Re: [Tinycc-devel] tricky little bounds-checking bug

[grischka]

Joe Soroka wrote:
> ---------------------
> char xyz[123];
>
> void main(void)
> {
>     int i = 0;
>     xyz[0] = !i;
> }
> --------------------
>
> This comes from trying to get tcc to run itself with bounds-checking
> turned on.  This is a reduced form of "init isid table" in
> preprocess_new().
>
> Looking at the disassembly, it seems that the '!' operator causes a
> register to be stomped on.  Some other expressions do the same thing,
> like "i || 1".
>
> I've tried to fix it, but I'm kinda lost in the bounds-checking logic.
>  Anyone have any ideas?

I recall there was a similar problem without bounds-checking:
    http://landley.net/hg/tinycc/rev/3f48bed56ab4
The patch is part of:
    
http://repo.or.cz/w/tinycc.git/commitdiff/54bf8c05566a34f4d578ed6d33d6262dc924a703
logged as:
    +  437: Call 'saveregs()' before jumping with logical and/or/not (grischka)

--- grischka