Re: Miscompilation of glibc with CVS mainline

[Daniel Jacobowitz <drow@mvista.com>]

On Thu, Jan 02, 2003 at 12:48:23PM -0500, John David Anglin wrote:
> > > > Here's a small testcase that has the same behaviour:
> > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > > extern void weak_func (void *arg);
> > > > asm (".weak weak_func");
> > > > 
> > > > void
> > > > test (void *arg)
> > > > {
> > > >   if (&weak_func != (void *)0)
> > > >     weak_func (arg);
> > > >   
> > > > }
> > > 
> > > As GCC is not told in any way that weak_func is actually weak, I think
> > > it is glibc's fault.
> > 
> > This is definitely a gcc problem.  This is the code arising from
> > Andreas' testcase for hppa-linux at -O2:
> > 
> >         stw %r2,-20(%r30)
> > 	ldo 64(%r30),%r30
> > 	ldw -84(%r30),%r2
> > 	bl weak_func,%r0
> > 	ldo -64(%r30),%r30
> > 
> > We have completely lost the `if'.  As a result, weak_func is always
> > called.
> 
> There is another problem.  The call to weak_func has been turned into
> a sibcall.  It seems that TARGET_FUNCTION_OK_FOR_SIBCALL isn't being
> consulted as we don't allow indirect sibcalls on hppa-linux.

This isn't an indirect call, though.  weak_func is not a pointer...

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer