DAGCombiner: Partially revert r192795, getNOT was fixed not to create illegal constants.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194959 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "Micro-optimization"

This reverts commit f1d9fe9d04ce93f6d5dcebbd2cb6a07414d7a029.

This was causing PR17964. We need to use thread data before regular data.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194960 91177308-0d34-0410-b5e6-96231b3b80d8
Testcase for PR17964

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194961 91177308-0d34-0410-b5e6-96231b3b80d8