[PATCH][gdb/testsuite] Add label option to proc cu

[Simon Marchi]

On 2021-08-26 7:56 a.m., Tom de Vries via Gdb-patches wrote:
> Hi,
> 
> We can use current dwarf assembly infrastructure to declare a label that marks
> the start of the CU header:
> ...
>   declare_labels header_start_cu_a
>   _section ".debug_info"
>   header_start_cu_a : cu {} {
>   }
>   _section ".debug_info"
>   header_start_cu_b : cu {} {
>   }
> ...
> on the condition that we switch to the .debug_info section before, which makes
> this style of use fragile.
> 
> Another way to achieve the same is to use the label as generated by the cu
> proc itself:
> ...
>   variable _cu_label
>   cu {} {
>   }
>   set header_start_cu_a $_cu_label
>   cu {} {
>   }
>   set header_start_cu_b $_cu_label
> ...
> but again that seems fragile given that adding a new CU inbetween will
> silently result in the wrong value for the label.

And this is done by poking in the internals of the framework, not good.

> Add a label option to proc cu such that we can simply do:
> ...
>   declare_labels header_start_cu_a
>   cu { label header_start_cu_a } {
>   }
>   cu { label header_start_cu_b } {
>   }

That looks like the right way to do it.  But can we make it so the
caller doesn't need to use declare_labels?  For example, with rnglists'
-post-header-label switch, it's not needed, so I presume it would be
possible here.

Simon