RFR: 8304034: Remove redundant and meaningless comments in opto [v2]

[Yi Yang]

> Please help review this trivial change to remove redundant and meaningless comments in `hotspot/share/opto` directory.
> 
> They are either
> 1. Repeat the function name that the function they comment for.
> 2. Makes no sense, e.g. `//----Idealize----` 
> 
> And I think original CC-style code (`if( test )`,`call( arg )`) can be formatted in one go, instead of formatting the near code when someone touches them. But this may form a big patch, and it confuses code blame, so I left this work until we reach a consensus.
> 
> Thanks!

Yi Yang has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  8304034: Remove redundant and meaningless comments in opto

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12995/files
  - new: https://git.openjdk.org/jdk/pull/12995/files/944d2295..5680a6ce

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12995&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12995&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12995.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12995/head:pull/12995

PR: https://git.openjdk.org/jdk/pull/12995