Speedup RBASIC_FIELDS_COUNT (#15273)

We know the argument is not a class, module or special const, so we can
skip these checks.

1 files changed, 1 insertions, 1 deletions

diff --git a/shape.h b/shape.h
index ec5c25b32f..d9cfe48759 100644
--- a/shape.h
+++ b/shape.h
@@ -395,7 +395,7 @@ ROBJECT_FIELDS_COUNT(VALUE obj)
 static inline uint32_t
 RBASIC_FIELDS_COUNT(VALUE obj)
 {
-    return RSHAPE(rb_obj_shape_id(obj))->next_field_index;
+    return RSHAPE(RBASIC_SHAPE_ID(obj))->next_field_index;
 }
 
 static inline bool