RFR: 8328528: C2 should optimize long-typed parallel iv in an int counted loop [v4]

[Kangcheng Xu]

> Currently, parallel iv optimization only happens in an int counted loop with int-typed parallel iv's. This PR adds support for long-typed iv to be optimized. 
> 
> Additionally, this ticket contributes to the resolution of [JDK-8275913](https://bugs.openjdk.org/browse/JDK-8275913). Meanwhile, I'm working on adding support for parallel IV replacement for long counted loops which will depend on this PR.

Kangcheng Xu has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 22 additional commits since the last revision:

 - add more expressive comments and test cases
 - Merge branch 'master' into long-typed-parallel-iv
 - update comments to clarify on type casting
 - add pseudocode for subgraphs before/after the transformation
 - remove WIP support for long counted loops
 - Merge branch 'master' into long-typed-parallel-iv
 - update tests
 - update tests
 - update tests
 - clean up code for pr
 - ... and 12 more: https://git.openjdk.org/jdk/compare/1ecc282b...85820dee

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18489/files
  - new: https://git.openjdk.org/jdk/pull/18489/files/dcd55681..85820dee

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18489&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18489&range=02-03

  Stats: 122774 lines in 3145 files changed: 56800 ins; 49870 del; 16104 mod
  Patch: https://git.openjdk.org/jdk/pull/18489.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18489/head:pull/18489

PR: https://git.openjdk.org/jdk/pull/18489