[Bug target/55181] [4.7/4.8 Regression] Expensive shift loop where a bit-testing instruction could be used

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55181

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> 2013-03-06 08:51:30 UTC ---
Note that a bit-test instruction can only be used if the and only feeds a
comparison against zero.  Not sure how canonical bit-test patterns should
look like, but combine should be able to work this out, no?  Unless we
mess things up earlier during generic expansion (which seems to be the
case)