IBM Support

IV86387: UNEXPECTED RESULT FROM INTEGER SHIFT BYTECODE

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APAR status

  • Closed as program error.

Error description

  • Error Message: This problem can manifest itself in various forms
    as a value in a register may be unexpectedly changed.
    .
    Stack Trace: N/A
    .
    This problem can only happen on z Systems.
    

Local fix

Problem summary

  • When generating instructions for integer shift bytecodes (ishr
    or ishl), the JIT compiler will use an NILL instruction with an
    immediate of 0x1F as part of the sequence. This instruction
    changes the value of the destination register. The JIT compiler
    can potentially make the mistake of not realizing that the
    original value of the destination register is still needed. If
    this is the case, then unexpected results will probably occur
    when the modified destination register is used as if it were the
    original value.
    

Problem conclusion

  • The JIT compiler has been updated to ensure that the generated
    code for integer shift bytecodes does not clobber values in
    registers which later need to be used.
    .
    This APAR will be fixed in the following Java Releases:
       7    SR9 FP50  (7.0.9.50)
       7 R1 SR3 FP50  (7.1.3.50)
       6    SR16 FP30 (6.0.16.30)
       6 R1 SR8 FP30  (6.1.8.30)
       8    SR3 FP10  (8.0.3.10)
    .
    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 number

    IV86387

  • Reported component name

    JIT

  • Reported component ID

    620700124

  • Reported release

    260

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-06-29

  • Closed date

    2016-06-29

  • Last modified date

    2016-06-29

  • 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

  • R130 PSY

       UP

  • R600 PSY

       UP



Document information

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

Software version: 260

Reference #: IV86387

Modified date: 29 June 2016