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From: "tema at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug middle-end/50716] New: Segmentation fault caused by misaligned vector access
Date: Thu, 13 Oct 2011 15:00:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50716

             Bug #: 50716
           Summary: Segmentation fault caused by misaligned vector access
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: tema@gcc.gnu.org


The following code segfaults on i386 + sse targets:

typedef int vec __attribute__((vector_size(16)));
int main ()
{
 int * arr = __builtin_malloc (1024);
 vec *p = (vec *) &arr[1];
 *p = (vec){1, 2, 3, 4};
 return *(char *)p;
}

The problem is that *p = (vec){1,2,3,4} produces aligned move instead of
unaligned.  Most likely this could be reproduced on any target with SIMD
extensions, where aligned move differs from unaligned.