RFR: 8354996: Reduce dynamic code generation for a single downcall [v2]

[Chen Liang]

> Perf numbers for simple main:
> Linking of `Class::forName0` down from ~152 to ~83
> 
> For calling little color management system https://bugs.openjdk.org/browse/JDK-8313344:
> JNI: ~45
> baseline panama: ~164
> patch: ~103
> 
> Also see #24705.

Chen Liang has updated the pull request incrementally with one additional commit since the last revision:

  Simplify FFM linker warmup

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24742/files
  - new: https://git.openjdk.org/jdk/pull/24742/files/f9a0533f..dbf7799c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24742&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24742&range=00-01

  Stats: 7 lines in 1 file changed: 0 ins; 6 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24742.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24742/head:pull/24742

PR: https://git.openjdk.org/jdk/pull/24742