When computing the demanded bits of Load SDNodes, make sure that we are looking at the loaded-value operand and not the ptr result (in case of pre-inc loads).
rdar://13348420



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177596 91177308-0d34-0410-b5e6-96231b3b80d8