[Bug fortran/32393] gfortran - incorrect run time results

[dir at lanl dot gov]

------- Comment #17 from dir at lanl dot gov  2007-06-21 16:29 -------
I have attached version that generates no warnings with gfortran or g95. As I
reduced, it the bug changed - that is the problem with optmization bugs - they
are hard to trap. Anyway there is still a bug for some compilers. gfortran on
the Macintosh and Linux are Ok. g77 is happy and gets the correct answer -

[dranta:~/tests] dir% g77 -o g95Test02 g95Test02.f
[dranta:~/tests] dir% g95Test02
1

 lower triangular matrix with   3 rows

 row   1    0.8000E+01
 row   2    0.9000E+01  0.1000E+02
 row   3    0.1100E+02  0.1200E+02  0.1300E+02
  iprec = 1
1

 lower triangular matrix with   3 rows

 row   1    0.1600E+02
 row   2    0.9000E+01  0.2000E+02
 row   3    0.1100E+02  0.1200E+02  0.2600E+02

g95 cannot decide which wrong answer it likes -

[dranta:~/tests] dir% g95 -Wall -g -o g95Test02 g95Test02.f
[dranta:~/tests] dir% g95Test02
1

 lower triangular matrix with   3 rows

 row   1   -0.2000E+01
 row   2    0.1000E+01  0.2000E+01
 row   3    0.3000E+01  0.4000E+01  0.5000E+01
  iprec = 1
1

 lower triangular matrix with   3 rows

 row   1   -0.3999E+01
 row   2    0.1000E+01  0.4000E+01
 row   3    0.3000E+01  0.4000E+01  0.1000E+02

[dranta:~/tests] dir% g95 -Wall -O3 -o g95Test02 g95Test02.f
[dranta:~/tests] dir% g95Test02
1

 lower triangular matrix with   3 rows

 row   1    0.8000E+01
 row   2    0.9000E+01  0.1000E+02
 row   3    0.1100E+02  0.1200E+02  0.1300E+02
  iprec = 1
1

 lower triangular matrix with   3 rows

 row   1    0.8000E+01
 row   2    0.9000E+01  0.1000E+02
 row   3    0.1100E+02  0.1200E+02  0.1300E+02

gfortran (i386-pc-mingw32) on windows now gets the wrong answer with -O3 -

rantad@XP-RANTAD ~/tests
$ gfortran -g -o g95Test02 g95Test02.f

rantad@XP-RANTAD ~/tests
$ g95Test02
1

 lower triangular matrix with   3 rows

 row   1    0.8000E+01
 row   2    0.9000E+01  0.1000E+02
 row   3    0.1100E+02  0.1200E+02  0.1300E+02
  iprec =           1
1

 lower triangular matrix with   3 rows

 row   1    0.1600E+02
 row   2    0.9000E+01  0.2000E+02
 row   3    0.1100E+02  0.1200E+02  0.2600E+02
rantad@XP-RANTAD ~/tests
$ gfortran -O3 -o g95Test02 g95Test02.f

rantad@XP-RANTAD ~/tests
$ g95Test02
1

 lower triangular matrix with   3 rows

 row   1    0.0000E+00
 row   2    0.1000E+01  0.2000E+01
 row   3    0.3000E+01  0.4000E+01  0.5000E+01
  iprec =           1
1

 lower triangular matrix with   3 rows

 row   1    0.0000E+00
 row   2    0.1000E+01  0.4000E+01
 row   3    0.3000E+01  0.4000E+01  0.1000E+02
rantad@XP-RANTAD ~/tests
$ gfortran --v
Using built-in specs.
Target: i386-pc-mingw32
Configured with: ../trunk/configure --prefix=/mingw
--enable-languages=c,fortran --with-gmp=/home/coudert/local --disable-nls
--with-ld=/mingw/bin/ld --with-as=/mingw/bin/as --disable-werror
--enable-bootstrap --enable-threads --build=i386-pc-mingw32 --disable-shared
--enable-libgomp
Thread model: win32
gcc version 4.3.0 20070522 (experimental)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32393