IZ67221: JAVA JIT COMPILE TIME CRASH ON AIX64 IN THE METHOD DECREFERENCEC OUNT()

APAR status

• Closed as program error.

Error description

• Error Message: A SIGSEGV occurs when the JIT is compiling a
  method. Commonly seen while compiling a method in the package
  "com/ibm/datatools/perf/console/..." but the possibility exists
  that the problem can occur while compiling methods from other
  packages.
  .
  Stack Trace:
  decReferenceCount__16TR_CodeGeneratorFP7TR_Node@AF226_56
  lstoreEvaluator__19TR_PPCTreeEvaluatorFP7TR_NodeP16TR_CodeGenera
  tor
  evaluate__16TR_CodeGeneratorFP7TR_Node
  doInstructionSelection__16TR_CodeGeneratorFv
  generateCodePhase1__16TR_CodeGeneratorFv
  generateCode__16TR_CodeGeneratorFv
  .
  The problem only exists in the 64bit PowerPC JIT compiler. The
  problem is not likely to occur using the default JIT, but has
  been seen a few times when using the compressed references JIT
  (-Xcompressedrefs option). The problem is unlikely to occur on
  Java5.
  

Local fix

• Disable the compilation of the method that the JIT was compiling
  when the SIGSEGV occurred.
  -Xjit:exclude={<full_method_signature>}
  i.e.
  -Xjit:excldue={package/class.method()V}
  

Problem summary

• The problem occurs when the JIT attempts to optimize away a long
  divide due to the fact that the divisor is determined to be the
  constant value 1. The problem only occurs when this
  transformation is done at a very late stage. The problem is rare
  because the transformation is almost always done at a much
  earlier stage of the compilation.
  

Problem conclusion

• This defect will be fixed in:
  6.0.0 SR8
  5.0.0 SR11 FP2
  .
  The JIT was modified so that it handles this transformation
  correctly.
  .
  To obtain the fix:
  Install build 20091231 or later
  

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:

  IZ67282

Fix information

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels

• R600 PSN

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