Remove the LowerMMXCONCAT_VECTORS function. It could never execute because there are no legal 64-bit vector types that could be used as inputs to a 128-bit concat_vectors. Remove a target specific SDNode and its patterns that become unused as a result.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161742 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed