IV38460: COMPILER HANG WITH -QIPA=LEVEL=2

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • The compiler hangs when compiling a large test case and when
    using the -qipa=level=2 option.
    
    The issue occurs with test cases that involve alot of pointer
    analysis.
    

Local fix

  • The workaround is to use -qipa=level=1
    

Problem summary

  • USERS AFFECTED:
    Users using ipa=level=2 or -O5 to compile their programs might
    be affected by this issue.
    
    PROBLEM DESCRIPTION:
    The problem is due to the larger number of symbols introduced
    for pointer analysis in the newer compilers when compared to
    before.
    In the newer compilers, the conservative mod/use sets contains
    all the address taken symbols, including those member symbols
    that are only used in the initilaization,
    while only their owner symbols are included in the previous
    releases. For this case, there are many such pointer type
    adress taken member symbols.
    So, a large number of these pointers are imported for
    inter-procedural pointer analysis, which slow down
    significantly the pointer analysis.
    

Problem conclusion

  • In pointer analysis, a threshold is added to allow the pointer
    targets to grow up to a certain limit when meeting two pointer
    lattices.
    If the threshold is exceeded, the target set becomes bottom.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV38460

  • 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

    2013-03-21

  • Closed date

    2013-06-17

  • Last modified date

    2013-06-17

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

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

    LI77646

Fix information

  • Fixed component name

    XL C FOR AIX

  • Fixed component ID

    5725C7100

Applicable component levels

  • RC10 PSY U860046

       UP C



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Document information


More support for:

XL C for AIX
Compiler

Software version:

12.1

Reference #:

IV38460

Modified date:

2013-06-17

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