destroy_hist_field
destroy_hist_field(hist_field->operands[i], level + 1);
destroy_hist_field(hist_field, 0);
destroy_hist_field(hist_field, 0);
destroy_hist_field(hist_data->fields[i], 0);
destroy_hist_field(ref_field, 0);
destroy_hist_field(alias, 0);
destroy_hist_field(operand1, 0);
destroy_hist_field(expr, 0);
destroy_hist_field(operand2, 0);
destroy_hist_field(operand1, 0);
destroy_hist_field(operand2, 0);
destroy_hist_field(operand1, 0);
destroy_hist_field(expr, 0);
destroy_hist_field(val, 0);
destroy_hist_field(val, 0);
destroy_hist_field(data->track_data.track_var, 0);
destroy_hist_field(field_var->var, 0);
destroy_hist_field(field_var->val, 0);
destroy_hist_field(hist_field, 0);