Re: [PATCH] gdb/stack.c: avoid stale pointers when printing frame arguments

[Bruno Larsen <blarsen@redhat.com>]

On 4/5/22 10:58, Tom Tromey wrote:
>>>>>> "Bruno" == Bruno Larsen <blarsen@redhat.com> writes:
> 
> Bruno> This sounds like a good idea. I am just not sure if you are
> Bruno> suggesting it as a fix instead of what I proposed, or to
> Bruno> implement later, can you clarify it please?
> 
> You don't have to do it.
> 
> Bruno> +  if (frame_cache_count < get_frame_cache_generation ())
> Bruno> +    reinit_frame_cache ();
> 
>>> I don't think I understand this bit.  If the generation changes,
>>> hasn't
>>> the cache already been cleared?
> 
> Bruno> If the cache has been cleared by printing a frame, it was done because
> Bruno> a function was called manually (probably). If it did happen, the cache
> Bruno> may have been invalidated and it is safer to rebuild
> Bruno> everything. print_frame_cache by itself doesn't reinitialize the frame
> Bruno> cache.
> 
> My understanding is that the generation only changes when
> reinit_frame_cache is called.  So if that's the case, why does it need
> to be reinitalized a second time?  That's the part I don't understand.

It has been reinitialized to call the function by hand (if you set debug frame 1 and call something by hand, you'll see a few refreshes), but it is not been refreshed after finishing the handmade call. We might still have dummy frames or incorrect information leftover from the function call.

> 
> thanks,
> Tom
> 


-- 
Cheers!
Bruno Larsen