IV47767: ARRAY ELEMENT INITIALIZED INCORRECTLY BY DOWNWARD COUNTING LOOP

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: N/A
  .
  In a compiled Java method, a loop that writes a constant value
  to consecutive elements of an array in reverse order may leave
  some of the elements with incorrect values. For example, the
  code below may trigger the incorrect behaviour:
  do {
   i--;
   a<OSB>i<CSB> = CONSTANT;
  } while (i > N);
  

Local fix

• This issue can be worked around with the
  -Xjit:disableIdiomRecognition option.
  

Problem summary

• The problem is caused by a JIT optimization which recognizes the
  array initialization loop, but incorrectly calculates the number
  of elements to be initialized.
  

Problem conclusion

• This defect will be fixed in:
  6.0.1 SR7
  7.0.0 SR6
  6.0.0 SR15
  .
  The JIT compiler has been updated to correctly calculate the
  number of elements to be initialized.
  

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:

Fix information

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels

• R260 PSY

     UP

• R600 PSY

     UP