http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49628
Ira Rosen <irar at il dot ibm.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |irar at il dot ibm.com
--- Comment #5 from Ira Rosen <irar at il dot ibm.com> 2011-07-05 06:43:18 UTC
---
(In reply to comment #4)
> I wonder where we are supposed to set GROUP_SIZE here
In vect_analyze_data_ref_access(),
but your patch does this:
/* Allow invariant loads in loops. */
if (loop_vinfo && dr_step == 0)
return DR_IS_READ (dr);
preventing detection of interleaving groups for invariant loads. Which is ok,
since you don't support them anyway.
> and how it possibly
> can connect to my change ... ah, the invariant loads from __x_copy.values
> no longer will inhibit vectorization early. The group is now indeed
> the __x_copy.values[] loads.
>
> The following fixes it (or rather, avoids looking at this group):
I think this change is correct, there is indeed nothing to enhance.
But this case revealed a problem in STMT_VINFO_STRIDED_ACCESS - it only checks
that the interleaving chain exists, but even if it exists, the access analysis
can later fail, so we should also check the group size:
Index: tree-vectorizer.h
===================================================================
--- tree-vectorizer.h (revision 175681)
+++ tree-vectorizer.h (working copy)
@@ -545,7 +547,7 @@ typedef struct _stmt_vec_info {
#define STMT_VINFO_GROUP_GAP(S) (S)->gap
#define STMT_VINFO_GROUP_SAME_DR_STMT(S) (S)->same_dr_stmt
#define STMT_VINFO_GROUP_READ_WRITE_DEPENDENCE(S) (S)->read_write_dep
-#define STMT_VINFO_STRIDED_ACCESS(S) ((S)->first_element != NULL &&
(S)->data_ref_info)
+#define STMT_VINFO_STRIDED_ACCESS(S) ((S)->first_element != NULL &&
(S)->data_ref_info && (S)->size > 0)
#define GROUP_FIRST_ELEMENT(S) (S)->first_element
#define GROUP_NEXT_ELEMENT(S) (S)->next_element
Thanks,
Ira
>
> Index: gcc/tree-vect-data-refs.c
> ===================================================================
> --- gcc/tree-vect-data-refs.c (revision 175802)
> +++ gcc/tree-vect-data-refs.c (working copy)
> @@ -1495,12 +1495,19 @@ vect_enhance_data_refs_alignment (loop_v
> && GROUP_FIRST_ELEMENT (stmt_info) != stmt)
> continue;
>
> + /* For invariant accesses there is nothing to enhance. */
> + if (integer_zerop (DR_STEP (dr)))
> + continue;
> +
> supportable_dr_alignment = vect_supportable_dr_alignment (dr, true);
> do_peeling = vector_alignment_reachable_p (dr);
> if (do_peeling)
