Compiling Xen on FreeBSD using clang ...

All,

As most of you are probably aware, Roger at Citrix R&D has been doing 
some incredible work to bring PVH domU/dom0 support to FreeBSD. There 
has also been an effort by other Xen developers to get the software to 
compile using clang. While most of these attempts appear to be on Linux 
platforms targeting arm processors, the FreeBSD version of binutils is 
quite a bit older. Clang still can't parse all of the assembly that Xen 
requires, so unfortunately the -no-integrated-as option has to be used 
in several cases.

Which brings me to my question, is there a way to ask clang to use the 
ports version of binutils when -no-integrated-as is passed to clang? The 
version of 'as' in base fails to compile such as ...

/tmp/misc-bf1339.s: Assembler messages:
/tmp/misc-bf1339.s:375: Error: unknown pseudo-op: `.cfi_sections'

If /usr/local/bin/as is symlinked to /usr/bin/as, the compile completes 
but I assume there is a better way to tell clang where the external as 
binary is when -no-integrated-as is invoked. I've googled a bunch but 
came up empty handed so far. I thought it would be worth asking here in 
case someone has already run across this problem and had more insight.

Thanks,

-Matthew