RFR: 8328528: C2 should optimize long-typed parallel iv in an int counted loop [v6]

[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 25 additional commits since the last revision:

 - Merge branch 'master' into long-typed-parallel-iv
 - add random strides to tests
 - fix tests on larger strides
 - 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
 - ... and 15 more: https://git.openjdk.org/jdk/compare/36c584a8...981b9600

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18489/files
  - new: https://git.openjdk.org/jdk/pull/18489/files/be0f596d..981b9600

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18489&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18489&range=04-05

  Stats: 189387 lines in 3331 files changed: 125262 ins; 46366 del; 17759 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