optimization control
--------------------

could be done with labels or blocks:

  some_label:
    for (int i : [0..10]) {
        code.opt.something(some_label);
        j += f(i);
    }
    
    codeblock some_block {
        for (int i : [0..10]) {
            code.opt.something(some_block);
            j += f(i);
        }
    }
    
    

move out
--------


  loops:
    for (int i : [0..i-1]) {
        for (int j : [0..j-1]) {
            
            code.opt.move_out_var(loops, [a]);
            if (a == 0) c += f(i, j);
            else if (a == 1) c += f(j, i);
            else c += f(i, i-j);
            
        }
    }

or
    
    // won't work. the code doesn't say which code should be moved out.
    // it could be if, if+for or if+for+for
  loops:
    for (int i : [0..i-1]) {
        for (int j : [0..j-1]) {
            
            if (a == 0) { code.opt.move_out(loops); c += f(i, j); }
            else if (a == 1) { code.opt.move_out(loops); c += f(j, i); }
            else { code.opt.move_out(loops); c += f(i, i-j); }
            
        }
    }
    
produces:
    
    if (a == 0) {
        for (int i : [0..i-1]) {
            for (int j : [0..j-1]) {
                c += f(i, j);
            }
        }
    } else if (a == 1) {
        for (int i : [0..i-1]) {
            for (int j : [0..j-1]) {
                c += f(j, i);
            }
        }
    } else {
        ...
    }


split_here
----------

  loops:
    for (int i : [0..i-1]) {
        for (int j : [0..j-1]) {
            
            lots();
            of();
            _code();
            
            code.opt.split_here(loops);
            
            even();
            more();
            _code();
            
        }
    }
    
produces:
    
  loops:
    for (int i : [0..i-1]) {
        for (int j : [0..j-1]) {
            
            lots();
            of();
            _code();
        }
    }
    for (int i : [0..i-1]) {
        for (int j : [0..j-1]) {
            
            even();
            more();
            _code();
        }
    }


enforced tail call optimization
--------------------------------


int f(int x, int y)
{
    if y <= 0 return x;
    else continue f(x+y, y-1);
}