Re: [patch] MIPS gas problems with gcc's explicit relocs

[Thiemo Seufer <ica2_ts at csv dot ica dot uni-stuttgart dot de>]

Andreas Schwab wrote:
> Eric Christopher <echristo@redhat.com> writes:
> 
> >> - Work around the problem by not using "m" constraints for (d)la in
> >>   the inline assembler, that is instead of
> >> 
> >> 	asm("dla\t%0,%1" : "=r" (result) : "m" (foo));
> >> 
> >>   something like
> >> 
> >> 	asm("dla\t%0,foo" : "=r" (result));
> >
> > I like this I think the most. It fits with what people are trying to do
> > with the la instruction, i.e. load an address for a symbol that they
> > know.
> 
> For "load address" and "push address" type insns there is the "p"
> constraint letter.  Wouldn't that be the correct constraint here?

Interestingly, "p" causes this expansion:

        lui     $2,%highest(foo)
	daddiu  $2,$2,%higher(foo)
	sll    $2,$2,16
	daddiu  $2,$2,%hi(foo)
	dsll    $2,$2,16
	ld      $2,%lo(foo)($2)
	#APP
	dla     $2,$2
	#NO_APP

So the inline assembler gets a fully loaded register for it.


Thiemo