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Re: Indicating function exit points in debug data
On Tue, 19 Mar 2019 at 22:40, Florian Weimer <fw@deneb.enyo.de> wrote:
> * Justin Paston-Cooper:
>
> > On Tue, 19 Mar 2019 at 21:52, Florian Weimer <fw@deneb.enyo.de> wrote:
> >>
> >> * Justin Paston-Cooper:
> >>
> >> > On Tue, 19 Mar 2019 at 21:29, Florian Weimer <fw@deneb.enyo.de>
> wrote:
> >> >>
> >> >> * Justin Paston-Cooper:
> >> >>
> >> >> > Tom Tromey suggested in that thread that this would be quite easy
> on
> >> >> > gdb's side if gcc indicates exit locations in the DWARF data, for
> >> >> > instance in the C case, it would indicate the locations of return
> >> >> > statements. On a related note, he mentions that the "finish"
> command
> >> >> > does not work for inlined functions because the compiler does not
> emit
> >> >> > the required information.
> >> >>
> >> >> What about calls to noreturn functions? I assume they would need
> >> >> breakpoints as well. It could be tricky if those are only called
> >> >> indirectly, I assume.
> >> >
> >> > Couldn't the brace following the final line of an inlined noreturn
> >> > function be viewed as its exit point and be indicated in the DWARF
> >> > information accordingly?
> >>
> >> That breakpoint would never be reached.
> >
> > Then if the break on exit command would break on return statements of
> > functions which return, then it could break on the final statement of
> > a noreturn?
>
> There's no final statement in a noreturn function because it will
> never return. It either has an endless loop, or it calls another
> noreturn function (which is at a certain point opaque to the compiler)
> which never returns.
>
> Sorry, I have a fealing we are talking past each other. With
> “noreturn function”, I mean a function that is annotated with the
> noreturn attribute:
>
> <
> https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute
> >
> Sorry about that, and thanks for the link. I jumped to conclusions with
regards to the meaning of noreturn.