[Bug middle-end/47383] ivopts miscompiles Pmode != ptr_mode

["hjl.tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47383

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> 2011-01-21 05:33:53 UTC ---
(In reply to comment #3)
> The ivopts pass transforms
> 
> 
>   unsigned int D.2715;
>   unsigned int D.2716;
> ...
>   D.2715_43 = (unsigned int) elems_3(D);
>   D.2716_42 = D.2715_43 + 4294967295;
>   n_49 = (int) D.2716_42;
> 
> leads o the wrong result when Pmode != unsigned int. Adding
> -fno-ivopts fixes the bug.
> 

This is OK due to cast to int. But

  long unsigned int D.2757;
  long unsigned int D.2749;
  long unsigned int D.2750;
  unsigned int ivtmp.20;
  int D.2748;
  unsigned int ivtmp.17;
...
  D.2749_6 = (long unsigned int) prephitmp.8_18;
  D.2750_34 = ivtmp.17_28 - D.2749_6;
  MEM[symbol: heap, index: D.2750_34, step: 8, offset: 2296B] = n_11;

looks wrong since it assumes D.2750_34 can be negative. But
D.2750_34 is unsigned. It won't work when ptr_mode == unsigned
and Pmode is unsigned long long.