A complete exercise

Consider the following three-address code program.

L0	n := 10
	s := 0
	i := 0
L1	if i > n goto L6
	j := i
	m := n
	p := m
	f := 1
L2	if p = 1 goto L3
	f := f * p
	p := p - 1
	goto L2
L3	a := f
	p := m - j
	f := 1
L4	if p = 1 goto L5
	f := f * p
	p := p - 1
	goto L4
L5	b := f
	c := a quo b
	s := s + c
	i := i - 1
	goto L1
L6

1. Give the flow graph of this program.
2. Identify the back edges and the loops.
3. For each basic block B compute the data-flow sets gen(B) and kill (B) of the generated and killed variable definitions.
4. Deduce from this study a significant optimization for the above code.