RFR: 8347009: Speed ​​up parseInt and parseLong [v17]

[Shaojin Wen]

> This is an optimization for decimal Integer.parseInt and Long.parseLong, which improves performance by about 10%. The optimization includes:
> 1. Improve performance by parsing 2 numbers at a time, which has performance improvements for numbers with length >= 3.
> 2. It uses charAt(0) for the first number. Assuming that the optimization can eliminate boundary checks, this will be more friendly to parsing numbers with length 1.
> 3. It removes the reliance on the Character.digit method and eliminates the reliance on the CharacterDataLatin1#DIGITS cache array, which avoids performance degradation caused by cache misses.

Shaojin Wen has updated the pull request incrementally with two additional commits since the last revision:

 - fix comments
 - Update src/java.base/share/classes/jdk/internal/util/DecimalDigits.java
   
   Co-authored-by: Raffaello Giulietti <raffaello.giulietti at oracle.com>

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/22919/files
  - new: https://git.openjdk.org/jdk/pull/22919/files/0c43e9ae..c8f514f2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22919&range=16
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22919&range=15-16

  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/22919.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22919/head:pull/22919

PR: https://git.openjdk.org/jdk/pull/22919