Compiling the Example
leaf: sub $sp, $sp, 4 # room for 1 word
sw $s0, 0($sp) # store $s0
add $t0, $a0, $a1 # $t0 = g + h
add $t1, $a2, $a3 # $t1 = i + j
sub $s0, $t0, $t1 # $s0 = f
add $v0, $s0, $zero # copy result
lw $s0, 0($sp) # restore $s0
add $sp, $sp, 4 # put $sp back