[PATCH] D57377: [CGP] Add support for sinking operands to their users, if they are free.

Fri Feb 1 06:16:28 PST 2019

fhahn added a comment.

In D57377#1377221 <https://reviews.llvm.org/D57377#1377221>, @spatel wrote:

> We already have various sinking transforms in CGP, so this is the right approach IMO. I do wonder if we could adapt the existing (cmp/and-mask/etc) sinking that we already have in CGP to use this hook as a refinement, but that can be a follow-up of this patch.

Thanks, I'll take a look at that as a follow-up.

> I'm not sure yet if/how we'd use this with x86 shuffles, but there's always hope. :)

It is not really related to shuffles, but rather to any operations that could be done for free with a target instruction.

> You might be interested in looking at some recent DAGCombiner and x86 patches that are motivated by narrowing the width of vector ops and shuffles:
>  D55126 <https://reviews.llvm.org/D55126>
>  D55866 <https://reviews.llvm.org/D55866>
>  D56604 <https://reviews.llvm.org/D56604>
>  D56875 <https://reviews.llvm.org/D56875>
>  D57156 <https://reviews.llvm.org/D57156>
>  D57336 <https://reviews.llvm.org/D57336>

Great, those look quite useful!

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https://reviews.llvm.org/D57377