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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


            

            


                        

            Modified date:
            

            01 June 2012
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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