[16] RFR[S]: 8251216: Implement MD5 intrinsics on AArch64

[Ludovic Henry]

Hello,

Bug: https://bugs.openjdk.java.net/browse/JDK-8251216
Webrev: http://cr.openjdk.java.net/~luhenry/8251216/webrev.00

Testing: Linux-AArch64, fastdebug, test/hotspot/jtreg/compiler/intrinsics/sha/ test/hotspot/jtreg:tier1 test/jdk:tier1

This patch implements the MD5 intrinsic on AArch64 following its implementation on x86 [1]. The performance improvements are the following (on Linux-AArch64 on a Marvell TX2):

-XX:-UseMD5Intrinsics
Benchmark              (digesterName)  (length)  (provider)   Mode  Cnt     Score    Error   Units
MessageDigests.digest             md5        64     DEFAULT  thrpt   10  1616.238 ± 28.082  ops/ms
MessageDigests.digest             md5      1024     DEFAULT  thrpt   10   215.030 ±  0.691  ops/ms
MessageDigests.digest             md5   1048576     DEFAULT  thrpt   10     0.228 ±  0.001  ops/ms

-XX:+UseMD5Intrinsics
Benchmark              (digesterName)  (length)  (provider)   Mode  Cnt     Score    Error   Units
MessageDigests.digest             md5        64     DEFAULT  thrpt   10  2005.233 ± 40.513  ops/ms => 24% speedup
MessageDigests.digest             md5      1024     DEFAULT  thrpt   10   275.979 ±  0.455  ops/ms => 28% speedup
MessageDigests.digest             md5   1048576     DEFAULT  thrpt   10     0.279 ±  0.001  ops/ms => 22% speedup

Thank you,
Ludovic

[1] https://bugs.openjdk.java.net/browse/JDK-8250902