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

[Alan Modra <amodra@gmail.com>]

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.)

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

-- 
Alan Modra
Australia Development Lab, IBM