[X86] Add support for lowering v4i64 and v8i64 shuffles directly to PALIGNR. I think shuffle combine can figure it out later, but we should try to get it right up front.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@284914 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed