[AMDGPU] Consider loads from flat addrspace to be potentially divergent

In general we can't assume flat loads are uniform, and cases where we can prove
they are should be handled through infer-address-spaces.

Differential Revision: https://reviews.llvm.org/D50991



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340343 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed