use vars qw( %ALLOPS %OPMAP @QUEUE_OPCODES_TO_FIX );
CHECK
{
    walkallops_filtered( sub { foo( $op ) ... }, \ &queue_opcode );
    fix_opcode( $_ ) for @QUEUE_OPCODES_TO_FIX;
}

sub queue_opcode
{
    my $op = shift;
    push @QUEUE_OPCODES_TO_FIX, $op;
}

sub foo
{
    my $op = shift;
    my $addr = $$op;
    $ALLOPS{ $addr } = $op;
    for my $m ( qw( next sibling ppaddr first last other pmreplroot pmreplstart pmnext ) )
    {
        my $to = eval { ${ $op->$m } };
        next unless $to;

        push @{$OPMAP{ $addr }}, "$to $m";
    }
}

x_opcode
{
    my $op = shift;
    my $addr = $$op;

    # Construct the new program fragment in reverse order so parent nodes
    # can point to child nodes. See the tree immedia

    # null
    #    or
    #       $OP
    #       die
    #          pushmark
    #          null2
    #             gvsv
    
    my $gvsv = B::SVOP->new( gvsv => 2, '$!' );
    my $null2 = B::OP->new( null => 6 );
    $null2->private( 1 );
    my $pushmark = B::OP->new( pushmark => 2 );
    my $die = B::LISTOP->new( die => 5, $pushmark, $null2 );
    $die->targ( 1 );
    $die->private( 1 );
    $pushmark->sibling( $null2 );
    my $or = B::LOGOP->new( or => 2, $op, $die );
    $or->private( 1 );
    my $null = B::OP->new( null => 5 );
    $null->private( 1 );

    # Tree order
    my $orig_sibling = $op->sibling;
    $op->sibling( $die );
    
    # Now thread the execution order.
    my $orig_next = $op->next;
    # EXT -> $op
    #     -> OR
    #     -> $orig_next || $pushmark
    #        ( null2 -> gvsv )
    #     -> gvsv
    #     -> die
    $op->next( $or );

    $or->next( $orig_next );
    $or->other( $pushmark );
    $null->next( $orig_next );

    $pushmark->next( $gvsv );
    $null2->next( $gvsv ); # Also but this is skipped anyway.

    $gvsv->next( $die );
    
    $die->next( $orig_next );
    
    # Now change everything that currently points to $op so that it points to
    my @referrents = @{ $OPMAP{ $addr } };
#    use YAML 'Dump';
#    print Dump( $addr, \%OPMAP ) or die $!;exit;
    foreach my $referrent ( @referrents )
    {
	my ( $referrent_addr,
	     $referrent_attr ) = split ' ', $referrent;
	print "$$op $referrent_addr $referrent_attr\n" or die $!;
	
#	my $co = B::class( $op );
#	my $cn = $op->oldname;
#	my $c = B::class( $referrent_obj );
#	my $n = $referrent_obj->oldname;
	
#	$referrent_obj->$referrent_attr( $op );
#	print STDERR "$referrent_obj->$referrent_attr( $op )\n" or die $!;
    }
}