[ARM] Fix for PR36577
Don't PerformSHLSimplify if the given node is used by a node that
also uses a constant because we may get stuck in an infinite combine
loop.
bugzilla: https://bugs.llvm.org/show_bug.cgi?id=36577
Patch by Sam Parker.
Differential Revision: https://reviews.llvm.org/D44097
This fixes a hang when compiling one particular file in java/openjdk8
for armv6 and armv7.
Reported by: swills
PR: 226388
a3fedceefa