For this pseudoinstruction:
move $rt, $rs
Are both the addi and add assembly code acceptable? So could I use either
add $rt, $rs, $0
or
addi $rt, $rs, $0
?
Edit: I think I made a mistake with addi
add $rt, $rs, $0
would be the same as
addi $rt, $rs, 0
since add adds registers, and I need a constant for the immediate for addi
1 Answer
The addi instruction requires an immediate operand rather than a register, so the $0 would actually be 0:
add $rt, $rs, $0 addi $rt, $rs, 0 Both will work and have all the needed information encoded into the instruction itself):
add $d, $s, $t 0000 00ss ssst tttt dddd d000 0010 0000 addi $t, $s, i 0010 00ss ssst tttt iiii iiii iiii iiii However, it would be more usual to just use the zero-locked $0 register in this particular case since that is, after all, its purpose.
I would also tend to use the unsigned variant however, since I seem to recall there may be extra overflow checking done for signed instructions:
addu $rt, $rs, $0 
