Re: [Tinycc-devel] x86_64: second struct va_arg fails

[Henry Kroll]

On Wed, 2010-12-15 at 03:07 +0100, grischka wrote:
> Henry Kroll wrote:
> > x86_64 fails to copy the second struct passed to va_arg.
> > 
> > static struct myspace {
> >     short int profile;
> > } bob = { 42 };
> > 
> > void badfunc(int eek, ...) {
> >     va_list ack;
> >     int validate;
> >     struct myspace george, bill;
> >     va_start(ack, eek);
> >         bill     = va_arg(ack, struct myspace);
> >         george   = va_arg(ack, struct myspace);
> >         validate = va_arg(ack, int);
> > [...]
> > int main(int argc, char **argv) {
> >     badfunc(0, bob, bob, bob.profile);
> > [...]
> 
> This line from tcc's include/stdarg.h might give a hint:
>      /* XXX: this lacks the support of aggregated types. */                  \
> 
> I have no idea though how such support would look like.
> 
If it helps, gcc fixed a similar problem recently, according to Iain
Sandoe 2010-07-24 08:08:00 UTC "fixed at least >= 4.4." Perhaps if I can
find the commit I will get a clue to expand the search. BTW I adapted
this test from the following bug report while trying to figure out why
GTK+ was crashing on mouse clicks. This is certainly easier to debug
than mouse clicks.
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18742
I noticed that "short int profile" can be replaced simply by "int
profile" and no change. I did a regression test and found no time when
it worked, so I started with 9d347f87426aebabe4eb52207b2f9ea8d2274809
and put a break on void gfunc_call(int nb_args) in x86_64-gen.c:593: and
poked around, wondering what type_size() should be returning. I didn't
think to look at stdarg.h or regress gcc and see what differences in the
gcc implementation fixed it, but I suppose that would be the logical
step.