PEI: Skip dead objects when looking at CSRs

On AMDGPU if an SGPR is spilled to a VGPR, the frame index
is deleted. If there were any CSR SGPRs, this woudl
assert when setting the offset.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@301961 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed