[Bug fortran/51338] New: seg fault in gfc_dep_compare_expr with -O2

[Bug fortran/51338] New: seg fault in gfc_dep_compare_expr with -O2

[dcb314 at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

             Bug #: 51338
           Summary: seg fault in gfc_dep_compare_expr with -O2
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dcb314@hotmail.com

[Bug fortran/51338] seg fault in gfc_dep_compare_expr with -O2

[dcb314 at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

--- Comment #1 from dcb <dcb314 at hotmail dot com> 2011-11-28 21:10:25 UTC ---
Created attachment 25940
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25940
preprocessed Fortran code

[Bug fortran/51338] seg fault in gfc_dep_compare_expr with -O2

[bdavis at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

Bud Davis <bdavis at gcc dot gnu.org> changed:

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

--- Comment #2 from Bud Davis <bdavis at gcc dot gnu.org> 2011-11-28 21:40:40 UTC ---
Program received signal SIGSEGV, Segmentation fault.
0x081bc9af in gfc_dep_compare_expr (e1=0x0, e2=0x0) at
../../gcc/gcc/fortran/dependency.c:242
242    {
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.7.el6_0.5.i686
(gdb) bt
#0  0x081bc9af in gfc_dep_compare_expr (e1=0x0, e2=0x0) at
../../gcc/gcc/fortran/dependency.c:242
#1  0x081bd105 in are_identical_variables (e1=0x905d440, e2=0x905c520) at
../../gcc/gcc/fortran/dependency.c:177
#2  gfc_dep_compare_expr (e1=0x905d440, e2=0x905c520) at
../../gcc/gcc/fortran/dependency.c:438
#3  0x081be244 in gfc_dep_compare_functions (e1=0x905d668, e2=0x905d2f0,
impure_ok=true)
    at ../../gcc/gcc/fortran/dependency.c:221
#4  0x0823bf67 in cfe_expr_0 (e=0x905cdb8, walk_subtrees=0xbfffee3c, data=0x0)
    at ../../gcc/gcc/fortran/frontend-passes.c:386
#5  0x0823bbd6 in gfc_expr_walker (e=0x905cdb8, exprfn=0x823bea0
<cfe_expr_0(gfc_expr**, int*, void*)>, data=0x0)
    at ../../gcc/gcc/fortran/frontend-passes.c:1039
#6  0x0823c72c in gfc_code_walker (c=0x905c4b8, codefn=0x823ae40
<cfe_code(gfc_code**, int*, void*)>, 
    exprfn=0x823bea0 <cfe_expr_0(gfc_expr**, int*, void*)>, data=0x0) at
../../gcc/gcc/fortran/frontend-passes.c:1361
#7  0x0823c70e in gfc_code_walker (c=0x905c670, codefn=0x823ae40
<cfe_code(gfc_code**, int*, void*)>, 
    exprfn=0x823bea0 <cfe_expr_0(gfc_expr**, int*, void*)>, data=0x0) at
../../gcc/gcc/fortran/frontend-passes.c:1363
#8  0x0823c70e in gfc_code_walker (c=0x905c150, codefn=0x823ae40
<cfe_code(gfc_code**, int*, void*)>, 
    exprfn=0x823bea0 <cfe_expr_0(gfc_expr**, int*, void*)>, data=0x0) at
../../gcc/gcc/fortran/frontend-passes.c:1363
#9  0x0823c70e in gfc_code_walker (c=0x9058620, codefn=0x823ae40
<cfe_code(gfc_code**, int*, void*)>, 
    exprfn=0x823bea0 <cfe_expr_0(gfc_expr**, int*, void*)>, data=0x0) at
../../gcc/gcc/fortran/frontend-passes.c:1363
#10 0x0823c70e in gfc_code_walker (c=0x9057608, codefn=0x823ae40
<cfe_code(gfc_code**, int*, void*)>, 
    exprfn=0x823bea0 <cfe_expr_0(gfc_expr**, int*, void*)>, data=0x0) at
../../gcc/gcc/fortran/frontend-passes.c:1363
#11 0x0823d25c in optimize_namespace (ns=0x9055320) at
../../gcc/gcc/fortran/frontend-passes.c:510
#12 0x0823d2ea in gfc_run_passes (ns=0x9055320) at
../../gcc/gcc/fortran/frontend-passes.c:80
#13 0x0818a4b9 in resolve_all_program_units () at
../../gcc/gcc/fortran/parse.c:4342
#14 gfc_parse_file () at ../../gcc/gcc/fortran/parse.c:4608
#15 0x081c641d in gfc_be_parse_file () at ../../gcc/gcc/fortran/f95-lang.c:250
#16 0x085a97c5 in compile_file (argc=21, argv=0xbffff1f4) at
../../gcc/gcc/toplev.c:565

[Bug fortran/51338] seg fault in gfc_dep_compare_expr with -O2

[bdavis at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

--- Comment #3 from Bud Davis <bdavis at gcc dot gnu.org> 2011-11-28 21:59:02 UTC ---
Reduced:

      SUBROUTINE PAXCUT(CHIN,CHOUT)
      CHARACTER*(*) CHIN,CHOUT
      IF(INDEX(CHOUT(K:),'.OR.').EQ.INDEX(CHOUT(K:),'.AND.')) THEN
      ENDIF
      END

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-11-28
                 CC|                            |tkoenig at gcc dot gnu.org
            Summary|seg fault in                |[4.6/4.7 Regression] seg
                   |gfc_dep_compare_expr with   |fault in
                   |-O2                         |gfc_dep_compare_expr with
                   |                            |-O2
     Ever Confirmed|0                           |1

--- Comment #4 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2011-11-28 22:22:59 UTC ---
Workaround -fno-frontend-optimize.

Revision 164728 (20100929) is OK
revision 165415 (20101013) gives the segmentation fault.

Likely

Revision 165248

Author:    tkoenig
Date:    Sun Oct 10 09:52:46 2010 UTC (13 months, 2 weeks ago)
Changed paths:    7
Log Message:    
2010-10-09  Thomas Koenig  <tkoenig@gcc.gnu.org>

    * frontend-passes.c:  Include opts.h.
    (optimize_comparison):  Renamed from optimize_equality.
    Change second argument to operation to be compared.
    Use flag_finite_math_only to avoid comparing REAL and
    COMPLEX only when NANs are honored.  Simplify comparing
    of string concatenations where left or right operands are
    equal.  Simplify all comparison operations, based on the result
    of gfc_dep_compare_expr.
    * dependency.c:  Include arith.h.
    (gfc_are_identical_variables):  Volatile variables should not
    compare equal to themselves.
    (gfc_dep_compare_expr):  Handle string constants and string
    concatenations.

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[bdavis at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

--- Comment #5 from Bud Davis <bdavis at gcc dot gnu.org> 2011-11-28 22:49:33 UTC ---
Index: gcc/gcc/fortran/dependency.c
===================================================================
--- gcc/gcc/fortran/dependency.c    (revision 181789)
+++ gcc/gcc/fortran/dependency.c    (working copy)
@@ -245,6 +245,10 @@
   int i;
   gfc_expr *n1, *n2;

+  /* nothing to do here, move along */
+  if (e1 == NULL && e2 == NULL)
+     return 0;
+
   n1 = NULL;
   n2 = NULL;

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[bdavis at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

--- Comment #6 from Bud Davis <bdavis at gcc dot gnu.org> 2011-11-28 23:20:27 UTC ---
The above patch has no new testsuite regressions.
If someone wants to check and make sure the optimisation(s) that could or were
being done is still correct, and check this in, feel free to do so.

1 Hour 40 minutes after bug posted.  not bad.....

--bud

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[tkoenig at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |tkoenig at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #7 from Thomas Koenig <tkoenig at gcc dot gnu.org> 2011-11-29 17:45:05 UTC ---
(In reply to comment #6)
> The above patch has no new testsuite regressions.
> If someone wants to check and make sure the optimisation(s) that could or were
> being done is still correct, and check this in, feel free to do so.
> 
> 1 Hour 40 minutes after bug posted.  not bad.....
> 

I'll look at it.  Thanks for the analysis and the fix!

Thomas

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.6.3

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[burnus at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

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

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

--- Comment #8 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-12-05 14:40:56 UTC ---
(In reply to comment #7)
> I'll look at it.  Thanks for the analysis and the fix!

Thomas' patch: http://gcc.gnu.org/ml/fortran/2011-11/msg00254.html
Review (approval): http://gcc.gnu.org/ml/fortran/2011-12/msg00023.html

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4
                 CC|                            |jakub at gcc dot gnu.org

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[tkoenig at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

--- Comment #9 from Thomas Koenig <tkoenig at gcc dot gnu.org> 2011-12-05 20:11:53 UTC ---
Author: tkoenig
Date: Mon Dec  5 20:11:44 2011
New Revision: 182024

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=182024
Log:
2011-12-05  Thomas Koenig  <tkoenig@gcc.gnu.org>

    PR fortran/51338
    * dependency.c (are_identical_variables):  Handle case where
    end fields of substring references are NULL.

2011-12-05  Thomas Koenig  <tkoenig@gcc.gnu.org>

    PR fortran/51338
    * gfortran.dg/assumed_charlen_substring_1.f90:  New test.


Added:
    trunk/gcc/testsuite/gfortran.dg/assumed_charlen_substring_1.f90
Modified:
    trunk/gcc/fortran/ChangeLog
    trunk/gcc/fortran/dependency.c
    trunk/gcc/testsuite/ChangeLog

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[tkoenig at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

--- Comment #10 from Thomas Koenig <tkoenig at gcc dot gnu.org> 2011-12-11 20:03:47 UTC ---
Author: tkoenig
Date: Sun Dec 11 20:03:43 2011
New Revision: 182209

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=182209
Log:
2011-12-11  Thomas Koenig  <tkoenig@gcc.gnu.org>

    PR fortran/51338
    Backport from trunk
    * dependency.c (are_identical_variables):  Handle case where
    end fields of substring references are NULL.

2011-12-11  Thomas Koenig  <tkoenig@gcc.gnu.org>

    PR fortran/51338
    Backport from trunk
    * gfortran.dg/assumed_charlen_substring_1.f90:  New test.


Modified:
    branches/gcc-4_6-branch/gcc/fortran/ChangeLog
    branches/gcc-4_6-branch/gcc/fortran/dependency.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog

[Bug fortran/51338] [4.6/4.7 Regression] seg fault in gfc_dep_compare_expr with -O2

[tkoenig at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51338

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

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

--- Comment #11 from Thomas Koenig <tkoenig at gcc dot gnu.org> 2011-12-11 20:04:39 UTC ---
Fixed on trunk and 4.6, closing.