RFR: 8328528: C2 should optimize long-typed parallel iv in an int counted loop [v3]

[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 incrementally with one additional commit since the last revision:

  update comments to clarify on type casting

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18489/files
  - new: https://git.openjdk.org/jdk/pull/18489/files/efc270ec..dcd55681

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18489&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18489&range=01-02

  Stats: 9 lines in 1 file changed: 7 ins; 0 del; 2 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