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avutil: use getauxval(3) for CPU capabilities on linux/android ARM

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getauxval is marginally faster, and works even when procfs is not mounted

support on Linux was added in glibc 2.16
support on Android was added in 4.4 (API 20)
fixes #6578

Signed-off-by: Aman Karmani <aman@tmm1.net>
This commit is contained in:
Aman Karmani 2022-02-04 12:14:57 -08:00
parent 04cc7a5548
commit 2f299c0b8b
2 changed files with 22 additions and 3 deletions
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1
configure vendored
View File

@ -6261,6 +6261,7 @@ check_func_headers lzo/lzo1x.h lzo1x_999_compress
check_func_headers mach/mach_time.h mach_absolute_time
check_func_headers stdlib.h getenv
check_func_headers sys/stat.h lstat
check_func_headers sys/auxv.h getauxval
check_func_headers windows.h GetModuleHandle
check_func_headers windows.h GetProcessAffinityMask

24
libavutil/arm/cpu.c
View File

@ -38,6 +38,10 @@
#include <string.h>
#include "libavutil/avstring.h"
#if HAVE_GETAUXVAL
#include <sys/auxv.h>
#endif
#define AT_HWCAP 16
/* Relevant HWCAP values from kernel headers */
@ -48,6 +52,19 @@
#define HWCAP_VFPv3 (1 << 13)
#define HWCAP_TLS (1 << 15)
static int get_auxval(uint32_t *hwcap)
{
#if HAVE_GETAUXVAL
unsigned long ret = getauxval(AT_HWCAP);
if (ret == 0)
return -1;
*hwcap = ret;
return 0;
#else
return -1;
#endif
}
static int get_hwcap(uint32_t *hwcap)
{
struct { uint32_t a_type; uint32_t a_val; } auxv;
@ -106,9 +123,10 @@ int ff_get_cpu_flags_arm(void)
int flags = CORE_CPU_FLAGS;
uint32_t hwcap;
if (get_hwcap(&hwcap) < 0)
if (get_cpuinfo(&hwcap) < 0)
return flags;
if (get_auxval(&hwcap) < 0)
if (get_hwcap(&hwcap) < 0)
if (get_cpuinfo(&hwcap) < 0)
return flags;
#define check_cap(cap, flag) do { \
if (hwcap & HWCAP_ ## cap) \