RFR: 8375272: [IR Framework] Miscellaneous clean-ups [v2]

[Christian Hagedorn]

> This patch applies various unrelated clean-ups split out from a first prototype for [JDK-8375270](https://bugs.openjdk.org/browse/JDK-8375270). This should ease reviews. I left some comments in the PR to further explain some details.
> 
> Thanks,
> Christian

Christian Hagedorn has updated the pull request incrementally with one additional commit since the last revision:

  review Marc & Damon

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/29362/files
  - new: https://git.openjdk.org/jdk/pull/29362/files/4cc62a32..460e85a3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29362&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29362&range=00-01

  Stats: 3 lines in 3 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/29362.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29362/head:pull/29362

PR: https://git.openjdk.org/jdk/pull/29362