* [Bug fortran/56293] I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons
2013-02-12 9:51 [Bug fortran/56293] New: I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons burnus at gcc dot gnu.org
@ 2013-02-12 9:52 ` burnus at gcc dot gnu.org
2013-02-12 10:23 ` tobi at gcc dot gnu.org
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From: burnus at gcc dot gnu.org @ 2013-02-12 9:52 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56293
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> 2013-02-12 09:52:09 UTC ---
Ditto for READ:
0x00007ffff7b9b55f in _gfortrani_convert_real (dtp=dtp@entry=0x7fffffffde40,
dest=dest@entry=0x601084 <sss_+4>, buffer=0x604fb0 "445.54",
length=length@entry=16) at libgfortran/io/read.c:155
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug fortran/56293] I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons
2013-02-12 9:51 [Bug fortran/56293] New: I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons burnus at gcc dot gnu.org
2013-02-12 9:52 ` [Bug fortran/56293] " burnus at gcc dot gnu.org
@ 2013-02-12 10:23 ` tobi at gcc dot gnu.org
2013-02-12 12:35 ` [Bug fortran/56293] Segfault when trying to access pass-by-reference value of " burnus at gcc dot gnu.org
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From: tobi at gcc dot gnu.org @ 2013-02-12 10:23 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56293
Tobias Schlüter <tobi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |tobi at gcc dot gnu.org
--- Comment #2 from Tobias Schlüter <tobi at gcc dot gnu.org> 2013-02-12 10:23:32 UTC ---
This is valid behavior, -fno-align-common is documented to potentially break
stuff (though the documentation could be more explicit on that).
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug fortran/56293] Segfault when trying to access pass-by-reference value of a not-word-aligned REAL(16) / -fno-align-commons
2013-02-12 9:51 [Bug fortran/56293] New: I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons burnus at gcc dot gnu.org
2013-02-12 9:52 ` [Bug fortran/56293] " burnus at gcc dot gnu.org
2013-02-12 10:23 ` tobi at gcc dot gnu.org
@ 2013-02-12 12:35 ` burnus at gcc dot gnu.org
2013-02-12 12:40 ` rguenth at gcc dot gnu.org
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From: burnus at gcc dot gnu.org @ 2013-02-12 12:35 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56293
Tobias Burnus <burnus at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|I/O: Segfault in |Segfault when trying to
|write_float when trying to |access pass-by-reference
|print a not-word-aligned |value of a not-word-aligned
|REAL(16) / |REAL(16) /
|-fno-align-commons |-fno-align-commons
--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2013-02-12 12:35:19 UTC ---
Also occurs if one calls ("call foo(p)"):
subroutine foo(x)
real(16) :: x, y
y = x ! FAILS HERE
! print *, y
end subroutine foo
instead of "print *, p".
The bug is probably somewhere in gcc/fortran/trans-common.c's. For instance at
build_common_decl, which uses:
if (!com->is_bind_c)
DECL_ALIGN (decl) = BIGGEST_ALIGNMENT;
or/and in "build_field", which has:
known_align = (offset & -offset) * BITS_PER_UNIT;
if (known_align == 0 || known_align > BIGGEST_ALIGNMENT)
known_align = BIGGEST_ALIGNMENT;
desired_align = update_alignment_for_field (rli, field, known_align);
if (desired_align > known_align)
(field) = 1;
or …
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug fortran/56293] Segfault when trying to access pass-by-reference value of a not-word-aligned REAL(16) / -fno-align-commons
2013-02-12 9:51 [Bug fortran/56293] New: I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons burnus at gcc dot gnu.org
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2013-02-12 12:35 ` [Bug fortran/56293] Segfault when trying to access pass-by-reference value of " burnus at gcc dot gnu.org
@ 2013-02-12 12:40 ` rguenth at gcc dot gnu.org
2013-02-12 13:07 ` burnus at gcc dot gnu.org
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From: rguenth at gcc dot gnu.org @ 2013-02-12 12:40 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56293
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> 2013-02-12 12:39:55 UTC ---
(In reply to comment #3)
> Also occurs if one calls ("call foo(p)"):
> subroutine foo(x)
> real(16) :: x, y
> y = x ! FAILS HERE
> ! print *, y
> end subroutine foo
> instead of "print *, p".
>
>
> The bug is probably somewhere in gcc/fortran/trans-common.c's. For instance at
> build_common_decl, which uses:
>
> if (!com->is_bind_c)
> DECL_ALIGN (decl) = BIGGEST_ALIGNMENT;
>
> or/and in "build_field", which has:
>
> known_align = (offset & -offset) * BITS_PER_UNIT;
> if (known_align == 0 || known_align > BIGGEST_ALIGNMENT)
> known_align = BIGGEST_ALIGNMENT;
>
> desired_align = update_alignment_for_field (rli, field, known_align);
> if (desired_align > known_align)
> (field) = 1;
>
> or …
The problem is that you are in no way dealing with the interface
mismatches in a correct way. Not that I think you can.
I suggest to remove -fno-align-commons.
Or is there a fortran way to say that
subroutine foo(x)
real(16) :: x, y
may receive an unaligned x?
It seems to me that with an -fno-align-commons common you cannot do very
much. You'd have to make sure to always access it though the common
and never pass pieces of it to another function (maybe the frontend could
warn about this). Can you specify -fno-align-commons per common block?
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug fortran/56293] Segfault when trying to access pass-by-reference value of a not-word-aligned REAL(16) / -fno-align-commons
2013-02-12 9:51 [Bug fortran/56293] New: I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons burnus at gcc dot gnu.org
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2013-02-12 12:40 ` rguenth at gcc dot gnu.org
@ 2013-02-12 13:07 ` burnus at gcc dot gnu.org
2013-03-10 15:32 ` tkoenig at gcc dot gnu.org
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From: burnus at gcc dot gnu.org @ 2013-02-12 13:07 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56293
--- Comment #5 from Tobias Burnus <burnus at gcc dot gnu.org> 2013-02-12 13:07:10 UTC ---
Some tests with ifort, which by default uses unaligned commons: The first test
case works, i.e. I/O with the unaligned "p" works. However, if one calls a user
procedure ("call foo(p)"), it segfaults.
Possible solutions:
a) Copy-in/copy-out around procedure calls - which is fun with large arrays.
b) Require the user to annotate the functions to possibly accept unaligned
input – or do so automatically. (With all the fun of third-party libraries like
LAPACK, BLAS, ...)
c) Simply deprecating the -fno-align-commons flag, improving the wording of
the diagnostic and the description in the man page.
Somehow, I am in favour of (c).
The question is also whether one can construct a fully standard-conform example
which fails without -fno-align-commons – and whether some real-world code uses
COMMON in a way that would fails with alignments/padding.
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug fortran/56293] Segfault when trying to access pass-by-reference value of a not-word-aligned REAL(16) / -fno-align-commons
2013-02-12 9:51 [Bug fortran/56293] New: I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons burnus at gcc dot gnu.org
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2013-02-12 13:07 ` burnus at gcc dot gnu.org
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2013-03-11 0:16 ` tobi at gcc dot gnu.org
2014-01-07 14:04 ` dominiq at lps dot ens.fr
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From: tkoenig at gcc dot gnu.org @ 2013-03-10 15:32 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56293
Thomas Koenig <tkoenig at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |tkoenig at gcc dot gnu.org
--- Comment #6 from Thomas Koenig <tkoenig at gcc dot gnu.org> 2013-03-10 15:32:14 UTC ---
> The question is also whether one can construct a fully standard-conform example
> which fails without -fno-align-commons – and whether some real-world code uses
> COMMON in a way that would fails with alignments/padding.
program main
real a,f1,f2,d
common /foo/ a,f1,f2,d
a = 1.0
d = 1.0
call s1
end
subroutine s1
real a,b
double precision d
common /foo/ a,d,b
print *,a
print *,b
end
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug fortran/56293] Segfault when trying to access pass-by-reference value of a not-word-aligned REAL(16) / -fno-align-commons
2013-02-12 9:51 [Bug fortran/56293] New: I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons burnus at gcc dot gnu.org
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2013-03-10 15:32 ` tkoenig at gcc dot gnu.org
@ 2013-03-11 0:16 ` tobi at gcc dot gnu.org
2014-01-07 14:04 ` dominiq at lps dot ens.fr
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From: tobi at gcc dot gnu.org @ 2013-03-11 0:16 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56293
--- Comment #7 from Tobias Schlüter <tobi at gcc dot gnu.org> 2013-03-11 00:15:43 UTC ---
(In reply to comment #6)
> > The question is also whether one can construct a fully standard-conform example
> > which fails without -fno-align-commons – and whether some real-world code uses
> > COMMON in a way that would fails with alignments/padding.
>
> program main
> real a,f1,f2,d
> common /foo/ a,f1,f2,d
> a = 1.0
> d = 1.0
> call s1
> end
> subroutine s1
> real a,b
> double precision d
> common /foo/ a,d,b
> print *,a
> print *,b
> end
That's not valid. I'm looking at the F95 working draft:
according to note 5.33
"""Association in different scoping units between objects of default type,
objects of double precision real type, and sequence structures is permitted
according to the rules for equivalence objects (5.5.1)."""
and in 5.5.1. we have
"""If an equivalence-object is of type default integer, default real, double
precision real, default complex, default logical, or numeric sequence type, all
of the objects in the equivalence set shall be of these types."""
^ permalink raw reply [flat|nested] 9+ messages in thread* [Bug fortran/56293] Segfault when trying to access pass-by-reference value of a not-word-aligned REAL(16) / -fno-align-commons
2013-02-12 9:51 [Bug fortran/56293] New: I/O: Segfault in write_float when trying to print a not-word-aligned REAL(16) / -fno-align-commons burnus at gcc dot gnu.org
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2013-03-11 0:16 ` tobi at gcc dot gnu.org
@ 2014-01-07 14:04 ` dominiq at lps dot ens.fr
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From: dominiq at lps dot ens.fr @ 2014-01-07 14:04 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56293
Dominique d'Humieres <dominiq at lps dot ens.fr> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |WAITING
Last reconfirmed| |2014-01-07
Ever confirmed|0 |1
--- Comment #8 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> c) Simply deprecating the -fno-align-commons flag, improving the wording
> of the diagnostic and the description in the man page.
>
> Somehow, I am in favour of (c).
Me too.
^ permalink raw reply [flat|nested] 9+ messages in thread