xlstm/mlstm.rs: mLSTM attention on GPU — gpu_matmul for Q*K^T outer
products, gpu_broadcast_mul_col for gating, zero host downloads
(was: 7 to_vec() calls downloading Q,K,V,i,f,o,c)
xlstm/network.rs: gpu_select_dim1 for per-timestep extraction
(was: to_vec() + CPU slice)
kan/spline.rs: B-spline evaluation on GPU — gpu_floor for indices,
gpu_gather_dim0 for grid lookups, gpu_mul/add/sub for lerp
(was: 3 to_vec() downloads + CPU Cox-de Boor)
liquid/candle_cfc.rs + training.rs: gpu_select_dim1 for 3D timesteps
(was: to_vec() + CPU extraction)
Remaining liquid/cells.rs + network.rs to_vec() calls are on Rust
slices (&[FixedPoint]), not GPU tensors — false positives.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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