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lavu/riscv: add hwprobe() for CPU detection

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This adds the Linux-specific function call to detect CPU features. Unlike
the more portable auxillary vector, this supports extensions other than
single lettered ones. At this point, FFmpeg already needs this to detect
Zba and Zbb at run-time, and probably will need it for Zvbb in the near
future.

Support will be available in glibc 2.40 onward.
This commit is contained in:
Rémi Denis-Courmont 2023-11-18 22:09:57 +02:00
parent d7333ba6f2
commit 95d1052fba
2 changed files with 28 additions and 0 deletions
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3
configure vendored
View File

@ -2298,6 +2298,7 @@ HEADERS_LIST="
OpenGL_gl3_h
poll_h
pthread_np_h
sys_hwprobe_h
sys_param_h
sys_resource_h
sys_select_h
@ -5537,6 +5538,8 @@ elif enabled ppc; then
elif enabled riscv; then
check_headers sys/hwprobe.h
if test_cpp_condition stddef.h "__riscv_zbb"; then
enable fast_clz
fi

25
libavutil/riscv/cpu.c
View File

@ -18,8 +18,10 @@
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#define _GNU_SOURCE
#include "libavutil/cpu.h"
#include "libavutil/cpu_internal.h"
#include "libavutil/macros.h"
#include "libavutil/log.h"
#include "config.h"
@ -27,10 +29,33 @@
#include <sys/auxv.h>
#define HWCAP_RV(letter) (1ul << ((letter) - 'A'))
#endif
#ifdef HAVE_SYS_HWPROBE_H
#include <sys/hwprobe.h>
#endif
int ff_get_cpu_flags_riscv(void)
{
int ret = 0;
#ifdef HAVE_SYS_HWPROBE_H
struct riscv_hwprobe pairs[] = {
{ RISCV_HWPROBE_KEY_BASE_BEHAVIOR, 0 },
{ RISCV_HWPROBE_KEY_IMA_EXT_0, 0 },
};
if (__riscv_hwprobe(pairs, FF_ARRAY_ELEMS(pairs), 0, NULL, 0) == 0) {
if (pairs[0].value & RISCV_HWPROBE_BASE_BEHAVIOR_IMA)
ret |= AV_CPU_FLAG_RVI;
if (pairs[1].value & RISCV_HWPROBE_IMA_FD)
ret |= AV_CPU_FLAG_RVF | AV_CPU_FLAG_RVD;
if (pairs[1].value & RISCV_HWPROBE_IMA_V)
ret |= AV_CPU_FLAG_RVV_I32 | AV_CPU_FLAG_RVV_I64
| AV_CPU_FLAG_RVV_F32 | AV_CPU_FLAG_RVV_F64;
if (pairs[1].value & RISCV_HWPROBE_EXT_ZBA)
ret |= AV_CPU_FLAG_RVB_ADDR;
if (pairs[1].value & RISCV_HWPROBE_EXT_ZBB)
ret |= AV_CPU_FLAG_RVB_BASIC;
} else
#endif
#if HAVE_GETAUXVAL
{
const unsigned long hwcap = getauxval(AT_HWCAP);