On Wed, 4 Nov 2020, H.J. Lu wrote:
> On Wed, Nov 4, 2020 at 1:03 PM Hans-Peter Nilsson <h...@bitrange.com> wrote:
> >
> > On Wed, 4 Nov 2020, H.J. Lu wrote:
> > > On Wed, Nov 4, 2020 at 10:09 AM Hans-Peter Nilsson <h...@bitrange.com>
> > > wrote:
> > > >
> > > > On Wed, 4 Nov 2020, Jozef Lawrynowicz wrote:
> > > > > I personally do not see the problem with the .retain attribute,
> > > > > however
> > > > > if it is going to be a barrier to getting the functionality
> > > > > committed, I
> > > > > am happy to change it, since I really just want the functionality in
> > > > > upstream sources.
> > > > >
> > > > > If a global maintainer would comment on whether any of the proposed
> > > > > approaches are acceptable, then I will try to block out time from
> > > > > other
> > > > > deadlines so I can work on the fixups and submit a patch in time for
> > > > > the
> > > > > GCC 11 freeze.
> > > > >
> > > > > Thanks,
> > > > > Jozef
> > > >
> > > > I'm not much more than a random voice, but an assembly directive
> > > > that specifies the symbol (IIUC your .retain directive) to
> > >
> > > But .retain directive DOES NOT adjust symbol attribute.
I see I missed to point out that I was speaking about the *gcc
symbol* attribute "used".
> > > Instead, it sets
> > > the SHF_GNU_RETAIN bit on the section which contains the symbol
> > > definition. The same section can have many unrelated symbols.
> >
> > That's an implementation detail *left to the assembler and
> > linker*. It's not something the compiler needs to know, and
> > teoretically it could even change.
> >
>
> The ELF extension is SHF_GNU_RETAIN. .retain directive is a hack
> which I strongly objected and showed that it wasn't needed to implement
> SHF_GNU_RETAIN in binutils.
It's still an implementation detail better kept in the
assembler, that the mechanism used to retain a symbol for the
compiler, happens to map to a section attribute. Some may call
*that* a hack.
It's cleaner to the compiler if it can pass on to the assembler
the specific symbol that needs to be kept.
brgds, H-P
