https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104015
Kewen Lin <linkw at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
CC| |rguenth at gcc dot gnu.org,
| |rsandifo at gcc dot gnu.org
Assignee|unassigned at gcc dot gnu.org |linkw at gcc dot gnu.org
--- Comment #2 from Kewen Lin <linkw at gcc dot gnu.org> ---
With further investigation, this isn't duplicated. Now we have the function
partial_vectors_supported_p to get boolean supports_partial_vectors.
on rs6000, it's:
bool
partial_vectors_supported_p (void)
{
return HAVE_len_load_v16qi || HAVE_len_store_v16qi;
}
#define HAVE_len_load_v16qi (TARGET_P9_VECTOR && TARGET_64BIT)
#define HAVE_len_store_v16qi (TARGET_P9_VECTOR && TARGET_64BIT)
The above optabs are supported from Power9 already.
However, we only enable it from Power10 due to known performance issue on
Power9.
/* The lxvl/stxvl instructions don't perform well before Power10. */
if (TARGET_POWER10)
SET_OPTION_IF_UNSET (&global_options, &global_options_set,
param_vect_partial_vector_usage, 1);
else
SET_OPTION_IF_UNSET (&global_options, &global_options_set,
param_vect_partial_vector_usage, 0);
So checking optab supports look not robust.
I had a check with the below fix, it works:
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index ba67de490bb..49d53fb3383 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -3026,7 +3026,8 @@ vect_analyze_loop (class loop *loop, vec_info_shared
*shared)
vector_modes[0] = autodetected_vector_mode;
mode_i = 0;
- bool supports_partial_vectors = partial_vectors_supported_p ();
+ bool supports_partial_vectors =
+ partial_vectors_supported_p () && param_vect_partial_vector_usage != 0;
poly_uint64 first_vinfo_vf = LOOP_VINFO_VECT_FACTOR (first_loop_vinfo);
while (1)
But, is there some reason not use the LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P of
first_loop_vinfo? It respects param_vect_partial_vector_usage and checks
partial vector supports (LOOP_VINFO_MASKS and LOOP_VINFO_LENS) during the
analysis phase, it looks good fit for this need of supports_partial_vectors.
