powerpc64: system-clang-8 -> system-clang-9 based head via source: any special instructions?

[Mark Millard]

Now that head has llvm9 based clang/clang++ as cc/c++
(with llvm9 being involved in the transition to ELFv2),
are there special instructions for system-clang based
buildworld buildkernel then installkernel installworld
based updates?  The system is based on WITHOUT_LIB32=
as stands. (I frequently amd64->powerpc64 cross build
due to time preferences.) The system does have a
variety of ports installed ( that were built via
ports-mgmt/poudriere-devel ). So more than the system
would be involved overall/eventually.

For reference, my existing powerpc64 configuration is
system-clang-8 based:

QUOTE
FreeBSD 13.0-CURRENT #19 r352341M: Sat Sep 14 19:40:27 PDT 2019
    markmi at FBSDFHUGE:/usr/obj/powerpc64vtsc_clang_altbinutils/powerpc.powerpc64/usr/src/powerpc.powerpc64/sys/GENERIC64vtsc-NODBG powerpc
FreeBSD clang version 8.0.1 (tags/RELEASE_801/final 366581) (based on LLVM 8.0.1)
END QUOTE

devel/powerpc64-binutils supplies the ld used in the
builds (including cross-builds). As stands the powerpc64
system-ld is via base/binutils cross-building. (Similarly
for ports-mgmt/pkg.)

So I am familiar with doing these sorts of builds. I
also sometimes do builds based on devel/powerpc64-gcc
and devel/powerpc64-xtoolchain-gcc as well. Build via
devel/llvm8 have been rare: I use system-clang instead.

The powerpc64 systems involved are old multi-socket
PowerMacs, mostly 2 socket with 2 cores each, depending
on what I have access to at the time.

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)