16. MIPS register names and conventions

• 
        Number Name     Usage                   Preserved?
        ------ ------- -----------------------  ----------
            $0 $zero    constant 0x00000000     N/A
            $1 $at      assembler temporary     No
         $2-$3 $v0-$v1  function return values  No
         $4-$7 $a0-$a3  function arguments      No
        $8-$15 $t0-$t7  temporaries             No
       $16-$23 $s0-$s7  saved temporaries       Yes
       $24-$25 $t8-$t9  more temporaries        No
       $26-$27 $k0-$k1  reserved for OS kernel  N/A
           $28 $gp      global pointer          Yes
           $29 $sp      stack pointer           Yes
           $30 $fp      frame pointer           Yes
           $31 $ra      return address          Yes
  
  

• Preserved column idicates who is responsible for saving registers when a procedure is called:

  • No -- caller is responsible

  • Yes -- callee is responsible