[PATCH] Make InstCombine aware of TargetTransformInfo when optimize extension

[David Majnemer]

On Tue, Jun 30, 2015 at 9:34 AM, Justin Holewinski <jholewinski at nvidia.com>
wrote:

>
> > On Jun 26, 2015, at 4:20 AM, Chandler Carruth <chandlerc at gmail.com>
> wrote:
> >
> > This doesn't seem like the right approach at all.
> >
> > I don't think we want to use cost heuristics to dictate the canonical
> form in the IR. It makes the canonicalization *much* more complex and hard
> to manage.
>
> I agree.  I would prefer not to mix the concepts of legality and
> performance here.
>
> >
> > I think that NVPTX should either change the datalayout to make i64
> illegal (and that seems reasonable for instcombine to respect, but that
> would for example mean it would be an *absolute* decision, not a cost
> decision) or you'll need to do a late transform to narrow the operations as
> much as possible.
>
> I don’t see how we could remove i64 as a legal type in NVPTX.  Our pointer
> size is 64-bit, so we need a container for pointers.
>

I think other folks are doing (or would like to be doing) this sort of
thing: http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-June/087248.html


>
> >
> >
> > http://reviews.llvm.org/D10750
> >
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