https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63510
--- Comment #13 from Chen Gang <gang.chen.5i5j at gmail dot com> --- gcc version 6.0.0 20151023 (experimental) (GCC) has no this issue (I guess, the reason is that it calls gimple_simplify instead of fold_binary). For me, this issue can be closed. Thanks.
