmarks, including the new
> Integers.toStringTiny, can be observed.
>
> Baseline:
>
> Benchmark (size) Mode Cnt Score Error Units
> Integers.toStringTiny 500 avgt 50 21.862 ± 0.211 us/op
>
>
> Patch:
>
> Benchmark (size) Mode Cnt Score Error Units
> Integers.toStringTiny 500 avgt 50 20.619 ± 0.330 us/op
This pull request has now been integrated.
Changeset: 71ca85f5
Author: Claes Redestad <redes...@openjdk.org>
URL:
https://git.openjdk.java.net/jdk/commit/71ca85f5a6741a2db55a529192564f94b269fbd9
Stats: 42 lines in 4 files changed: 11 ins; 16 del; 15 mod
8278831: Use table lookup for the last two bytes in Integer.getChars
Reviewed-by: jlaskey, rriggs
-------------
PR: https://git.openjdk.java.net/jdk/pull/6854
