[patch] tree-vrp.c: Teach VRP that &p->a is nonzero if p is known to be nonzero.

[Richard Henderson]

On Sun, May 01, 2005 at 07:08:30PM -0400, Kazu Hirata wrote:
> One question I have is whether it is safe to ignore the wrapping that
> might happen to a pointer.  If I have the following on a 32-bit system
> 
>   struct s { int a; int b; } *p;
> 
> and p is 0xfffffffc, then &p->b could be 0.  Should I worry about such
> a case?

No.  Pointer arithmetic isn't allowed to wrap.  IIRC we assume this
elsewhere, independently of -fwrapv.


r~