[PATCH] D14234: [ARM] Recognize bit-reversal idioms

[James Molloy via llvm-commits]

OK, then I have a better idea: let's do it in instcombine.

Instcombine already does stuff like this for byteswaps -  it should be
possible to make it cover this case too. Instcombine is also a better place
to cover the bittwiddling hacks Joerg mentioned. I only discounted it
originally because I felt this was too ARM specific to plumb right the way
through the midend.

Does this sound alright?

On Mon, 2 Nov 2015 at 20:22 Matt Arsenault via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> arsenm added a comment.
>
> In http://reviews.llvm.org/D14234#279410, @jmolloy wrote:
>
> > Hi Matt,
> >
> > Sure. That's certainly a possibility. Does your target have a similar
> instruction?
> >
> > James
>
>
> Yes, AMDGPU has a bitreverse instruction
>
>
> Repository:
>   rL LLVM
>
> http://reviews.llvm.org/D14234
>
>
>
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