[Bug tree-optimization/96688] Failure to optimize shift-right+not of constant to avoid not

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96688

--- Comment #1 from Gabriel Ravier <gabravier at gmail dot com> ---
int f(int x)
{
    return ~(x + 123);
}

A very similar optimization can be done with this, by converting this to
`return ~123 - x;` (and the constant can be swapped out with pretty much any
other constant here too).