Hi, > diff -u gcc/tree-ssa-loop-niter.c (working copy) gcc/tree-ssa-loop-niter.c > (working copy) > --- gcc/tree-ssa-loop-niter.c (working copy) > +++ gcc/tree-ssa-loop-niter.c (working copy) > @@ -2875,6 +2875,16 @@ > low = lower_bound_in_type (type, type); > high = upper_bound_in_type (type, type); > > + /* In C, pointer arithmetic p + 1 cannot use a NULL pointer, and p - 1 > cannot > + produce a NULL pointer. The contrary would mean NULL points to an > object, > + while NULL is supposed to compare unequal with the address of all > objects. > + Furthermore, p + 1 cannot produce a NULL pointer and p - 1 cannot use a > + NULL pointer since that would mean wrapping, which we assume here not to > + happen. So, we can exclude NULL from the valid range of pointer > + arithmetic. */ > + if (int_cst_value (low) == 0) > + low = build_int_cstu (TREE_TYPE (low), TYPE_ALIGN_UNIT (TREE_TYPE > (type))); > + > record_nonwrapping_iv (loop, base, step, stmt, low, high, false, true); > }
OK, Zdenek
