On 08/17/2017 04:40 AM, Kamil Dudka wrote:
> -typedef short int DELTA;	/* to hold displacement within one context */
> +typedef int DELTA;		/* to hold displacement within one context */

Thanks for the heads-up. Although that fixes things for that particular 
test case, it won't work for larger cases. The type should be ptrdiff_t 
instead of int.

As its FIXME comment says, ptx is riddled with integer-overflow bugs. I 
installed the attached patch to fix the bug that you mentioned along 
with the other low-hanging fruit that I found, and am marking the bug as 
fixed upstream. I expect some other integer-overflow bugs can still 
occur in practice, but at least this patch is a significant improvement.

This patch prefers signed integer types like ptrdiff_t to unsigned types 
like size_t, as signed types allow for better checking when compiled 
with sanitization.