[PATCH] D39228: [SCEV] Enhance SCEVFindUnsafe for division

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev added a comment.

Hi Evgeny!

I see the difference before the LSR: for the last loop, in the `*** IR Dump Before Loop Strength Reduction ***` section we have two more Phis. It has two more Phis and more instructions in body (with repeating pattern). Most likely it is unrolling changed the number of unrolled iterations.

For first two loops, in one case it just changed iteration space from 0->len to len->0 which shouldn't have significant performance impact; in another case nothing changed but variable name.

So I believe that problem dwells before LSR, most likely in unrolling.


Repository:
  rL LLVM

https://reviews.llvm.org/D39228