- Add run-time CPU feature detection for FreeBSD / OpenBSD

Index: source/common/cpu.cpp
--- source/common/cpu.cpp.orig
+++ source/common/cpu.cpp
@@ -31,6 +31,10 @@
 #include "cpu.h"
 #include "common.h"
 
+#include <errno.h>
+#if HAVE_GETAUXVAL || HAVE_ELF_AUX_INFO
+#include <sys/auxv.h>
+#endif
 #if MACOS || SYS_FREEBSD
 #include <sys/types.h>
 #include <sys/sysctl.h>
@@ -41,7 +45,7 @@
 #include <machine/cpu.h>
 #endif
 
-#if X265_ARCH_ARM && !defined(HAVE_NEON)
+#if X265_ARCH_ARM && !defined(HAVE_NEON) && !(HAVE_GETAUXVAL || HAVE_ELF_AUX_INFO)
 #include <signal.h>
 #include <setjmp.h>
 static sigjmp_buf jmpbuf;
@@ -137,6 +141,22 @@ const cpu_name_t cpu_names[] =
     { "", 0 },
 };
 
+unsigned long x265_getauxval(unsigned long type)
+{
+#if HAVE_GETAUXVAL
+    return getauxval(type);
+#elif HAVE_ELF_AUX_INFO
+    unsigned long aux = 0;
+    int ret = elf_aux_info(type, &aux, sizeof(aux));
+    if (ret != 0)
+        errno = ret;
+    return aux;
+#else
+    errno = ENOSYS;
+    return 0;
+#endif
+}
+
 #if X265_ARCH_X86
 
 extern "C" {
@@ -357,6 +377,8 @@ void PFX(cpu_neon_test)(void);
 int PFX(cpu_fast_neon_mrc_test)(void);
 }
 
+#define X265_ARM_HWCAP_NEON (1U << 12)
+
 uint32_t cpu_detect(bool benableavx512)
 {
     int flags = 0;
@@ -364,6 +386,11 @@ uint32_t cpu_detect(bool benableavx512)
 #if HAVE_ARMV6 && ENABLE_ASSEMBLY
     flags |= X265_CPU_ARMV6;
 
+#if HAVE_GETAUXVAL || HAVE_ELF_AUX_INFO
+    unsigned long hwcap = x265_getauxval(AT_HWCAP);
+
+    if (hwcap & X265_ARM_HWCAP_NEON) flags |= X265_CPU_NEON;
+#else
     // don't do this hack if compiled with -mfpu=neon
 #if !HAVE_NEON
     static void (* oldsig)(int);
@@ -381,6 +408,7 @@ uint32_t cpu_detect(bool benableavx512)
 #endif // if !HAVE_NEON
 
     flags |= X265_CPU_NEON;
+#endif
 
     // fast neon -> arm (Cortex-A9) detection relies on user access to the
     // cycle counter; this assumes ARMv7 performance counters.