RFR: 8341013: Optimize x86/aarch64 MD5 intrinsics by reducing data dependency [v2]

[Andrew Haley]

On Fri, 27 Sep 2024 13:45:46 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Thanks! I can't measure any difference at all with that change, seems to perform identically.
>
> I see, Thanks!

Unless you really want zero extension it's better to use `mov` than `movw` (or `orrw`). 
On many AArch64 implementations `mov` doesn't even issue. Instead, it is handled by the renamer during the decode stage. However, because it has to clear the upper 32 bits, `movw` does issue.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21203#discussion_r1778763993