One of the core operations of the transformer network[1] is a (LxL) x (LxE) matrix multiply (where L is the sentence length and E is the network width). Can you be more specific about how you would get good performance without specializing on L?
L can be as small as 1 and bigger than 512. For small L it makes sense to do different optimizations than large L. A loop based GEMM doesn’t help with that.
[1] https://arxiv.org/abs/1706.03762