IZ97842: COMPILER WARNING WHEN INLINING WITH -Q64

May 2012 PTF for XL C/C++ for AIX, V10.1
January 2013 PTF for XL C for AIX, V10.1
January 2013 PTF for XL C/C++ for AIX, V10.1
XL C/C++ for AIX Fix Pack 18 (July 2013 PTF) for 10.1
XL C/C++ for AIX Fix Pack 19 (October 2013 PTF) for 10.1
XL C/C++ for AIX Fix Pack 21 (October 2015 PTF) for 10.1
XL C for AIX Fix Pack 21 (October 2015 PTF) for 10.1
May 2011 PTF for XL C/C++ for AIX, V10.1
May 2011 PTF for XL C for AIX, V10.1
October 2011 PTF for XL C/C++ for AIX, V10.1
October 2011 PTF for XL C for AIX, V10.1
February 2012 PTF for XL C for AIX, V10.1
February 2012 PTF for XL C/C++ for AIX, V10.1
May 2012 PTF for XL C for AIX, V10.1
September 2012 PTF for XL C for AIX, V10.1
September 2012 PTF for XL C/C++ for AIX, V10.1
XL C for AIX Fix Pack 18 (July 2013 PTF) for 10.1
XL C for AIX Fix Pack 19 (October 2013 PTF) for 10.1
XL C for AIX Fix Pack 20 (October 2014 PTF) for 10.1
XL C/C++ for AIX Fix Pack 20 (October 2014 PTF) for 10.1

APAR status

• Closed as program error.

Error description

• When inlining with -q64, a compiler warning is generated
  indicating that inlining has failed. In most cases, this warning
  will not appear if compiling with -q32.
  
  ===== Test Case:
  test.c:
  struct fred {
          int jjj;
  } freddy;
  
  static inline long bar(struct fred fff, int kkk) {
          return fff.jjj+kkk;
  }
  
  main()
  {
          long bbb;
          freddy.jjj = 3;
          bbb = bar(freddy,2);
          printf("bbb = %d (should be 5)\n",bbb);
  }
  ======================
  
  ===== Observed Output:
  $ xlc -q64 -O2 -c test.c
  1500-029: (W) WARNING: subprogram bar could not be inlined into
  main.
  
  $ xlc -q32 -O2 -c test.c
  $
  

Local fix

• In most cases, compiling with -q32 will hide the problem.
  

Problem summary

• PROBLEM DESCRIPTION:
  Failure to inline.  If you pass a structure by value and the
  size of the structure is not a multiple of the size of a
  register, then the compiler refuses to inline because it thinks
  there is a type mismatch.  This is more likely to happen with
  -q64 but it can happen with -q32.
  
  USERS AFFECTED:
  Users who depend on inlining.
  

Problem conclusion

• The fix is to compare the size of the rounded up parameter with
  the size of the argument before issuing a diagnostic and
  refusing to do the inlining.
  

Temporary fix

Comments

APAR Information

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

  IZ92004

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

Fix information

• Fixed component name

  XL C AIX

• Fixed component ID

  5724U8000

Applicable component levels