[X86][SSE] Add v2f64 u2 shuffle test

Adds missing coverage for SHUFPD undef argument lowering, and also shows a missed opportunity to remove a unnecessary move compared to 02 shuffle mask.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@322175 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed