optimize unrolling
optimize unrolling

keisuke-umezawa/chainer,keisuke-umezawa/chainer,hvy/chainer,tkerola/chainer,niboshi/chainer,niboshi/chainer,keisuke-umezawa/chainer,okuta/chainer,hvy/chainer,niboshi/chainer,pfnet/chainer,okuta/chainer,chainer/chainer,hvy/chainer,niboshi/chainer,chainer/chainer,wkentaro/chainer,wkentaro/chainer,okuta/chainer,wkentaro/chainer,wkentaro/chainer,okuta/chainer,keisuke-umezawa/chainer,chainer/chainer,chainer/chainer,hvy/chainer