Solution
--------
	
1)	For a machine having 128 bit of vector registers, the vectorization factor (VF) is the ratio of 128 by the
	size of data type in bits. Here data type for which vector operation is performed will decide the denominator.
	If the same machine have 'int' of size 32 bit, VF will be 4. So, VF is dependent on the data type.

2)	Considering VF=4 i.e. size of vector register is 128 bits and size of 'int' is 32 bits.
a)	For all -ve value of 'X', statement S1 has a loop-carried anti dependence over itself which doesn't prohibits
	the vectorization. Therefore vectorization is always possible for X<0.
	For X=0, S1 has loop-independent anti dependence over itself. Hence vectorization is possible.
	For 0<X<4, S1 has loop-carried flow dependence and also the distance between the two iterations which are
	dependent is lesser than VF. So vectorizing above loop, will not be able to honour the dependence. Hence
	vectorization is not possible.
	For X>=4, S1 has loop-carried flow dependence but also the distance between the two dependent iteration is
	greater than VF. Hence vectorization is still possible in presence flow dependence as the vectorized program
	will honour the dependences.

b)	As mentioned in solution to above section, for 0<X<4, vectorization will not be done by gcc-4.7.2 because
	dependences will not be maintained.

c)	In the program, total no. of iterations i.e. 251 is not completely divisible by VF i.e. 4. Hence some
	iterations, here 3, will get peeled and will not be part of vectorized loop.
	The above program will therefore execute 62 iterations in vectorized body and remaining 3 in sequential order.
	The 3 iterations which will be peeled can be any iterations and the actual decision is taken by gcc-4.7.2.
	Below is the portion from the dump created which illustrates the peeling.
	
		<bb 3>:	
			........
			# ivtmp.17_38 = PHI <ivtmp.17_39(7), 0(2)>
			........
			ivtmp.17_39 = ivtmp.17_38 + 1;
			if (ivtmp.17_39 < 62)
			goto <bb 7>;
			else
			goto <bb 4>;


		<bb 5>:
			..........
			# ivtmp.4_17 = PHI <ivtmp.4_22(6), 3(4)>
			.......... 
			ivtmp.4_22 = ivtmp.4_17 - 1;
			if (ivtmp.4_22 != 0)
			goto <bb 6>;
			else
			goto <bb 8>;