RFR: 8277617: Optimize array copy and clear on x86_64 [v4]

[Sandhya Viswanathan]

> Currently 32-byte instructions are used for small array copy and clear. 
> This can be optimized by using 64-byte instructions.
> 
> Please review.
> 
> Best Regards,
> Sandhya

Sandhya Viswanathan has updated the pull request incrementally with one additional commit since the last revision:

  Override threshold only if flag is default

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6512/files
  - new: https://git.openjdk.java.net/jdk/pull/6512/files/c90e7004..021bc659

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6512&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6512&range=02-03

  Stats: 21 lines in 2 files changed: 14 ins; 6 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6512.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6512/head:pull/6512

PR: https://git.openjdk.java.net/jdk/pull/6512