LI76298: PERFORMANCE OF 32B LOOP COUNTERS IN 64B MODE

July 2011 Update for XL Fortran for Linux, V13.1
October 2011 Update for XL Fortran for Linux, V13.1
June 2012 Update for XL Fortran for Linux, V13.1
October 2012 Update for XL Fortran for Linux, V13.1
XL Fortran for Linux Fix Pack 8 (June 2013 Update) for 13.1

APAR status

• Closed as program error.

Error description

• A performance degration is encountered when compiling a program
  in 64 bit mode that contains 32 bit loop counters.
  

Local fix

• N/A.
  

Problem summary

• PROBLEM DESCRIPTION:
  Potential performance degradation for 64-bit programs with
  32-bit loop control variables compared to previous versions of
  the compiler.
  
  USERS AFFECTED:
  Those using -q64 -O3 and up where 32-bit integer types are used
  as loop counters on hot loops.
  

Problem conclusion

• Improved code generation for 32-bit loop counters in 64-bit
  mode to improve software pipelining.
  

Temporary fix

Comments

APAR Information

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

  IZ99295

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

Fix information

• Fixed component name

  XL FORTRAN LINU

• Fixed component ID

  5724X1600

Applicable component levels

• RD10 PSY

     UP