find_var_field
hist_field = find_var_field(hist_data, var_name);
hist_field = find_var_field(test_data, var_name);
if (find_var_field(var_hist_data, var_name)) {
hist_field = find_var_field(test_data, var_name);
var = find_var_field(operand1->var.hist_data, operand1->name);
var = find_var_field(operand2->var.hist_data, operand2->name);
hist_field = find_var_field(hist_data, var_name);