I would probably do this as (or as nested if's as ikegami suggested):

{
    my $x;
    if( $x = f() and g($x) ) {
        ...
    }
}
[download]

If you really didn't like the extra block/indent, you could also do:

{
    last unless( my $x = f() );
    last unless(  g($x)      );
    ...

}
[download]