[randomNumber7]

It was always only a suggestion to the compiler, to hold this variable in a register.

Compilers got so good at optimization that there is little point using it.

If a variable is held in a register you can't access it with a pointer. So if your intention is it should be in a register you can't take the address.

[tardedmeme]

It once told the compiler to hold the value in a register because the compiler wasn't very smart at all.