Re: [PATCH v2 06/19] gendwarfksyms: Add a cache for processed DIEs

[Sami Tolvanen]

On Thu, Aug 29, 2024 at 03:15:02AM +0900, Masahiro Yamada wrote:
> On Fri, Aug 16, 2024 at 2:39 AM Sami Tolvanen <samitolvanen@xxxxxxxxxx> wrote:
> > +static int append_item(struct die *cd, struct die_fragment **res)
> > +{
> > +       struct die_fragment *prev;
> > +       struct die_fragment *df;
> > +
> > +       df = malloc(sizeof(struct die_fragment));
> > +       if (!df) {
> > +               error("malloc failed");
> > +               return -1;
> > +       }
> > +
> > +       df->type = EMPTY;
> > +       df->next = NULL;
> > +
> > +       prev = cd->list;
> > +       while (prev && prev->next)
> > +               prev = prev->next;
> 
> 
> 
> So, this entirely traverses the singly-linked list
> every time a new item is appended to the tail.
> 
> 
> In my analysis, this while loop iterates for thousands
> of times in total for emitting each export symbol.
> 
> 
> Why isn't this list_add_tail()?

Good catch, I'll fix this in the next version. Keeping track of the
last element should be sufficient, but I agree, using the existing
list implementation is probably cleaner. Thanks!

Sami