Alternatives for outdated assembler (AS)?

[Joshua Root]

> $ export AS=/Applications/Xcode.app/Contents/Developer//Toolchains/XcodeDefault.xctoolchain/usr/bin/as

FYI, that is the same Apple fork of an ancient version of GNU as that
you would have at /usr/bin/as. But it doesn't look like the build system
you are using does anything different in response to AS being set in the
environment.

So it looks like you've been using the LLVM assembler all along. Either
your inline asm is using some less-common syntax that LLVM hasn't got
around to implementing yet, or it's just invalid and GNU as happens to
accept it anyway. (We saw a fair bit of the latter during the transition
to clang.)

- Josh