optimize "static" for loop

[xhliu]

for(uint i=0; i<2; i++) {
   sum += i;
}

==>

int i = 0;
loop (__LoopCount__0) {
   if (i < 2) {
       sum += i;
       i++;
   }
}

When i starts from CTC and ends at CTC, step size is also CTC, and it is not written inside the loop body, we can directly go to ==>

int i = 0;
loop (2) {
       sum += i;
       i++;
}

If it starts from 0 ==>

loop (2) : i {
       sum += i;
}