[Bug middle-end/56281] missed VRP optimization on i for signed i << n from undefined left shift in ISO C

[vincent-gcc at vinc17 dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56281

--- Comment #5 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
I've clarified the bug title to say that this is a range on the first operand.