> Can you try with different levels of optimisation (no -O, -O, -O1, -O2,
> -Os)?

Hmmm.  Interesting:

no -O	d = 0 9223372036854775808
-O	d = 0 0
-O1	d = 0 0
-O2	d = 0 0
-Os	d = 0 0

It's rare that adding optimisation makes the bug to go away :-)

-- 
$jhi++; # http://www.iki.fi/jhi/
        # There is this special biologist word we use for 'stable'.
        # It is 'dead'. -- Jack Cohen