[Bug fortran/35759] New: WHERE with overlap with ELSEWHERE error

[Bug fortran/35759] New: WHERE with overlap with ELSEWHERE error

[dick dot hendrickson at gmail dot com]

The following program computes the wrong result for a WHERE where
different sections of the same array are in both the WHERE and
ELSEWHERE section.  It's "as if" the ELSEWHERE block were
ignored.

Dick Hendrickson

      program RG0023
! fails on Windows XP
! gcc version 4.4.0 20080312 (experimental) [trunk revision 133139]


      integer UDA1L(6)
      integer ::  UDA1R(6), expected(6) = (/2,0,5,0,3,0/)
      LOGICAL LDA(5)

      UDA1L(1:6) = 0
      uda1r = (/1,2,3,4,5,6/)
      lda = (/ (i/2*2 .ne. I, i=1,5) /)

      WHERE (LDA)                !          expected
        UDA1L(1:5) = UDA1R(2:6)  !  uda1l = 2,0,4,0,6,0
      ELSEWHERE
        UDA1L(2:6) = UDA1R(6:2:-1) !uda1l = 2,0,5,0,3,0
      ENDWHERE

      print *, 'expected = ',expected
      print *, 'computed = ', uda1l

      END

gfortran:gfortran rg0023.f

gfortran:a
 expected =            2           0           5           0           3      
0
 computed =            2           0           4           0           6      
0


-- 
           Summary: WHERE with overlap with ELSEWHERE error
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dick dot hendrickson at gmail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35759

[Bug fortran/35759] WHERE with overlap with ELSEWHERE error

[burnus at gcc dot gnu dot org]

------- Comment #1 from burnus at gcc dot gnu dot org  2008-03-29 23:23 -------
Confirm.

The algorithm below does essentially:

while (1,0,1,0,1)
  uda1l( 1 _ 3 _ 5) = 2 3 4 5 6
else
  udal1 ( _ 3 _ 5 _) = 6 5 4 3 2
done

That is
1. uda1l(1) = 2
2. uda1l(3) = 5 <---\__
3. uda1l(3) = 4 <---/
4. uda1l(5) = 3 <---\__
5. uda1l(6) = 4 <---/

The order is wrong. The procedure has to be:

1. Establish control mask (i.e. 1,0,1,0,1) and run WHERE
  while (1,0,1,0,1)
    uda1l( 1 _ 3 _ 5) = 2 3 4 5 6
  end

2. Establish pending controlmask for ELSEWHERE (i.e. 0,1,0,1,0)
  elsewhile (0,1,0,1)
    uda1l( 1 _ 3 _ 5) = 2 3 4 5 6
  end


  {
    static logical(kind=4) A.2[5] = {1, 0, 1, 0, 1};
    static integer(kind=4) A.1[6] = {1, 2, 3, 4, 5, 6};

    (void) __builtin_memset ((void *) &uda1l, 0, 24);
    (void) __builtin_memcpy ((void *) &uda1r, (void *) &A.1, 24);
    (void) __builtin_memcpy ((void *) &lda, (void *) &A.2, 20);
    {
      integer(kind=8) S.3;

      S.3 = 1;
      while (1)
        {
          if (S.3 > 5) goto L.1;
          if (lda[S.3 + -1])
            {
              uda1l[S.3 + -1] = uda1r[S.3];
            }
          else
            {
              uda1l[S.3] = uda1r[6 - S.3];
            }
          S.3 = S.3 + 1;
        }
      L.1:;
    }


-- 

burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |wrong-code
   Last reconfirmed|0000-00-00 00:00:00         |2008-03-29 23:23:44
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35759

[Bug fortran/35759] WHERE with overlap with ELSEWHERE error

[pault at gcc dot gnu dot org]

------- Comment #2 from pault at gcc dot gnu dot org  2008-03-30 12:40 -------
This one should be straightforward, if lengthy to correct:

gfc_trans_where_2 is completely correct, as can be verified by doubling up the
line making the assignment in the WHERE block. ie:

      WHERE (LDA)                !          expected
        UDA1L(1:5) = UDA1R(2:6)  !  uda1l = 2,0,4,0,6,0
        UDA1L(1:5) = UDA1R(2:6)  !  uda1l = 2,0,4,0,6,0
      ELSEWHERE
        UDA1L(2:6) = UDA1R(6:2:-1) !uda1l = 2,0,5,0,3,0
      ENDWHERE

gfc_trans_where_3 is selected for a simple WHERE/ELSEWHERE, with no
dependencies and a single assignment expression in each block.  This is
selected by Dick's testscase.  It is also wrong, as indicated by Tobias in #1!

gfc_trans_where_3 will have to be split into two loops, instead of a single
loop with an expression.

Cheers

Paul


-- 

pault at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |pault at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2008-03-29 23:23:44         |2008-03-30 12:40:39
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35759

[Bug fortran/35759] WHERE with overlap with ELSEWHERE error

[pault at gcc dot gnu dot org]

------- Comment #3 from pault at gcc dot gnu dot org  2008-05-16 21:12 -------
Subject: Bug 35759

Author: pault
Date: Fri May 16 21:12:04 2008
New Revision: 135443

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=135443
Log:
2008-05-16  Paul Thomas  <pault@gcc.gnu.org>

        PR fortran/35756
        PR fortran/35759
        * trans-stmt.c (gfc_trans_where): Tighten up the dependency
        check for calling gfc_trans_where_3.

        PR fortran/35743
        * trans-stmt.c (gfc_trans_where_2): Set the mask size to zero
        if it is calculated to be negative.

        PR fortran/35745
        * trans-stmt.c (gfc_trans_where_3, gfc_trans_where_assign): Set
        ss->where for scalar right hand sides.
        * trans-array.c (gfc_add_loop_ss_code): If ss->where is set do
        not evaluate scalars outside the loop.  Clean up whitespace.
        * trans.h : Add a bitfield 'where' to gfc_ss.

2008-05-16  Paul Thomas  <pault@gcc.gnu.org>

        PR fortran/35756
        PR fortran/35759
        * gfortran.dg/where_1.f90: New test.

        PR fortran/35743
        PR fortran/35745
        * gfortran.dg/where_2.f90: New test.

Added:
    trunk/gcc/testsuite/gfortran.dg/where_1.f90
    trunk/gcc/testsuite/gfortran.dg/where_2.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/trans-array.c
    trunk/gcc/fortran/trans-stmt.c
    trunk/gcc/fortran/trans.h
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35759

[Bug fortran/35759] WHERE with overlap with ELSEWHERE error

[pault at gcc dot gnu dot org]

------- Comment #4 from pault at gcc dot gnu dot org  2008-05-17 07:11 -------
Subject: Bug 35759

Author: pault
Date: Sat May 17 07:10:13 2008
New Revision: 135461

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=135461
Log:
2008-05-17  Paul Thomas  <pault@gcc.gnu.org>

        Backport from mainline:
        PR fortran/35756
        PR fortran/35759
        * trans-stmt.c (gfc_trans_where): Tighten up the dependency
        check for calling gfc_trans_where_3.

        PR fortran/35743
        * trans-stmt.c (gfc_trans_where_2): Set the mask size to zero
        if it is calculated to be negative.

        PR fortran/35745
        * trans-stmt.c (gfc_trans_where_3, gfc_trans_where_assign): Set
        ss->where for scalar right hand sides.
        * trans-array.c (gfc_add_loop_ss_code): If ss->where is set do
        not evaluate scalars outside the loop.  Clean up whitespace.
        * trans.h : Add a bitfield 'where' to gfc_ss.

       PR fortran/36233
       * interface.c (compare_actual_formal): Do not check sizes if the
       actual is BT_PROCEDURE.

2008-05-17  Paul Thomas  <pault@gcc.gnu.org>

        Backport from mainline:
        PR fortran/35756
        PR fortran/35759
        * gfortran.dg/where_1.f90: New test.

        PR fortran/35743
        PR fortran/35745
        * gfortran.dg/where_2.f90: New test.

       PR fortran/36233
       * gfortran.dg/actual_procedure_1.f90: New test

Added:
    branches/gcc-4_3-branch/gcc/testsuite/gfortran.dg/actual_procedure_1.f90
    branches/gcc-4_3-branch/gcc/testsuite/gfortran.dg/where_1.f90
    branches/gcc-4_3-branch/gcc/testsuite/gfortran.dg/where_2.f90
Modified:
    branches/gcc-4_3-branch/gcc/fortran/ChangeLog
    branches/gcc-4_3-branch/gcc/fortran/interface.c
    branches/gcc-4_3-branch/gcc/fortran/trans-array.c
    branches/gcc-4_3-branch/gcc/fortran/trans-stmt.c
    branches/gcc-4_3-branch/gcc/fortran/trans.h
    branches/gcc-4_3-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35759

[Bug fortran/35759] WHERE with overlap with ELSEWHERE error

[pault at gcc dot gnu dot org]

------- Comment #5 from pault at gcc dot gnu dot org  2008-05-17 07:16 -------
Fixed on trunk and 4.3.

Thanks for the report.

Paul


-- 

pault at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35759