IV51008: MISSING LOAD WITH -O3

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
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

• There are certain scenarios where the compiler might remove a
  necessary load 'after' a sync() instruction before its
  used.
  
  
  An example is the following:
  
  .L1629:
   lwz         r3,96(r31)
   lwz         r6,104(r31)    <---- load of r6
   subf        r4,r6,r3
   addi        r0,r3,-1
   rlwinm.     r3,r4,0,15,31
   beq         .L2014
  
   rlwinm      r4,r0,0,15,31
   stw         r4,96(r31)
   sync                      <---- sync instruction
   ld          r3,144(r31)
   rlwinm      r5,r0,3,12,28
   subf        r0,r6,r0      <---- r6 is being used in subf
  without it being loaded again after the sync instruction
   rlwinm      r0,r0,0,15,31
   cmplw       cr0,r0,r27
   ldx         r3,r3,r5
   std         r3,112(r1)
   beq         .L1655
  
   cmpdi       cr0,r0,0
   bne         .L173
  

Local fix

• N/A
  

Problem summary

• USERS AFFECTED:
  Users coding in assembly and those who use the sync instruction
  may be affected by this issue.
  
  PROBLEM DESCRIPTION:
  The compiler forgets to generate a load after the sync
  instruction.
  

Problem conclusion

• The compiler has been fixed to invalidate all aliasing symbols
  before sync the instruction so that they will be reloaded after
  sync instruction.
  

Temporary fix

Comments

APAR Information

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

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

  LI77616 LI77679 IV53311 LI77789 LI77797

Fix information

• Fixed component name

  XL C AIX

• Fixed component ID

  5724U8000

Applicable component levels

• RA10 PSY UP

     C