Re: [RFA] unexpected multiple location for breakpoint

[Michael Snyder <msnyder@vmware.com>]

Joel Brobecker wrote:
>>> I worry about the effect at -O0. It is common to see the same source
>>> line being split across the code.  For instance, with conditional
>>> loops, the condition evaluation is often placed at the end of the
>>> loop, and its code is associated to the initial line.
>> Are you saying that GCC does that under -O0?  I'd be surprised.  But I
>> realize that it does that for higher optimization levels.  Still, my
>> question is how would it be worse to have the inferior stop several
>> times through the loop than not stop at all?
> 
> Actually, it does, even at -O0. I don't think it's unreasonable.
> I don't think we are worse, but the reason why I bring it up is because
> it's a definite departure from what we've been trying to do so far
> (minimize the number of breakpoint locations). In fact, the patch
> that triggered this discussion was trying to go one step further.
> So, I'm just wondering if there might be some issues that I am not
> taking into consideration.
> 
> I'm willing to make that change, but this is going to require general
> consent among the maintainers (and I'm not looking forward to all
> the mods in the testsuite to adjust it :-/).

I haven't been following the discussion all that closely.

I know that some statements, such as for loops, do tend to get broken up 
even at -O0, and gdb has various means of compensating for it.  I'm not 
sure what the situation is/was with single-location breakpoints... I 
imagine that the break at the for loop would only be hit on the first 
iteration.