[PATCH] D96119: [Codegenprepare][X86] Use usub with overflow opt for IV increment

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev planned changes to this revision.
mkazantsev added a comment.

> I'd suggest tweaking this patch to add the hasOneUse check on the phi. With that change, I'd also LGTM this.

It won't pass a motivating test. Effectively, it doesn't really create a intersection of ranges of `IV` and `IV.next`, even if formally it does. In fact, comparison itself is the point where we compute something equivalent to `IV.next`. I'll write an elaborate comment explaining this.

Our internal testing has found a functional bug with this patch. I'm putting this on hold while investigating.


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