Test i4

PPC i4 (IFour)
"WW reordering"

{0:r5=x; 0:r6=y; 
 1:r5=x; 1:r6=y; 
 2:r5=x;
 3:r6=y;
 x=0; y=0;}

P0           | P1           |P2           |P3          ;
li r1,1      | li r3,3      |lwz r1,0(r5) |lwz r1,0(r6);
stw r1,0(r5) | stw r3,0(r6) |lwz r2,0(r5) |lwz r2,0(r6);
li r2,2      | li r4,4      |             |            ;
stw r2,0(r6) | stw r4,0(r5) |             |            ;
             |              |             |            ;


exists(2:r1=4 /\ 2:r2=1 /\ 3:r1=2 /\ 3:r2=3)