Mips: Remove immarg from copy and insert intrinsics
These intrinsics do in fact work with non-constant index arguments.
These are lowered to either the generic
ISD::INSERT_VECTOR_ELT/ISD::EXTRACT_VECTOR_ELT, or to
VEXTRACT_SEXT_ELT. The handling of these all accept variable
indexes. Turning these into generic instructions which do allow
variables introduces complications in a future change to immarg
handling.
Since these just turn into generic instructions, these are kind of
pointless and should probably just be autoupgraded to
extractelement/insertelement.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@366328
91177308-0d34-0410-b5e6-
96231b3b80d8