lebedev.ri added inline comments.
================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp:1070
InstCombinerImpl &IC) {
if (!Cmp.hasOneUse() || !isa<Constant>(Cmp.getOperand(1)))
return nullptr;
----------------
nikic wrote:
> nikic wrote:
> > I'm wondering what to do about this one use check. Should we canonicalize
> > even if the compare has other uses?
> >
> > We are folding cmp+sub+select into abs or abs+sub. However, both cmp and
> > sub can potentially have extra uses.
> Here's how dropping the one use check would look like:
> https://gist.github.com/nikic/3dece504951cba82415fed2d6aa876bf
>
> Nominally, we are only increasing instruction count for the combination of
> nabs with extra uses on both icmp and sub.
I think we shouldn't have one-use checks here, yes.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87188/new/
https://reviews.llvm.org/D87188
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