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/******************************************************************************

 *

 * Module Name: aslopt- Compiler optimizations

 *

 *****************************************************************************/

/******************************************************************************

 *

 * 1. Copyright Notice

 *

 * Some or all of this work - Copyright (c) 1999 - 2011, Intel Corp.

 * All rights reserved.

 *

 * 2. License

 *

 * 2.1. This is your license from Intel Corp. under its intellectual property

 * rights.  You may have additional license terms from the party that provided

 * you this software, covering your right to use that party's intellectual

 * property rights.

 *

 * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a

 * copy of the source code appearing in this file ("Covered Code") an

 * irrevocable, perpetual, worldwide license under Intel's copyrights in the

 * base code distributed originally by Intel ("Original Intel Code") to copy,

 * make derivatives, distribute, use and display any portion of the Covered

 * Code in any form, with the right to sublicense such rights; and

 *

 * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent

 * license (with the right to sublicense), under only those claims of Intel

 * patents that are infringed by the Original Intel Code, to make, use, sell,

 * offer to sell, and import the Covered Code and derivative works thereof

 * solely to the minimum extent necessary to exercise the above copyright

 * license, and in no event shall the patent license extend to any additions

 * to or modifications of the Original Intel Code.  No other license or right

 * is granted directly or by implication, estoppel or otherwise;

 *

 * The above copyright and patent license is granted only if the following

 * conditions are met:

 *

 * 3. Conditions

 *

 * 3.1. Redistribution of Source with Rights to Further Distribute Source.

 * Redistribution of source code of any substantial portion of the Covered

 * Code or modification with rights to further distribute source must include

 * the above Copyright Notice, the above License, this list of Conditions,

 * and the following Disclaimer and Export Compliance provision.  In addition,

 * Licensee must cause all Covered Code to which Licensee contributes to

 * contain a file documenting the changes Licensee made to create that Covered

 * Code and the date of any change.  Licensee must include in that file the

 * documentation of any changes made by any predecessor Licensee.  Licensee

 * must include a prominent statement that the modification is derived,

 * directly or indirectly, from Original Intel Code.

 *

 * 3.2. Redistribution of Source with no Rights to Further Distribute Source.

 * Redistribution of source code of any substantial portion of the Covered

 * Code or modification without rights to further distribute source must

 * include the following Disclaimer and Export Compliance provision in the

 * documentation and/or other materials provided with distribution.  In

 * addition, Licensee may not authorize further sublicense of source of any

 * portion of the Covered Code, and must include terms to the effect that the

 * license from Licensee to its licensee is limited to the intellectual

 * property embodied in the software Licensee provides to its licensee, and

 * not to intellectual property embodied in modifications its licensee may

 * make.

 *

 * 3.3. Redistribution of Executable. Redistribution in executable form of any

 * substantial portion of the Covered Code or modification must reproduce the

 * above Copyright Notice, and the following Disclaimer and Export Compliance

 * provision in the documentation and/or other materials provided with the

 * distribution.

 *

 * 3.4. Intel retains all right, title, and interest in and to the Original

 * Intel Code.

 *

 * 3.5. Neither the name Intel nor any other trademark owned or controlled by

 * Intel shall be used in advertising or otherwise to promote the sale, use or

 * other dealings in products derived from or relating to the Covered Code

 * without prior written authorization from Intel.

 *

 * 4. Disclaimer and Export Compliance

 *

 * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED

 * HERE.  ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE

 * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT,  ASSISTANCE,

 * INSTALLATION, TRAINING OR OTHER SERVICES.  INTEL WILL NOT PROVIDE ANY

 * UPDATES, ENHANCEMENTS OR EXTENSIONS.  INTEL SPECIFICALLY DISCLAIMS ANY

 * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A

 * PARTICULAR PURPOSE.

 *

 * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES

 * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR

 * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,

 * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY

 * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL

 * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.  THESE LIMITATIONS

 * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY

 * LIMITED REMEDY.

 *

 * 4.3. Licensee shall not export, either directly or indirectly, any of this

 * software or system incorporating such software without first obtaining any

 * required license or other approval from the U. S. Department of Commerce or

 * any other agency or department of the United States Government.  In the

 * event Licensee exports any such software from the United States or

 * re-exports any such software from a foreign destination, Licensee shall

 * ensure that the distribution and export/re-export of the software is in

 * compliance with all laws, regulations, orders, or other restrictions of the

 * U.S. Export Administration Regulations. Licensee agrees that neither it nor

 * any of its subsidiaries will export/re-export any technical data, process,

 * software, or service, directly or indirectly, to any country for which the

 * United States government or any agency thereof requires an export license,

 * other governmental approval, or letter of assurance, without first obtaining

 * such license, approval or letter.

 *

 *****************************************************************************/

#include "aslcompiler.h"

#include "aslcompiler.y.h"

#include "acparser.h"

#include "amlcode.h"

#include "acnamesp.h"

#define _COMPONENT          ACPI_COMPILER

        ACPI_MODULE_NAME    ("aslopt")

static UINT32 OptTotal = 0;

/* Local prototypes */

static ACPI_STATUS

OptSearchToRoot (

    ACPI_PARSE_OBJECT       *Op,

    ACPI_WALK_STATE         *WalkState,

    ACPI_NAMESPACE_NODE     *CurrentNode,

    ACPI_NAMESPACE_NODE     *TargetNode,

    ACPI_BUFFER             *TargetPath,

    char                    **NewPath);

static ACPI_STATUS

OptBuildShortestPath (

    ACPI_PARSE_OBJECT       *Op,

    ACPI_WALK_STATE         *WalkState,

    ACPI_NAMESPACE_NODE     *CurrentNode,

    ACPI_NAMESPACE_NODE     *TargetNode,

    ACPI_BUFFER             *CurrentPath,

    ACPI_BUFFER             *TargetPath,

    ACPI_SIZE               AmlNameStringLength,

    UINT8                   IsDeclaration,

    char                    **ReturnNewPath);

static ACPI_STATUS

OptOptimizeNameDeclaration (

    ACPI_PARSE_OBJECT       *Op,

    ACPI_WALK_STATE         *WalkState,

    ACPI_NAMESPACE_NODE     *CurrentNode,

    ACPI_NAMESPACE_NODE     *TargetNode,

    char                    *AmlNameString,

    char                    **NewPath);

/*******************************************************************************

 *

 * FUNCTION:    OptSearchToRoot

 *

 * PARAMETERS:  Op                  - Current parser op

 *              WalkState           - Current state

 *              CurrentNode         - Where we are in the namespace

 *              TargetNode          - Node to which we are referring

 *              TargetPath          - External full path to the target node

 *              NewPath             - Where the optimized path is returned

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Attempt to optimize a reference to a single 4-character ACPI

 *              name utilizing the search-to-root name resolution algorithm

 *              that is used by AML interpreters.

 *

 ******************************************************************************/

static ACPI_STATUS

OptSearchToRoot (

    ACPI_PARSE_OBJECT       *Op,

    ACPI_WALK_STATE         *WalkState,

    ACPI_NAMESPACE_NODE     *CurrentNode,

    ACPI_NAMESPACE_NODE     *TargetNode,

    ACPI_BUFFER             *TargetPath,

    char                    **NewPath)

{

    ACPI_NAMESPACE_NODE     *Node;

    ACPI_GENERIC_STATE      ScopeInfo;

    ACPI_STATUS             Status;

    char                    *Path;

    ACPI_FUNCTION_NAME (OptSearchToRoot);

    /*

     * Check if search-to-root can be utilized.  Use the last NameSeg of

     * the NamePath and 1) See if can be found and 2) If found, make

     * sure that it is the same node that we want.  If there is another

     * name in the search path before the one we want, the nodes will

     * not match, and we cannot use this optimization.

     */

    Path = &(((char *) TargetPath->Pointer)[TargetPath->Length -

                                            ACPI_NAME_SIZE]),

    ScopeInfo.Scope.Node = CurrentNode;

    /* Lookup the NameSeg using SEARCH_PARENT (search-to-root) */

    Status = AcpiNsLookup (&ScopeInfo, Path, ACPI_TYPE_ANY, ACPI_IMODE_EXECUTE,

                    ACPI_NS_SEARCH_PARENT | ACPI_NS_DONT_OPEN_SCOPE,

                    WalkState, &(Node));

    if (ACPI_FAILURE (Status))

    {

        return (Status);

    }

    /*

     * We found the name, but we must check to make sure that the node

     * matches.  Otherwise, there is another identical name in the search

     * path that precludes the use of this optimization.

     */

    if (Node != TargetNode)

    {

        /*

         * This means that another object with the same name was found first,

         * and we cannot use this optimization.

         */

        return (AE_NOT_FOUND);

    }

    /* Found the node, we can use this optimization */

    ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS,

        "NAMESEG:   %-24s", Path));

    /* We must allocate a new string for the name (TargetPath gets deleted) */

    *NewPath = ACPI_ALLOCATE_ZEROED (ACPI_NAME_SIZE + 1);

    ACPI_STRCPY (*NewPath, Path);

    if (ACPI_STRNCMP (*NewPath, "_T_", 3))

    {

        AslError (ASL_OPTIMIZATION, ASL_MSG_SINGLE_NAME_OPTIMIZATION, Op,

                *NewPath);

    }

    return (AE_OK);

}

/*******************************************************************************

 *

 * FUNCTION:    OptBuildShortestPath

 *

 * PARAMETERS:  Op                  - Current parser op

 *              WalkState           - Current state

 *              CurrentNode         - Where we are in the namespace

 *              TargetNode          - Node to which we are referring

 *              CurrentPath         - External full path to the current node

 *              TargetPath          - External full path to the target node

 *              AmlNameStringLength - Length of the original namepath

 *              IsDeclaration       - TRUE for declaration, FALSE for reference

 *              ReturnNewPath       - Where the optimized path is returned

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Build an optimal NamePath using carats

 *

 ******************************************************************************/

static ACPI_STATUS

OptBuildShortestPath (

    ACPI_PARSE_OBJECT       *Op,

    ACPI_WALK_STATE         *WalkState,

    ACPI_NAMESPACE_NODE     *CurrentNode,

    ACPI_NAMESPACE_NODE     *TargetNode,

    ACPI_BUFFER             *CurrentPath,

    ACPI_BUFFER             *TargetPath,

    ACPI_SIZE               AmlNameStringLength,

    UINT8                   IsDeclaration,

    char                    **ReturnNewPath)

{

    UINT32                  NumCommonSegments;

    UINT32                  MaxCommonSegments;

    UINT32                  Index;

    UINT32                  NumCarats;

    UINT32                  i;

    char                    *NewPath;

    char                    *NewPathExternal;

    ACPI_NAMESPACE_NODE     *Node;

    ACPI_GENERIC_STATE      ScopeInfo;

    ACPI_STATUS             Status;

    BOOLEAN                 SubPath = FALSE;

    ACPI_FUNCTION_NAME (OptBuildShortestPath);

    ScopeInfo.Scope.Node = CurrentNode;

    /*

     * Determine the maximum number of NameSegs that the Target and Current paths

     * can possibly have in common.  (To optimize, we have to have at least 1)

     *

     * Note: The external NamePath string lengths are always a multiple of 5

     * (ACPI_NAME_SIZE + separator)

     */

    MaxCommonSegments = TargetPath->Length / ACPI_PATH_SEGMENT_LENGTH;

    if (CurrentPath->Length < TargetPath->Length)

    {

        MaxCommonSegments = CurrentPath->Length / ACPI_PATH_SEGMENT_LENGTH;

    }

    /*

     * Determine how many NameSegs the two paths have in common.

     * (Starting from the root)

     */

    for (NumCommonSegments = 0;

         NumCommonSegments < MaxCommonSegments;

         NumCommonSegments++)

    {

        /* Compare two single NameSegs */

        if (ACPI_STRNCMP (

            &((char *) TargetPath->Pointer)[(NumCommonSegments *

                                             ACPI_PATH_SEGMENT_LENGTH) + 1],

            &((char *) CurrentPath->Pointer)[(NumCommonSegments *

                                              ACPI_PATH_SEGMENT_LENGTH) + 1],

            ACPI_NAME_SIZE))

        {

            /* Mismatch */

            break;

        }

    }

    ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, " COMMON: %u",

        NumCommonSegments));

    /* There must be at least 1 common NameSeg in order to optimize */

    if (NumCommonSegments == 0)

    {

        return (AE_NOT_FOUND);

    }

    if (NumCommonSegments == MaxCommonSegments)

    {

        if (CurrentPath->Length == TargetPath->Length)

        {

            ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, " SAME PATH"));

            return (AE_NOT_FOUND);

        }

        else

        {

            ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, " SUBPATH"));

            SubPath = TRUE;

        }

    }

    /* Determine how many prefix Carats are required */

    NumCarats = (CurrentPath->Length / ACPI_PATH_SEGMENT_LENGTH) -

                NumCommonSegments;

    /*

     * Construct a new target string

     */

    NewPathExternal = ACPI_ALLOCATE_ZEROED (

        TargetPath->Length + NumCarats + 1);

    /* Insert the Carats into the Target string */

    for (i = 0; i < NumCarats; i++)

    {

        NewPathExternal[i] = '^';

    }

    /*

     * Copy only the necessary (optimal) segments from the original

     * target string

     */

    Index = (NumCommonSegments * ACPI_PATH_SEGMENT_LENGTH) + 1;

    /* Special handling for exact subpath in a name declaration */

    if (IsDeclaration && SubPath && (CurrentPath->Length > TargetPath->Length))

    {

        /*

         * The current path is longer than the target, and the target is a

         * subpath of the current path. We must include one more NameSeg of

         * the target path

         */

        Index -= ACPI_PATH_SEGMENT_LENGTH;

        /* Special handling for Scope() operator */

        if (Op->Asl.AmlOpcode == AML_SCOPE_OP)

        {

            NewPathExternal[i] = '^';

            i++;

            ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, "(EXTRA ^)"));

        }

    }

    /* Make sure we haven't gone off the end of the target path */

    if (Index > TargetPath->Length)

    {

        Index = TargetPath->Length;

    }

    ACPI_STRCPY (&NewPathExternal[i], &((char *) TargetPath->Pointer)[Index]);

    ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, " %-24s", NewPathExternal));

    /*

     * Internalize the new target string and check it against the original

     * string to make sure that this is in fact an optimization. If the

     * original string is already optimal, there is no point in continuing.

     */

    Status = AcpiNsInternalizeName (NewPathExternal, &NewPath);

    if (ACPI_FAILURE (Status))

    {

        AslCoreSubsystemError (Op, Status, "Internalizing new NamePath",

            ASL_NO_ABORT);

        ACPI_FREE (NewPathExternal);

        return (Status);

    }

    if (ACPI_STRLEN (NewPath) >= AmlNameStringLength)

    {

        ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS,

            " NOT SHORTER (New %u old %u)",

            (UINT32) ACPI_STRLEN (NewPath), (UINT32) AmlNameStringLength));

        ACPI_FREE (NewPathExternal);

        return (AE_NOT_FOUND);

    }

    /*

     * Check to make sure that the optimization finds the node we are

     * looking for.  This is simply a sanity check on the new

     * path that has been created.

     */

    Status = AcpiNsLookup (&ScopeInfo,  NewPath,

                    ACPI_TYPE_ANY, ACPI_IMODE_EXECUTE,

                    ACPI_NS_DONT_OPEN_SCOPE, WalkState, &(Node));

    if (ACPI_SUCCESS (Status))

    {

        /* Found the namepath, but make sure the node is correct */

        if (Node == TargetNode)

        {

            /* The lookup matched the node, accept this optimization */

            AslError (ASL_OPTIMIZATION, ASL_MSG_NAME_OPTIMIZATION,

                Op, NewPathExternal);

            *ReturnNewPath = NewPath;

        }

        else

        {

            /* Node is not correct, do not use this optimization */

            Status = AE_NOT_FOUND;

            ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, " ***** WRONG NODE"));

            AslError (ASL_WARNING, ASL_MSG_COMPILER_INTERNAL, Op,

                "Not using optimized name - found wrong node");

        }

    }

    else

    {

        /* The lookup failed, we obviously cannot use this optimization */

        ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, " ***** NOT FOUND"));

        AslError (ASL_WARNING, ASL_MSG_COMPILER_INTERNAL, Op,

            "Not using optimized name - did not find node");

    }

    ACPI_FREE (NewPathExternal);

    return (Status);

}

/*******************************************************************************

 *

 * FUNCTION:    OptOptimizeNameDeclaration

 *

 * PARAMETERS:  Op                  - Current parser op

 *              WalkState           - Current state

 *              CurrentNode         - Where we are in the namespace

 *              AmlNameString       - Unoptimized namepath

 *              NewPath             - Where the optimized path is returned

 *

 * RETURN:      Status. AE_OK If path is optimized

 *

 * DESCRIPTION: Perform a simple optimization of removing an extraneous

 *              backslash prefix if we are already at the root scope.

 *

 ******************************************************************************/

static ACPI_STATUS

OptOptimizeNameDeclaration (

    ACPI_PARSE_OBJECT       *Op,

    ACPI_WALK_STATE         *WalkState,

    ACPI_NAMESPACE_NODE     *CurrentNode,

    ACPI_NAMESPACE_NODE     *TargetNode,

    char                    *AmlNameString,

    char                    **NewPath)

{

    ACPI_STATUS             Status;

    char                    *NewPathExternal;

    ACPI_GENERIC_STATE      ScopeInfo;

    ACPI_NAMESPACE_NODE     *Node;

    ACPI_FUNCTION_TRACE (OptOptimizeNameDeclaration);

    if (((CurrentNode == AcpiGbl_RootNode) ||

        (Op->Common.Parent->Asl.ParseOpcode == PARSEOP_DEFINITIONBLOCK)) &&

            (AmlNameString[0] == '\\'))

    {

        /*

         * The current scope is the root, and the namepath has a root prefix

         * that is therefore extraneous.  Remove it.

         */

        *NewPath = &AmlNameString[1];

        /* Debug output */

        Status = AcpiNsExternalizeName (ACPI_UINT32_MAX, *NewPath,

                    NULL, &NewPathExternal);

        if (ACPI_FAILURE (Status))

        {

            AslCoreSubsystemError (Op, Status, "Externalizing NamePath",

                ASL_NO_ABORT);

            return (Status);

        }

        /*

         * Check to make sure that the optimization finds the node we are

         * looking for.  This is simply a sanity check on the new

         * path that has been created.

         */

        ScopeInfo.Scope.Node = CurrentNode;

        Status = AcpiNsLookup (&ScopeInfo, *NewPath,

                        ACPI_TYPE_ANY, ACPI_IMODE_EXECUTE,

                        ACPI_NS_DONT_OPEN_SCOPE, WalkState, &(Node));

        if (ACPI_SUCCESS (Status))

        {

            /* Found the namepath, but make sure the node is correct */

            if (Node == TargetNode)

            {

                /* The lookup matched the node, accept this optimization */

                AslError (ASL_OPTIMIZATION, ASL_MSG_NAME_OPTIMIZATION,

                    Op, NewPathExternal);

                ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS,

                    "AT ROOT:   %-24s", NewPathExternal));

            }

            else

            {

                /* Node is not correct, do not use this optimization */

                Status = AE_NOT_FOUND;

                ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS,

                    " ***** WRONG NODE"));

                AslError (ASL_WARNING, ASL_MSG_COMPILER_INTERNAL, Op,

                    "Not using optimized name - found wrong node");

            }

        }

        else

        {

            /* The lookup failed, we obviously cannot use this optimization */

            ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS,

                " ***** NOT FOUND"));

            AslError (ASL_WARNING, ASL_MSG_COMPILER_INTERNAL, Op,

                "Not using optimized name - did not find node");

        }

        ACPI_FREE (NewPathExternal);

        return (Status);

    }

    /* Could not optimize */

    return (AE_NOT_FOUND);

}

/*******************************************************************************

 *

 * FUNCTION:    OptOptimizeNamePath

 *

 * PARAMETERS:  Op                  - Current parser op

 *              Flags               - Opcode info flags

 *              WalkState           - Current state

 *              AmlNameString       - Unoptimized namepath

 *              TargetNode          - Node to which AmlNameString refers

 *

 * RETURN:      None.  If path is optimized, the Op is updated with new path

 *

 * DESCRIPTION: Optimize a Named Declaration or Reference to the minimal length.

 *              Must take into account both the current location in the

 *              namespace and the actual reference path.

 *

 ******************************************************************************/

void

OptOptimizeNamePath (

    ACPI_PARSE_OBJECT       *Op,

    UINT32                  Flags,

    ACPI_WALK_STATE         *WalkState,

    char                    *AmlNameString,

    ACPI_NAMESPACE_NODE     *TargetNode)

{

    ACPI_STATUS             Status;

    ACPI_BUFFER             TargetPath;

    ACPI_BUFFER             CurrentPath;

    ACPI_SIZE               AmlNameStringLength;

    ACPI_NAMESPACE_NODE     *CurrentNode;

    char                    *ExternalNameString;

    char                    *NewPath = NULL;

    ACPI_SIZE               HowMuchShorter;

    ACPI_PARSE_OBJECT       *NextOp;

    ACPI_FUNCTION_TRACE (OptOptimizeNamePath);

    /* This is an optional optimization */

    if (!Gbl_ReferenceOptimizationFlag)

    {

        return_VOID;

    }

    /* Various required items */

    if (!TargetNode || !WalkState || !AmlNameString || !Op->Common.Parent)

    {

        return_VOID;

    }

    ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, "%5d [%12.12s] [%12.12s] ",

        Op->Asl.LogicalLineNumber,

        AcpiPsGetOpcodeName (Op->Common.Parent->Common.AmlOpcode),

        AcpiPsGetOpcodeName (Op->Common.AmlOpcode)));

    if (!(Flags & (AML_NAMED | AML_CREATE)))

    {

        if (Op->Asl.CompileFlags & NODE_IS_NAME_DECLARATION)

        {

            /* We don't want to fuss with actual name declaration nodes here */

            ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS,

                "******* NAME DECLARATION\n"));

            return_VOID;

        }

    }

    /*

     * The original path must be longer than one NameSeg (4 chars) for there

     * to be any possibility that it can be optimized to a shorter string

     */

    AmlNameStringLength = ACPI_STRLEN (AmlNameString);

    if (AmlNameStringLength <= ACPI_NAME_SIZE)

    {

        ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS,

            "NAMESEG %4.4s\n", AmlNameString));

        return_VOID;

    }

    /*

     * We need to obtain the node that represents the current scope -- where

     * we are right now in the namespace.  We will compare this path

     * against the Namepath, looking for commonality.

     */

    CurrentNode = AcpiGbl_RootNode;

    if (WalkState->ScopeInfo)

    {

        CurrentNode = WalkState->ScopeInfo->Scope.Node;

    }

    if (Flags & (AML_NAMED | AML_CREATE))

    {

        /* This is the declaration of a new name */

        ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, "NAME"));

        /*

         * The node of interest is the parent of this node

         * (the containing scope)

         */

        CurrentNode = Op->Asl.Parent->Asl.Node;

        if (!CurrentNode)

        {

            CurrentNode = AcpiGbl_RootNode;

        }

    }

    else

    {

        /* This is a reference to an existing named object */

        ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, "REF "));

    }

    /*

     * Obtain the full paths to the two nodes that we are interested in

     * (Target and current namespace location) in external

     * format -- something we can easily manipulate

     */

    TargetPath.Length = ACPI_ALLOCATE_LOCAL_BUFFER;

    Status = AcpiNsHandleToPathname (TargetNode, &TargetPath);

    if (ACPI_FAILURE (Status))

    {

        AslCoreSubsystemError (Op, Status, "Getting Target NamePath",

            ASL_NO_ABORT);

        return_VOID;

    }

    TargetPath.Length--;    /* Subtract one for null terminator */

    /* CurrentPath is the path to this scope (where we are in the namespace) */

    CurrentPath.Length = ACPI_ALLOCATE_LOCAL_BUFFER;

    Status = AcpiNsHandleToPathname (CurrentNode, &CurrentPath);

    if (ACPI_FAILURE (Status))

    {

        AslCoreSubsystemError (Op, Status, "Getting Current NamePath",

            ASL_NO_ABORT);

        return_VOID;

    }

    CurrentPath.Length--;   /* Subtract one for null terminator */

    /* Debug output only */

    Status = AcpiNsExternalizeName (ACPI_UINT32_MAX, AmlNameString,

                NULL, &ExternalNameString);

    if (ACPI_FAILURE (Status))

    {

        AslCoreSubsystemError (Op, Status, "Externalizing NamePath",

            ASL_NO_ABORT);

        return_VOID;

    }

    ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS,

        "%37s (%2u) ==> %-32s(%2u) %-32s",

        (char *) CurrentPath.Pointer, (UINT32) CurrentPath.Length,

        (char *) TargetPath.Pointer, (UINT32) TargetPath.Length, ExternalNameString));

    ACPI_FREE (ExternalNameString);

    /*

     * Attempt an optmization depending on the type of namepath

     */

    if (Flags & (AML_NAMED | AML_CREATE))

    {

        /*

         * This is a named opcode and the namepath is a name declaration, not

         * a reference.

         */

        Status = OptOptimizeNameDeclaration (Op, WalkState, CurrentNode,

                    TargetNode, AmlNameString, &NewPath);

        if (ACPI_FAILURE (Status))

        {

            /*

             * 2) now attempt to

             *    optimize the namestring with carats (up-arrow)

             */

            Status = OptBuildShortestPath (Op, WalkState, CurrentNode,

                            TargetNode, &CurrentPath, &TargetPath,

                            AmlNameStringLength, 1, &NewPath);

        }

    }

    else

    {

        /*

         * This is a reference to an existing named object

         *

         * 1) Check if search-to-root can be utilized using the last

         *    NameSeg of the NamePath

         */

        Status = OptSearchToRoot (Op, WalkState, CurrentNode,

                        TargetNode, &TargetPath, &NewPath);

        if (ACPI_FAILURE (Status))

        {

            /*

             * 2) Search-to-root could not be used, now attempt to

             *    optimize the namestring with carats (up-arrow)

             */

            Status = OptBuildShortestPath (Op, WalkState, CurrentNode,

                            TargetNode, &CurrentPath, &TargetPath,

                            AmlNameStringLength, 0, &NewPath);

        }

    }

    /*

     * Success from above indicates that the NamePath was successfully

     * optimized.  We need to update the parse op with the new name

     */

    if (ACPI_SUCCESS (Status))

    {

        HowMuchShorter = (AmlNameStringLength - ACPI_STRLEN (NewPath));

        OptTotal += HowMuchShorter;

        ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, " REDUCED %2u (%u)",

            (UINT32) HowMuchShorter, OptTotal));

        if (Flags & AML_NAMED)

        {

            if (Op->Asl.AmlOpcode == AML_ALIAS_OP)

            {

                /*

                 * ALIAS is the only oddball opcode, the name declaration

                 * (alias name) is the second operand

                 */

                Op->Asl.Child->Asl.Next->Asl.Value.String = NewPath;

                Op->Asl.Child->Asl.Next->Asl.AmlLength = ACPI_STRLEN (NewPath);

            }

            else

            {

                Op->Asl.Child->Asl.Value.String = NewPath;

                Op->Asl.Child->Asl.AmlLength = ACPI_STRLEN (NewPath);

            }

        }

        else if (Flags & AML_CREATE)

        {

            /* Name must appear as the last parameter */

            NextOp = Op->Asl.Child;

            while (!(NextOp->Asl.CompileFlags & NODE_IS_NAME_DECLARATION))

            {

                NextOp = NextOp->Asl.Next;

            }

            /* Update the parse node with the new NamePath */

            NextOp->Asl.Value.String = NewPath;

            NextOp->Asl.AmlLength = ACPI_STRLEN (NewPath);

        }

        else

        {

            /* Update the parse node with the new NamePath */

            Op->Asl.Value.String = NewPath;

            Op->Asl.AmlLength = ACPI_STRLEN (NewPath);

        }

    }

    else

    {

        ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, " ALREADY OPTIMAL"));

    }

    /* Cleanup path buffers */

    ACPI_FREE (TargetPath.Pointer);

    ACPI_FREE (CurrentPath.Pointer);

    ACPI_DEBUG_PRINT_RAW ((ACPI_DB_OPTIMIZATIONS, "\n"));

    return_VOID;

}