Dynamo (torch.compile fullgraph) cannot trace through CuTeDSL internals
(cute.compile, JIT, etc.). The autograd.Function approach was unreliable
with fullgraph mode — Dynamo would still try to trace through it.
Fix: torch.library.custom_op makes Dynamo treat our GEMM as an opaque
black box. No reimplementing the kernel — just route through the existing
runner via a registry pattern:
- Runners registered in global dict with integer IDs
- Custom op takes (tensors, runner_id, shape_hint) -> tensor
- Dynamo calls fake impl for shape inference, never touches the runner
- At execution time, real impl looks up runner and calls _run_impl
Changes:
- New: cutedsl/custom_ops.py (custom op definitions + registry)
- New: tests/test_custom_op.py (local unit tests, no GPU needed)
- Removed: _Nvfp4LinearApply, _MoEApply (autograd.Function classes)
- Updated: nvfp4_linear.py, runner.py, cutedsl.py, nvfp4_cutedsl.py
to use custom ops instead of autograd.Function
- Updated: cutedsl_quant_method.py to use custom op + registry
- Add orig_to_new_prefix mappings (layers→model.layers, embed_tokens→model.embed_tokens, etc.)
AutoWeightsLoader strips the model. prefix before the mapper runs, so these are required
- Move .self_attn.compressor. → .attn.mla_attn.compressor. before .self_attn. → .attn.
in substr_renames so compressor keys get the mla_attn prefix before the general rename
- Remove suffix renames (head.weight→lm_head.weight, embed.weight→embed_tokens.weight)
that were causing double-mapping since the NVFP4 checkpoint already uses lm_head/embed_tokens
- Add unit test: tests/test_nvfp4_mapper.py (39 cases, no vLLM/CUDA needed)
- CuTeDSLNvfp4Linear: generic single-GEMM runner for any NVFP4 projection
- test_attention.py: tests q_a_proj, q_b_proj, kv_proj, o_b_proj vs BF16
- Same pad+swizzle pattern as shared expert, but no SiLU/fusion
- CuTeDSLSharedExpertRunner: num_groups=1 GEMM, no scatter/routing
- _assemble_scales_single_group: pad to 128 rows + Blackwell swizzle
- All buffers pre-allocated for cudagraph compatibility
- Updated test to use dedicated runner instead of MoE runner hack
Dedicated runner (shared_expert_pipeline.py) and test (test_shared_expert.py).
Tried reusing MoE runner with 1 expert — fails because MoE runner assumes
hidden_size != HC_DIM for scatter. Need dedicated runner with correct
scale assembly. Will continue tomorrow.
float4_e2m1fn_x2 packs 2 values per byte along K, not N.
The GEMM output N dimension is the logical N from mat_b.shape[2],
not 2x packed. Previous n_dim*2 was wrong — it accidentally worked
in the test because intermediate_size*2 == 2*intermediate_size.
Real model with N=9216 exposed the bug.
