[PATCH] D69350: [ARM] Replace arm_neon_vqadds with sadd_sat

Sjoerd Meijer via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Tue Nov 12 01:21:07 PST 2019


SjoerdMeijer accepted this revision.
SjoerdMeijer added inline comments.
This revision is now accepted and ready to land.


================
Comment at: llvm/test/CodeGen/ARM/addsubo-legalization.ll:88
   %y = load <2 x i64>, <2 x i64>* %ptr2, align 8
   %s = call {<2 x i64>, <2 x i1>} @llvm.usub.with.overflow.v2i64(<2 x i64> %x, <2 x i64> %y)
   %m = extractvalue {<2 x i64>, <2 x i1>} %s, 0
----------------
dmgreen wrote:
> SjoerdMeijer wrote:
> > Nit, just curious why this one is unaffected. Looking at the changes below, I was perhaps expecting similar changes here.
> Good question. It looks like the default expansion for SADD/SUBO can go via a SADD/SUBSAT, but the UADD/SUBO prefers to go via ADD/SUBCARRY.
> 
> We could add expansion for UADDO to UADDSAT, but I think it's best not to do that here.
Cheers, agreed, LGTM


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D69350/new/

https://reviews.llvm.org/D69350





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