[Mesa-dev] [PATCH] glsl/list: Add an exec_list_validate function

[Matt Turner]

On Wed, Nov 5, 2014 at 5:12 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
>
>
> On Wed, Nov 5, 2014 at 2:46 PM, Matt Turner <mattst88 at gmail.com> wrote:
>>
>> On Wed, Nov 5, 2014 at 2:00 PM, Jason Ekstrand <jason at jlekstrand.net>
>> wrote:
>> > This can be very useful for trying to debug list corruptions.
>> >
>> > Signed-off-by: Jason Ekstrand <jason.ekstrand at intel.com>
>> > Cc: Ian Romanick <idr at freedesktop.org>
>> > ---
>> >  src/glsl/list.h | 14 ++++++++++++++
>> >  1 file changed, 14 insertions(+)
>> >
>> > diff --git a/src/glsl/list.h b/src/glsl/list.h
>> > index aac13fd..1d18ec9 100644
>> > --- a/src/glsl/list.h
>> > +++ b/src/glsl/list.h
>> > @@ -521,6 +521,20 @@ exec_node_insert_list_before(struct exec_node *n,
>> > struct exec_list *before)
>> >     exec_list_make_empty(before);
>> >  }
>> >
>> > +static inline void
>> > +exec_list_validate(struct exec_list *list)
>> > +{
>> > +   assert(list->head->prev == (struct exec_node *) &list->head);
>> > +   assert(list->tail == NULL);
>> > +   assert(list->tail_pred->next == (struct exec_node *) &list->tail);
>> > +
>> > +   for (struct exec_node *node = list->head;
>> > +        node->next != NULL; node = node->next) {
>>
>> Just use foreach_in_list().
>
>
> Sure, I can do that.
>
>> > +      assert(node->next->prev == node);
>> > +      assert(node->prev->next == node);
>> > +   }
>> > +}
>>
>> Are you intending to call this from gdb? I'm having a hard time
>> imagining committing code that *sometimes* corrupts lists, which seems
>> like why this function would be useful to call from real code.
>
>
> It is useful to call from gdb but I also call it all over nir_validate.c.  I
> spent most of today fighting linked list corruptions, and this was very
> helpful for tracking them down.  Another option would be rename it to
> exec_list_is_valid and make it return a bool.  Then the standard procedure
> would be "assert(exec_list_is_valid(list))".  Would that be better?
>
>>
>> If you just want to call it from gdb, wrap the whole thing in #ifndef
>> NDEBUG. I don't want to ever accidentally call this function and think
>> it validated something when it actually did nothing.

Yeah, ignore all this.

Reviewed-by: Matt Turner <mattst88 at gmail.com>