[X86][SSE] Add support for combining target shuffles to MOVSS/MOVSD

Only do this on pre-SSE41 targets where we should be lowering to BLENDPS/BLENDPD instead

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278228 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed