Since d6de1e1a71406c75a4ea4d5a2fe84289f07ea3a1, no attributes is quivalent to
setting attribute to false.
This is a preliminary commit for https://reviews.llvm.org/D99080
Refactored parts of the hardware loop pass to generate
more. Also, added more tests.
Differential Revision: http://reviews.llvm.org/D9568
llvm-svn: 236896