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

[Eric Christopher]

They do. I was asking for a positive feature rather than a negative one
just to keep a decent lattice of adding features to a function - that said,
I don't think this will get in the way too much. Go ahead and pick the name
that sounds least bad and go for it :)

-eric

On Thu, Jul 9, 2015 at 11:48 AM Akira Hatanaka <ahatanak at gmail.com> wrote:

> 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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