RFR: 8337282: Speed ​​up StringConcat with more simpleConcat [v2]

[Shaojin Wen]

> StringConcatFactory improves startup speed and running performance through simpleConcat, but simpleConcat is currently given priority and only supports the following scenarios:
> 
> // x instanceof Object
> prefix + x
> x = subfix
> 
> // x instanceof Object && z instanceof Object
> x + y
> 
> 
> This PR improves startup and running performance by supporting more scenarios including
> 
> // x instanceof byte/short/int/char/boolean/float/double
> prefix + x
> x + suffix
> 
> // x instanceof byte/short/int/char/boolean/float/double/Integer/Long/Object
> prefix + suffix
> 
> // x instanceof Object
> x + y + suffix
> 
> // x instanceof Object
> x + y + suffix

Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:

  1. rename simpleConcat -> makeSimpleConcat
  2. add comments
  3. support none-constants 3 parameters

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20355/files
  - new: https://git.openjdk.org/jdk/pull/20355/files/37f42b10..9099527c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20355&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20355&range=00-01

  Stats: 21 lines in 1 file changed: 5 ins; 0 del; 16 mod
  Patch: https://git.openjdk.org/jdk/pull/20355.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20355/head:pull/20355

PR: https://git.openjdk.org/jdk/pull/20355