Clang8 crash on rpi3 at r349989 building openjdk8

[bob prohaska]

In trying to compile www/chromium on an rpi3 at r349989 with
ports at 507005 clang8 crashed in a way that superficially 
resembled earlier "OOMA" kills. However, there's no swap use 
to speak of and no complaints of excessive swap delay on the console
.....
Compiling /usr/work/usr/ports/java/openjdk8/work/openjdk-jdk8u-jdk8u222-b10.1/hotspot/src/share/vm/interpreter/invocationCounter.cpp
Assertion failed: (isa<X>(Val) && "cast<Ty>() argument of incompatible type!"), function cast, file /usr/src/contrib/llvm/include/llvm/Support/Casting.h, line 255.
Compiling /usr/work/usr/ports/java/openjdk8/work/openjdk-jdk8u-jdk8u222-b10.1/hotspot/src/share/vm/memory/iterator.cpp
Compiling /usr/work/usr/ports/java/openjdk8/work/openjdk-jdk8u-jdk8u222-b10.1/hotspot/src/share/vm/runtime/java.cpp
Compiling /usr/work/usr/ports/java/openjdk8/work/openjdk-jdk8u-jdk8u222-b10.1/hotspot/src/share/vm/classfile/javaAssertions.cpp
Compiling /usr/work/usr/ports/java/openjdk8/work/openjdk-jdk8u-jdk8u222-b10.1/hotspot/src/share/vm/runtime/javaCalls.cpp
Compiling /usr/work/usr/ports/java/openjdk8/work/openjdk-jdk8u-jdk8u222-b10.1/hotspot/src/share/vm/classfile/javaClasses.cpp
c++: error: unable to execute command: Abort trap (core dumped)
c++: error: clang frontend command failed due to signal (use -v to see invocation)
FreeBSD clang version 8.0.1 (branches/release_80 364487) (based on LLVM 8.0.1)
Target: aarch64-unknown-freebsd13.0
Thread model: posix
InstalledDir: /usr/bin
c++: 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.
.....

The clang8 crash report files and the swap usage log are at

http://www.zefox.net/~fbsd/rpi3/swaptests/r349989/

Thanks for reading and any suggestions.

bob prohaska