IZ96359: INCORRECT CALCULATION FOR COMPLEX NUMBER

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

APAR status

• Closed as program error.

Error description

• When dividing a complex number by one, an incorrect real number
  is observed and a core is generated.
  
  This occurs when compiling the below test case with any of the
  following options:
  
  " -qsmp=omp"
  " -qsmp=omp -qinline=level=5"
  
  ==== Test Case:
  test.cpp:
  #include <iostream>
  #include <complex>
  
  using namespace std;
  
  int main()
  {
     complex<double> ddd;
     ddd = 1.0;
  
  #pragma omp parallel for
     for ( int i=0; i<4; ++i )
     {
        complex<double> csum;
  
        csum = 2.0 / ddd;
  
  #pragma omp critical
        clog << csum << " <- expected:  (2,0)" << endl;
     }
  }
  ==========
  
  ==== Actual Output:
  # xlC_r -qsmp=omp test.cpp && ./a.out
  (-1.78686e-308,-0) <- expected:  (2,0)
  (-1.78686e-308,-0) <- expected:  (2,0)
  Segmentation fault (core dumped)
  #
  

Local fix

• Use '-qsmp=omp -qinline=level=4'.
  

Problem summary

• PROBLEM DESCRIPTION:
  Incorrect calculation of complex number with -O3 -qhot.
  
  USERS AFFECTED:
  Users of at levels -O3 -qhot and higher.
  

Problem conclusion

• In an outlined procedure the real and complex members of a
  complex number were not privatized into that procedure but the
  owner was. So the stores into them did not go into the location
  of the owner causing runtime failures when the owner was
  referenced. The fix ensures that the owner and its members will
  become local to the outlined procedure.
  

Temporary fix

Comments

APAR Information

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

  LI75817

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

Fix information

• Fixed component name

  XL C FOR AIX

• Fixed component ID

  5724X1200

Applicable component levels