[jdk18] RFR: 8278508: Enable X86 maskAll instruction pattern for 32 bit JVM. [v2]

[Jatin Bhateja]

> - Vector.maskAll was accelerated for AVX-512 target, but  x86 existing backend implementation does not enable maskAll instruction patterns for 32 bit JVM, due to which operations fall backs over replicateB operation which broadcasts the mask value in a vector.
> - In some cases after unboxing-boxing optimization this vector eventually reaches to XorVMask which has different operands one held in opmask register and other in vector.
> 
> Kindly review and share your feedback.
> 
> Best Regards,
> Jatin

Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:

  8278508: Review comments resolution.

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

Changes:
  - all: https://git.openjdk.java.net/jdk18/pull/24/files
  - new: https://git.openjdk.java.net/jdk18/pull/24/files/583e5e48..4fb1ea1b

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk18&pr=24&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk18&pr=24&range=00-01

  Stats: 3 lines in 3 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk18/pull/24.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18 pull/24/head:pull/24

PR: https://git.openjdk.java.net/jdk18/pull/24