get_comparison
comparison = get_comparison(one, two);
int get_comparison(struct expression *left, struct expression *right);
comparison = get_comparison(offset, size);
orig_comparison = get_comparison(left_expr, right_expr);
comparison = get_comparison(r_left, r_right);
comparison = get_comparison(expr->left, expr->right);
comparison = get_comparison(expr->left, expr->right);