RFR: 8196331: Optimize Character.digit for latin1 input (original) (raw)

Claes Redestad claes.redestad at oracle.com
Mon Jan 29 19:37:20 UTC 2018

I ran with a smaller byte[] initially and saw about a 10% improvement from removing the branch, which is why I felt the superfluous bytes were motivated.

/Claes

Paul Sandoz <paul.sandoz at oracle.com> skrev: (29 januari 2018 19:14:44 CET) >>>> On Jan 29, 2018, at 9:44 AM, Martin Buchholz <martinrb at google.com> >wrote: >>>> Thanks. I might try to shrink the size of the static array, by only >> storing values between '0' and 'z', at the cost of slightly greater >lookup >> costs for each char. >>>>I was wondering the same, or just clip the end of the array to’z' >>if (ch <= ‘z’ && radix …) { // Might even fold the upper bounds check_ >for DIGITS > value = DIGITS[ch]; > ... >}_ >>Paul. >>> On Mon, Jan 29, 2018 at 3:15 AM, Claes Redestad ><claes.redestad at oracle.com> >> wrote: >>>>> Hi, >>>>>> for the latin1 block of CharacterData we can improve the >>> digit(int, int) implementation by providing an optimized lookup >>> table. This improves microbenchmarks exercising Integer.parseInt, >>> Long.parseLong and UUID.fromString etc by around 50%for typical >>> inputs. >>>>>> Webrev: http://cr.openjdk.java.net/~redestad/8196331/open.00/ >>> Bug: https://bugs.openjdk.java.net/browse/JDK-8196331 >>>>>> The lookup array is pre-calculated to minimize startup impact >>> (adds 1,027 bytecodes executed during initialization) >>>>>> /Claes >>>

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