transformation much more careful. Truncating binary '01' to '1' sounds like it's
safe until you realize that it switched from positive to negative under a signed
interpretation, and that depends on the icmp predicate.
Also a few miscellaneous cleanups.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97721 91177308-0d34-0410-b5e6-96231b3b80d8
