IBM Support

IZ94357: COMPILING WITH IPA LEADS TO INCORRECT OUTPUT

Fixes are available

May 2011 PTF for XL C for AIX, V11.1
May 2011 PTF for XL C/C++ for AIX, V11.1
August 2011 PTF for XL C/C++ for AIX, V11.1
November 2011 PTF for XL C/C++ for AIX, V11.1
January 2012 PTF for XL C for AIX, V11.1
January 2012 PTF for XL C/C++ for AIX, V11.1
April 2012 PTF for XL C for AIX, V11.1
April 2012 PTF for XL C/C++ for AIX, V11.1
July 2012 PTF for XL C/C++ for AIX, V11.1
October 2012 PTF for XL C for AIX, V11.1
October 2012 PTF for XL C/C++ for AIX, V11.1
February 2013 PTF for XL C for AIX, V11.1
February 2013 PTF for XL C/C++ for AIX, V11.1
XL C/C++ for AIX Fix Pack 14 (May 2013 PTF) for 11.1
XL C for AIX Fix Pack 14 (May 2013 PTF) for 11.1
XL C/C++ for AIX Fix Pack 15 (August 2013 PTF) for 11.1
XL C for AIX Fix Pack 15 (August 2013 PTF) for 11.1
XL C/C++ for AIX Fix Pack 16 (November 2013 PTF) for 11.1
XL C for AIX Fix Pack 17 (February 2014 PTF) for 11.1
XL C/C++ for AIX Fix Pack 17 (February 2014 PTF) for 11.1
XL C/C++ for AIX Fix Pack 18 (May 2014 PTF) for 11.1
XL C/C++ for AIX Fix Pack 19 (August 2014 PTF) for 11.1
XL C/C++ for AIX Fix Pack 20 (November 2014 PTF) for 11.1
XL C for AIX Fix Pack 21 (April 2015 PTF) for 11.1
XL C/C++ for AIX Fix Pack 21 (April 2015 PTF) for 11.1
XL C/C++ for AIX Fix Pack 22 (September 2015 PTF) for 11.1
XL C for AIX Fix Pack 23 (March 2016 PTF) for 11.1
XL C/C++ for AIX Fix Pack 23 (March 2016 PTF) for 11.1
XL C for AIX Fix Pack 24 (September 2016 PTF) for 11.1
XL C/C++ for AIX Fix Pack 24 (September 2016 PTF) for 11.1
August 2011 PTF for XL C for AIX, V11.1
November 2011 PTF for XL C for AIX, V11.1
July 2012 PTF for XL C for AIX, V11.1
XL C for AIX Fix Pack 16 (November 2013 PTF) for 11.1
XL C for AIX Fix Pack 18 (May 2014 PTF) for 11.1
XL C for AIX Fix Pack 19 (August 2014 PTF) for 11.1
XL C for AIX Fix Pack 20 (November 2014 PTF) for 11.1
XL C for AIX Fix Pack 22 (September 2015 PTF) for 11.1

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APAR status

  • Closed as program error.

Error description

  • The following test case demonstrates the inocorrect output:
    
    $cat test.c
    #include <stdio.h>
    
    int c;
    int cia();
    int check1();
    int check2();
    
    int foo() {
      unsigned g1=0, g2=0;
    
      if (check1()) { g1=1;}
      if (check2()) { g2=1;}
    
      unsigned char f1 = cia();
    
      if ((( (c?1:0) || g1 || g2) && (f1 ))) return 1;
      return 0;
    }
    
    
    int cia() { return 1; }
    int check1() { return 0;}
    int check2() { return 0;}
    
    int main() {
      c=1;
      printf("foo =  %d\n", foo());
    
      return 0;
    }
    
    ======ACTUAL OUTPUT:
    $xlc -+ test.c -q64 -qhot -qlist -qnoinline ; ./a.out
    foo =  0
    $
    
    ======EXPECTED OUTPUT:
    $./a.out
    foo =  1
    

Local fix

  • n/a
    

Problem summary

  • USERS AFFECTED:
    Users compiling the applications with ipa maybe affected by
    this issue.
    
    PROBLEM DESCRIPTION:
    A specific internal branching optimization was not merging the
    branches correctly while handling the first jump label.
    

Problem conclusion

  • The fix was to check if there is any jump to the label from
    outside of the predicate group when grouping the predicates
    with branch collapsing.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IZ94357

  • Reported component name

    XL C/C++ AIX

  • Reported component ID

    5724X1300

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-02-03

  • Closed date

    2011-04-20

  • Last modified date

    2011-04-20

Fix information

  • Fixed component name

    XL C FOR AIX

  • Fixed component ID

    5724X1200

Applicable component levels



Document information

More support for: XL C for AIX

Software version: 11.1

Reference #: IZ94357

Modified date: 20 April 2011