LI77659: COMPILER ADDS UNNECESSARY STORE FOR VECTOR

XL C/C++ for Linux Fix Pack 8 (October 2015 Update) for 12.1
XL C/C++ for Linux Fix Pack 4 (October 2013 Update) for 12.1
XL C/C++ for Linux Fix Pack 5 (December 2013 Update) for 12.1
XL C/C++ for Linux Fix Pack 6 (February 2014 Update) for 12.1
XL C/C++ for Linux Fix Pack 7 (May 2014 Update) for 12.1

APAR status

• Closed as program error.

Error description

• The compiler generates unnecessary store for vector in the
  following code:
  
  $ cat test.cpp
  double extract0(vector double v)
  {
    return v[0];
  }
  $
  $ cat test.lst
  .
  .
    VR's set/used:   --u- ---- ---- ----  ---- ---- ---- ----
       | 000000                           PDEF
  extract0(vector double)
       | 000000                           AKA       extract0__Fad
      1|                                  PROC      v,vs34
      0| 000000 stdu     F821FF81   1     ST8U
  gr1,#stack(gr1,-128)=gr1
      0| 000004 addi     38000070   1     LI        gr0=112
      3| 000008 xxlor    F0221496   1     VOR       vs1=vs34,vs34
      0| 00000C stxvd2x  7C410799   1     VSTQD
  v(gr1,gr0,0)=vs34
      4| 000010 addi     38210080   1     AI        gr1=gr1,128
      4| 000014 bclr     4E800020   1     BA        lr
  .
  .
  $
  
  No stack adjustment and no stxvd2x is required.
  

Local fix

• N/A
  

Problem summary

• USERS AFFECTED:
  Users who compile vector cases and are using vector elements
  may be affected by this issue.
  
  PROBLEM DESCRIPTION:
  The compiler generates unnecessary stores for vector cases when
  using vector elements.
  

Problem conclusion

• A specific compiler optimization was enabled to remove the
  uncessary stores for vector cases when using vector elements.
  

Temporary fix

Comments

APAR Information

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

  IV38465

• 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

• RC10 PSN IV38465

     UP06/09/13