Summary:
We don't have sign-/zero-extending ldg/ldu instructions defined,
so we need to emulate them with explicit CVTs. We were originally
handling the i8 case, but not any other cases.
Fixes PR26185
Reviewers: jingyue, jlebar
Subscribers: jholewinski
Differential Revision: http://reviews.llvm.org/D19615
llvm-svn: 268272