Re: [sdcc-devel] [ sdcc-Bugs-734169 ] Fatal error: modulo not converted to Fcall

[Johan K. <joh...@id...>]

> void d (int);
>
> unsigned char *p;
>
> void main (void)
> {
>   unsigned i;
>
>   p = 0;
>   i = 0;
>   do
>   {
>     p[i] = 0;
>     if (i % 1000 == 0)
>       d (i);
>   } while (++i < 0x8000);
> }
>
> > gen.c:3955: genMod: Assertion `0' failed.
>
> SDCCcse.c 1.17 (cseBBlock):1540 inserts a POINTER in the
> type chain of IC_LEFT (BBlock 2, 1. ic, iTemp8).
> This changes IC_LEFT of the 2. ic too, where the modulo is
> computed.
> SDCCopt.c 1.30 (convertToFcall):516 doesn't convert the mod
> (2. ic) to an Fcall, because IS_INTEGRAL(leftType) is false.
> IS_INTEGRAL checks type, not etype. etype is still integral.
>
> I see what's happening, but I've no idea, at which stage the bug
> occurs.

Good thinking, indeed the problem occured long before that. The main problem
is "p=0", you probably want "p=(unsigned char xdata*)0" or this would never
do what you expect :), but you insist on "p=0".

Now the compiler sees "p[i]=0" and icode-s that as "*(p+i)=0" (iTemp3 in
dumpdflow) in this example. Now the optimizer (knowing that p==0 and never
changes later) says "*(0+i)" then "*i" (iTemp2 in dumpgcse) and then decides
that i (replaced by iTemp8) MUST be a pointer (to an array or structure
member) (in dumploopg).

SDCCcse.c:1.77 fixes this, but doesn't "warn" anymore for this obvious
error.


HTH
Johan