RFR: 8357289: Break down the String constructor into smaller methods [v3]

[Shaojin Wen]

> Through JVM Option +PrintInlining, we found that String has a constructor codeSize of 852, which is too large. This caused failed to inline.
> 
> The following is the output information of PrintInlining:
> 
>                 @ 9   java.lang.String::<init> (12 bytes)   inline (hot)
> !m                 @ 1   java.nio.charset.Charset::defaultCharset (52 bytes)   inline (hot)
> !                  @ 8   java.lang.String::<init> (852 bytes)   failed to inline: hot method too big
> 
> 
> In Java code, the big method that cannot be inlined is the following constructor
> 
> 
> String(Charset charset, byte[] bytes, int offset, int length) {}
> 
> The above String constructor is too large; break it down into smaller methods with a codeSize under 325 to allow them to be inlined by the C2.

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

  create method share variant val & coder

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25290/files
  - new: https://git.openjdk.org/jdk/pull/25290/files/b6f0a2db..fab7728b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25290&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25290&range=01-02

  Stats: 38 lines in 1 file changed: 14 ins; 11 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/25290.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25290/head:pull/25290

PR: https://git.openjdk.org/jdk/pull/25290