These will be widened in the DAG. In the meanwhile early
widening prevents otherwise possible vectorization of
such loads.
Differential Revision: https://reviews.llvm.org/D77835
Preserves the low bound of the !range. I don't think
it's legal to do anything with the top half since it's
theoretically reading garbage.
llvm-svn: 334045
Stanislav Mekhanoshin