[Bug tree-optimization/81110] tree-vrp optimize unsigned comparison to signed

[qian.liu at ingenic dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81110

--- Comment #1 from Ada Liu <qian.liu at ingenic dot com> ---
Comment on attachment 41567
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41567
reduced testcase

>
>unsigned short  d[2];
>__attribute__ ((noinline))int  DiffInt ()
>{
>  if ((unsigned long)(65536*d[1]+d[0]) < (1<<28)){
>    return -1;
>  }
>  return 0;
>}
>
>void main()
>{
>  d[0] = 0xffff;
>  d[1] = 0xffff;
>  if (DiffInt())
>    __builtin_abort();
>  
>}