[PM/LoopUnswitch] Detect irreducible control flow within loops and skip unswitching non-trivial edges.
Summary:
This fixes the bug pointed out in review with non-trivial unswitching.
This also provides a basis that should make it pretty easy to finish
fleshing out a routine to scan an entire function body for irreducible
control flow, but this patch remains minimal for disabling loop
unswitch.
Reviewers: sanjoy, fedor.sergeev
Subscribers: mcrosier, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D45754
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330357 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed