[X86][SSE] Add extra v16i16 shl x,c -> pmullw test

We want to compare shifts with repeated vs non-repeated v8i16 shuffle masks (for PBLENDW ymm) 

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336333 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed