[Bug tree-optimization/85315] missed range optimisation opportunity for derefences where index must be 0 or otherwise constrained

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85315

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Note for
int x;

...
  *(&x + (a + b))
if x is common we need to take -funconstrained-commons into account, similarly
for vars that end with flexible array members or similar arrays.