From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-357225-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 3511 invoked by alias); 21 May 2011 23:23:34 -0000
Received: (qmail 3502 invoked by uid 22791); 21 May 2011 23:23:34 -0000
X-SWARE-Spam-Status: No, hits=-2.7 required=5.0	tests=ALL_TRUSTED,AWL,BAYES_00
X-Spam-Check-By: sourceware.org
Received: from localhost (HELO gcc.gnu.org) (127.0.0.1)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sat, 21 May 2011 23:23:20 +0000
From: "dominiq at lps dot ens.fr" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/49103] [4.6/4.7 Regression] local variables exchange values / wrong code with -O3
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: fortran
X-Bugzilla-Keywords:
X-Bugzilla-Severity: normal
X-Bugzilla-Who: dominiq at lps dot ens.fr
X-Bugzilla-Status: NEW
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Changed-Fields:
Message-ID: <bug-49103-4-SrACfqMEEs@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-49103-4@http.gcc.gnu.org/bugzilla/>
References: <bug-49103-4@http.gcc.gnu.org/bugzilla/>
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
Content-Type: text/plain; charset="UTF-8"
MIME-Version: 1.0
Date: Sat, 21 May 2011 23:29:00 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
X-SW-Source: 2011-05/txt/msg01892.txt.bz2

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49103

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2011-05-21 23:11:01 UTC ---
Reverting revision 169083 on trunk fixes this pr (see
http://gcc.gnu.org/ml/gcc-patches/2011-01/msg01442.html for its motivation).
Further reduced test:

!----------------------------------
module dg_grid

implicit none

integer :: par_world_dims = 3

type world_t
   integer :: dims
   real(kind=8), dimension(:), pointer :: lengths
end type

contains

subroutine grid_new(grid)
   type(world_t), intent(inout) :: grid

   grid%dims = par_world_dims
   call grid_faces(grid)

end subroutine

! Start looking here: This is the routine that gives trouble.
subroutine grid_faces(grid)
   type(world_t), intent(inout) :: grid

   integer :: dimi, bordi
   integer, dimension(par_world_dims-1) :: fgrades
   integer, dimension(par_world_dims-1) :: fbasegrades

   do dimi=1,grid%dims-2

      ! The bug makes those two arrays exchange values temporarily.
      fbasegrades = (/ 1, 1 /)
      fgrades = (/ 2, 2 /)
      do bordi=1,2
         write(*,*) 'Here is the bug. The grades should be (2 2):', fgrades
         write(*,*) 'Compare the base grades:', fbasegrades
      end do
      write(*,*) 'grades again', fgrades

   end do
end subroutine

end module

program test_gcc46gridbug

use dg_grid

implicit none

type(world_t) :: grid

call grid_new(grid)

end program
!----------------------------------