please confirm serious objective-c bug in gcc-4.x.x

[Robert William Fuller <hydrologiccycle at gmail dot com>]

Forwarding is broken for Objective-C on x86_64, but it works on i386. 
The self pointer is wrong after a message is forwarded on x86_64. 
Here's the output, and the sample code:

output on 32-bit:

forwarding for selector display from 134536384 to 134536136
worked, self == receiver
foo is 1234567890, and should be 1234567890

output on 64-bit:

forwarding for selector display from 6330720 to 6330224
broken, self != receiver
foo is 6330224, and should be 1234567890

sample code:

// Objective-C x86_64 bug:  self is wrong on forward;
// broken on gcc-4.1.2, 4.3.0, and 4.3.1

#include <stdio.h>
#include <stdlib.h>
#include <objc/Object.h>
#include <objc/objc-api.h>

id forwarder, receiver;

@interface Forwarder:Object
{
    id receiver;
}

-initWithReceiver:theReceiver;

@end

@interface Receiver:Object
{
    int foo;
}

-display;
-initWithFoo:(int)theFoo;

@end

@implementation Receiver

-initWithFoo:(int)theFoo
{
    foo = theFoo;
    return self;
}

-display
{
    if (self == receiver) {
        printf("worked, self == receiver\n");
    } else {
        printf("broken, self != receiver\n");
    }
    printf("foo is %d, and should be %d\n", foo, 1234567890);
    return self;
}

@end

@implementation Forwarder

-initWithReceiver:theReceiver
{
    [super init];
    receiver = theReceiver;
    return self;
}

-(retval_t) forward:(SEL)theSel:(arglist_t)theArgFrame
{
    if (receiver) {

        printf("forwarding for selector %s from %ld to %ld\n",
            sel_get_name(theSel), self, receiver);

        //return objc_msg_sendv(itsNextLink, theSel, theArgFrame);
        return [receiver performv:theSel:theArgFrame];

    } else {
        return [self doesNotRecognize:theSel];
    }
}

@end

int main()
{
    receiver = [[Receiver alloc] initWithFoo:1234567890];
    forwarder = [[Forwarder alloc] initWithReceiver:receiver];

    [forwarder display];

    exit(EXIT_SUCCESS);
    return 0;
}