IV20144: INCORRECT OUTPUT FROM SYSTEM.ARRAYCOPY WHEN INLINED INTO AOT-COM PILED CODE

APAR status

• Closed as program error.

Error description

• Error Message: When a Java method that moves data within an
  array using System.arraycopy is AOT-compiled, the
  System.arraycopy call is inlined for performance reasons. If the
  source and destination ranges overlap, the inlined code can be
  incorrect and can produce incorrect content in the array. This
  may lead to unexpected exceptions or crashes.
  In many applications, this problem manifests itself as a
  corrupted string after the string has undergone special
  character escaping or Unicode character decoding.
  For example, escaping the backslash in the string "foo\bar"
  should result in the string "foo%5cbar", but this problem can
  corrupt the string to "fooo5cbar". Another example is decoding
  the string "foo\U0024bar", which should result in "foo$bar",
  however it can be corrupted into "ffo$bar" instead.
  This problem affects z/OS and z/Linux.
  .
  Stack Trace:
  .
  

Local fix

• This problem can be avoided by disabling AOT compilations with
  the -Xnoaot option. Alternatively, it can be avoided by using
  the "gencon" GC policy, with the -Xgcpolicy:gencon option.
  

Problem summary

• The problem is caused when the JIT compiler optimizes an
  arraycopy of primitive arrays into a simple memory copy, but is
  unable to determine the exact type of the arrays. In this
  scenario, the System z code generator can emit instructions to
  copy an incorrect number of array elements.
  

Problem conclusion

• This defect will be fixed in:
  6.0.0 SR12
  6.0.1 SR3
  7.0.0 SR2
  .
  The JIT compiler has been updated to prevent the improper
  optimization of such arraycopy calls.
  

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

• R600 PSY

     UP

• R260 PSY

     UP