[m-rev.] for review: rename the .ll_debug grade component for hlc grades to .c_debug

[Julien Fischer]

On Wed, 21 Dec 2022, Peter Wang wrote:

> On Wed, 21 Dec 2022 11:29:20 +1100 Julien Fischer <jfischer at opturion.com> wrote:
>>
>>
>> On Wed, 21 Dec 2022, Peter Wang wrote:
>>
>>> On Tue, 20 Dec 2022 22:41:25 +1100 "Zoltan Somogyi" <zoltan.somogyi at runbox.com> wrote:
>>>> For review by anyone.
>>>>
>>>> I am particularly seeking opinions on the XXX in the log file:
>>>> the treatment of the --c-debug option to mgnuc.
>>>
>>> It's pretty confusing.
>>>
>>> Looking at the thread that prompted this change,
>>> I don't really see how renaming .ll_debug to .c_debug helps.
>>>
>>> How about renaming .ll_debug to .rt_debug, .debug_runtime,
>>> or something like that?
>>
>> To me that makes it seems as though it's for debugging the runtime.  (I
>> guess you meant runtime in a broader context though?) The intent of both
>> the .ll_debug grades and the --c-debug option is to compile things in
>> way that is suitable for use with tools like gdb or valgrind. That goes
>> for the runtime code, C code generated by the compiler and handwritten C
>> code in foreign_proc or foreign_code blocks.
>>
>> --c-debug is the older of the two, and IIRC the .ll_debug component
>> was introduced (at least partly) because it was fiddly to set
>> things up consistently using --c-debug (i.e. ensure that -g -O0 was
>> passed to gcc everywhere it needs to be).
>
> Ok, I got confused. The .c_debug name makes sense then.
>
> I think we should leave the mmc/mgnuc --c-debug (-g) option alone.

For the mgnuc script (at least) it is required. We build the runtime
with it enabled.  From runtime/Mmakefile:

     # We intentionally compile with C level debugging enabled so that
     # problems in the runtime can be debugged without having to recompile
     # it. The cost of doing this is negligible. The runtime can be compiled
     # without debugging enabled by removing the `--c-debug' flag below.
     MGNUCFLAGS      += --c-debug --no-ansi

> Can we drop any options to add or remove the .c_debug grade component
> (previously .ll_debug)? If you want to use such a grade, just specify it
> directly.

I think the only documented one is the configure option that Zoltan recently
renamed to --enable-hlc-gdb-grades.  Under its original name that option
was added by Peter Ross, so it was presumably an MC thing?

Julien.