https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82189
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-09-12
CC| |rguenth at gcc dot gnu.org
Blocks| |53947
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think what is missing is merging of two "vectors", aka, permutations of
different load chains:
/* Grouped store or load. */
if (STMT_VINFO_GROUPED_ACCESS (vinfo_for_stmt (stmt)))
{
if (REFERENCE_CLASS_P (lhs))
{
/* Store. */
;
}
else
{
/* Load. */
first_load = GROUP_FIRST_ELEMENT (vinfo_for_stmt (stmt));
if (prev_first_load)
{
/* Check that there are no loads from different interleaving
chains in the same node. */
if (prev_first_load != first_load)
{
if (dump_enabled_p ())
{
dump_printf_loc (MSG_MISSED_OPTIMIZATION,
vect_location,
"Build SLP failed: different "
"interleaving chains in one node ");
dump_gimple_stmt (MSG_MISSED_OPTIMIZATION, TDF_SLIM,
stmt, 0);
}
/* Mismatch. */
continue;
this is because we do not have a suitable way to represent those at the
moment. So we split the store group and get the two element vectorization.
As we don't have a good intermediate representation for SLP at the moment
we can't really perfomr post-detection "optimization" on the SLP tree.
unified autovect to the rescue...
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53947
[Bug 53947] [meta-bug] vectorizer missed-optimizations
