LI76928: COMPILER HANG IN IPA WITH -QHOT=LEVEL=2

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • When compiling a large test case with -qhot=level=2, the
    compiler seems to hang causing a long compile time.
    
    ====== Compiler line:
    bgxlf_r -v -g -O3 -qstrict -qhot=level=2 -qsmp=omp
    

Local fix

  • Use -qhot=level=1 as a workaround.
    

Problem summary

  • An extremely long compile time is seen at -qhot=level=2 for a
    six level nested loop.
    
    Users of -qhot=level=2 when there is a 6-level loop nest with
    certain lower bound and upper bounds are affected by this
    issue.
    It is dependent on the lower bound and upper bounds of the
    loop. In this case the loop is manually tiled.
    
    Polyhedral works on a mathematical representation of loop nests
    in the user program. This representation is modified throughout
    polyhedral framework.
    When a certain algorithm is slow on a specific class of input
    (passed in the form of mathematical representation) it might be
    difficult to translate it back to a class of user programs.
    

Problem conclusion

  • The fix involves modifying a loop auto transformation
    optimization, when the number of dimensions of a scop are
    larger than a threshold.
    

Temporary fix

Comments

APAR Information

  • APAR number

    LI76928

  • Reported component name

    XL FORTRAN FOR

  • Reported component ID

    5799AH100

  • Reported release

    E10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-08-10

  • Closed date

    2012-11-23

  • Last modified date

    2012-11-23

  • 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 FORTRAN FOR

  • Fixed component ID

    5799AH100

Applicable component levels

  • RE10 PSY

       UP



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Document information


More support for:

XL Fortran for Blue Gene/Q

Software version:

ALL VERSIONS

Reference #:

LI76928

Modified date:

2012-11-23

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