Tighten checks so we can see existing codegen 

The 2-element vector case shows a surprising bug: we failed to
eliminate ops on undefs, so there are 4 fmax calls even though
there can only be 2 valid elements in the inputs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254920 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed