Re: [RFC,patch] Linker plugin - extend API for offloading corner case (aka: LDPT_REGISTER_CLAIM_FILE_HOOK_V2 linker plugin hook [GCC PR109128])

[Richard Biener <rguenther@suse.de>]

On Thu, 11 May 2023, Alan Modra wrote:

> On Thu, May 04, 2023 at 11:02:25AM +0000, Richard Biener via Binutils wrote:
> > So since we expect the linker to use the host side table is there a way
> > for the plugin to exactly query that (the set of symbols the linker
> > uses from the object passed to the plugin)?
> 
> That would be possible and relatively easy to implement, but might be
> slow.
> 
> >  Because if the linker
> > uses something from the file but _not_ the host side offload table
> > (-ffunction-sections -fdata-sections) then things would still go
> > wrong, right?
> 
> > Is there a way to connect both in a way that the linker discards
> > either if the other isn't present?
> 
> No, or at least I do not want to even think about implementing such a
> linker "feature".  The problem is that after you have modified the
> global linker symbol table after adding an object's symbols, it is
> virtually impossible to restore the state of symbols to what they
> would be without that object.  (Yes, we do that sort of thing for
> as-needed shared libraries, but the restoration happens immediately
> after adding the symbols.  I also regret implementing it the way I
> did.)

Thanks for explaining.

> The patch posted is OK from the linker side of things.

OK, then lets go with it and hope it fixes the issue for good.

Thanks,
Richard.