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List:       gcc-fortran
Subject:    Re: Yet Another Opportunity to Optimize by the Front End.
From:       Paul Thomas <paulthomas2 () wanadoo ! fr>
Date:       2006-10-30 22:39:06
Message-ID: 45467F0A.2000305 () wanadoo ! fr
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Toon,
>
>       allocate (temp (m,n))
>       loop over n
>          loop over m
>             temp (...) = x(...) == y(...)
>       loop over n
>          loop over m
>             all = all .and. temp(...)
>
Steven and Paul were more intelligent than that:

  integer, parameter :: N = 10
  type :: toon
     integer :: wim (N) = (/(i, i = 1, N)/)
  end type toon
  type (toon) :: current
  integer :: wim(N) = (/(i, i = 1, N)/)
  call moene (wim)
contains
  subroutine moene (wim)
    integer :: wim (N)
    if (any(current%wim /= wim)) call abort ()
  end subroutine moene
end

produces:

moene (wim)
{
  int4[10] * D.951;
  logical4 test.0;

  test.0 = 0;
  D.951 = &current.wim;
  {
    int4 S.1;

    S.1 = 1;
    while (1)
      {
        if (S.1 > 10) goto L.2; else (void) 0;
        if ((*D.951)[NON_LVALUE_EXPR <S.1> + -1] != 
(*wim)[NON_LVALUE_EXPR <S.1> + -1] != 0)
          {
            test.0 = 1;
            goto L.1;
          }
        else
          {
            (void) 0;
          }
        S.1 = S.1 + 1;
      }
    L.2:;
  }
  L.1:;
  if (test.0)
    {
      _gfortran_abort ();
    }
  else
    {
      (void) 0;
    }
}


MAIN__ ()
{
  static struct toon current = {.wim={1, 2, 3, 4, 5, 6, 7, 8, 9, 10}};
  int4 i;
  static int4 wim[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
  static void moene (int4[10] *);

  _gfortran_set_std (70, 127, 0);
  moene (&wim);
}

ie. there is a single loop with an early bale-out for the condition 
being met.

Or have I misunderstood what you are wanting to do?

Cheers

Paul


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