LI78456: COMPILER SHOULD USE XXLOR INSTEAD OF XVCPSGND WHEN USING -QARCH=PWR8

XL C/C++ for Linux Fix Pack 2 (February 2015 Update) for 13.1

APAR status

• Closed as program error.

Error description

• xlC compiler uses xvcpsgnd (6cycle) instead of xxlor (2cycle) if
  compiling for POWER 8 for the following test case:
  
  ===== COMPILE COMMAND:
  xlC -c -O2 -q64 -qlist -qarch=pwr8 -qaltivec -qtune=pwr8
  test.cpp
  
  ===== TESTCASE:
  $ cat test.cpp
  double fsel(double a, double b, double c, double d)
  {
    return a < b ? c : d;
  }
  $
  
  
  ===== ACTUAL OUTPUT:
       | 000000                           PDEF     fsel(double,
  double, double, double)
       | 000000                           AKA       fsel__FdN31
      1|                                  PROC
  a,b,c,d,vs1-vs4
      3| 000000 xscmpudp F0011118   1     CFL       cr0=vs1,vs2
      3| 000004 bc       4080000C   0     BF
  CL.2,cr0,0x20/flt,taken=50%(0,0)
      3| 000008 xvcpsgnd F0231F80   2     LRVS      vs1=vs3
      0| 00000C bclr     4E800020   0     BA        lr
      3|                              CL.2:
      3| 000010 xvcpsgnd F0242780   1     LRVS      vs1=vs4
      4| 000014 bclr     4E800020   0     BA        lr
       |               Tag Table
       | 000018        00000000 00092200 00000000 00000018
       |               Instruction count            6
       |               Straight-line exec time      4
  
  
  
  ===== EXPECTED OUTPUT:
  Compiler should use xxlor instead of xvcpsgnd
  

Local fix

• N/A
  

Problem summary

• USERS AFFECTED:
  Users who use -qalitvec on POWER 8 may be affected by this
  issue.
  
  PROBLEM DESCRIPTION:
  Compiler uses xvcpsgnd instead of xxlor which may result in
  less optimal runtime performance.
  

Problem conclusion

• Compiler has been changed to use xxlor instead of  xvcpsgnd if
  compiling for POWER 8.
  

Temporary fix

Comments

APAR Information

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

  IV67336

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

Fix information

• Fixed component name

  XL C/C++ FOR LI

• Fixed component ID

  5725C7300

Applicable component levels

• RD10 PSY

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