RFR: 8339217: Optimize ClassFile API loadConstant [v4]

[Shaojin Wen]

> This is a large method. By splitting it into multiple methods with the same name, the caller can automatically select based on the different types of parameters, avoiding this large call that cannot be inlined, which can also improve startup performance.
> 
> * current
> 
> CodeBuilder {
>     default CodeBuilder loadConstant(ConstantDesc value) { ... }
> }
> 
> java.lang.classfile.CodeBuilder::loadConstant (465 bytes)   failed to inline: callee is too large

Shaojin Wen has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - Merge remote-tracking branch 'upstream/master' into optim_classfile_loadconstant_2020408
   
   # Conflicts:
   #	src/java.base/share/classes/java/lang/classfile/CodeBuilder.java
 - comments
 - fix comment
 - since 24
 - optimize loadConstant

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Changes: https://git.openjdk.org/jdk/pull/20761/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20761&range=03
  Stats: 87 lines in 2 files changed: 59 ins; 22 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/20761.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20761/head:pull/20761

PR: https://git.openjdk.org/jdk/pull/20761