GELU Fusion with cuBLASLt (SLOWER because it only merges in FP16 mode, not BF16/FP32...) #338
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… properly for FP32/BF16, and it's actually non-fused and SLOWER!
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It turns out that not only is cuBLASLt not able to fuse BF16 GELU (or RELU) into a BF16 matmul, it also ends up with a strange kernel that is slower than our own GELU kernel as it does 2 writes per element (?!) rather than the expected 1.
This happens for FP32 and BF16 in GELU, RELU, GELU_AUX, and RELU_AUX modes as far as I can tell. In theory cuBLASLt also supports GELU backwards, but I assume it will have similar problems so I didn't try it.
Obviously this shouldn't be merged, only posting this here for future reference...