PH68887: METAL C CLOBBERS HIGH ORDER BITS

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When using a unsigned short for a typedef, Metal C compiler
  generates a LLGH that will overwrite the bits of the high halves
  with zeros.
  
  Based on the description of LLGH from the Principles of
  Operation:
  """
  For LOAD LOGICAL HALFWORD (LLGH, LLGHR) and LOAD LOGICAL
  HALFWORD RELATIVE LONG (LLGHRL), zeros are placed in bit
  positions 0-47 of general register R1
  """ For example with this testcase:
  ===== TESTCASE:
  
  #pragma csect(code,"CSQXOJWT")
  #pragma csect(static,"CSTXOJWT")
  
  #include <metal.h>
  
  typedef unsigned short myint;
  // typedef long long int myint;
  // typedef int myint;
  
  int func3(char * pcs);
  
  const char * func2(myint s1, myint s2)
  {  char * pcs = "some string";
   return pcs;
  }
  
  int func1(myint s1, myint s2)
  {  int i;
   char cs[32];
   i = strlen(func2(s1, s2));
   memcpy(cs, func2(s1, s2), i);
   return func3(cs);
  }
  
  ===== COMPILE COMMAND:
  
  xlC -S -qmetal -O2 -qlist -qsource -qnoinline -qnosearch
  -I/usr/include/metal test.c > test.lst
  
  ===== ACTUAL OUTPUT:
  
  * {
  
  
  *   int i;
  
  
  *   char cs[32];
  
  
  *   i = strlen(func2(s1, s2));
  
  
          USING @@PARMD@1,1
  
  
          LLGH  2,@8s1@2+2             ----> LLGH generated
  
  
          LLGH  4,@9s2@3+2
  
  
          LA    1,76(,13)               #MX_TEMP1
  
  
          ST    2,76(,13)               #MX_TEMP1
  
  
          ST    4,80(,13)               #MX_TEMP1
  
  
          MVC   8(4,13),#NAB_1
  
  
          BRASL 14,FUNC2
  
  
  
  Compiler needs to be corrected to generate a instruction that
  does not remove the high order bits.
  

Local fix

• NA
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of IBM z/OS XL C/C++ V2.4              *
  *                 with the METAL, HGPR(PRESERVE), and ILP32    *
  *                 options                                      *
  *                 and source code that uses 2 byte data        *
  *                 types (e.g. short),                          *
  ****************************************************************
  * PROBLEM DESCRIPTION: The compiler may generate code          *
  *                      that does clobbers the high half of     *
  *                      some general                            *
  *                      registers.                              *
  ****************************************************************
  * RECOMMENDATION: Install the PTF                              *
  ****************************************************************
  N/A
  

Problem conclusion

• Install the PTF
  

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:

Modules/Macros

• CCNECICS CCNECWI  CCNED240 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

• R7C0 PSY UO07332

     UP26/04/23 P F604

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.