IV44284: USE LFIWAX/LFIWZX FOR INT TO FLOAT CONVERSION

XL C/C++ for AIX Fix Pack 4 (June 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 5 (September 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C/C++ for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C for AIX Fix Pack 4 (June 2013 PTF) for 12.1
XL C for AIX Fix Pack 5 (September 2013 PTF) for 12.1
XL C for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 21 (January 2019 Update) for 12.1
XL C for AIX Fix Pack 21 (January 2019 Update) for 12.1

APAR status

• Closed as program error.

Error description

• Compiler is not using lfiwax/lfiwzx assembler instruction
  for int to double conversion.
  
  Consider the following testcase:
  
  $cat intToDbl.C
  
  /******************************/
  
  double intToDbl(signed int *in)
  {
    return (double)(*in);
  }
  
  double intToDbl(signed int in)
  {
    return (double)(in);
  }
  
  double uintToDbl(unsigned int *in)
  {
    return (double)(*in);
  }
  
  double uintToDbl(unsigned int in)
  {
    return (double)(in);
  }
  /******************************/
  
  Compile the source file as:
  
  xlC -c -q64 -qlist -O2 intToDbl.C -qarch=pwr7
  
  
  Review output in intToDbl.lst file:
  
  ...
  ...
  
       | 000000                           PDEF     intToDbl(int *)
       | 000000                           AKA       intToDbl__FPi
      3|                                  PROC      in,gr3
      5| 000000 lwa      E8030002   1     L4A
  gr0=(int)(gr3,0)
      5| 000004 std      F801FFF0   1     ST8
  #MX_CONVF1_0(gr1,-16)=gr0
      5| 000008 lfd      C801FFF0   1     LFL
  vs0=#MX_CONVF1_0(gr1,-16)
      5| 00000C xscvsxdd F02005E0   1     FCFID     vs1=vs0,fcr
  
  
  Instead, the compiler should generate a lfiwax + xscvsxdd
  sequence:
  
  | 000000                           PDEF     intToDbl(int *)
       | 000000                           AKA       intToDbl__FPi
      1|                                  PROC      in,gr3
      3| 000000 lfiwax   7C001EAE   1     LFIWAX
  vs0=(int)(gr3,0)
      3| 000004 xscvsxdd F02005E0   1     FCFID     vs1=vs0,fcr
  

Local fix

• Not applicable
  

Problem summary

• compiler does not uses lfiwax/lfiwzx instructions for int to
  float conversion with -q64
  

Problem conclusion

• Relaxing the opportunity check code to use new instruction with
  -q64
  

Temporary fix

Comments

APAR Information

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

  IV37628

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

Fix information

• Fixed component name

  XL C FOR AIX

• Fixed component ID

  5725C7100

Applicable component levels