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IV69565: MISSED COMPLEX TYPE SIMD OPPORTUNITY CAUSING PERFORMANCE ISSUE

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • A loop compiled with -qsimd=auto containing complex data types
    is not vectorized.
    
    
    
       === EXAMPLE ===
    
    double _Complex shl[val];
    
    while(cnt++<100000000)
    {
      for(int s = 0; s < 8; s++)
      {
        shl[0 + 3*(s)] += tmp[s] * Factor;
        shl[1 + 3*(s)] += tmp[s] * Factor;
      }
    }
    
    $ xlC_r test.C -q64 -O3 -qhot -qsimd=auto
    
    1586-551 (I) Loop (loop index 6) at test.C <line 20> was not
    SIMD vectorized because it contains unsupported vector data
    types.
    
    (Note:  example is not a compilable source)
    

Local fix

Problem summary

  • PROBLEM DESCRIPTION:
    Some auto-SIMD optimization opportunities are missed for double
    complex multiply and converts.
    
    USERS AFFECTED:
    Double complex users using auto-SIMD.
    

Problem conclusion

  • Double complex multiply and convert operations (taking 2 double
    values and creating a double complex from them) are now
    automatically vectorized.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV69565

  • Reported component name

    XL C FOR AIX

  • Reported component ID

    5725C7100

  • Reported release

    D10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2015-02-17

  • Closed date

    2015-10-14

  • Last modified date

    2015-10-14

  • 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 FOR AIX

  • Fixed component ID

    5725C7100

Applicable component levels

  • RD10 PSY

       UP



Document information

More support for: XL C for AIX
Compiler

Software version: 13.1

Reference #: IV69565

Modified date: 14 October 2015