[Bug fortran/34107] New: seg fault when writing into character variable when code compiled with -maling-double

[Bug fortran/34107] New: seg fault when writing into character variable when code compiled with -maling-double

[j dot m dot h dot thomas at dl dot ac dot uk]

I'm using the latest (precompiled) version of gfortran (GNU Fortran (GCC) 4.3.0
20071105 (experimental) [trunk revision 129892]). The following code:

program test
 integer :: pid
 character (len=10) :: chpid

 pid=12345

 write(chpid,'(i10)')pid
 write(*,*)"chpid is ",chpid

end program test

when compiled with:

gfortran -o test.gfortran90 -g -malign-double  ./test.f90

on my ubuntu box (Ubuntu 6.06.1 LTS,  Intel(R) Pentium(R) 4 CPU 2.80GHz), seg
faults as shown below:

Program received signal SIGSEGV, Segmentation fault.
0xb7f86f46 in next_char (fmt=0x8050528, literal=0)
   at /home/fx/gfortran_nightbuild/trunk/libgfortran/io/format.c:91
91      /home/fx/gfortran_nightbuild/trunk/libgfortran/io/format.c: No such
file or directory.
       in /home/fx/gfortran_nightbuild/trunk/libgfortran/io/format.c


(gdb) bt
#0  0xb7f86f46 in next_char (fmt=0x8050528, literal=0)
   at /home/fx/gfortran_nightbuild/trunk/libgfortran/io/format.c:91
#1  0xb7f86fb1 in format_lex (fmt=0x8050528)
   at /home/fx/gfortran_nightbuild/trunk/libgfortran/io/format.c:181
#2  0xb7f87c65 in *_gfortrani_parse_format (dtp=0xbfbc1aa8)
   at /home/fx/gfortran_nightbuild/trunk/libgfortran/io/format.c:981
#3  0xb7f91e69 in data_transfer_init (dtp=0xbfbc1aa8, read_flag=0)
   at /home/fx/gfortran_nightbuild/trunk/libgfortran/io/transfer.c:1802
#4  0x08048616 in test () at ./test.f90:7 

If I remove the -malign-double flag, the code runs fine. 

The same code in FORTRAN77 format works fine with g77 (with the -malign-double
flag), but also crashes gfortran.


-- 
           Summary: seg fault when writing into character variable when code
                    compiled with -maling-double
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: j dot m dot h dot thomas at dl dot ac dot uk
  GCC host triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34107

[Bug fortran/34107] seg fault when writing into character variable when code compiled with -maling-double

[pault at gcc dot gnu dot org]

------- Comment #1 from pault at gcc dot gnu dot org  2007-11-15 10:54 -------
Jens,

I cannot reproduce this bug, even with the same flags that you are using, under
Cygwin_NT and last night's build.  I will check on a Linux system tonight.

I have downrated the severity because "critical" refers to bugs that prevent
the gcc build.  I assure you that the gfortran maintainers will take the report
just as seriously.

Thanks for the report

Paul


-- 

pault at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pault at gcc dot gnu dot org
           Severity|critical                    |normal


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34107

[Bug fortran/34107] seg fault when writing into character variable when code compiled with -maling-double

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2007-11-15 11:26 -------
-malign-double changes the ABI.  You need to rebuild libgfortran with that
option.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34107

[Bug fortran/34107] seg fault when writing into character variable when code compiled with -maling-double

[pault at gcc dot gnu dot org]

------- Comment #3 from pault at gcc dot gnu dot org  2007-11-15 11:58 -------
(In reply to comment #2)
> -malign-double changes the ABI.  You need to rebuild libgfortran with that
> option.

Ah! Thanks, Richard.  For that, I'll take a look at achar_4.f90 for you:)

Paul


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34107

[Bug fortran/34107] seg fault when writing into character variable when code compiled with -maling-double

[jvdelisle at gcc dot gnu dot org]

------- Comment #4 from jvdelisle at gcc dot gnu dot org  2007-11-15 14:57 -------
There is a good chance that if you try to build the runtime library with
malign-double that you will break it.  My recommendation is don't use
-malign-double for I/O related things.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34107