[PATCH] D55787: [X86] Use UADDSAT/USUBSAT instead of ADDUS/SUBUS

Mon Dec 17 14:56:45 PST 2018

nikic marked 2 inline comments as done.
nikic added a comment.

In D55787#1333621 <https://reviews.llvm.org/D55787#1333621>, @RKSimon wrote:

> In D55787#1333569 <https://reviews.llvm.org/D55787#1333569>, @craig.topper wrote:
>
> > You’ll need to use an intrinsic to test the changes Simon asked for. The existing combines for X86 do their own split for AVX1.
>
>
> If that is going to be tricky you can just add a Subtarget->hasInt256() limit and a TODO comment.

I plan to add tests for llvm.uadd.sat/llvm.usub.sat with vectors, which are also going to exercise this case. We need those tests anyway :)

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https://reviews.llvm.org/D55787