This function is used on all architectures, not just X86.

--- x265/source/common/cpu.cpp
+++ x265/source/common/cpu.cpp
@@ -110,6 +110,11 @@
     { "", 0 },
 };
 
+bool detect512()
+{
+    return(enable512);
+}
+
 #if X265_ARCH_X86
 
 extern "C" {
@@ -123,10 +128,6 @@
 #pragma warning(disable: 4309) // truncation of constant value
 #endif
 
-bool detect512()
-{
-    return(enable512);
-}
 uint32_t cpu_detect(bool benableavx512 )
 {