assemblycpu-architectureinstruction-setrisc

Why the RISC instruction sets usually do not contain register to register copy instruction?

I had this question on my exam and i am confused because as far as i know that

move $t0, $a0               # COPY $A0 TO $T0

in MIPS instruction provides that and MIPS is a RISC processor. Am I missing something?

Solution

  • Move is a pseudo-instruction, and when assembled will really be a different instruction.

    For instance

    move $t0, $zero gets implemented as addu $t0, $zero, $zero