dynamic dimension added

[weihanmines]

Supports four values of dynamic dimension. They are [64, 128, 192, 256].

[liligwu]

EmbeddingBag UTs passed.
tbe-fwd-dyn-dim_test_log.txt

[carlushuang]

I would not say this is a good change to support dynamic emb-dim. A good convention is to implement some granularity in emb-dim (like 64, 128, 192, 256, 512...), and if the input dim is, e.g. 269, just choose the kernel of 512.
Another approach is to implement a emb=64 kernel with arbitrary loop along the row of such emb=64, so it can support 64, 128, 192, etc. And then when loading data inside current 64-wide row, always check if current index is out of range.

[carlushuang]

the code size is enlarged 4x due to you expand everything in this loop, potentially will damage the I-CACHE and cost more power. Beside, emb=64 will lose the occupancy, because it will have the same register usage of emb=256. How would you gonna to support any other emb_dim not 64x?

[HaiShaw]

@carlushuang , I would agree that your first approach is more straightforward.

[HaiShaw]

@weihanmines to the 2 macro functions, we may inline device function them, with or without inline depends on the performance.