http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49093
--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> 2011-05-31 08:22:51 UTC --- On Tue, 31 May 2011, irar at il dot ibm.com wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49093 > > Ira Rosen <irar at il dot ibm.com> changed: > > What |Removed |Added > ---------------------------------------------------------------------------- > CC| |irar at il dot ibm.com > > --- Comment #3 from Ira Rosen <irar at il dot ibm.com> 2011-05-31 07:31:02 > UTC --- > The problem here is that > vol.2_8 ={v} g_324[g_97_22]; > is skipped during determination of the vectorization factor, because it has no > uses. The vf is set to 4, and then the analysis fails on the char data-ref. > > I think we should just not vectorize when there is a volatile access in a > loop. > Is that reasonable? I think that's reasonable for 4.6. But we don't need to make data-ref analysis fail just because of volatile references - we for example can easily unroll a loop with volatile loads/stores. Of course this case seems to be special - how do we deal with stmts with no uses during vectorization? Or do we assume they don't happen because usually DCE gets rid of them? Richard.
