[Bug driver/81519] Enhancement: Add --help=target-distcc or similar to dump clean, optimal CFLAGS without using -march=native

["daniel.santos at pobox dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81519

--- Comment #7 from Daniel Santos <daniel.santos at pobox dot com> ---
(In reply to Martin Liška from comment #4)
> Ok, so I've briefly investigated source code and providing such information
> is definitely not a simple task :/
> 
> I would recommend to fix PR39851 and then one will just compare output of
> following 2 invocations:
> 
> gcc --help=target  -Q
> gcc --help=target -march=native -Q 
> 
> Will it work for you?
> 
> Note that fully understand which ISA extensions are enable when is also
> quite complex.

I've thought about this some more and I'm starting to think that all of this
can be determined with a script that iteratively calls gcc --help=target -Q
with various machine flags to determine which -mno-* flags are really needed
and which -m<isa> flags include others.  So in effect, I'm thinking that we can
produce optimal C(XX)FLAGS with a script and your PR39851 fix.  I'll have to
test this out.

Thanks