CURRENT: build failure with clang 3.7.0

I hit on a box this nasty/sticky error when performing buildworld.

/usr/src is on r288980

svn status gives

#: [src] svn st
?       .snap
?       .sujournal
?       etc/rc.d/tests
?       sys/amd64/conf/HAGENVONTRONJE

By the way, it seems that etc/rc.d/tests doesn't get deleted via "make
delete-old".

The failure is shown below.

My /etc/src.conf is this:

#
CPUTYPE?=               native
#
CFLAGS+=                -O3 -pipe
COPTFLAGS+=             -O3 -pipe
#
#CXXFLAGS+=             -std=c++11
#
WITH_CLANG_FULL=        YES
WITH_CLANG_EXTRAS=      YES
WITH_LLDB=              YES
#
WITH_IDEA=              YES
#
#WITH_BSD_GREP=         YES
#
#WITH_OFED=             YES
WITH_NAND=              YES
#WITH_CTF=              YES
#
WITH_SVN=               YES
#
MALLOC_PRODUCTION=      YES
#
#WITHOUT_DEBUG_FILES=   YES
#
PORTS_MODULES=
PORTS_MODULES+=         emulators/virtualbox-ose-kmod

I use this /etc/src.conf also on other machines, but with
CXXFLAGS+=             -std=c++11
enabled. It works on two out of three, the third (not the reported one here)
fails in atf-c++, I will report later when I have access to the box.
The strange thing on that is that I use the very specific non-vanilla src.conf
on several systems and they work and do well, even with CURRENT as discussed
here, but there are problems I can not fathom since source tree and compilation
flags are the same and even the startig revision of the building machine's
CURRENT is the same.

regards,

oliver

[...]

--- ieee802_11_common.o ---
cc  -O2 -pipe -O3 -O3 -pipe -march=native
-I/usr/src/usr.sbin/wpa/wpa_supplicant
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//hostapd
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/common
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/crypto
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/drivers
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/l2_packet
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/utils
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/wps
-DCONFIG_CTRL_IFACE -DCONFIG_CTRL_IFACE_UNIX -DCONFIG_BACKEND_FILE
-DCONFIG_DEBUG_SYSLOG  -DCONFIG_DRIVER_BSD  -DCONFIG_DRIVER_NDIS
-DCONFIG_DRIVER_WIRED  -DCONFIG_GAS  -DCONFIG_HS20  -DCONFIG_IEEE80211R
-DCONFIG_INTERWORKING  -DCONFIG_PEERKEY  -DCONFIG_PRIVSEP  -DCONFIG_SMARTCARD
-DCONFIG_TERMINATE_ONLASTIF  -DCONFIG_TLS=openssl  -DCONFIG_WPS  -DCONFIG_WPS2
-DCONFIG_WPS_UPNP  -DPKCS12_FUNCS  -DEAP_GTC  -DEAP_LEAP  -DEAP_MD5
-DEAP_MSCHAPv2  -DEAP_OTP  -DEAP_PEAP  -DEAP_PSK  -DEAP_TLS  -DEAP_TTLS
-DIEEE8021X_EAPOL -DCONFIG_SHA256 -DEAP_TLS_OPENSSL
-I/usr/src/usr.sbin/wpa/wpa_supplicant
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//hostapd
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/common
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/crypto
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/drivers
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/l2_packet
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/utils
-I/usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/wps
-DCONFIG_CTRL_IFACE -DCONFIG_CTRL_IFACE_UNIX -std=gnu99
-fstack-protector-strong   -Qunused-arguments
-c /usr/src/usr.sbin/wpa/wpa_supplicant/../../../contrib/wpa//src/common/ieee802_11_common.c
-o ieee802_11_common.o Cannot emit physreg copy instruction UNREACHABLE
executed
at /usr/src/lib/clang/libllvmx86codegen/../../../contrib/llvm/lib/Target/X86/X86InstrInfo.cpp:3935!
cc: error: unable to execute command: Abort trap cc: error: clang frontend
command failed due to signal (use -v to see invocation) FreeBSD clang version
3.7.0 (tags/RELEASE_370/final 246257) 20150906 Target:
x86_64-unknown-freebsd11.0 Thread model: posix cc: note: diagnostic msg: PLEASE
submit a bug report to https://bugs.freebsd.org/submit/ and include the crash
backtrace, preprocessed source, and associated run script. --- usr.bin.all__D
--- --- ex_abbrev.o --- cc  -O2 -pipe -O3 -O3 -pipe -march=native
-D__REGEX_PRIVATE -I/usr/src/usr.bin/vi -I/usr/src/usr.bin/vi/../../contrib/nvi
-I/usr/src/usr.bin/vi/../../contrib/nvi/regex -DUSE_WIDECHAR -DUSE_ICONV
-std=gnu99 -fstack-protector-strong -Wno-pointer-sign -Wno-empty-body
-Wno-string-plus-int -Wno-unused-const-variable -Wno-tautological-compare
-Wno-unused-value -Wno-parentheses-equality -Wno-unused-function
-Wno-enum-conversion -Wno-unused-local-typedef -Wno-switch -Wno-switch-enum
-Wno-knr-promoted-parameter -Wno-parentheses -Qunused-arguments
-c /usr/src/usr.bin/vi/../../contrib/nvi/ex/ex_abbrev.c -o ex_abbrev.o ---
usr.sbin.all__D --- cc: note: diagnostic msg: ********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
cc: note: diagnostic msg: /tmp/ieee802_11_common-b7c29f.c
cc: note: diagnostic msg: /tmp/ieee802_11_common-b7c29f.sh
cc: note: diagnostic msg: 

********************
*** [ieee802_11_common.o] Error code 254

make[5]: stopped in /usr/src/usr.sbin/wpa/wpa_supplicant
1 error