RFR: 8289051: C2: Cleanup PhaseCCP::analyze() [v2]

[Christian Hagedorn]

> As part of [JDK-8288683](https://bugs.openjdk.org/browse/JDK-8288683), which went into JDK 19, I separated out most of the included refactorings into this cleanup RFE to make the fix as small as possible.
> 
> This cleanup includes:
> - More comments and better descriptions.
> - Renamed some variables.
> - Split code into multiple methods to improve the readability.
> 
> Thanks,
> Christian

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

  Update src/hotspot/share/opto/phaseX.cpp
  
  Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/9833/files
  - new: https://git.openjdk.org/jdk/pull/9833/files/5ba8f725..ab4a0c39

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=9833&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=9833&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9833.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9833/head:pull/9833

PR: https://git.openjdk.org/jdk/pull/9833