IJ45659: JAVA JIT: MISSING TYPE CHECKING ALLOWED INVALID OBJECT FIELD ACCESSES

APAR status

• Closed as program error.

Error description

• Error Message: SIGSEGV in JIT compiled method
  .
  Stack Trace: N/A
  .
  The issue can occur with any OpenJ9 based JVM on any platform.
  The APAR addresses an issue that was not properly covered by the
  previous APAR IJ24023.
  

Local fix

• The problem can be avoid by disable a JIT optimization using the
  following java command line option:
  -Xjit:disableBlockVersioner
  Using this option will have a minor effect on performance, but
  the cost is very likely to be less then 2% in almost all most
  cases.
  

Problem summary

• The JIT is doing a compile time instanceOf check in an attempt
  to eliminate the need for a runtime instanceOf check prior to
  executing an optimized block version with bound-checks and
  null-checks removed. This compile time instanceOf was in some
  cases incorrectly passing (eliminating a runtime instanceOf
  check) when it should have failed and generated a runtime
  instanceOf check.
  

Problem conclusion

• The JIT was modified such that it will generate a runtime
  instanceOf check when one is required.
  https://github.com/eclipse/omr/pull/6906
  .
  This APAR will be fixed in the following Releases:
  .
  IBM SDK, Java Technology Edition
     8    SR8 FP5   (8.0.8.5)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  maintenance can be found at:
             https://www.ibm.com/support/pages/java-sdk
  

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