[PATCH] D34619: [ARM] Enable partial and runtime unrolling

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

There are two kinds of SCEV expressions which are not invariant: SCEVAddRecExpr, and SCEVUnknown.  If you have a SCEVAddRecExpr, you can show the loop nest is similar to your testcase, and I guess that might change the profitability of unrolling.  If you have a SCEVUnknown, I can't see how you would conclude anything useful; there's a strong possibility the trip count is actually constant, but the compiler can't prove it because of aliasing or something like that.


https://reviews.llvm.org/D34619