[llvm-commits] [PATCH] Simplify ARM Neon vmull_n_* intrinsics.

[Chandler Carruth]

On Mon, Apr 23, 2012 at 11:18 PM, Lang Hames <lhames at gmail.com> wrote:

> Hi All,
>
> Could someone who's more familiar with InstCombine please take a look at
> this patch for me? It's meant to enable simplification of ARM neon
> vmull_n_* intrinsics by zext/sexting (as appropriate) their arguments so
> that they can be analyzed with SimplifyMulInst.
>

Rather than introducing zext/sext instructions, why not teach
SimplifyMulInst to look through the existing vmull_n_* intrinsics?


>
> It seems to fix my test case, but it has at least one issue: The sext/zext
> instructions hang around after InstSimplify if the vmull isn't simplified -
> I have to explicitly run DCE afterwards to get rid of them (see the output
> for the complex1 function in the test case for an example of this). Tips on
> the right way to solve this would be appreciated.
>
> Cheers,
> Lang.
>
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