'sp' in debugger

[JarheadHME]

Hey, I'm running the debugger and am trying to find certain things in the game, and I think I know where I need to be looking, but I'm not sure how I see it. The asm says

Code:

sp

in place of what would normally be a registry, like

Code:

r4

or something. I don't see sp anywhere in the big registry list, so I'm led to believe it's elsewhere, but I'm not sure where to look. Can someone point me in the right direction?

On a separate note, I see in the breakpoints tab there's a column called "active", I'm led to believe that means I can deactivate certain breakpoints but keep them in the list to reactivate later, but I can't seem to figure out how I would do that. Any help?

[MayImilae]

*waves her magic moderator wand*

Moved to Developer Discussion!

[JonnyH]

"SP" likely stands for "Stack Pointer" - which register that refers to depends on the ABI, but I believe PowerPC tends to use gpr1.

Here's a description of IBM's recommendations for the powerpc - it's likely that the gamecube/wii use a similar (or the same) set.
https://www.ibm.com/support/knowledgecenter/en/ssw_aix_72/com.ibm.aix.alangref/idalangref_reg_use_conv.htm

EDIT: That seems to agree with the YAGCD page here:
http://hitmen.c02.at/files/yagcd/yagcd/chap3.html