[Bug fortran/50069] New: FORALL fails on a character array

[Bug fortran/50069] New: FORALL fails on a character array

[zeccav at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50069

             Bug #: 50069
           Summary: FORALL fails on a character array
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zeccav@gmail.com


Created attachment 24997
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24997
compile it and run

Must be compiled and run. g95 and Intel ifort deliver the correct result.

[Bug fortran/50069] FORALL fails on a character array

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50069

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burnus at gcc dot gnu.org

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-08-15 12:12:12 UTC ---
Wild guess: Dependency analysis (forward/backward etc.) does not take character
substrings into account. If so, it vaguely reminds me of PR 47674.

[Bug fortran/50069] FORALL fails on a character array

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50069

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-08-17
     Ever Confirmed|0                           |1
      Known to fail|                            |4.1.2, 4.3.4, 4.4.0, 4.5.1,
                   |                            |4.6.1, 4.7.0

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-08-17 08:21:34 UTC ---
Draft patch:

diff --git a/gcc/fortran/trans-stmt.c b/gcc/fortran/trans-stmt.c
index a911a5b..7d85413 100644
--- a/gcc/fortran/trans-stmt.c
+++ b/gcc/fortran/trans-stmt.c
@@ -2452,6 +2452,9 @@ forall_make_variable_temp (gfc_code *c, stmtblock_t *pre,
stmtblock_t *post)
          tmp = gfc_conv_array_offset (old_sym->backend_decl);
          gfc_conv_descriptor_offset_set (pre, tse.expr, tmp);
        }
+      else
+       gfc_conv_descriptor_offset_set (pre, tse.expr,
+               build_int_cst (gfc_array_index_type, -1));
     }
   else
     {

[Bug fortran/50069] FORALL fails on a character array

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50069

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-08-17 08:44:30 UTC ---
(In reply to comment #2)
> Draft patch:

This patch fails for gfortran.dg/forall_12.f90 test (of PR31217 and PR33811):

    character(LEN=12) :: a(2) = "123456789012"
    forall (i = 3:10) a(:)(i:i+2) = a(:)(i-2:i)

The result with the patch is
 12@+@+
instead of
 121234567890

 * * *

For the test of comment 0, gfortran (unpatched) produces:
    atmp.1.offset = 0;
and accesses
    atmp.1.data)[atmp.1.offset + 1]

While for the now failing test case forall_12.f90, gfortran (unpatched)
produces also
    atmp.1.offset = 0;
but uses
      D.1578 = atmp.1.offset;
      D.1577 = ... atmp.1.data;
      &(*D.1577)[S.5 + D.1578]
where S.5 is the loop variable, which runs from 0 to 1.


Thus, the actual problem seems to be that "a(1)" is translated into
"a[1+offset]" instead of "a[0+offset]".

[Bug fortran/50069] FORALL fails on a character array

[zeccav at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50069

Vittorio Zecca <zeccav at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|4.6.1                       |4.8.0

--- Comment #4 from Vittorio Zecca <zeccav at gmail dot com> 2013-04-16 08:50:50 UTC ---
I still have the same bug on gfortran 4.8.0.

[Bug fortran/50069] FORALL fails on a character array

[zeccav at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50069

--- Comment #5 from Vittorio Zecca <zeccav at gmail dot com> ---
Still on gfortran 5.2.0

[Bug fortran/50069] FORALL fails on a character array

[zmi007 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50069

zmi <zmi007 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |zmi007 at gmail dot com

--- Comment #6 from zmi <zmi007 at gmail dot com> ---
A am not sure if its the same bug, but I get ICE for the function

!-----------------------------------------------------------------------
!Function
!-----------------------------------------------------------------------
function  reverse(string) ! bind(c, name='reverse')
implicit none
character(len=*), intent(in) :: string
character(len=:),allocatable :: reverse
reverse = string
forall (i=1:len(reverse)) reverse(i:i) =
reverse(len(reverse)-i+1:len(reverse)-i+1)
end function reverse



forall (i=1:len(reverse)) reverse(i:i) =
reverse(len(reverse)-i+1:len(reverse)-i+1)
 1
internal compiler error: in gfc_conv_variable, at fortran/trans-expr.c:2368


gfortran --version
GNU Fortran (SUSE Linux) 5.2.1 20150721 [gcc-5-branch revision 226027]