IV20278: INCORRECT BLOCK VERSIONING CAUSING CRASHES

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APAR status

  • Closed as program error.

Error description

  • Error Message: The JVM crashes while executing an AOT-compiled
    Java method and tries to dereference an invalid pointer.  This
    problem can only happen when AOT compilation support is enabled
    and the block versioning optimization makes the wrong decision.
    .
    Stack Trace: N/A
    .
    

Local fix

  • The problem can be avoided by either:
    (1) disabling block versioning option using the
    -Xjit:disableBlockVersioner option
    (2) disablling AOT compilation support using the -Xnoaot option
    

Problem summary

  • This problem can only occur when AOT compilation support is
    enabled.  The problem is caused by the block versioning
    optimization.  The optimization makes certain assumptions about
    an instanceof check that is present when creating the multiple
    versions of the block, but in one particular scenario, this
    assumption is incorrect and as a result, some versions of the
    block are generated incorrectly.
    

Problem conclusion

  • This defect will be fixed in:
    6.0.1 SR2
    7.0.0 SR1
    6.0.0 SR11
    .
    The JVM is updated to prevent block versioner from proceeding
    further under the scenario identified.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV20278

  • Reported component name

    JIT

  • Reported component ID

    620700124

  • Reported release

    260

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-04-26

  • Closed date

    2012-04-26

  • Last modified date

    2012-06-01

  • 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

  • R260 PSY

       UP

  • R600 PSY

       UP



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Document information


More support for:

Runtimes for Java Technology
Just In Time (JIT) Compiler

Software version:

260

Reference #:

IV20278

Modified date:

2012-06-01

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