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  • gibMay 8, 2008 12:45 AM PDT   
    /Qfp-stack-check
    The following program is fine when compiled (on Windows) with
    ifort err.f90
    but when compiled with the fp stack checking option
    ifort /Qfp-stack-check err.f90
    it gives access violation when executed.

    In my debugging efforts I've been turning on all the stack checking options, but this one seems to create a bug itself. 
    Interestingly, commenting out either of the two executable statements in subroutine zzz makes it OK.
    Any comments Steve?

    cheers
    Gib

    ! err.f90
    module errmod
    implicit none
    contains
    subroutine zzz(m)
    integer :: m(3)
    integer :: n(3)
    real :: x(3)

    x = m
    n = x

    end subroutine
    end module

    program err
    use errmod
    integer :: site(3) = (/1,2,3/)
    call zzz(site)
    end



    Les NeilsonMay 8, 2008 4:25 AM PDT
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    		 #1
    Re: /Qfp-stack-check

    The option is /Qfpstkchk

    I tried your code both from the command line and within VS without a problem
    (VS2005 and IVF 9.1.028)

    Les



    Steve Lionel (Intel)May 8, 2008 9:08 AM PDT
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    		 #2 Reply To #1
    Re: /Qfp-stack-check
    Access violation is exactly what to expect when the FP stack check option finds a problem.

    I can reproduce the error - let me investigate.


    Steve

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    Steve Lionel (Intel)May 8, 2008 10:18 AM PDT
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    		 #3 Reply To #2
    Re: /Qfp-stack-check
    By the way, the correct spelling of the option in version 10.1 is /Qfp-stack-check.  The older spelling /Qfpstkchk has been deprecated. I don't see the error with 9.1 nor with the internal build of our next major release (still a ways away).

    As best as I can tell, this is a compiler bug.  It occurs only with optimization level 2 or 3.  I have reported this to development.  If you report the issue to Intel Support, please reference T85092-CP.


    Steve

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    gibMay 8, 2008 4:54 PM PDT
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    		 #4 Reply To #3
    Re: /Qfp-stack-check
    Thanks Steve.


    Steve Lionel (Intel)May 9, 2008 11:43 AM PDT
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    		 #5
    Re: /Qfp-stack-check
    The problem you encountered was reported earlier and is fixed in our next major release.  A workaround is to use /QxN or whatever other appropriate version of /Qx is that would generate SSE code instead of x87 (no FP stack, runs faster.) Reference: T80134-CP.


    Steve

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    Doctor Fortran blog
    @DoctorFortran on Twitter

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