http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37780
--- Comment #2 from amker.cheng <amker.cheng at gmail dot com> 2012-03-20 07:58:09 UTC --- the special case could be easily detected when gimplifying. but actually I am not sure whether it can be done even in middle end, since the middle end should not depend on any target information, like CLZ_DEFINED_VALUE_AT_ZERO, right?
