Re: [RFA/PATCH] PR/9711: quadratic slowdown for deep stack traces

Doug Evans
2009-09-07T07:30:07Z

On Thu, Sep 3, 2009 at 11:36 AM, Joel Brobecker<brobecker@adacore.com> wrote:
> 2009-09-03  Joel Brobecker  <brobecker@adacore.com>
>
>        Avoid quadratic behavior when computing the value of a register.
>        * frame.c (frame_cache): New static constant.
>        (frame_cache_add, frame_cache_find, frame_cache_invalidate):
>        New functions.
>        (get_frame_id): Minor reformatting. Add the frame to the frame cache.
>        (frame_find_by_id): Search the frame cache first before walking all
>        frames starting from te current_frame.
>        (reinit_frame_cache): Add call to frame_cache_invalidate ();

Hi.

Nit: It seems like there's a redundant call to frame_id_eq in frame_find_by_id.

+/* Search the frame cache for an entry with the given frame ID.
+ If found, return that frame. Otherwise return NULL. */
+static struct frame_info *
+frame_cache_find (struct frame_id id)
+{
+ if (frame_cache && frame_id_eq (frame_cache->this_id.value, id))
+ return frame_cache;
+
+ return NULL;
+}

@@ -514,6 +547,11 @@ frame_find_by_id (struct frame_id id)
if (!frame_id_p (id))
return NULL;

+ /* Try using the frame cache first. */
+ frame = frame_cache_find (id);
+ if (frame && frame_id_eq (frame->this_id.value, id))
+ return frame;
+
for (frame = get_current_frame (); ; frame = prev_frame)
{
struct frame_id this = get_frame_id (frame);