On Tue, Jul 5, 2011 at 2:35 AM, Richard Guenther <rguent...@suse.de> wrote: > On Tue, 5 Jul 2011, Ira Rosen wrote: > >> Richard Guenther <rguent...@suse.de> wrote on 04/07/2011 03:30:59 PM: >> > > >> > > Richard Guenther <rguent...@suse.de> wrote on 04/07/2011 02:38:50 PM: >> > > >> > > > Handling of negative steps broke one of the many asserts in >> > > > the vectorizer. The following patch drops one that I can't >> > > > make sense of. I think all asserts need comments - especially >> > > > this one would, as I can't see why using vf is correct to >> > > > test against and not nelements (and why <= vf and not < vf). >> > > >> > > There is an explanation 10 rows above the assert. It doesn't make sense >> to >> > > peel more than vf iterations (and not nelements, since for the case of >> > > multiple types it may help to align more data-refs - see the comment in >> the >> > > code). IIRC <= is for the case of aligned access, but I am not sure >> about >> > > that, so maybe you are right. >> > > >> > > I don't see how it is related to negative steps. >> > > >> > > I think that the real reason for this failure is that the loads are >> > > actually irrelevant (hence, vf=4 that doesn't take char loads into >> > > account), but we don't check that when we analyze data-refs. So, in my >> > > opinion, the proper fix will add such check. >> > >> > The following also works for me: >> > >> > Index: tree-vect-data-refs.c >> > =================================================================== >> > --- tree-vect-data-refs.c (revision 175802) >> > +++ tree-vect-data-refs.c (working copy) >> > @@ -1495,6 +1495,9 @@ vect_enhance_data_refs_alignment (loop_v >> > stmt = DR_STMT (dr); >> > stmt_info = vinfo_for_stmt (stmt); >> > >> > + if (!STMT_VINFO_RELEVANT (stmt_info)) >> > + continue; >> > + >> > /* For interleaving, only the alignment of the first access >> > matters. */ >> > if (STMT_VINFO_STRIDED_ACCESS (stmt_info) >> > >> > does that look better or do you propose to clean the datarefs >> > vector from those references? >> >> Well, this is certainly enough to fix the PR. >> I am not sure if we can just remove these data-refs from the dependence >> checks. After that all the alignment and access checks are at least >> redundant. > > Ok. The following is what I have tested for this PR and also for > PR49628. > > Bootstrapped and tested on x86_64-unknown-linux-gnu, ok for trunk? > > Thanks, > Richard. > > 2011-07-04 Richard Guenther <rguent...@suse.de> > > PR tree-optimization/49518 > PR tree-optimization/49628 > * tree-vect-data-refs.c (vect_enhance_data_refs_alignment): Skip > irrelevant and invariant data-references. > (vect_analyze_data_ref_access): For invariant loads clear the > group association. > > * g++.dg/torture/pr49628.C: New testcase. > * gcc.dg/torture/pr49518.c: Likewise. >
This caused: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50017 -- H.J.
