[Bug tree-optimization/65752] Too strong optimizations int -> pointer casts

[post+gcc at ralfj dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65752

--- Comment #59 from post+gcc at ralfj dot de ---
> With the C provenance proposal this example is undefined since 'a' is not
exposed (it's address is not converted to an integer).

However, from what I can tell, GCC's behavior does not change if we insert
'(uintptr_t) &a;' at the beginning of the function. That change should be
sufficient to make the example well-defined again.