[x86] add smin/smax with zero tests

These are vector tests corresponding to the discussion at:
http://lists.llvm.org/pipermail/llvm-dev/2016-November/106868.html

Apart from the lack of min/max matching, the and/andn difference 
shows a lack of DAG-level canonicalization.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286737 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed