IBM Support

IV48060: IMPROVEMENTS TO MEMSET GENERATED CODE

Fixes are available

XL C/C++ for AIX Fix Pack 5 (September 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 8 (March 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 12 (May 2015 PTF) for 12.1
XL C/C++ for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 15 (April 2016 Update) for 12.1
XL C for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 16 (July 2016 Update) for 12.1
XL C/C++ for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C for AIX Fix Pack 17 (November 2016 Update) for 12.1
XL C for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 18 (February 2017 Update) for 12.1
XL C for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C/C++ for AIX Fix Pack 19 (August 2017 Update) for 12.1
XL C for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C/C++ for AIX Fix Pack 20 (March 2018 Update) for 12.1
XL C for AIX Fix Pack 5 (September 2013 PTF) for 12.1
XL C for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C/C++ for AIX Fix Pack 6 (December 2013 PTF) for 12.1
XL C for AIX Fix Pack 7 (January 2014 PTF) for 12.1
XL C for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 9 (July 2014 PTF) for 12.1
XL C for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C/C++ for AIX Fix Pack 10 (October 2014 PTF) for 12.1
XL C for AIX Fix Pack 11 (February 2015 PTF) for 12.1
XL C for AIX Fix Pack 13 (August 2015 Update) for 12.1
XL C for AIX Fix Pack 14 (December 2015 Update) for 12.1
XL C/C++ for AIX Fix Pack 21 (January 2019 Update) for 12.1
XL C for AIX Fix Pack 21 (January 2019 Update) for 12.1

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • Compiler adds improvements to memset generated code.
    

Local fix

  • N/A
    

Problem summary

  • inefficient code being generated for memset.  There are several
    issues 1) The constant area is used to hold the splatted value
    of the character 2) we don't always widen the stores to 8 bytes
    3) there are unnecessary multiply instructions generated by
    widening
    

Problem conclusion

  • The test in macro expansion to decide whether to use 4 byte or
    8 byte stores was incorrect.   Having macro expansion generate
    8 byte stores means that widening is no longer involved.  Also,
    instead of putting the constant into the constant area, let the
    normal macro expansion code decide how to manifest the
    constant.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV48060

  • Reported component name

    XL C/C++ FOR AI

  • Reported component ID

    5725C7200

  • Reported release

    C10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-09-10

  • Closed date

    2013-09-18

  • Last modified date

    2013-09-20

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

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

    LI77578 LI77668

Fix information

  • Fixed component name

    XL C FOR AIX

  • Fixed component ID

    5725C7100

Applicable component levels



Document information

More support for: XL C for AIX
Compiler

Software version: 12.1

Reference #: IV48060

Modified date: 20 September 2013