Merge commit df08b2fe8b35 from llvm git (by Dimitry Andric):
[AArch64] Avoid crashing on invalid -Wa,-march= values
As reported in https://bugs.freebsd.org/260078, the gnutls Makefiles
pass -Wa,-march=all to compile a number of assembly files. Clang does
not support this -march value, but because of a mistake in handling
the arguments, an unitialized Arg pointer is dereferenced, which can
cause a segfault.
Work around this by adding a check if the local WaMArch variable is
initialized, and if so, using its value in the diagnostic message.
Reviewed By: tschuett
Differential Revision: https://reviews.llvm.org/D114677
PR: 260078
Reported by: bz
MFC after: 3 days
a9cd5c30d6