IV02380: INCORRECT TRAP WITH MAXVAL AND MINVAL

January 2012 PTF for XL Fortran for AIX, V13.1
April 2012 PTF for XL Fortran for AIX, V13.1
July 2012 PTF for XL Fortran for AIX, V13.1
October 2012 PTF for XL Fortran for AIX, V13.1
February 2013 PTF for XL Fortran for AIX, V13.1
May 2013 PTF for XL Fortran for AIX, V13.1
XL Fortran for AIX Fix Pack 15 (August 2013 PTF) for 13.1
XL Fortran for AIX Fix Pack 16 (November 2013 PTF) for 13.1
XL Fortran for AIX Fix Pack 17 (February 2014 PTF) for 13.1
XL Fortran for AIX Fix Pack 21 (April 2015 PTF) for 13.1
XL Fortran for AIX Fix Pack 22 (September 2015 PTF) for 13.1
XL Fortran for AIX Fix Pack 23 (March 2016 PTF) for 13.1
XL Fortran for AIX Fix Pack 24 (September 2016 PTF) for 13.1

APAR status

• Closed as program error.

Error description

• When the either the MAXVAL or MINVAL functions are applied on
  NaN masked elements, an invalid exception is encountered during
  runtime.
  
  In the testcase below, 'tmparray' is a one-dimension array with
  two elements, the first of which is not explicitely assigned a
  value. Compiler option -qinitauto=7FBFFFFF is used to assign a
  float NaN to the first element.
  
  When compiling this test case with '-qflttrap=invalid:enable
  -qinitauto=7FBFFFFF -qnooptimize', an invalid exception is
  observed.
  
  
  ===== TESTCASE:
  program main
          real tmparray(2)
          tmparray(2) = 10.
          print *, maxval(tmparray, mask = (/.false., .true./))
  end program main
  
  
  ===== ACTUAL OUTPUT:
  $ xlf -qflttrap=invalid:enable -qinitauto=7FBFFFFF -qnooptimize
  main.f
  ** main   === End of Compilation 1 ===
  1501-510  Compilation successful for file main.f.
  $ ./a.out
  Trace/BPT trap (core dumped)
  $
  
  
  ===== EXPECTED OUTPUT:
  $ xlf -qflttrap=invalid:enable -qinitauto=7FBFFFFF -qnooptimize
  main.f
  ** main   === End of Compilation 1 ===
  1501-510  Compilation successful for file main.f.
  $ ./a.out
   10.00000000
  $
  

Local fix

• Within the test case, replace:
  print *, maxval(tmparray, mask = (/.false., .true./))
  
  with
  print *, maxval(pack(tmparray, mask = (/.false., .true./)))
  

Problem summary

• PROBLEM DESCRIPTION:
  The compiler is not generating a short circuiting AND on the
  user supplied MASK when expanding these intrinsics. This causes
  all portions of the expression determining the MAXVAL or MINVAL
  to be evaluated whether the user requested it or not. When this
  particular test case is run with these options, the runtime
  correctly traps on the yscal(1) as the user specified
  -qinitauto=7FBFFFFF (NaN).
  
  USERS AFFECTED:
  Users that debug using -qinitauto=7FBFFFFF
  -qflttrap=invalid:enable
  

Problem conclusion

• The fix included generating a short circuiting AND on the user
  specified MASK, which stops the remainder of the expression
  from being evaluated.
  

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:

  LI76467 LI76473 IV10112

Fix information

• Fixed component name

  XL FORTRAN FOR

• Fixed component ID

  5724X1500

Applicable component levels

• RD10 PSY U848520

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