[cfe-dev] Clang -Wa options (for integrated as)

[Renato Golin]

Folks,

Two bugs related -Wa option parsing in Clang that I could just easily
add them one after the other, but I wanted to ask for your opinion
first, as I don't even know where to start if not doing the obvious
fix.

http://llvm.org/bugs/show_bug.cgi?id=20339
http://llvm.org/bugs/show_bug.cgi?id=20700

These two bugs show that -Wa option doesn't accept much, and a look at
the driver code show me that "static void
CollectArgsForIntegratedAssembler()" is incomplete, to say the least.

The questions that pop to mind are:

1. If I just want to add a new options to "allow" default behaviour to
ignore its own flag (like -mimplitic-it=arm) and warn on improper use
or missing features (like the work around for PR20700), would that be
a good idea?

2. To implement -mfpu, I'd either have to re-use the current FPU
parsing (which is not yet centralised), or I could leave that parsing
to the underlying assembler. If that's so, do we try to validate here?
Or do we ignore any unknown syntax and just hope the receiving end
will validate and warn/error?

3. Clang basically ignores anything passed down to gas and only
validates things for the integrated assembler, shouldn't we have
similar behaviour and actually validate in our assembler?

cheers,
--renato