// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/*******************************************************************************
 *
 * Module Name: dsutils - Dispatcher utilities
 *
 ******************************************************************************/

#include <acpi/acpi.h>
#include "accommon.h"
#include "acparser.h"
#include "amlcode.h"
#include "acdispat.h"
#include "acinterp.h"
#include "acnamesp.h"
#include "acdebug.h"

#define _COMPONENT          ACPI_DISPATCHER
ACPI_MODULE_NAME("dsutils")

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_clear_implicit_return
 *
 * PARAMETERS:  walk_state          - Current State
 *
 * RETURN:      None.
 *
 * DESCRIPTION: Clear and remove a reference on an implicit return value. Used
 *              to delete "stale" return values (if enabled, the return value
 *              from every operator is saved at least momentarily, in case the
 *              parent method exits.)
 *
 ******************************************************************************/
void acpi_ds_clear_implicit_return(struct acpi_walk_state *walk_state)
{
        ACPI_FUNCTION_NAME(ds_clear_implicit_return);

        /*
         * Slack must be enabled for this feature
         */
        if (!acpi_gbl_enable_interpreter_slack) {
                return;
        }

        if (walk_state->implicit_return_obj) {
                /*
                 * Delete any "stale" implicit return. However, in
                 * complex statements, the implicit return value can be
                 * bubbled up several levels.
                 */
                ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                                  "Removing reference on stale implicit return obj %p\n",
                                  walk_state->implicit_return_obj));

                acpi_ut_remove_reference(walk_state->implicit_return_obj);
                walk_state->implicit_return_obj = NULL;
        }
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_do_implicit_return
 *
 * PARAMETERS:  return_desc         - The return value
 *              walk_state          - Current State
 *              add_reference       - True if a reference should be added to the
 *                                    return object
 *
 * RETURN:      TRUE if implicit return enabled, FALSE otherwise
 *
 * DESCRIPTION: Implements the optional "implicit return".  We save the result
 *              of every ASL operator and control method invocation in case the
 *              parent method exit. Before storing a new return value, we
 *              delete the previous return value.
 *
 ******************************************************************************/

u8
acpi_ds_do_implicit_return(union acpi_operand_object *return_desc,
                           struct acpi_walk_state *walk_state, u8 add_reference)
{
        ACPI_FUNCTION_NAME(ds_do_implicit_return);

        /*
         * Slack must be enabled for this feature, and we must
         * have a valid return object
         */
        if ((!acpi_gbl_enable_interpreter_slack) || (!return_desc)) {
                return (FALSE);
        }

        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                          "Result %p will be implicitly returned; Prev=%p\n",
                          return_desc, walk_state->implicit_return_obj));

        /*
         * Delete any "stale" implicit return value first. However, in
         * complex statements, the implicit return value can be
         * bubbled up several levels, so we don't clear the value if it
         * is the same as the return_desc.
         */
        if (walk_state->implicit_return_obj) {
                if (walk_state->implicit_return_obj == return_desc) {
                        return (TRUE);
                }
                acpi_ds_clear_implicit_return(walk_state);
        }

        /* Save the implicit return value, add a reference if requested */

        walk_state->implicit_return_obj = return_desc;
        if (add_reference) {
                acpi_ut_add_reference(return_desc);
        }

        return (TRUE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_is_result_used
 *
 * PARAMETERS:  op                  - Current Op
 *              walk_state          - Current State
 *
 * RETURN:      TRUE if result is used, FALSE otherwise
 *
 * DESCRIPTION: Check if a result object will be used by the parent
 *
 ******************************************************************************/

u8
acpi_ds_is_result_used(union acpi_parse_object * op,
                       struct acpi_walk_state * walk_state)
{
        const struct acpi_opcode_info *parent_info;

        ACPI_FUNCTION_TRACE_PTR(ds_is_result_used, op);

        /* Must have both an Op and a Result Object */

        if (!op) {
                ACPI_ERROR((AE_INFO, "Null Op"));
                return_UINT8(TRUE);
        }

        /*
         * We know that this operator is not a
         * Return() operator (would not come here.) The following code is the
         * optional support for a so-called "implicit return". Some AML code
         * assumes that the last value of the method is "implicitly" returned
         * to the caller. Just save the last result as the return value.
         * NOTE: this is optional because the ASL language does not actually
         * support this behavior.
         */
        (void)acpi_ds_do_implicit_return(walk_state->result_obj, walk_state,
                                         TRUE);

        /*
         * Now determine if the parent will use the result
         *
         * If there is no parent, or the parent is a scope_op, we are executing
         * at the method level. An executing method typically has no parent,
         * since each method is parsed separately. A method invoked externally
         * via execute_control_method has a scope_op as the parent.
         */
        if ((!op->common.parent) ||
            (op->common.parent->common.aml_opcode == AML_SCOPE_OP)) {

                /* No parent, the return value cannot possibly be used */

                ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                                  "At Method level, result of [%s] not used\n",
                                  acpi_ps_get_opcode_name(op->common.
                                                          aml_opcode)));
                return_UINT8(FALSE);
        }

        /* Get info on the parent. The root_op is AML_SCOPE */

        parent_info =
            acpi_ps_get_opcode_info(op->common.parent->common.aml_opcode);
        if (parent_info->class == AML_CLASS_UNKNOWN) {
                ACPI_ERROR((AE_INFO, "Unknown parent opcode Op=%p", op));
                return_UINT8(FALSE);
        }

        /*
         * Decide what to do with the result based on the parent. If
         * the parent opcode will not use the result, delete the object.
         * Otherwise leave it as is, it will be deleted when it is used
         * as an operand later.
         */
        switch (parent_info->class) {
        case AML_CLASS_CONTROL:

                switch (op->common.parent->common.aml_opcode) {
                case AML_RETURN_OP:

                        /* Never delete the return value associated with a return opcode */

                        goto result_used;

                case AML_IF_OP:
                case AML_WHILE_OP:
                        /*
                         * If we are executing the predicate AND this is the predicate op,
                         * we will use the return value
                         */
                        if ((walk_state->control_state->common.state ==
                             ACPI_CONTROL_PREDICATE_EXECUTING) &&
                            (walk_state->control_state->control.predicate_op ==
                             op)) {
                                goto result_used;
                        }
                        break;

                default:

                        /* Ignore other control opcodes */

                        break;
                }

                /* The general control opcode returns no result */

                goto result_not_used;

        case AML_CLASS_CREATE:
                /*
                 * These opcodes allow term_arg(s) as operands and therefore
                 * the operands can be method calls. The result is used.
                 */
                goto result_used;

        case AML_CLASS_NAMED_OBJECT:

                if ((op->common.parent->common.aml_opcode == AML_REGION_OP) ||
                    (op->common.parent->common.aml_opcode == AML_DATA_REGION_OP)
                    || (op->common.parent->common.aml_opcode == AML_PACKAGE_OP)
                    || (op->common.parent->common.aml_opcode == AML_BUFFER_OP)
                    || (op->common.parent->common.aml_opcode ==
                        AML_VARIABLE_PACKAGE_OP)
                    || (op->common.parent->common.aml_opcode ==
                        AML_INT_EVAL_SUBTREE_OP)
                    || (op->common.parent->common.aml_opcode ==
                        AML_BANK_FIELD_OP)) {
                        /*
                         * These opcodes allow term_arg(s) as operands and therefore
                         * the operands can be method calls. The result is used.
                         */
                        goto result_used;
                }

                goto result_not_used;

        default:
                /*
                 * In all other cases. the parent will actually use the return
                 * object, so keep it.
                 */
                goto result_used;
        }

result_used:
        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                          "Result of [%s] used by Parent [%s] Op=%p\n",
                          acpi_ps_get_opcode_name(op->common.aml_opcode),
                          acpi_ps_get_opcode_name(op->common.parent->common.
                                                  aml_opcode), op));

        return_UINT8(TRUE);

result_not_used:
        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                          "Result of [%s] not used by Parent [%s] Op=%p\n",
                          acpi_ps_get_opcode_name(op->common.aml_opcode),
                          acpi_ps_get_opcode_name(op->common.parent->common.
                                                  aml_opcode), op));

        return_UINT8(FALSE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_delete_result_if_not_used
 *
 * PARAMETERS:  op              - Current parse Op
 *              result_obj      - Result of the operation
 *              walk_state      - Current state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Used after interpretation of an opcode. If there is an internal
 *              result descriptor, check if the parent opcode will actually use
 *              this result. If not, delete the result now so that it will
 *              not become orphaned.
 *
 ******************************************************************************/

void
acpi_ds_delete_result_if_not_used(union acpi_parse_object *op,
                                  union acpi_operand_object *result_obj,
                                  struct acpi_walk_state *walk_state)
{
        union acpi_operand_object *obj_desc;
        acpi_status status;

        ACPI_FUNCTION_TRACE_PTR(ds_delete_result_if_not_used, result_obj);

        if (!op) {
                ACPI_ERROR((AE_INFO, "Null Op"));
                return_VOID;
        }

        if (!result_obj) {
                return_VOID;
        }

        if (!acpi_ds_is_result_used(op, walk_state)) {

                /* Must pop the result stack (obj_desc should be equal to result_obj) */

                status = acpi_ds_result_pop(&obj_desc, walk_state);
                if (ACPI_SUCCESS(status)) {
                        acpi_ut_remove_reference(result_obj);
                }
        }

        return_VOID;
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_resolve_operands
 *
 * PARAMETERS:  walk_state          - Current walk state with operands on stack
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Resolve all operands to their values. Used to prepare
 *              arguments to a control method invocation (a call from one
 *              method to another.)
 *
 ******************************************************************************/

acpi_status acpi_ds_resolve_operands(struct acpi_walk_state *walk_state)
{
        u32 i;
        acpi_status status = AE_OK;

        ACPI_FUNCTION_TRACE_PTR(ds_resolve_operands, walk_state);

        /*
         * Attempt to resolve each of the valid operands
         * Method arguments are passed by reference, not by value. This means
         * that the actual objects are passed, not copies of the objects.
         */
        for (i = 0; i < walk_state->num_operands; i++) {
                status =
                    acpi_ex_resolve_to_value(&walk_state->operands[i],
                                             walk_state);
                if (ACPI_FAILURE(status)) {
                        break;
                }
        }

        return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_clear_operands
 *
 * PARAMETERS:  walk_state          - Current walk state with operands on stack
 *
 * RETURN:      None
 *
 * DESCRIPTION: Clear all operands on the current walk state operand stack.
 *
 ******************************************************************************/

void acpi_ds_clear_operands(struct acpi_walk_state *walk_state)
{
        u32 i;

        ACPI_FUNCTION_TRACE_PTR(ds_clear_operands, walk_state);

        /* Remove a reference on each operand on the stack */

        for (i = 0; i < walk_state->num_operands; i++) {
                /*
                 * Remove a reference to all operands, including both
                 * "Arguments" and "Targets".
                 */
                acpi_ut_remove_reference(walk_state->operands[i]);
                walk_state->operands[i] = NULL;
        }

        walk_state->num_operands = 0;
        return_VOID;
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_create_operand
 *
 * PARAMETERS:  walk_state      - Current walk state
 *              arg             - Parse object for the argument
 *              arg_index       - Which argument (zero based)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Translate a parse tree object that is an argument to an AML
 *              opcode to the equivalent interpreter object. This may include
 *              looking up a name or entering a new name into the internal
 *              namespace.
 *
 ******************************************************************************/

acpi_status
acpi_ds_create_operand(struct acpi_walk_state *walk_state,
                       union acpi_parse_object *arg, u32 arg_index)
{
        acpi_status status = AE_OK;
        char *name_string;
        u32 name_length;
        union acpi_operand_object *obj_desc;
        union acpi_parse_object *parent_op;
        u16 opcode;
        acpi_interpreter_mode interpreter_mode;
        const struct acpi_opcode_info *op_info;

        ACPI_FUNCTION_TRACE_PTR(ds_create_operand, arg);

        /* A valid name must be looked up in the namespace */

        if ((arg->common.aml_opcode == AML_INT_NAMEPATH_OP) &&
            (arg->common.value.string) &&
            !(arg->common.flags & ACPI_PARSEOP_IN_STACK)) {
                ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "Getting a name: Arg=%p\n",
                                  arg));

                /* Get the entire name string from the AML stream */

                status = acpi_ex_get_name_string(ACPI_TYPE_ANY,
                                                 arg->common.value.buffer,
                                                 &name_string, &name_length);

                if (ACPI_FAILURE(status)) {
                        return_ACPI_STATUS(status);
                }

                /* All prefixes have been handled, and the name is in name_string */

                /*
                 * Special handling for buffer_field declarations. This is a deferred
                 * opcode that unfortunately defines the field name as the last
                 * parameter instead of the first. We get here when we are performing
                 * the deferred execution, so the actual name of the field is already
                 * in the namespace. We don't want to attempt to look it up again
                 * because we may be executing in a different scope than where the
                 * actual opcode exists.
                 */
                if ((walk_state->deferred_node) &&
                    (walk_state->deferred_node->type == ACPI_TYPE_BUFFER_FIELD)
                    && (arg_index == (u32)
                        ((walk_state->opcode == AML_CREATE_FIELD_OP) ? 3 : 2))) {
                        obj_desc =
                            ACPI_CAST_PTR(union acpi_operand_object,
                                          walk_state->deferred_node);
                        status = AE_OK;
                } else {        /* All other opcodes */

                        /*
                         * Differentiate between a namespace "create" operation
                         * versus a "lookup" operation (IMODE_LOAD_PASS2 vs.
                         * IMODE_EXECUTE) in order to support the creation of
                         * namespace objects during the execution of control methods.
                         */
                        parent_op = arg->common.parent;
                        op_info =
                            acpi_ps_get_opcode_info(parent_op->common.
                                                    aml_opcode);

                        if ((op_info->flags & AML_NSNODE) &&
                            (parent_op->common.aml_opcode !=
                             AML_INT_METHODCALL_OP)
                            && (parent_op->common.aml_opcode != AML_REGION_OP)
                            && (parent_op->common.aml_opcode !=
                                AML_INT_NAMEPATH_OP)) {

                                /* Enter name into namespace if not found */

                                interpreter_mode = ACPI_IMODE_LOAD_PASS2;
                        } else {
                                /* Return a failure if name not found */

                                interpreter_mode = ACPI_IMODE_EXECUTE;
                        }

                        status =
                            acpi_ns_lookup(walk_state->scope_info, name_string,
                                           ACPI_TYPE_ANY, interpreter_mode,
                                           ACPI_NS_SEARCH_PARENT |
                                           ACPI_NS_DONT_OPEN_SCOPE, walk_state,
                                           ACPI_CAST_INDIRECT_PTR(struct
                                                                  acpi_namespace_node,
                                                                  &obj_desc));
                        /*
                         * The only case where we pass through (ignore) a NOT_FOUND
                         * error is for the cond_ref_of opcode.
                         */
                        if (status == AE_NOT_FOUND) {
                                if (parent_op->common.aml_opcode ==
                                    AML_CONDITIONAL_REF_OF_OP) {
                                        /*
                                         * For the Conditional Reference op, it's OK if
                                         * the name is not found;  We just need a way to
                                         * indicate this to the interpreter, set the
                                         * object to the root
                                         */
                                        obj_desc =
                                            ACPI_CAST_PTR(union
                                                                 acpi_operand_object,
                                                                 acpi_gbl_root_node);
                                        status = AE_OK;
                                } else if (parent_op->common.aml_opcode ==
                                           AML_EXTERNAL_OP) {
                                        /*
                                         * This opcode should never appear here. It is used only
                                         * by AML disassemblers and is surrounded by an If(0)
                                         * by the ASL compiler.
                                         *
                                         * Therefore, if we see it here, it is a serious error.
                                         */
                                        status = AE_AML_BAD_OPCODE;
                                } else {
                                        /*
                                         * We just plain didn't find it -- which is a
                                         * very serious error at this point
                                         */
                                        status = AE_AML_NAME_NOT_FOUND;
                                }
                        }

                        if (ACPI_FAILURE(status)) {
                                ACPI_ERROR_NAMESPACE(walk_state->scope_info,
                                                     name_string, status);
                        }
                }

                /* Free the namestring created above */

                ACPI_FREE(name_string);

                /* Check status from the lookup */

                if (ACPI_FAILURE(status)) {
                        return_ACPI_STATUS(status);
                }

                /* Put the resulting object onto the current object stack */

                status = acpi_ds_obj_stack_push(obj_desc, walk_state);
                if (ACPI_FAILURE(status)) {
                        return_ACPI_STATUS(status);
                }

                acpi_db_display_argument_object(obj_desc, walk_state);
        } else {
                /* Check for null name case */

                if ((arg->common.aml_opcode == AML_INT_NAMEPATH_OP) &&
                    !(arg->common.flags & ACPI_PARSEOP_IN_STACK)) {
                        /*
                         * If the name is null, this means that this is an
                         * optional result parameter that was not specified
                         * in the original ASL. Create a Zero Constant for a
                         * placeholder. (Store to a constant is a Noop.)
                         */
                        opcode = AML_ZERO_OP;   /* Has no arguments! */

                        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                                          "Null namepath: Arg=%p\n", arg));
                } else {
                        opcode = arg->common.aml_opcode;
                }

                /* Get the object type of the argument */

                op_info = acpi_ps_get_opcode_info(opcode);
                if (op_info->object_type == ACPI_TYPE_INVALID) {
                        return_ACPI_STATUS(AE_NOT_IMPLEMENTED);
                }

                if ((op_info->flags & AML_HAS_RETVAL) ||
                    (arg->common.flags & ACPI_PARSEOP_IN_STACK)) {
                        /*
                         * Use value that was already previously returned
                         * by the evaluation of this argument
                         */
                        status = acpi_ds_result_pop(&obj_desc, walk_state);
                        if (ACPI_FAILURE(status)) {
                                /*
                                 * Only error is underflow, and this indicates
                                 * a missing or null operand!
                                 */
                                ACPI_EXCEPTION((AE_INFO, status,
                                                "Missing or null operand"));
                                return_ACPI_STATUS(status);
                        }
                } else {
                        /* Create an ACPI_INTERNAL_OBJECT for the argument */

                        obj_desc =
                            acpi_ut_create_internal_object(op_info->
                                                           object_type);
                        if (!obj_desc) {
                                return_ACPI_STATUS(AE_NO_MEMORY);
                        }

                        /* Initialize the new object */

                        status =
                            acpi_ds_init_object_from_op(walk_state, arg, opcode,
                                                        &obj_desc);
                        if (ACPI_FAILURE(status)) {
                                acpi_ut_delete_object_desc(obj_desc);
                                return_ACPI_STATUS(status);
                        }
                }

                /* Put the operand object on the object stack */

                status = acpi_ds_obj_stack_push(obj_desc, walk_state);
                if (ACPI_FAILURE(status)) {
                        return_ACPI_STATUS(status);
                }

                acpi_db_display_argument_object(obj_desc, walk_state);
        }

        return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_create_operands
 *
 * PARAMETERS:  walk_state          - Current state
 *              first_arg           - First argument of a parser argument tree
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Convert an operator's arguments from a parse tree format to
 *              namespace objects and place those argument object on the object
 *              stack in preparation for evaluation by the interpreter.
 *
 ******************************************************************************/

acpi_status
acpi_ds_create_operands(struct acpi_walk_state *walk_state,
                        union acpi_parse_object *first_arg)
{
        acpi_status status = AE_OK;
        union acpi_parse_object *arg;
        union acpi_parse_object *arguments[ACPI_OBJ_NUM_OPERANDS];
        u32 arg_count = 0;
        u32 index = walk_state->num_operands;
        u32 prev_num_operands = walk_state->num_operands;
        u32 new_num_operands;
        u32 i;

        ACPI_FUNCTION_TRACE_PTR(ds_create_operands, first_arg);

        /* Get all arguments in the list */

        arg = first_arg;
        while (arg) {
                if (index >= ACPI_OBJ_NUM_OPERANDS) {
                        return_ACPI_STATUS(AE_BAD_DATA);
                }

                arguments[index] = arg;
                walk_state->operands[index] = NULL;

                /* Move on to next argument, if any */

                arg = arg->common.next;
                arg_count++;
                index++;
        }

        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                          "NumOperands %d, ArgCount %d, Index %d\n",
                          walk_state->num_operands, arg_count, index));

        /* Create the interpreter arguments, in reverse order */

        new_num_operands = index;
        index--;
        for (i = 0; i < arg_count; i++) {
                arg = arguments[index];
                walk_state->operand_index = (u8)index;

                status = acpi_ds_create_operand(walk_state, arg, index);
                if (ACPI_FAILURE(status)) {
                        goto cleanup;
                }

                ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                                  "Created Arg #%u (%p) %u args total\n",
                                  index, arg, arg_count));
                index--;
        }

        return_ACPI_STATUS(status);

cleanup:
        /*
         * We must undo everything done above; meaning that we must
         * pop everything off of the operand stack and delete those
         * objects
         */
        walk_state->num_operands = (u8)(i);
        acpi_ds_obj_stack_pop_and_delete(new_num_operands, walk_state);

        /* Restore operand count */
        walk_state->num_operands = (u8)(prev_num_operands);

        ACPI_EXCEPTION((AE_INFO, status, "While creating Arg %u", index));
        return_ACPI_STATUS(status);
}

/*****************************************************************************
 *
 * FUNCTION:    acpi_ds_evaluate_name_path
 *
 * PARAMETERS:  walk_state      - Current state of the parse tree walk,
 *                                the opcode of current operation should be
 *                                AML_INT_NAMEPATH_OP
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Translate the -name_path- parse tree object to the equivalent
 *              interpreter object, convert it to value, if needed, duplicate
 *              it, if needed, and push it onto the current result stack.
 *
 ****************************************************************************/

acpi_status acpi_ds_evaluate_name_path(struct acpi_walk_state *walk_state)
{
        acpi_status status = AE_OK;
        union acpi_parse_object *op = walk_state->op;
        union acpi_operand_object **operand = &walk_state->operands[0];
        union acpi_operand_object *new_obj_desc;
        u8 type;

        ACPI_FUNCTION_TRACE_PTR(ds_evaluate_name_path, walk_state);

        if (!op->common.parent) {

                /* This happens after certain exception processing */

                goto exit;
        }

        if ((op->common.parent->common.aml_opcode == AML_PACKAGE_OP) ||
            (op->common.parent->common.aml_opcode == AML_VARIABLE_PACKAGE_OP) ||
            (op->common.parent->common.aml_opcode == AML_REF_OF_OP)) {

                /* TBD: Should we specify this feature as a bit of op_info->Flags of these opcodes? */

                goto exit;
        }

        status = acpi_ds_create_operand(walk_state, op, 0);
        if (ACPI_FAILURE(status)) {
                goto exit;
        }

        if (op->common.flags & ACPI_PARSEOP_TARGET) {
                new_obj_desc = *operand;
                goto push_result;
        }

        type = (*operand)->common.type;

        status = acpi_ex_resolve_to_value(operand, walk_state);
        if (ACPI_FAILURE(status)) {
                goto exit;
        }

        if (type == ACPI_TYPE_INTEGER) {

                /* It was incremented by acpi_ex_resolve_to_value */

                acpi_ut_remove_reference(*operand);

                status =
                    acpi_ut_copy_iobject_to_iobject(*operand, &new_obj_desc,
                                                    walk_state);
                if (ACPI_FAILURE(status)) {
                        goto exit;
                }
        } else {
                /*
                 * The object either was anew created or is
                 * a Namespace node - don't decrement it.
                 */
                new_obj_desc = *operand;
        }

        /* Cleanup for name-path operand */

        status = acpi_ds_obj_stack_pop(1, walk_state);
        if (ACPI_FAILURE(status)) {
                walk_state->result_obj = new_obj_desc;
                goto exit;
        }

push_result:

        walk_state->result_obj = new_obj_desc;

        status = acpi_ds_result_push(walk_state->result_obj, walk_state);
        if (ACPI_SUCCESS(status)) {

                /* Force to take it from stack */

                op->common.flags |= ACPI_PARSEOP_IN_STACK;
        }

exit:

        return_ACPI_STATUS(status);
}