RFR: 8347009: Speed ​​up parseInt and parseLong [v4]

[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 11 additional commits since the last revision:

 - emptyInput -> nullInput
 - use CharacterDataLatin1.instance::isDigit
 - add comments
 - reduce codeSize
 - bug fix for bound check
 - reduce codeSize
 - remove unused code
 - code format
 - bug fix
 - bug fix
 - ... and 1 more: https://git.openjdk.org/jdk/compare/9ea08455...fd51c1ce

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/22919/files
  - new: https://git.openjdk.org/jdk/pull/22919/files/9ea08455..fd51c1ce

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22919&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22919&range=02-03

  Stats: 67 lines in 3 files changed: 17 ins; 12 del; 38 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