patch 7.4.2024
Problem:    More buf_valid() calls can be optimized.
Solution:   Use bufref_valid() instead.
diff --git a/src/structs.h b/src/structs.h
index e092e6b..0cf2800 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1431,7 +1431,7 @@
     char_u	*ch_callback;	/* call when a msg is not handled */
     partial_T	*ch_partial;
 
-    buf_T	*ch_buffer;	/* buffer to read from or write to */
+    bufref_T	ch_bufref;	/* buffer to read from or write to */
     int		ch_nomodifiable; /* TRUE when buffer can be 'nomodifiable' */
     int		ch_nomod_error;	/* TRUE when e_modifiable was given */
     int		ch_buf_append;	/* write appended lines instead top-bot */
@@ -2925,7 +2925,7 @@
     int		use_aucmd_win;	/* using aucmd_win */
     win_T	*save_curwin;	/* saved curwin */
     win_T	*new_curwin;	/* new curwin */
-    buf_T	*new_curbuf;	/* new curbuf */
+    bufref_T	new_curbuf;	/* new curbuf */
     char_u	*globaldir;	/* saved value of globaldir */
 #endif
 } aco_save_T;