[PATCH] Teach DAGCombiner to fold inverted bit tests

[David Majnemer]

It cannot go into InstCombine because then it would be in a
non-canonical form, SimplifyDemandedUseBits will undo the operation.


On Mon, May 6, 2013 at 11:05 AM, Rafael Espíndola <
rafael.espindola at gmail.com> wrote:

> since this reduces the occurrences of 'y', shouldn't it be in instcombine?
>
> On 6 May 2013 01:25, David Majnemer <david.majnemer at gmail.com> wrote:
> > This patch changes DAGCombiner to do the following:
> >   (xor (and x, y), y) -> (and (not x), y)
> >
> > This is nice because we avoid emitting an immediate twice for tagets like
> > X86.
> >
> > --
> > David Majnemer
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> >
>
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