Move the check for a locked GIL into a cold function and closer to th…

…e locking.

src/gil.rs

@@ -332,6 +332,17 @@ impl LockGIL {
 
         Self { count }
     }
+
+    #[cold]
+    fn check(current: isize) {
+        match current {
+            GIL_LOCKED_DURING_TRAVERSE => panic!(
+                "Access to the GIL is prohibited while a __traverse__ implmentation is running."
+            ),
+            current if current < 0 => panic!("Access to the GIL is currently prohibited."),
+            _ => (),
+        }
+    }
 }
 
 impl Drop for LockGIL {
@@ -452,13 +463,7 @@ fn increment_gil_count() {
     // Ignores the error in case this function called from `atexit`.
     let _ = GIL_COUNT.try_with(|c| {
         let current = c.get();
-        match current {
-            GIL_LOCKED_DURING_TRAVERSE => panic!(
-                "Access to the GIL is prohibited while a __traverse__ implmentation is running."
-            ),
-            current if current < 0 => panic!("Access to the GIL is currently prohibited."),
-            _ => (),
-        }
+        LockGIL::check(current);
         c.set(current + 1);
     });
 }