Hi Richard,
The attached patch tries to fold strlen (s) eq/ne 0 to *s eq/ne 0 on GIMPLE.
I am not sure where was the ideal place to put this transform in and ended up
adding it to strlen_optimize_stmt().
Does that look OK ?

I needed to add TODO_update_ssa to strlen pass, otherwise we hit the
following assert in execute_todo():
if (flag_checking
      && cfun
      && need_ssa_update_p (cfun))
    gcc_assert (flags & TODO_update_ssa_any);

Bootstrap+test in progress on x86_64-unknown-linux-gnu.

Thanks,
Prathamesh