[X86] Add masked variable tests for funnel undef/zero argument combines

I've avoided 'modulo' masks as we'll SimplifyDemandedBits those in the future, and we just need to check that the shift variable is 'in range'

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353644 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed