hg: jdk/jdk: 8209420: Track membars for volatile accesses so they can be properly optimized

[rwestrel at redhat.com]

Changeset: d7029542d67a
Author:    roland
Date:      2018-08-14 16:54 +0200
URL:       http://hg.openjdk.java.net/jdk/jdk/rev/d7029542d67a

8209420: Track membars for volatile accesses so they can be properly optimized
Reviewed-by: adinn, aph, thartmann

! src/hotspot/cpu/aarch64/aarch64.ad
! src/hotspot/share/gc/shared/c2/barrierSetC2.cpp
! src/hotspot/share/opto/compile.cpp
! src/hotspot/share/opto/memnode.cpp
! src/hotspot/share/opto/memnode.hpp