Is there a danger in using the $gp register to store a value? I guess my question is what is the true functionality of $gp and is it invoked behind-the-scenes somehow so that if I were to use it, things could go very very wrong?
Answer
Well, $gp register points to the global area. Convention indicates that you should store it when you write a function (see .cprestore).
If you need to use it (honestly, cant see why), remeber these things:
1)Always store it in the Saved Register Area of your stack.
2)Always load that value into the $gp when destroying the stack.
3) Dont use it. (i.e dont access global scope)
Also, i'm not sure, but you can forget about PIC code.