Bug#323646: gcc-4.0: -O1 -msse2 -ftree-vectorize breaks certain code

[Alexander Toresson]

Package: gcc-4.0
Version: 4.0.1-2
Severity: normal


When compiled with -O1 -msse2 -ftree-vectorize, the following code
snippet segfaults on data[i] = 1;:

#include <stdlib.h>

void *NM_First;

void *NM_Allocate(int bytes)
{
        void *ret;
        while (1)
        {
                ret = NM_First;
                NM_First = (void*) ((long) NM_First + bytes);
                return ret;
        }
        return 0;
}


void* repeat_atom()
{
        double *data;
        void* item;
        int i;
        data = NM_Allocate(16);
        for (i=0; i < 4; i++)
        {
                data[i] = 1;
        }
        item = NM_Allocate(12);
        return item;    
}

int main()
{
        struct ITEM *array1, *array2;
        
        NM_First = malloc(256);
        
        array1 = repeat_atom();
        array2 = repeat_atom();
        
        return 0;
}

This was tested on a Pentium M Sonoma.

Regards, Alexander Toresson

-- System Information:
Debian Release: testing/unstable
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.12.1.custom.1.1
Locale: LANG=sv_SE.UTF-8, LC_CTYPE=sv_SE.UTF-8 (charmap=UTF-8)

Versions of packages gcc-4.0 depends on:
ii  binutils                      2.16.1-3   The GNU assembler, linker and bina
ii  cpp-4.0                       4.0.1-2    The GNU C preprocessor
ii  gcc-4.0-base                  4.0.1-2    The GNU Compiler Collection (base 
ii  libc6                         2.3.5-4    GNU C Library: Shared libraries an
ii  libgcc1                       1:4.0.1-2  GCC support library

Versions of packages gcc-4.0 recommends:
ii  libc6-dev                     2.3.5-4    GNU C Library: Development Librari
pn  libmudflap0-dev               <none>     (no description available)

-- no debconf information