functional_one_hot

[Zailiang]

add one_hot:

[github-actions]

Speed stats:

GPU Name: GeForce GTX 1080 

PyTorch resnet50 time: 145.9ms (= 7293.6ms / 50, input_shape=[16, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 128.3ms (= 6413.1ms / 50, input_shape=[16, 3, 224, 224], backward is enabled)
Relative speed: 1.14 (= 145.9ms / 128.3ms)

PyTorch resnet50 time: 83.9ms (= 4197.1ms / 50, input_shape=[8, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 74.4ms (= 3722.2ms / 50, input_shape=[8, 3, 224, 224], backward is enabled)
Relative speed: 1.13 (= 83.9ms / 74.4ms)

PyTorch resnet50 time: 57.4ms (= 2871.0ms / 50, input_shape=[4, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 48.0ms (= 2400.5ms / 50, input_shape=[4, 3, 224, 224], backward is enabled)
Relative speed: 1.20 (= 57.4ms / 48.0ms)

PyTorch resnet50 time: 49.0ms (= 2451.6ms / 50, input_shape=[2, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 39.2ms (= 1959.4ms / 50, input_shape=[2, 3, 224, 224], backward is enabled)
Relative speed: 1.25 (= 49.0ms / 39.2ms)

PyTorch resnet50 time: 42.5ms (= 2126.0ms / 50, input_shape=[1, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 36.6ms (= 1831.1ms / 50, input_shape=[1, 3, 224, 224], backward is enabled)
Relative speed: 1.16 (= 42.5ms / 36.6ms)

[strint]

这里为什么要默认设置成 double？

这里建议改为float，之前lazy日常使用比较多的就是float。