PI57057: NAME CONFLICT WITH LOCAL AND __ASM VARIABLES CAUSING INCORRECT SIZEOF RESULT

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When setting up and using a WTO __asm instruction, similar to
  the reentrancy example in:
  
  https://www.ibm.com/support/knowledgecenter/SSLTBW_2.1.0/com.
  ibm.zos.v2r1.ccrug00/asmmacrospec.htm
  
  , a variable called 'parmList' is created using the list form of
  the WTO instruction, defined to DS:128 in size:
  
  
    ===============================
    __asm("listmsg1 WTO 'hello world',MF=L": "DS:128"(listmsg1));
  
    static void test()
    {
  
    __asm("parmList WTO 'hello world',MF=L" :"DS:128"(parmList));
    parmList = listmsg1;
  
    __asm( " WTO MF=(E,(%0)) " : : "r"(&parmList));
  
    }
    ===============================
  
  
  Elsewhere in the same source, a simple 4 byte struct is also
  called 'parmList', unrelated to the WTO 'parmList' variable:
  
    ===============================
    typedef struct TestStruct
    {
      int value;
    } MyStruct;
    ....
    static void test2()
    {
      MyStruct parmList;
    ===============================
  
  When the program does a sizeof() for the struct 'parmList'
  variable, the code is incorrectly returning the 128 byte size
  from the WTO DS:128.
  
  From the compiler LIST/-qlist listing output:
  
    ===============================
    * * *   C R O S S R E F E R E N C E   L I S T I N G   * * *
  
    IDENTIFIER    DEFINITION  ATTRIBUTES
  
    parmList      23-0:23     Class = parameter, Length = 4
                              Type = pointer to struct
                              TestPlist_tag in function
                              test3
                              24-0:24
  
  
    vvvvvvvv <--- INCORRECT SIZE FOR THIS STRUCT --> vvv
    parmList      30-0:30     Class = auto, Length = 128
                              Type = struct TestPlist_tag in
                              function test2
                              35-0:35, 36-0:36
  
  
    parmList      12-0:12     Class = auto, Length = 128
                              Type = struct __ASM_DS_128 in
                              function test
                              13-0:13, 15-0:15
    ===============================
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: zOS XLC users with inline asm statements     *
  *                 defining data and with reused names.         *
  ****************************************************************
  * PROBLEM DESCRIPTION: Local data using the same name as       *
  *                      other ASM defined data ended up giving  *
  *                      the other ASM data size as the result   *
  *                      of sizeof.                              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  .
  

Problem conclusion

• Apply provided service.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  PI58807

Modules/Macros

•    CCNEP
  

Fix information

• Fixed component name

  C/C++ FOR MVS

• Fixed component ID

  56551210A

Applicable component levels

• R791 PSY UI35376

     UP16/03/10 P F603

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.