CLANG6, java/openjdk[7|8] compiler error: atomic.inline.hpp:70 error: unknown token in expression __asm__ volatile

On recent CURRENT (FreeBSD 12.0-CURRENT #0 r328002: Mon Jan 15 15:28:18 CET
2018 amd64) both ports java/openjdk7 and java/openjdk8 fail to compile with
devel/openjdk8's error as follows:


[...]
In file included
from /usr/ports/java/openjdk8/work/openjdk/hotspot/src/share/vm/runtime/atomic.inline.hpp:70: /usr/ports/java/openjdk8/work/openjdk/hotspot/src/os_cpu/bsd_x86/vm/atomic_bsd_x86.inline.hpp:95:21:
error: unknown token in expression __asm__ volatile (LOCK_IF_MP(%4) "cmpxchgl
%1,(%3)"


Regards,

Oliver