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IJ49445: __BUILTIN_EXPECT WITH OPT CAUSING MEMBER VALUES TO NOT BE UPDATED

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APAR status

  • Closed as program error.

Error description

  • When using the __builtin_expect built-in function with
optimization enabled, code motion and inlining is causing a
subsequent C++ object member assignment to not be updated,
resulting in an older value remaining in the member variable.

Local fix

  • - Lower optimization level
- Avoid usage of __builtin_expect in the failing code scenario

Problem summary

  • USERS AFFECTED:
Users who have testcases that that make use of __builtin_expect
and who compile with -O3 may be affected by this issue.

PROBLEM DESCRIPTION:
The compiler had a bug in its aliasing algorithm that was
causing incorrect aliasing instructions for __builtin_expect
code.

Problem conclusion

  • The compiler backend has been fixed to handle the above
scenario.

Temporary fix

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    IJ49445
    • 

  • Reported component name
    XL C/C++ FOR AI
    • 

  • Reported component ID
    5725C7200
    • 

  • Reported release
    G10
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt / Xsystem
    • 

  • Submitted date
    2023-12-05
    • 

  • Closed date
    2024-02-13
    • 

  • Last modified date
    2024-02-13
    • 





    

  • 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
    XL C/C++ FOR AI
    • 

  • Fixed component ID
    5725C7200
    • 



Applicable component levels


    








      
              
                            

              

              [{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSGH3R","label":"XL C\/C++ for AIX"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"G10","Line of Business":{"code":"LOB57","label":"Power"}}]
              

                                                                    

          
 
        

      

    

      

        

          

            
Document Information


            

            


                        

            Modified date:
            

            13 February 2024
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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