Assume result from allocator will be valid

This adds a fastpath in class_call_alloc_func to simply return if the
class matches the one expected.

I think we could probably just remove this check, or move it to the debug
build.

1 files changed, 4 insertions, 2 deletions

diff --git a/object.c b/object.c
index bcafab3c3d..158bb0b219 100644
--- a/object.c
+++ b/object.c
@@ -2238,8 +2238,10 @@ class_call_alloc_func(rb_alloc_func_t allocator, VALUE klass)
 
     obj = (*allocator)(klass);
 
-    if (rb_obj_class(obj) != rb_class_real(klass)) {
-        rb_raise(rb_eTypeError, "wrong instance allocation");
+    if (UNLIKELY(RBASIC_CLASS(obj) != klass)) {
+        if (rb_obj_class(obj) != rb_class_real(klass)) {
+            rb_raise(rb_eTypeError, "wrong instance allocation");
+        }
     }
     return obj;
 }