checkasm: replace gettimeofday with clock_gettime

tests/checkasm/checkasm.c:55:5: warning: implicit declaration of function 'gettimeofday' is invalid in C99 [-Wimplicit-function-declaration]
    gettimeofday(&tv, NULL);
    ^

meson.build

@@ -113,11 +113,23 @@ if host_machine.system() == 'windows'
     # On Windows, we use a compatibility layer to emulate pthread
     thread_dependency = []
     thread_compat_dep = declare_dependency(sources : files('src/win32/thread.c'))
+
+    rt_dependency = []
 else
     thread_dependency = dependency('threads')
     thread_compat_dep = []
-endif
 
+    rt_dependency = []
+    if cc.has_function('clock_gettime', prefix : '#include <time.h>', args : test_args)
+        cdata.set('HAVE_CLOCK_GETTIME', 1)
+    else
+        rt_dependency = cc.find_library('rt', required: false)
+        if not cc.has_function('clock_gettime', prefix : '#include <time.h>', args : test_args, dependencies : rt_dependency)
+            error('clock_gettime not found')
+        endif
+        cdata.set('HAVE_CLOCK_GETTIME', 1)
+    endif
+endif
 
 # Header checks
 

tests/checkasm/checkasm.c

@@ -45,15 +45,24 @@ static unsigned get_seed(void) {
 #else
 #include <unistd.h>
 #include <signal.h>
-#include <sys/time.h>
+#include <time.h>
+#ifdef __APPLE__
+#include <mach/mach_time.h>
+#endif
 #define COLOR_RED    1
 #define COLOR_GREEN  2
 #define COLOR_YELLOW 3
 
 static unsigned get_seed(void) {
-    struct timeval tv;
-    gettimeofday(&tv, NULL);
-    return (unsigned) (tv.tv_usec + tv.tv_sec * 1000000);
+#ifdef __APPLE__
+    mach_timebase_info_data_t info;
+    mach_timebase_info(&info);
+    return (unsigned) (mach_absolute_time() * info.numer / info.denom);
+#elif defined(HAVE_CLOCK_GETTIME)
+    struct timespec ts;
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+    return (unsigned) (1000000000ULL * ts.tv_sec + ts.tv_nsec);
+#endif
 }
 #endif
 

tests/meson.build

@@ -90,7 +90,7 @@ if is_asm_enabled
         include_directories: dav1d_inc_dirs,
         c_args: [stackalign_flag, stackrealign_flag],
         build_by_default: false,
-        dependencies : [thread_dependency, m_lib],
+        dependencies : [thread_dependency, rt_dependency, m_lib],
         )
 
     test('checkasm', checkasm, is_parallel: false)

tools/meson.build

@@ -69,19 +69,6 @@ endif
 # Configuratin data for cli_config.h
 cli_cdata = configuration_data()
 
-rt_dependency = []
-if host_machine.system() != 'windows'
-    if cc.has_function('clock_gettime', prefix : '#include <time.h>', args : test_args)
-        cli_cdata.set('HAVE_CLOCK_GETTIME', 1)
-    else
-        rt_dependency = cc.find_library('rt', required: false)
-        if not cc.has_function('clock_gettime', prefix : '#include <time.h>', args : test_args, dependencies : rt_dependency)
-            error('clock_gettime not found')
-        endif
-        cli_cdata.set('HAVE_CLOCK_GETTIME', 1)
-    endif
-endif
-
 cli_config_h_target = configure_file(output: 'cli_config.h', configuration: cli_cdata)
 
 # dav1d cli tool sources