LI77510: INLINING CAUSING INCORRECT OUTPUT

XL C/C++ for Blue Gene/Q Fix Pack 12 (May 2015 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 14 (May 2016 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 15 (October 2017 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 5 (August 2013 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 6 (November 2013 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 7 (February 2014 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 8 (May 2014 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 9 (August 2014 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 10 (November 2014 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 11 (February 2015 Update) for 12.1
XL C/C++ for Blue Gene/Q Fix Pack 13 (August 2015 Update) for 12.1

APAR status

• Closed as program error.

Error description

• ===== DESCRIPTION:
  The following test case produces an incorrect result when -O2 is
  used. Disabling inlining with -qnoinline
  avoids the issue.
  
  
  
  
  ========Testcase:
  $ cat test.cpp
  #include <cstdio>
  
  struct X {
  
    struct Y {
      int free() {
        x->y=NULL;
        return value;
      }
      int value;
      X* x;
    };
  
    int pop() {
      return y->free();
    }
    Y*y;
  };
  
  
  int main() {
    X x;
    X::Y y;
  
    y.x=&x;
    y.value=8200;
  
    x.y=&y;
  
    printf("%d\n", x.pop());
  }
  
  $
  
  
  
  
  ===== ACTUAL OUTPUT:
  $ xlC -O2 test.cpp
  $ ./a.out
  0
  $
  
  
  ===== EXPECTED OUTPUT:
  $ xlC -O2 test.cpp
  $ ./a.out
  8200
  $
  

Local fix

• Use -qnoinline as a workaround.
  

Problem summary

• TBD
  

Problem conclusion

• TBD
  

Temporary fix

Comments

APAR Information

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

  IV44221

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

Fix information

• Fixed component name

  XL C/C++ FOR BG

• Fixed component ID

  5799AG100

Applicable component levels