LSV: Fix adjust alloca alignment trick for AMDGPU

This was checking the hardcoded address space 0 for the stack.
Additionally, this should be checking for legality with
the adjusted alignment, so defer the alignment check.

Also try to split if the unaligned access isn't allowed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342442 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed