PH40308: INCORRECT STRUCT ARRAY FUNCTION PARAMETER WHEN ACCESSED VIA __PTR32 POINTER

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When compiling in 64-bit mode, the function parameter list code
  generation for a pointer parameter using a __ptr32 qualification
  that accesses an array member in a struct may be calculated
  incorrectly.
  
  
  
     === TEST CASE ===
  
  int func(int*x, int z);
  
  struct a {
    int z;
    int y;
    int x[10];
  };
  
  int main() {
    struct a *__ptr32 test = 0;
    int z = func(test->x, sizeof(&(test->x[0])) + sizeof(test));
    return z;
  }
  
  
  Compile:
  xlc -S -Wc,"METAL,NOSE,SSCOMM,LP64,OPTIMIZE(3),
                         SEARCH(/usr/include/metal/)" test.c
  
  
  Incorrect:
  *   struct a *__ptr32 test = 0;         000010
           LGHI  14,0                     000010
  *   int z = func(test->x, ...           000011
  
  Correct:
  *   struct a *__ptr32 test = 0;         000010
  *   int z = func(test->x, ...           000011
           LGHI  14,8                     000011
  

Local fix

• Specify a pointer type instead of the array type in the struct.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Uses accessing array members in structs      *
  *                 using alternate amode pointers to the        *
  *                 structure                                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Access to array struct members via a    *
  *                      ptr32 qualified pointer in 64-bit mode  *
  *                      may give incorrect offsets into the     *
  *                      structure.                              *
  ****************************************************************
  * RECOMMENDATION: Provide a cast.                              *
  ****************************************************************
  N/A
  

Problem conclusion

• Fix this specialized point optimization/code gen.
  

Temporary fix

Comments

APAR Information

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

  PH35278

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

Modules/Macros

• CCNECICS CCNECWI  CCNED230 CCNEDSCT CCNEDWRT CCNEFILT CCNEHIFC
  CCNEIPA3 CCNEIPAO CCNEMDEP CCNEOPTP CCNEP    CCNEPP   CCNETBY
  CCNMSGE  CCNMSGT  CCNQIPA
  

Fix information

• Fixed component name

  C/C++ FOR MVS

• Fixed component ID

  56551210A

Applicable component levels

• R7B0 PSY UI77052

     UP21/09/29 P F109

Fix is available

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