https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61680
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work|4.10.0 |5.0
--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
For 4.8 we can't backport the patch as group analysis and dependence analysis
are still the wrong way around. A simple
Index: gcc/tree-vect-data-refs.c
===================================================================
--- gcc/tree-vect-data-refs.c (revision 215073)
+++ gcc/tree-vect-data-refs.c (working copy)
@@ -2307,6 +2307,17 @@ vect_analyze_group_access (struct data_r
while (next)
{
+ /* Check that there is no load-store dependencies for this loads
+ to prevent a case of load-store-load to the same location. */
+ if (GROUP_READ_WRITE_DEPENDENCE (vinfo_for_stmt (next))
+ || GROUP_READ_WRITE_DEPENDENCE (vinfo_for_stmt (prev)))
+ {
+ if (dump_enabled_p ())
+ dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+ "READ_WRITE dependence in interleaving.");
+ return false;
+ }
+
/* Skip same data-refs. In case that two or more stmts share
data-ref (supported only for loads), we vectorize only the first
stmt, and the rest get their vectorized loads from the first
@@ -2323,17 +2334,6 @@ vect_analyze_group_access (struct data_r
return false;
}
- /* Check that there is no load-store dependencies for this loads
- to prevent a case of load-store-load to the same location.
*/
- if (GROUP_READ_WRITE_DEPENDENCE (vinfo_for_stmt (next))
- || GROUP_READ_WRITE_DEPENDENCE (vinfo_for_stmt (prev)))
- {
- if (dump_enabled_p ())
- dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
- "READ_WRITE dependence in
interleaving.");
- return false;
- }
-
/* For load use the same data-ref load. */
GROUP_SAME_DR_STMT (vinfo_for_stmt (next)) = prev;
will regress testcases in vect.exp.
Like with two other 4.8 vectorizer miscompiles it's hard to fix them without
turning the vectorizer upside down (aka backport most of the re-org
from GCC 4.9).
