Preserve assumption cache in loop-rotate.

No testcase included because I can't figure out how to reduce it.
(It's easy to write a testcase where rotation clones an assume,
but that doesn't actually seem to trigger the crash in opt on
its own; maybe an issue with the laziness?)

Differential Revision: https://reviews.llvm.org/D26434



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286410 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed