http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55481
--- Comment #14 from Zdenek Dvorak <rakdver at gcc dot gnu.org> 2012-12-10 18:19:07 UTC --- This is a problem in rewrite_use_nonlinear_expr, which should leave the statement defining the biv untouched (as suggested in the comment at its beginning) but does not. Investigating further...