https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122938
Bug ID: 122938
Summary: vect: No fallback to non-partial vect when
IFN_LEN_FOLD_EXTRACT_LAST is available.
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rdapp at gcc dot gnu.org
Target Milestone: ---
Target: riscv
Haven't done any analysis, just filing for bookkeeping so I have something to
refer to in the source (not yet upstream).
When riscv VLS modes for load/store and len_fold_extract_last in particular are
available vect/vect-cond-2.c is not vectorized anymore.
If the optab is not available we do
else if (!nested_cycle_p)
{
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
"conditional reduction prevents the use"
" of partial vectors.\n");
LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo) = false;
and fall back to non-partial vectors, vectorizing the loop.
If it is available we fail to analyze a part of the reduction and give up.
Will fill in more information here once I get to it.
