RFR: 8341831: PhaseCFG::insert_anti_dependences asserts with "no loads" [v4]

[Igor Veresov]

> `CacheWB` nodes are peculiar in a sense that they both are anti-dependent and produce memory. I think it's reasonable to relax the assert in `insert_anti_dependences()` to work around their properties.

Igor Veresov has updated the pull request incrementally with one additional commit since the last revision:

  Address Dean's comment

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21455/files
  - new: https://git.openjdk.org/jdk/pull/21455/files/ae69ee4b..914b97ac

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21455&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21455&range=02-03

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21455.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21455/head:pull/21455

PR: https://git.openjdk.org/jdk/pull/21455