Compiler error using __builtin_ia32_paddd

[David Robinson <drtr at enjura dot com>]

Summary:

 Compiling this program below with gcc -O2 -Wall -o try try.c -mmmx
produces:
try.c: In function `main':
try.c:35: Internal compiler error in simplify_gen_subreg, at
simplify-rtx.c:2711Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions.

Version: gcc 3.1 compiled for i686-pc-linux-gnu, on Redhat 7.2, Linux
         kernel 2.4.18, CPU PentiumIII-M.

Source:
#include <stdio.h>
#include <stdlib.h>

typedef int _v2si __attribute__ ((mode(V2SI)));

typedef union
{
    _v2si v;
    int i[2];
} v2si_u;


typedef union
{
    _v2si v;
    int i[2];
} v2si __attribute__ ((aligned(__alignof__(_v2si))));


int
main(int argc, char **argv)
{
    v2si x, y, z;

    x.i[0] = 12;
    x.i[1] = 17;
    y.i[0] = 23;
    y.i[1] = 56;

    z.v = __builtin_ia32_paddd(x.v, y.v);

    printf("%d %d\n", z.i[0], z.i[1]);

    exit(0);
}