Improve ASSIGN_OBJ RC inference

ASSIGN_OBJ may only modify RC if it implements __set.

Closes phpGH-13237

Author: iluuu1994

Zend/Optimizer/zend_inference.c

@@ -3029,7 +3029,14 @@ static zend_always_inline zend_result _zend_update_type_info(
 			break;
 		case ZEND_ASSIGN_OBJ:
 			if (opline->op1_type == IS_CV) {
-				tmp = (t1 & (MAY_BE_REF|MAY_BE_OBJECT))|MAY_BE_RC1|MAY_BE_RCN;
+				zend_class_entry *ce = ssa_var_info[ssa_op->op1_use].ce;
+				bool add_rc = !ce
+					|| ce->__set
+					/* Non-default write_property may be set within create_object. */
+					|| ce->create_object
+					|| ce->default_object_handlers->write_property != zend_std_write_property
+					|| ssa_var_info[ssa_op->op1_use].is_instanceof;
+				tmp = (t1 & (MAY_BE_REF|MAY_BE_OBJECT|MAY_BE_RC1|MAY_BE_RCN))|(add_rc ? (MAY_BE_RC1|MAY_BE_RCN) : 0);
 				UPDATE_SSA_TYPE(tmp, ssa_op->op1_def);
 				COPY_SSA_OBJ_TYPE(ssa_op->op1_use, ssa_op->op1_def);
 			}