K 10
svn:author
V 5
markj
K 8
svn:date
V 27
2020-02-03T18:23:35.042839Z
K 7
svn:log
V 465
Add LSE-based atomic(9) implementations.

These make use of the cas*, ld* and swp instructions added in ARMv8.1.
Testing shows them to be significantly more performant than LL/SC-based
implementations.

No functional change here since the wrappers still unconditionally
select the _llsc variants.

Reviewed by:	andrew, kib
MFC after:	1 month
Submitted by:	Ali Saidi <alisaidi@amazon.com> (original version)
Differential Revision:	https://reviews.freebsd.org/D23324

END