generic_vector_cost is not currently used by any SVE target
by default; it has to be specifically selected by -mtune=generic.
Its SVE costing has historically been somewhat idealised, since
it predated any actual SVE cores. This seems like a useful
tradition to continue, at least for testing purposes.
The ideal case is that gathers and scatters do not induce a specific
one-off overhead. This patch therefore sets the gather/scatter init
costs to zero.
This patch is necessary to switch -mtune=generic over to the
"new" vector costs.
Tested on aarch64-linux-gnu. Pushed as previously agreed with
Tamar and Kyrill.
Richard
gcc/
* config/aarch64/tuning_models/generic.h (generic_sve_vector_cost):
Set gather_load_x32_init_cost and gather_load_x64_init_cost to 0.
---
gcc/config/aarch64/tuning_models/generic.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/gcc/config/aarch64/tuning_models/generic.h
b/gcc/config/aarch64/tuning_models/generic.h
index 101969bdbb9..ee2f3ff4266 100644
--- a/gcc/config/aarch64/tuning_models/generic.h
+++ b/gcc/config/aarch64/tuning_models/generic.h
@@ -105,8 +105,8 @@ static const sve_vec_cost generic_sve_vector_cost =
2, /* fadda_f64_cost */
4, /* gather_load_x32_cost */
2, /* gather_load_x64_cost */
- 12, /* gather_load_x32_init_cost */
- 4, /* gather_load_x64_init_cost */
+ 0, /* gather_load_x32_init_cost */
+ 0, /* gather_load_x64_init_cost */
1 /* scatter_store_elt_cost */
};
--
2.25.1
