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Re: va-arg-25.c still fails on i686-linux


> Jan Hubicka <hubicka@ucw.cz> writes:
> 
> >> 
> >> On 09/01/2004, at 11:06 PM, Zack Weinberg wrote:
> >> 
> >> >
> >> >I am still seeing va-arg-25.c fail at all optimization levels on
> >> >i686-linux.  It has done so, as far as I can tell, ever since it
> >> >was introduced.  Could you please either fix it or XFAIL it?
> >> >
> >> I think it would be better if an x86 port maintainer looked at this 
> >> failure.  The testcase does not fail on powerpc-Darwin.
> >
> > It don't even need x86 port maintainer :)
> > The problem is wrong aligning of va_arg inside builtins.c when argument
> > alignment exceeds PARM_BOUNDARY.
> >
> > Additionally I noticed some problems with SSE enabled (we mistakely used
> > SSE regiser for variadic call and output warning)
> >
> > Note that I am not quite sure about the PAD_VARARGS_DOWN check, it just
> > seems appropriate at that place.
> >
> > Bootstrapping/regtesting in progress, OK if it passes?
> 
> The concept looks good but I am nervous about a change in
> machine-independent code.  Can you arrange testing on a few more
> architectures?  (especially ones with complicated rules about
> arguments being passed in registers - ia64 comes to mind).

Every architecture passing arguments in registers use it's own va_arg
expander (see ia64_va_arg).  This code triggers only in quite specific
case of architecture having no register passing convention but still
requiring larger alignment than word for some operands.  I know only of
i386 being such a crazy creature.

> 
> Also please add commentary to std_expand_builtin_va_arg explaining
> what this code is doing.
/* va_list pointer is alligned to PARM_BOUNDARY.  If argument actually
   require greater alignment, we much perform dynamic alignment.  */

sounds fine?

Honza
> 
> zw


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