[PATCH] D11026: [ARM] Define subtarget feature "dont-use-movt" to disallow emitting movt/movw pairs

[Akira Hatanaka]

I think those names look better than "dont-use-movt".

On Thu, Jul 9, 2015 at 8:53 AM, Duncan P. N. Exon Smith <
dexonsmith at apple.com> wrote:

>
> > On 2015-Jul-08, at 16:16, Akira Hatanaka <ahatanak at gmail.com> wrote:
> >
> >
> >> On 2015-Jul-08, at 13:52, Eric Christopher <echristo at gmail.com> wrote:
> >>
> >> Let's have the feature be a positive feature that just happens to be on
> by default in a lot of places. +/-dont-use-movt seems weird.
> >>
> > Do you mean I should replace ARMSubtarget::DontUseMovt with
> ARMSubtarget::UseMovt which is true by default? That should work.
> >
> > Or do you mean we should use FeatureUseMovt :
> SubtargetFeature<"use-movt"> instead of
> FeatureDontUseMovt<"dont-use-movt">? If I understand correctly how
> subtarget features work, I think that would require clang (and other
> front-ends) to add feature "+use-movt" whenever we want to allow emitting
> movt/movw pairs as opposed to adding "+dont-use-movt" only when we want to
> disallow doing so. Assuming you would want to allow movt/movw pairs in the
> common case, wouldn't it be better to use a negative feature?
>
> Maybe there's another negative name that isn't as strange.  Something
> like "avoid-movt" or "no-movt"?
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