IJ19899: CRASH WHILE THROWING A CLASSCASTEXCEPTION

APAR status

• Closed as program error.

Error description

• Error Message: JVM crashes while throwing a ClassCastException
  on x86 64 bit with compressed references.
  System corefile analysis will find that one of the two class
  pointers has the high bits set (0xFFFFFFFF????????).
  .
  Stack Trace: The native callstack will include
  jitThrowClassCastException
  .
  

Local fix

• The problem can be avoided by using the JVM command line option
  -Xjit:disableInlineCheckcast
  Note that there can only be one -Xjit on the command line, so if
  necessary multiple options can be combined with commas.
  Alternatively, disabling compressed references will also avoid
  the problem.
  -Xnocompressedrefs
  

Problem summary

• When creating a class cast exception the 32 bit constant class
  pointer was passed to a helper method using a push immediate
  instruction. Unfortunately this instruction sign extends the 32
  bit value to 64 bits, so if a class pointer is allocated in
  memory above 2GB the called code fails while attempting to read
  from an incorrect pointer value.
  

Problem conclusion

• The x86 code generator was modified to use a different
  instruction sequence when passing class pointers that are in
  memory above 2GB.
  .
  This APAR will be fixed in the following Java Releases:
   8 SR6 (8.0.6.0)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
   https://www.ibm.com/developerworks/java/jdk/
  

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:

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels