On Thu, Jun 06, 2019 at 06:14:29PM -0500, Segher Boessenkool wrote:
> Hi Mike,
>
> On Thu, Jun 06, 2019 at 06:42:16PM -0400, Michael Meissner wrote:
> > 2019-06-06 Michael Meissner <[email protected]>
> >
> > * config/rs6000/rs6000-cpus.def (ISA_FUTURE_MASKS_SERVER): Delete
> > enabling -mprefixed-addr and -mpcrel by default.
>
> Why disable prefixed-addr?
Convenience, but I could leave it in, since we don't yet have any prefixed
instruction support.
> > * config/rs6000/rs6000.c (rs6000_option_override_internal): Make
> > -mpcrel and -mprefixed-addr act like other swtiches (i.e. using
>
> Typo ("switches").
Thanks.
> > -mpcrel automatically sets -mcpu=future and -mprefixed-addr, and
>
> Automatically setting -mcpu= is a bad thing. Instead, we should just
> error out if someone tries to use -mpcrel with a CPU (or ABI, etc.) that
> doesn't support it. Or, is there any special reason you want it?
Well, I was trying to be consistant with the other things (-mpower9-vector
automaically sets all of the other power9 options). If you feel we don't need
the consistancy, I can remove that part of the patch.
As I mentioned elsewhere, there is a real problem with options specified on the
command line and pragma/attribute target (basically if you set -mpcrel on the
command line, and then do '#pragma GCC target ("cpu=power9")', it will
currently complain that -mfuture or -mcpu=future is not set. I wanted to do
the minimum patch so other people could start using the target.
> In the future, we will not have an -mprefixed-addr option (it will be
> always on for CPUs that support it), and I don't see any real reason
> to allow disabling pcrel either, but we'll see.
Well I suspect for at least several months we will need the ability to turn off
pc-relative support but allow the other future stuff.
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: [email protected], phone: +1 (978) 899-4797
