Question

For the following C statement, what is the corresponding MIPS assembly code? Assume that the variables i andj are assigned to registers $50 and $s1, respectively and the base address of the arrays A and B are in registers $s6 and $57, respectively. B[i] = A[B[j]+12];

Answer 1

# i, j in $s0, $s1
# A, B in $s6, $s7
# B[i] = A[B[j] + 12];

sll $t0, $s1, 2     # making j indexable
add $t0, $t0, $s7   # $s0 = &B[j]
lw $t0, 0($t0)      # $t0 = B[j]
addi $t0, $t0, 12   # $t0 = B[j] + 12
sll $t0, $t0, 2     # making B[j] + 12 indexable
add $t0, $t0, $s6   # $t0 = &A[B[j] + 12]
lw $t0, 0($t0)      # $t0 = A[B[j] + 12]

sll $t1, $s0, 2     # making i indexable
add $t1, $t1, $s7   # $t1 = &B[i]
sw $t0, 0($t1)      # B[i] = A[B[j] + 12]