https://gcc.gnu.org/g:abeeccef92892fe519cc417b30ae22ce9da2d5e6
commit r15-3261-gabeeccef92892fe519cc417b30ae22ce9da2d5e6
Author: Richard Sandiford <richard.sandif...@arm.com>
Date: Wed Aug 28 16:41:09 2024 +0100
aarch64: Assume zero gather/scatter set-up cost for -mtune=generic
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.
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.
Diff:
---
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 101969bdbb9c..ee2f3ff42663 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 */
};
