IBM Support

IV33086: INCORRECT UPDATE OF SHIFTED RESULT IN JIT COMPILED CODE

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APAR status

  • Closed as program error.

Error description

  • Error Message: A conditional write of an arithmetically shifted
    value is incorrectly executed, even if the condition evaluates
    to false.
    .
    Stack Trace: N/A
    .
    

Local fix

  • This issue can be avoided by using the -Xjit:disableZGryphon
    option.
    

Problem summary

  • This problem is caused by a z196-specific optimization that
    exploits conditional move instructions to eliminate unnecessary
    branches.  If a shift right arithmetic instruction (SRA/SRAG) is
    generated within the optimized code sequence, it could change
    the condition code that is used by subsequent instructions.
    

Problem conclusion

  • This defect will be fixed in:
    6.0.1 SR5
    7.0.0 SR4
    .
    The JIT compiler has been updated to prevent arithmetic shifts
    from being generated in this scenario.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV33086

  • Reported component name

    JIT

  • Reported component ID

    620700124

  • Reported release

    260

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-12-05

  • Closed date

    2012-12-05

  • Last modified date

    2012-12-05

  • 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



Document information

More support for: Runtimes for Java Technology
Just In Time (JIT) Compiler

Software version: 260

Reference #: IV33086

Modified date: 05 December 2012