[patch/rfc] Add a sentinel frame

[Andrew Cagney]

> Andrew
> 
> Hi Andrew,
> I'm getting lots of internal errors due to the fact that this function is called while running x86-64 testsuite on mainline.
> 
> +static void
> +sentinel_frame_pop (struct frame_info *frame,
> +            void **cache,
> +            struct regcache *regcache)
> +{
> +  internal_error (__FILE__, __LINE__, "Function sentinal_frame_pop called");
> +}
> 
> How can I avoid these errors?

Can you please post a stack backtrace and a transcript illustrating the 
problem?  The above assertion is correct - for some reason GDB is trying 
to pop the wrong frame :-(

Andrew