On Tue, Apr 19, 2016 at 09:44:37AM +0300, Alexander Monakov wrote:
> On Tue, 19 Apr 2016, AKASHI Takahiro wrote:
> > > looking at [2] i don't see why
> > >
> > > func:
> > > mov x9, x30
> > > bl _tracefunc
> > > <function body>
> >
> > Actually,
> > mov x9, x30
> > bl _tracefunc
> > mov x30, x9
> > <function body>
>
> I think here Szabolcs' point was that the last instruction can be eliminated:
> _tracefunc can be responsible for restoring x30, and can use x9 to return to
> its caller. It has a non-standard calling convention and needs to be
> implemented in assembly anyway.
OK, but in _tracefunc, x30 has been updated, and so we should
return as follows:
mov xTMP, x30
mov x30, x9
ret xTMP
We need one more temp register here...
Thanks,
-Takahiro AKASHI
> Alexander
