PI54409: IGYCB7300-W AN "IF" CONDITION INVOLVING A VOLATILE ITEM WAS INCORRECTLY EVALUATED AT COMPILE TIME AND CODE DISCARDED

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When the optimizer encountered an if condition it could evaluate
  at compile time, it incorrectly discarded code based on that
  evaluation although the if condition involved a volatile item.
  
  The contract for volatile items is that such an item "is loaded
  from memory each time it is referenced", which should prevent
  the optimizer from doing compile time evaluation of expressions
  involving such items and discarding code dependent on such a
  compile time evaluation.
  

Local fix

• Compile at OPT(0)
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of Enterprise COBOL V5.2 compiling     *
  *                 programs with OPT(1|2) and then running      *
  *                 them.  The programs assign a value to a      *
  *                 VOLATILE data item (e.g. a data item used in *
  *                 a check that prevents a CALL statement from  *
  *                 ever being executed, but prevents the        *
  *                 optimizer from removing the CALL statement,  *
  *                 forcing the called program to be resolved by *
  *                 the binder.)                                 *
  *                                                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Incorrect output at runtime: The        *
  *                      optimizer may replace a load of the     *
  *                      VOLATILE item with its assigned value   *
  *                      instead of loading the data item from   *
  *                      memory.                                 *
  *                                                              *
  ****************************************************************
  * RECOMMENDATION: Apply provided service.                      *
  ****************************************************************
  The compiler has an optimization that looks for values assigned
  to a data item and replaces loads of that item with the assigned
  value. That optimization wasn't checking if the item was marked
  VOLATILE.
  

Problem conclusion

• The compiler optimizer was fixed to correctly avoid optimization
  for data items with the VOLATILE attribute.
  

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:

Modules/Macros

• IGYCBE
  

Fix information

• Fixed component name

  ENT COBOL FOR Z

• Fixed component ID

  5655W3200

Applicable component levels

• R520 PSY UI34689

     UP16/01/28 P F601

Fix is available

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