[systemd-devel] [PATCH] build-sys: remove --gc-sections to fix debugging

[Gustavo Sverzut Barbieri]

On Thu, Nov 27, 2014 at 07:36:12PM +0100, David Herrmann wrote:
> Hi
>
> On Thu, Nov 27, 2014 at 7:31 PM, Gustavo Sverzut Barbieri
> <gustavo.barbieri at intel.com> wrote:
> > Currently configure.ac has the LTO logic inside an:
> >
> >         AS_CASE([$CFLAGS], [*-O[[12345\ ]]*], ....
> >
> > We can make the "else" block check/enable for gc-sections alongside
> > printing the result. See the attached (untested!) patch.
>
> Yes, thanks, this is the way to go! But..
>
> ..your patch fails it you build systemd with -O2 but your build-utils
> lack LTO support. CC_CHECK_FLAGS_APPEND only appends flags _iff_
> they're supported. So in your case, if -O2 is detected, but LTO is not
> available, you will end up with neither LTO nor --gc-sections.

arghhh... that's right :-/ we could do the AS_CASE() for -flto and add
gc-sections if not, but:


> Furthermore, please justify your changes in the changelog, so
> git-blame will tell people why gc-sections is disabled if LTO is used.
> If it was only redundancy you care about, then I see no reason to drop
> it. So please explain what we gain by dropping it.

you're right, we gain nothing from it... as people said before we
shouldn't try to work around a broken linker :-)

BR,

--
Gustavo Sverzut Barbieri
Intel Open source Technology Center