LI77181: INCORRECT RESULT WITH -QHOT

XL Fortran for Blue Gene/Q Fix Pack 12 (May 2015 Update) for 14.1
XL Fortran for Blue Gene/Q Fix Pack 14 (May 2016 Update) for 14.1
XL Fortran for Blue Gene/Q Fix Pack 15 (October 2017 Update) for 14.1
May 2013 Update for XL Fortran for Blue Gene/Q, V14.1
XL Fortran for Blue Gene/Q Fix Pack 5 (August 2013 Update) for 14.1
XL Fortran for Blue Gene/Q Fix Pack 6 (November 2013 Update) for 14.1
XL Fortran for Blue Gene/Q Fix Pack 7 (February 2014 Update) for 14.1
XL Fortran for Blue Gene/Q Fix Pack 8 (May 2014 Update) for 14.1
XL Fortran for Blue Gene/Q Fix Pack 9 (August 2014 Update) for 14.1
XL Fortran for Blue Gene/Q Fix Pack 10 (November 2014 Update) for 14.1
XL Fortran for Blue Gene/Q Fix Pack 11 (February 2015 Update) for 14.1
XL Fortran for Blue Gene/Q Fix Pack 13 (August 2015 Update) for 14.1

APAR status

• Closed as program error.

Error description

• test program produces incorrect result at runtime if compiled
  with -qhot.
  
  Adding "@PROCESS nohot" for the offending routines corrects the
  problem.
  

Local fix

• use -qnohot
  

Problem summary

• PROBLEM DESCRIPTION: incorrect result with -qhot
  
  USERS AFFECTED: the problem will happen when SIMD is enabled.
  It will affect three level or more nested loops, where the
  inner most loop has small iterations which can be fully
  unrolled. The statements in the inner most loops should contain
  three-dimensions arrays(should be stride on access, no control
  flow, no calls. also the array index should be simple
  expressions where compiler generated index code match specific
  internal pattern). The scenario is rare.
  

Problem conclusion

• SIMD is trying to change 3-dim array index pattern which is
  wrong. Keep the index order as original order of the 3D array.
  Apply applicable service.
  

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:

  LI77416

Fix information

• Fixed component name

  XL FORTRAN FOR

• Fixed component ID

  5799AH100

Applicable component levels

• RE10 PSY

     UP