[PATCH 2/2] mark lists to be repacked as dirty

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

Use a bit in the head of a ptrlist and set it when
DELETE_PTR() is called.
Check the bit when repacking a list and do nothing if the
bit is not set.

Note: delete_ptr_list_entry() & delete_ptr_list_last()
don't need any handling because they either always call
pack_ptr_list() or remove the last block when it becomes empty.

Suggested-by: Christopher Li <sparse@chrisli.org>
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 ptrlist.c | 7 +++++++
 ptrlist.h | 4 +++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/ptrlist.c b/ptrlist.c
index 5dc1117c..e817bad1 100644
--- a/ptrlist.c
+++ b/ptrlist.c
@@ -70,6 +70,11 @@ void pack_ptr_list(struct ptr_list **listp)
 
 	if (head) {
 		struct ptr_list *entry = head;
+
+		if (!head->dirty)
+			return;
+		head->dirty = 0;
+
 		do {
 			struct ptr_list *next;
 restart:
@@ -138,6 +143,7 @@ void **__add_ptr_list(struct ptr_list **listp, void *ptr, unsigned long tag)
 			list->prev = newlist;
 			last->next = newlist;
 		}
+		newlist->dirty = 0;
 		last = newlist;
 		nr = 0;
 	}
@@ -188,6 +194,7 @@ void * undo_ptr_list_last(struct ptr_list **head)
 
 	if (!first)
 		return NULL;
+	first->dirty = 1;
 	last = first;
 	do {
 		last = last->prev;
diff --git a/ptrlist.h b/ptrlist.h
index 61e159fd..c24bfb82 100644
--- a/ptrlist.h
+++ b/ptrlist.h
@@ -25,7 +25,8 @@
 #define LIST_NODE_NR (29)
 
 struct ptr_list {
-	int nr;
+	int nr:31;
+	unsigned int dirty:1;		// will need to be repacked
 	struct ptr_list *prev;
 	struct ptr_list *next;
 	void *list[LIST_NODE_NR];
@@ -254,6 +255,7 @@ extern void split_ptr_list_head(struct ptr_list *);
 		__this++;								\
 	}										\
 	*__this = (void *)0xf0f0f0f0;							\
+	__head->dirty = 1;								\
 	__list->nr--; __nr--;								\
 } while (0)
 
-- 
2.10.2