Program test1:

	sub $0, $0, $0      # $0=0

	lw $1, 0($0)        # $1=4, mem(0) = 4

	lw $2, 2($0)        # $2=12, mem(2) = 12

	sub $2, $2, $1      # $2=8

	add $4, $2, $2      # $4=16

	sw $4, 4($0)        # mem(4) = 16

	beq $4, $0, -7      # not taken

loop:

	add $4, $4, $4      # $4=32

	add $4, $4, $4      # $4=64

	beq $0, $0, -3      # taken, branch to loop

	sub $4, $4, $4      # foo inst

	sub $4, $4, $4      # foo inst

You can make slight changes to adapt this program to your instruction set. For example, you can remove the first sub if $0 is always zero in your design, or use branch like "beqz $4, -7" if that is what supported. You cannot reorder instructions to remove data dependence.