RH XFree86 spec file question

[Craig P Prescott <prescott phys ufl edu>]

Greets;

Was building XFree86 on my EV45 (aka 21064A) AlphaStation 250 last
night, and I was wondering why everything was getting compiled with
"-Wa,-m21164a".  Then saw this in the spec file:

<snip>
%build
%ifarch alpha
make World -C xc CDEBUGFLAGS="$RPM_OPT_FLAGS -Wa,-m21164a"
%else
</snip>

This was from 

ftp://updates.redhat.com/6.0/SRPMS/XFree86-3.3.5-1.6.0.src.rpm

So I went over and grabbed XFree sources from Rawhide...

ftp://ftp.redhat.com/pub/rawhide/SRPMS/SRPMS/XFree86-3.3.5-15.src.rpm

and took a look at the spec file.  The alpha stanza of %build is thus:

%build
%ifarch alpha
make World -C xc CDEBUGFLAGS="$RPM_OPT_FLAGS -Wa,-m21164a"
# we are having problems with the compiler on alpha.
make -C xc/programs/xterm CDEBUGFLAGS="-Wa,-m21164a"
make -C xc
rm xc/programs/xfs/os/io.o
pushd xc/programs/xfs/os
make CDEBUGFLAGS=""
cd ..
rm xfs
make CDEBUGFLAGS=""
popd
%else

In the spec file from XFree86-3.3.3.1-49.src.rpm (source rpm from
RH6.0), it is there, too:

%build
%ifarch alpha
make World -C xc CDEBUGFLAGS="$RPM_OPT_FLAGS -Wa,-m21164a"
%else

Anyway, this just seemed kinda weird, so I thought I'd ask about it
(I'm sure I'll learn something).  Anybody know what is up with this?
Just seems like a bad idea to tell the assembler (in my case) the
wrong chip...

Thanks in advance,
Craig