[vectorIntrinsics] RFR: 8283413: Add C2 mid-end and x86 back-end implementation for bit REVERSE and REVERSE_BYTES operation [v3]

[Jatin Bhateja]

> Hi All,
> 
> Patch includes following changes:-
> - New C2 IR nodes to support VectorOperations.REVERSE operation.
> - X86 backend implementation for targets supporting AVX2, AVX512 and GFNI features.
> 
> Please find below the performance data of Vector API JMH micros:-
> 
> System Configuration:
> ICX: Intel(R) Xeon(R) Platinum 8380 CPU @ 2.30GHz (40C 2S)
> CLX: Intel(R) Xeon(R) Platinum 8280 CPU @ 2.70GHz (28C 2S)
> 
> ![image](https://user-images.githubusercontent.com/59989778/159196997-fd1ae2ad-37ee-4294-9928-5764707bb456.png)
> 
> 
> 
> Kindly review and share your feedback.
> 
> Regards,
> Jatin

Jatin Bhateja has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:

 - 8283413: White space removal.
 - 8283413: Review comments resoultion, ReverseBytes IR and x86 backend support.
 - Merge branch 'vectorIntrinsics' of http://github.com/openjdk/panama-vector into JDK-8283413
 - 8283413: Adding Ideal transform for (ReverseV (ReverseV VEC)) => VEC and (ReverseV (ReverseV VEC MASK) MASK)) => VEC
 - 8283413: Add C2 mid-end and x86 back-end implementation for bit REVERSE operation

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

Changes: https://git.openjdk.java.net/panama-vector/pull/182/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=182&range=02
  Stats: 515 lines in 21 files changed: 507 ins; 2 del; 6 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/182.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/182/head:pull/182

PR: https://git.openjdk.java.net/panama-vector/pull/182