Based partially on code by Janne Grunau.
---
Updated to use both the direct HWCAP* macros and HWCAP_CPUID. A
not unreasonably old distribution like Ubuntu 20.04 does have
HWCAP_CPUID but not HWCAP2_I8MM in the distribution provided headers.
Alternatively I guess we could carry our own fallback hardcoded values
for the HWCAP* values we use and skip HWCAP_CPUID.
---
configure | 2 ++
libavutil/aarch64/cpu.c | 63 +++++++++++++++++++++++++++++++++++++++++
2 files changed, 65 insertions(+)
diff --git a/configure b/configure
index 50eb27ba0e..b39de74de5 100755
--- a/configure
+++ b/configure
@@ -2209,6 +2209,7 @@ HAVE_LIST_PUB="
HEADERS_LIST="
arpa_inet_h
+ asm_hwcap_h
asm_types_h
cdio_paranoia_h
cdio_paranoia_paranoia_h
@@ -6432,6 +6433,7 @@ check_headers io.h
enabled libdrm &&
check_headers linux/dma-buf.h
+check_headers asm/hwcap.h
check_headers linux/perf_event.h
check_headers libcrystalhd/libcrystalhd_if.h
check_headers malloc.h
diff --git a/libavutil/aarch64/cpu.c b/libavutil/aarch64/cpu.c
index 0c76f5ad15..4563959ffd 100644
--- a/libavutil/aarch64/cpu.c
+++ b/libavutil/aarch64/cpu.c
@@ -20,6 +20,67 @@
#include "libavutil/cpu_internal.h"
#include "config.h"
+#if (defined(__linux__) || defined(__ANDROID__)) && HAVE_GETAUXVAL &&
HAVE_ASM_HWCAP_H
+#include <stdint.h>
+#include <asm/hwcap.h>
+#include <sys/auxv.h>
+
+#define get_cpu_feature_reg(reg, val) \
+ __asm__("mrs %0, " #reg : "=r" (val))
+
+static int detect_flags(void)
+{
+ int flags = 0;
+ unsigned long hwcap, hwcap2;
+
+ // Check for support using direct individual HWCAPs
+ hwcap = getauxval(AT_HWCAP);
+#ifdef HWCAP_ASIMDDP
+ if (hwcap & HWCAP_ASIMDDP)
+ flags |= AV_CPU_FLAG_DOTPROD;
+#endif
+
+#ifdef AT_HWCAP2
+ hwcap2 = getauxval(AT_HWCAP2);
+#ifdef HWCAP2_I8MM
+ if (hwcap2 & HWCAP2_I8MM)
+ flags |= AV_CPU_FLAG_I8MM;
+#endif
+#endif
+
+ // Silence warnings if none of the hwcaps to check are known.
+ (void)hwcap;
+ (void)hwcap2;
+
+#if defined(HWCAP_CPUID)
+ // The HWCAP_* defines for individual extensions may become available
late, as
+ // they require updates to userland headers. As a fallback, see if we can
access
+ // the CPUID registers (trapped via the kernel).
+ // See
https://www.kernel.org/doc/html/latest/arm64/cpu-feature-registers.html
+ if (hwcap & HWCAP_CPUID) {
+ uint64_t tmp;
+
+ get_cpu_feature_reg(ID_AA64ISAR0_EL1, tmp);
+ if (((tmp >> 44) & 0xf) == 0x1)
+ flags |= AV_CPU_FLAG_DOTPROD;
+ get_cpu_feature_reg(ID_AA64ISAR1_EL1, tmp);
+ if (((tmp >> 52) & 0xf) == 0x1)
+ flags |= AV_CPU_FLAG_I8MM;
+ }
+#endif
+
+ return flags;
+}
+
+#else
+
+static int detect_flags(void)
+{
+ return 0;
+}
+
+#endif
+
int ff_get_cpu_flags_aarch64(void)
{
int flags = AV_CPU_FLAG_ARMV8 * HAVE_ARMV8 |
@@ -33,6 +94,8 @@ int ff_get_cpu_flags_aarch64(void)
flags |= AV_CPU_FLAG_I8MM;
#endif
+ flags |= detect_flags();
+
return flags;
}
--
2.37.1 (Apple Git-137.1)
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