Re: [RFA v2] arm-pikeos: software single step

[Joel Brobecker <brobecker@adacore.com>]

> > Attached is the patch I am testing. I am wondering if this is the best
> > way, though. What do you think?
> 
> It looks good to me.  You could use a range-for, because it's cool:
> 
>   for (asymbol *sym : symbol_table)
> 
> but what you have is also fine.

Unfortunately, it looks like the change is causing regressions, and
it is a bit obscure at the moment, which is not entirely surprising
when one deals with memory.

> > One question I asked myself is whether we needed the std::vector at
> > all, as the building of the vector is a bit clunky in this situation.
> > As I understand it, this is mostly to automate the destruction of
> > the array. I was wondering whether we could do without the std::vector
> > entirely, and just handle the array without a cleanup, since the code
> > is simple enough that we can make sure it doesn't throw (I was hoping
> > that eg marking the function noexcept would help guaranty that). But
> > at the end of the day, although it's manageable in this case, I felt
> > it was better to go with the safer approach.
> 
> Well, it would be fine to not use a vector, but in any case I would
> recommend the use of an object that ensures the memory is de-allocated in
> any case, whether it is an std::vector, an std::unique_ptr or a
> gdb::unique_xmalloc_ptr.  I don't see any advantage of doing a manual free
> over using one of those.
> 
> An alternative would be to use a VLA:
> 
>   asymbol *symbol_table[max_number_of_symbols];
> 
> which I think ends up being like an alloca.  But in this case there could be
> a huge number of symbols I suppose, so I would avoid that.

Yes, the table might be too large and blow the stack. All things
considered, I think the better model here seems to be to use a
gdb::unique_xmalloc_ptr. I tried that, and the code looks simpler,
but I get the same kind of regressions as above.

And unfortunately at this point, I have to hold off for a while,
because I am out of license, and then I will be traveling home.
But thanks a lot for all the feedback received so far; when I pick
things up again, I will not be starting from scratch.

-- 
Joel