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LI76986: VECTOR INITIALIZATION CREATES INEFFICIENT CODE

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • Consider testcase:
    
    //////////////////   test.C ///////////////////////
    extern "C" vector unsigned long long vec_xor_null()
    {
       vector unsigned long long v;
       return v ^ v;
    }
    
    extern "C" vector unsigned long long vec_builtin_null()
    {
       vector unsigned long long v;
       return vec_xor(v,v);
    }
    
    ////////////////////////////////////////////////////
    
    For those functions, compiler generate vspltisw instructions
    instead of more performance efficent xor instructions.
    

Local fix

  • N/A
    

Problem summary

  • Non-efficient code for vector initialization with zero
    

Problem conclusion

  • Problem had been fixed.
    

Temporary fix

Comments

APAR Information

  • APAR number

    LI76986

  • Reported component name

    XL C/C++ FOR LI

  • Reported component ID

    5725C7300

  • Reported release

    C10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-08-28

  • Closed date

    2012-08-28

  • Last modified date

    2012-08-28

  • APAR is sysrouted FROM one or more of the following:

    IV22825

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    XL C/C++ FOR LI

  • Fixed component ID

    5725C7300

Applicable component levels



Document information

More support for: XL C/C++ for Linux
Compiler

Software version: 12.1

Reference #: LI76986

Modified date: 28 August 2012