[FFmpeg-devel] [PATCH v2 4/5] aarch64: Add Apple runtime detection of dotprod and i8mm using sysctl

[Martin Storsjö]

For now, there's not much value in this since Clang don't support
enabling the dotprod or i8mm features with either .arch_extension
or .arch (it has to be enabled by the base arch flags passed to
the compiler). But it may be supported in the future.
---
 configure               |  2 ++
 libavutil/aarch64/cpu.c | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/configure b/configure
index b39de74de5..001287c169 100755
--- a/configure
+++ b/configure
@@ -2348,6 +2348,7 @@ SYSTEM_FUNCS="
     strerror_r
     sysconf
     sysctl
+    sysctlbyname
     usleep
     UTGetOSTypeFromString
     VirtualAlloc
@@ -6394,6 +6395,7 @@ 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 sys/sysctl.h sysctlbyname
 
 check_func_headers windows.h GetModuleHandle
 check_func_headers windows.h GetProcessAffinityMask
diff --git a/libavutil/aarch64/cpu.c b/libavutil/aarch64/cpu.c
index 4563959ffd..ffb00f6dd2 100644
--- a/libavutil/aarch64/cpu.c
+++ b/libavutil/aarch64/cpu.c
@@ -72,6 +72,28 @@ static int detect_flags(void)
     return flags;
 }
 
+#elif defined(__APPLE__) && HAVE_SYSCTLBYNAME
+#include <sys/sysctl.h>
+
+static int detect_flags(void)
+{
+    uint32_t value = 0;
+    size_t size;
+    int flags = 0;
+
+    size = sizeof(value);
+    if (!sysctlbyname("hw.optional.arm.FEAT_DotProd", &value, &size, NULL, 0)) {
+        if (value)
+            flags |= AV_CPU_FLAG_DOTPROD;
+    }
+    size = sizeof(value);
+    if (!sysctlbyname("hw.optional.arm.FEAT_I8MM", &value, &size, NULL, 0)) {
+        if (value)
+            flags |= AV_CPU_FLAG_I8MM;
+    }
+    return flags;
+}
+
 #else
 
 static int detect_flags(void)
-- 
2.37.1 (Apple Git-137.1)