Re: [RFA] OSF/1 - "next" over prologueless function call

[Daniel Jacobowitz <drow at mvista dot com>]

On Mon, Dec 01, 2003 at 10:35:32PM -0800, Richard Henderson wrote:
> On Mon, Dec 01, 2003 at 08:26:46PM -0800, Joel Brobecker wrote:
> > +  if (pc == func_start)
> > +    return 1;
> > +
> > +  if (pc == func_start + 8)
> > +    {
> > +      unsigned int inst;
> > +
> > +      /* ldah $gp,n($t12) */
> > +      inst = alpha_read_insn (func_start);
> > +      if ((inst & 0xffff0000) != 0x27bb0000)
> > +        return 0;
> > +
> > +      /* lda $gp,n($gp) */
> > +      inst = alpha_read_insn (func_start + 4);
> > +      if ((inst & 0xffff0000) != 0x23bd0000)
> > +        return 0;
> 
> Is there any chance we could get hold of the symbol associated with
> this function start?  On ELF detecting this condition can be 
> streamlined to 
> 
> 	sym->st_other & STO_ALPHA_STD_GPLOAD == STO_ALPHA_STD_GPLOAD
> 
> or from bfd, elf_link_hash_entry.other, though I don't remember off
> the top of my head how to get at the elf hash entry from asymbol.

I don't think you can.  They're not added to a link hash table unless
you're actually linking.

It looks like there's no way to go from the asymbol to the ELF symbol
either, and st_other isn't stashed anywhere.

> And yes indeed, the gnu tools do this same optimization.  Both at
> compile time and link time.
> 
> 
> r~
> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer