We don't have a good way of legalizing this if the frame index offset
is more than the 12-bits, which is size of MUBUF's offset field, so
now we store the frame index in the vaddr field.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226584 91177308-0d34-0410-b5e6-96231b3b80d8
