AMDGPU/SI: Fix LowerParameter() for i16 arguments

Summary:
If we are loading an i16 value from a 32-bit memory location, then
we need to be able to truncate the loaded value to i16.

Reviewers: arsenm

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, tony-tye, llvm-commits

Differential Revision: https://reviews.llvm.org/D25198

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@284397 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed