[Bug target/94145] Longcalls mis-optimize loading the function address

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94145

--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Alan Modra from comment #8)
> (In reply to Richard Biener from comment #7)
> > OTOH CSEing the load from the PLT once it is resolved _would_ be an
> > optimization.
> 
> Possibly.  Sometimes making the call sequence seem more efficient runs into
> stalls particularly when the called function is short.
>
> >  Asks for loop peeling I guess?
> 
> Yeah, that might be one way to get the first call of a function inside a
> loop over and done with.  And so you'd know the PLT entry was resolved and
> thus no longer volatile.

I suppose there's no (portable) way to "speculate" the call, thus _just_
eventually resolve the PLT?  That way we could do such hoisted PLT loads
as

  load PTL + speculate call
  load PTL

or rather always do

  resolve-and-load-PLT

since the times we want to lazily load the PLT with resolving later are
scarce?