[Bug c++/41950] New: Unaligned writes (?) to __m128

[Bug c++/41950] New: Unaligned writes (?) to __m128

[phresnel at gmail dot com]

C:\MinGW\bin>g++.exe -v
Es werden eingebaute Spezifikationen verwendet.
Ziel: mingw32
Konfiguriert mit: ../gcc-4.4.0/configure
--enable-languages=c,ada,c++,fortran,java,objc,obj-c++ --disable-sjlj-exception
s --enable-shared --enable-libgcj --enable-libgomp --with-dwarf2
--disable-win32-registry --enable-libstdcxx-debug --ena
ble-version-specific-runtime-libs --prefix=/mingw
--with-gmp=/mingw/src/gmp/root --with-mpfr=/mingw/src/mpfr/root --buil
d=mingw32
Thread-Modell: win32
gcc-Version 4.4.0 (GCC)



The following snippets crash the running application, I guess due to unaligned
writes, but __alignof__ gives me 16 for all three versions, so I really don't
know.

// 0) anonymous namespace: not happy
#include <xmmintrin.h>
namespace { __m128 a; }
int main () {a = _mm_set1_ps(.0f); }

// 1) external: happy
#include <xmmintrin.h>
__m128 a;
int main () { a = _mm_set1_ps(.0f); }

// 2) internal: not happy
#include <xmmintrin.h>
static __m128 a;
int main () { a = _mm_set1_ps(.0f); }


-- 
           Summary: Unaligned writes (?) to __m128
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: phresnel at gmail dot com
 GCC build triplet:


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41950

[Bug target/41950] Unaligned writes (?) to __m128

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2009-11-05 15:30 -------
I guess win32 doesn't know about aligned commons?  Try updating to 4.4.2.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |target
  GCC build triplet|                            |
 GCC target triplet|                            |mingw32


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41950

[Bug target/41950] Unaligned writes (?) to __m128

[sezeroz at gmail dot com]

------- Comment #2 from sezeroz at gmail dot com  2009-11-05 15:55 -------
PR target/37216 probably?  If that is so, gcc-4.4.2 won't help because the fix
hasn't been backported to 4.4, at least not yet.


-- 

sezeroz at gmail dot com changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41950

[Bug target/41950] Unaligned writes (?) to __m128

[ubizjak at gmail dot com]

------- Comment #3 from ubizjak at gmail dot com  2009-11-05 17:38 -------
(In reply to comment #1)
> I guess win32 doesn't know about aligned commons?  Try updating to 4.4.2.

You can also use -fno-common as a workaround.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41950

[Bug target/41950] Unaligned writes (?) to __m128

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2009-11-05 17:42 -------


*** This bug has been marked as a duplicate of 37216 ***


-- 

pinskia at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41950

[Bug target/41950] Unaligned writes (?) to __m128

[phresnel at gmail dot com]

------- Comment #5 from phresnel at gmail dot com  2009-11-06 09:24 -------
(In reply to comment #3)
> (In reply to comment #1)
> > I guess win32 doesn't know about aligned commons?  Try updating to 4.4.2.
> 
> You can also use -fno-common as a workaround.
> 

Unfortunately, this does not work for at least testcase 0),
__attribute__((nocommon)) does not to work either.

I will try out 4.5. asap (I am in relocation mode, i.e. only have access to my
work-pc at the moment, so updating is a bit clumsy here).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41950

[Bug target/41950] Unaligned writes (?) to __m128

[phresnel at gmail dot com]

------- Comment #6 from phresnel at gmail dot com  2009-11-06 09:32 -------
(In reply to comment #5)
> (In reply to comment #3)
> > (In reply to comment #1)
> > > I guess win32 doesn't know about aligned commons?  Try updating to 4.4.2.
> > 
> > You can also use -fno-common as a workaround.
> > 
> 
> Unfortunately, this does not work for at least testcase 0),
> __attribute__((nocommon)) does not to work either.
> 
> I will try out 4.5. asap (I am in relocation mode, i.e. only have access to my
> work-pc at the moment, so updating is a bit clumsy here).
> 

Self-reply: If all else fails, use _mm_alloc(size,align).


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41950