LI76653: LONG COMPILE TIME WITH -O AND -QMAXMEM=-1

XL C/C++ for Linux Fix Pack 9 (August 2013 Update) for 11.1
June 2012 Update for XL C/C++ for Linux, V11.1
October 2012 Update for XL C/C++ for Linux, V11.1
XL C/C++ for Linux Fix Pack 8 (June 2013 Update) for 11.1

APAR status

• Closed as program error.

Error description

• When a large test case is compiled with -O and -qmaxmem=-1, it
  takes a long time to compile. If -qmaxmem=-1 is removed, it
  finishes much quicker.
  

Local fix

• n/a
  

Problem summary

• USERS AFFECTED:
  Users with functions with large basic blocks who compile at -O
  and use -qmaxmem=-1 may be affected by this issue.
  
  PROBLEM DESCRIPTION:
  The compiler take a long time to compile the source file.
  Most of the time was spent in a specific optimization of the
  compiler where it would constantly look for induction variables
  within large loops.
  

Problem conclusion

• The fix is to put a check in 2 functions in the same file.  The
  functions are both looking for induction variables.
  The check asks if the current function contains loops.  If not
  return at once as there's no point in looking for
  induction variables.
  

Temporary fix

Comments

APAR Information

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

  IV00344

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

Fix information

• Fixed component name

  XL C/C++ FOR LI

• Fixed component ID

  5724X1400

Applicable component levels

• RB10 PSN IV00344

     UP06/09/13