Re: understanding elf_machine_load_address

[Daniel Jacobowitz <dan@debian.org>]

On Sat, Dec 08, 2001 at 09:52:01PM +0100, Andreas Jaeger wrote:
> Daniel Jacobowitz <dan@debian.org> writes:
> 
> > On Sat, Dec 08, 2001 at 04:18:53PM +0100, Andreas Jaeger wrote:
> >> >        "	bltzal $0, here\n"
> >> >        "	nop\n"
> >> >        "here:	subu %0, $31, %0\n"
> >> 
> >> Subtract shared address of "here" from address of "here" at build time
> >> - and you know at which address byte 0 of the shared library is
> >>   loaded.
> >
> > Wait a second.  Does bltzal fill in $31 even on a not-taken branch? 
> > Because bltzal $0 should never be taken.  My handy MIPS reference and
> > SPIM seem to agree that it won't fill in $31.
> 
> I just checked the MIPS R4000 Microprocessor Manual, 2nd Ed. by Joe
> Heinrich and it mentions "Unconditanally, the address of the
> instruction after the delay slot is placed in the link register, $31".
> Therefore the code is correct.

OK, thanks.  Yet another thing that changed between my simulator and my
hardware :)

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer