IJ31686: THE JIT INCORRECTLY COMPILES A METHOD CONSISTING OF NON-JAVAC GENERATED BYTECODES FROM JAVA 8.0.6.20 AND UP TO 8.0.6.30 ACROSS A

APAR status

• Closed as program error.

Error description

• Error Message: This problem can cause many kinds of symptoms:
  incorrect program result, exceptions or crashes in the JVM. One
  error message reported is NullPointerException
  .
  Stack Trace: The following is java stack trace for a failure we
  have seen, but this problem can cause other kinds of failures.
  Caused by: java.lang.NullPointerException
          at clojure.core$every_QMARK_.invokeStatic(core.clj:2570)
          at clojure.core$every_QMARK_.invoke(core.clj:2563)
          at
  clojure.core$maybe_destructured.invokeStatic(core.clj:4341)
          at clojure.core$maybe_destructured.invoke(core.clj:4338)
          at clojure.core$fn$psig__1016.invoke(core.clj:4411)
          at clojure.core$map$fn__563.invoke(core.clj:2646)
          at clojure.lang.LazySeq.sval(LazySeq.java:40)
          at clojure.lang.LazySeq.seq(LazySeq.java:49)
  .
  

Local fix

• This issue can be worked around by excluding the problematic
  java method being JIT compiled using
  -Xjit:exclude={bad/method*},dontInline={bad/method*}
  

Problem summary

• This problem is caused by the JIT compiler incorrectly
  eliminating stores to local slots where the value to store is
  loaded from the same local slot. When the local slot's value
  changes between the load and the store, the elimination become
  problematic.
  The following is an example of bytecodes that can expose the
  bug, notice that the value of local slot 0 is changed between
  the first load and the last store, and there is no branch in
  between.
  aload_0
  aconst_null
  astore_0
  astore_0
  Bytecodes compiled by javac from java code is unlikely to have
  this pattern
  

Problem conclusion

• The problem has been fixed in the JIT compiler to not eliminate
  such stores.
  .
  This APAR will be fixed in the following Java Releases:
     8    SR6 FP30  (8.0.6.30)
  .
  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:

Fix information

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels