Re: [Tinycc-devel] wrong preprocessor shift operation

[grischka]

Christian Jullien wrote:
> Simple code below is wrong, even when forcing to long or unsigned long :
>
>             printf("%08x\n", ((~0) >> 1));
>             printf("%08x\n", (unsigned long)((~(unsigned long)0) >> 1));
>             printf("%08x\n", (long)((~(long)0) >> 1));
>
> It prints
>
> ffffffff while 7fffffff is expected.

Well, shouldn't it be:
ffffffff
7fffffff
ffffffff

> I played a little bit with sources and
>
> F:\tmp\tinycc\win32>diff ..\tcc.BAK ..\tcc.c
> 5559,5560c5559,5572
> <     l1 = (t1 == VT_LLONG) ? v1->c.ll : v1->c.i;
> <     l2 = (t2 == VT_LLONG) ? v2->c.ll : v2->c.i;
> ---
> >     if (t1 == VT_LLONG) {
> >       l1 = v1->c.ll;
> >     } else {
> >       l1 = v1->c.i;
> >       l1 &= 0xffffffff;
> >     }
> >
> >     if (t2 == VT_LLONG) {
> >       l2 = v2->c.ll;
> >     } else {
> >       l2 = v2->c.i;
> >       l2 &= 0xffffffff;
> >     }

Probably "unsigned int" needs to be distinguished from "int".

Anyway, if you want to you can push a fix on our "mob" branch, See:
http://lists.gnu.org/archive/html/tinycc-devel/2008-11/msg00035.html

Thanks.