https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113576
--- Comment #15 from Richard Biener <rguenth at gcc dot gnu.org> --- (In reply to Richard Sandiford from comment #13) > I don't think there's any principle that upper bits must be zero. > How do we end up with a pattern that depends on that being the case? I think the problem is the cbranch pattern which looks at all of the QImode mask - but of course it doesn't know it's really V4BImode it's working on ... If there's no principle that the upper bits should be zero I think we need a way for the target to say so.
