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Improve ARM runtime feature detection on Linux

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getauxval(AT_HWCAP) is the best way to check for features on ARM and
AArch64, as it doesn’t require parsing a file, instead it just returns a
value provided by the kernel in our address space.
This commit is contained in:
Emmanuel Gil Peyrot 2020-11-03 23:28:20 +00:00
parent 0e820dee9b
commit 567cfc00d8
1 changed files with 20 additions and 0 deletions
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20
features/features_cpu.c
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@ -337,8 +337,27 @@ static void arm_enable_runfast_mode(void)
#endif
#if defined(__linux__) && !defined(CPU_X86)
#if __ARM_ARCH
#include <sys/auxv.h>
#endif
static unsigned char check_arm_cpu_feature(const char* feature)
{
#if __ARM_ARCH < 8
uint64_t hwcap = getauxval(AT_HWCAP);
if (!strcmp(feature, "neon"))
return (hwcap & HWCAP_ARM_NEON) != 0;
if (!strcmp(feature, "vfpv3"))
return (hwcap & HWCAP_ARM_VFPv3) != 0;
if (!strcmp(feature, "vfpv4"))
return (hwcap & HWCAP_ARM_VFPv4) != 0;
return 0;
#elif __ARM_ARCH == 8
uint64_t hwcap = getauxval(AT_HWCAP);
if (!strcmp(feature, "asimd"))
return (hwcap & HWCAP_ASIMD) != 0;
return 0;
#else
char line[1024];
unsigned char status = 0;
RFILE *fp = filestream_open("/proc/cpuinfo",
@ -362,6 +381,7 @@ static unsigned char check_arm_cpu_feature(const char* feature)
filestream_close(fp);
return status;
#endif
}
#if !defined(_SC_NPROCESSORS_ONLN)