[Bug target/91520] AVX512 target assembler fails for x86_64 Darwin

[iains at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91520

--- Comment #5 from Iain Sandoe <iains at gcc dot gnu.org> ---
(In reply to Eric Gallager from comment #4)
> (In reply to Iain Sandoe from comment #1)
> > 
> > I plan on publishing an update to my alternate assembler/linker pair that
> > incorporates the changes from LLVM-9 and isn't dependent on the release
> > schedule for Xcode.
> 
> Have you published this update yet?

The back port is on my LLVM-7.1.1 branch on github - so if one builds the
"llas" tool (only need to build LLVM, it's not necessary to build clang or any
of the libs).

then you can use --with-as=/path/to/llas 

the tool follows cctools command line (plus some llvm additions).

Hopefully, I'll bring the 7.x stuff forward to 8.x and also add llas to 9 and
10.
(but the 7.1.1 llas is sufficient to bootstrap powerpc, i686 and x86-64).

Not sure why I mentioned the linker in this context, there are some useful
bug-fixes but not relevant to this PR.  Not sure if the LLVM fixes have made it
into Xcode yet (but that would only be relevant to 10.14+).