util: Add ATTRIBUTE_OPTIMIZE(flags)

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30622>

meson.build

@@ -1044,6 +1044,7 @@ endforeach
 _attributes = [
   'const', 'flatten', 'malloc', 'pure', 'unused', 'warn_unused_result',
   'weak', 'format', 'packed', 'returns_nonnull', 'alias', 'noreturn',
+  'optimize',
 ]
 foreach a : cc.get_supported_function_attributes(_attributes)
   pre_args += '-DHAVE_FUNC_ATTRIBUTE_@0@'.format(a.to_upper())

src/util/macros.h

@@ -240,6 +240,12 @@ do {                       \
 #  endif
 #endif
 
+#ifdef HAVE_FUNC_ATTRIBUTE_OPTIMIZE
+#define ATTRIBUTE_OPTIMIZE(flags) __attribute__((__optimize__((flags))))
+#else
+#define ATTRIBUTE_OPTIMIZE(flags)
+#endif
+
 #ifdef __cplusplus
 /**
  * Macro function that evaluates to true if T is a trivially