[Tinycc-devel] tcc grammar problems

[jiang]

Hello everyone!

(s->a = (s->b = (s->c = n + 4)));


gcc & msvc:
--> 30 / 30 / 126 // Because the return value is left


tcc
--> 254 / 30 / 126 // Because the return is the right value


Shall tcc assignment modify what? Same with gcc&msvc.


于 2014年06月22日 01:49, jiang 写道:
> This is my patch (see Annex)
>
> tcc result is correct
> --> 254 / 30 / 126
>
> 1 1 1 1 1 1 1 0 -> 254
> 254 & 0x7f (c:7)
>
> 1 1 1 1 1 1 1 0 -> 254
> 0 1 1 1 1 1 1 1 -> 0x7f
> ---------------------&-----
> 0 1 1 1 1 1 1 0 -> 126
>
> (b:5)
> 0 1 1 1 1 1 1 0 -> 126
> 0 0 0 1 1 1 1 1 -> 0x1f
> ---------------------&-----
> 0 0 0 1 1 1 1 0 -> 30
>
>
> (a:9)
> 0 0 0 0 1 1 1 1 0 -> 30
> 1 1 1 1 1 1 1 1 1 -> 0x1ff
> ---------------------&-----
> 0 0 0 1 1 1 1 0 -> 30
>
> I guess gcc & mvc repeated use of the register, so wrong
>
> 于 2014年06月21日 22:25, address@hidden 写道:
> > jiang wrote:
> > > /* bitfield store handling */
> > > + SValue tmp;
> > > + tmp = vtop[0];
> > > [...]
> > > + vtop--;
> > > + vpushv(&tmp);
> >
> >
> > This is still not a solution. See
> >
> > #include <stdio.h>
> > int main(int argc, char **argv)
> > {
> > struct {
> > unsigned a:9, b:5, c:7;
> > } _s, *s = &_s;
> > int n = 250;
> >
> > s->a = s->b = s->c = n + 4;
> > printf("--> %d / %d / %d\n", s->a, s->b, s->c);
> > return 0;
> > }
> > --> 432 / 16 / 126
> >
> > gcc & msvc:
> > --> 30 / 30 / 126
> > tcc release_0_9_26
> > --> 254 / 30 / 126
> >
> > FWIW, the line above is the reason why I'm trying to investigate
> > this. Let's see if Mr. jiang can come up with something useful
> > (and how long it will take).
> >
> > -- gr