Fuse the residual k_get_rows_float in the gated-DeltaNet decode path (the biggest
single kernel vLLM lacks per MOE_GAP_VS_VLLM.md, ~5.2 ms/step MoE). 0019 fused the
SSM-state gather, 0021 fused the conv compute but kept a build_rs gather for the
conv taps; nsys located that conv-state tap gather (n_embd_r=24576 floats x 128
seqs, ~720 x ~115 us per 24-step window) as the last k_get_rows in the GDN path.
New op ggml_ssm_conv_update_inplace_ids reads each sequence's prior conv taps from
cache[ids[s]] in-kernel (identity in place from the write slot, non-identity via a
disjoint scratch), mirroring the 0019 in-place + ids fusion. Bit-exact: read VALUES
unchanged, only the read path changes. Helps both dense and MoE (shared GDN conv).
GATE test-backend-ops (CUDA0 2/2): SSM_CONV_UPDATE_IDS, SSM_CONV_UPDATE, SSM_CONV,
GATED_DELTA_NET, GET_ROWS all PASS. GATE greedy md5 (-temp 0 -seed 1 -n 48)
BYTE-IDENTICAL both models: q36-27b-nvfp4 5951a5b4..., q36-35b-a3b-nvfp4 07db32c2...
nsys: k_get_rows<float,float> 10174 -> 9454 instances, 186.3 -> 102.8 ms (720 conv
gathers eliminated, replaced by a ~1.1 us no-op gather).
Built and gated on the DGX llama tree (branch paged, commit 944636c, f32 default).
Assisted-by: Claude:opus-4.8 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
b1667b48ea
