[PATCH] D56636: [CodeGen][X86] Expand vector USUBSAT to UMAX+SUB

Mon Jan 14 07:21:16 PST 2019

RKSimon accepted this revision.
RKSimon added a comment.
This revision is now accepted and ready to land.

In D56636#1356065 <https://reviews.llvm.org/D56636#1356065>, @nikic wrote:

> In D56636#1356032 <https://reviews.llvm.org/D56636#1356032>, @RKSimon wrote:
>
> > X86 vXi64 costs?
>
>
> I've added vXi64 costs only for AVX512, as pmaxuq wasn't available previously. Should I also add costs based on the broadcast+2*xor+cmpgt+blend+sub sequence we get if there is no native umax?

Actually, thinking about this more - we'd be better off doing the non-legal umax cases in the fallback generic cost code that I mentioned in PR40123. I think that can wait for a followup patch.

LGTM.

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