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/* LoongArch CPU feature tuning.
This file is part of the GNU C Library.
Copyright (C) 2024 Free Software Foundation, Inc.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <stdbool.h>
#include <stdint.h>
#include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
#include <elf/dl-tunables.h>
#include <string.h>
#include <cpu-features.h>
#include <ldsodefs.h>
#include <sys/auxv.h>
#include <dl-tunables-parse.h>
#include <dl-symbol-redir-ifunc.h>
#define CHECK_GLIBC_IFUNC_CPU(f, name, len) \
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
if (tunable_str_comma_strcmp_cte (&f, #name)) \
{ \
if (f.disable) \
GLRO(dl_larch_cpu_features).hwcap &= (~HWCAP_LOONGARCH_##name); \
else \
GLRO(dl_larch_cpu_features).hwcap |= HWCAP_LOONGARCH_##name; \
break; \
}
attribute_hidden void
TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
{
/* The current IFUNC selection is based on microbenchmarks in glibc.
It should give the best performance for most workloads. But other
choices may have better performance for a particular workload or on
the hardware which wasn't available when the selection was made.
The environment variable:
GLIBC_TUNABLES=glibc.cpu.hwcaps=-xxx,yyy,-zzz,....
can be used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature
yyy and zzz, where the feature name is case-sensitive and has to
match the ones in cpu-features.h. It can be used by glibc developers
to tune for a new processor or override the IFUNC selection to
improve performance for a particular workload.
NOTE: the IFUNC selection may change over time. Please check all
multiarch implementations when experimenting. */
struct tunable_str_comma_state_t ts;
tunable_str_comma_init (&ts, valp);
struct tunable_str_comma_t n;
while (tunable_str_comma_next (&ts, &n))
{
switch (n.len)
{
default:
break;
case 3:
{
CHECK_GLIBC_IFUNC_CPU (n, LSX, 3);
CHECK_GLIBC_IFUNC_CPU (n, UAL, 3);
}
break;
case 4:
{
CHECK_GLIBC_IFUNC_CPU (n, LASX, 4);
}
break;
}
}
/* Ensure that the user has not enabled any unsupported features. */
GLRO(dl_larch_cpu_features).hwcap &= GLRO(dl_hwcap);
}
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