RFR: 8325083: jdk/incubator/vector/Double512VectorTests.java crashes in Assembler::vex_prefix_and_encode [v4]

[Jatin Bhateja]

> This bugfix patch limits the register class for operands of byte to double cast pattern to prevent reported assertion failure on Knights family CPUs.
> 
> Kindly review and share your feedback.
> 
> Best Regards,
> Jatin

Jatin Bhateja 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 five additional commits since the last revision:

 - Removing unrelated commit
 - Merge branch 'master' of http://github.com/openjdk/jdk into JDK-8325083
 - Review suggestion incorporated.
 - Removing redundant assertions
 - 8325083: jdk/incubator/vector/Double512VectorTests.java crashes in Assembler::vex_prefix_and_encode

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/19407/files
  - new: https://git.openjdk.org/jdk/pull/19407/files/098157e8..e2e70cdb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19407&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19407&range=02-03

  Stats: 4697 lines in 135 files changed: 3307 ins; 843 del; 547 mod
  Patch: https://git.openjdk.org/jdk/pull/19407.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19407/head:pull/19407

PR: https://git.openjdk.org/jdk/pull/19407