Test isa1v8

PPC isa1v8 (PPCIsaOneEight)
"example 1, ISA p 415"
(* A variation with no barriers *)
{
x=0;y=0;
0:r4=x; 1:r4=x ; 2:r4=x;
        1:r5=y ; 2:r5=y;

0:r1=1 ; 1:r2=2 ;
}
   P0        |  P1           |   P2         ;
stw r1,0(r4) | lwz r1,0(r4)  | lwz r1,0(r5) ;
             | stw r2,0(r5)  | lwz r2,0(r4) ;
locations [1:r1 ; 2:r1 ; 2:r2; ]
exists
  (1:r1=1 /\ 2:r1=2 /\ 2:r2=0)