[m-rev.] for post-commit review: fill in most of the grade modifiers section

[Julien Fischer]

On Fri, 8 Aug 2025 at 18:12, Zoltan Somogyi <zoltan.somogyi at runbox.com> wrote:
>
> > Does that grade component not apply to the LLDS
> > grades at all?
>
> Clearly, at the moment it does, but I think it is not something
> users should be doing. We can either
>
> - document the availability of c_debug in LLDS grades, but add
>   strong warnings about that not being useful, or
>
> - disable c_debug in LLDS grades.

I'm fine with the second option.

> The code in grade_spec.m suggests to me that the last time we had this
> argument, years ago, we probably chose the second option.
>
> Even us implementors have not needed to debug very low level details
> in years. When we do, we can just enable .c_debug in LLDS grades,
> track down and fix whatever issue needs fixing, and disable .c_debug
> in LLDS grades again.
>
> > Using gdb-level debugging will obviously be significantly
> > less useful in many of the LLDS grades because:
> >
> > 1. The Mercury-level debugger is available in those grades.
> > 2. Some of what we do in the asm_fast and reg grades might be a bit
> >    "interesting"  for gdb.
>
> I think "interesting", even in the sense of the Chinese curse, is underselling
> things a bit ...

I'm very aware of that ;-)

Julien.