tilelang-simplification

# TileLang Simplification Turn a broad request to "simplify TileLang" into a small set of evidence-backed changes that reduce maintained concepts, contracts, or code paths. Fewer lines are not sufficient: preserve correctness, useful diagnostics, supported targets, public compatibility, compile behavior, and kernel performance unless the user explicitly accepts a tradeoff. ## Choose The Working Mode - **Survey**: inspect broadly and report ranked candidates. Do not modify code, add TODOs, or create issues unless requested. - **Implement**: prove the selected candidate first, then make the smallest complete change, including tests, documentation, exports, registration, and build metadata affected by the removal. - **Review**: determine whether a proposed simplification is a net reduction and whether its evidence and validation cover all affected targets. For a broad survey, continue past the first plausible candidate. Prefer a few high-confidence reductions over a long list of speculative cleanups. ## Establish Repository Context Read `README.md` and `CONTRIBUTING.md`, inspect the worktree, and identify the requested base revision before judging current code. Exclude `3rdparty/`, `build/`, `docs/_build/`, caches, generated files, and vendored target stubs by default; include them only when the request specifically concerns generated, vendored, or packaging surface. Load the relevant domain skill before judging a candidate in that area: - target or execution backends: [`../tilelang-backend/SKILL.md`](../tilelang-backend/SKILL.md) and `tilelang/backend/README.md`; - layouts, fragments, inference, or CuTe conversion: [`../tilelang-layout/SKILL.md`](../tilelang-layout/SKILL.md); - legality checks, safety checks, or diagnostics: [`../tilelang-semantic/SKILL.md`](../tilelang-semantic/SKILL.md); - C++ TIR/ObjectRef ownership: [`../tilelang-tvm-ir/SKILL.md`](../tilelang-tvm-ir/SKILL.md); - broad C++ cleanup: [`../tilelang-cpp-style/SKILL.md`](../tilelang-cpp-style/SKILL.md); - builds and tests: [`../tilelang-build/SKILL.md`](../tilelang-build/SKILL.md). Do not load every domain skill for a narrow audit. ## What Counts As A Strong Candidate A strong candidate removes or folds a real maintenance burden and has direct evidence that the current surface costs more than it protects. Typical candidates include: - an internal API, option, pass, callback, registry entry, helper, or package with no production consumer; - a Python wrapper, C++ entry point, or FFI binding that duplicates another representation without owning validation, compatibility, or policy; - target selection or execution dispatch repeated outside `BackendContext` or a backend-owned pipeline; - backend-local implementations with genuinely identical semantics that can move behind an existing common boundary; - pass configuration, annotations, analyses, or state that are produced and propagated but never observed; - adjacent passes or lifecycle mechanisms that preserve the same fact and can be represented once; - obsolete compatibility facades, aliases, or migrations whose supported callers and documented transition window are gone; - tests, snapshots, examples, or generated expectations that exist only to pin an unused implementation detail; - hand-rolled utilities already provided by the Python/C++ standard library, TVM, or an existing dependency, when replacement deletes the implementation and its special-case tests without hiding equivalent complexity in glue; - build, packaging, or toolchain branches for artifacts that are no longer produced or consumed. Weak candidates include style-only churn, a single typo, an abstraction that merely looks complicated, or a target-specific path that appears unused only because the current machine cannot exercise it. Moving the same complexity behind a new wrapper is not simplification. ## Survey By Ownership Area For repository-wide work, divide the survey into these areas, in parallel when practical: 1. language APIs, Python exports, IR objects, FFI registrations, and compatibility aliases; 2. shared transforms, pass configuration, analyses, annotations, and pipeline ordering; 3. target backends, execution backends, codegen, runtime, cache, and toolchain integration; 4. layouts, intrinsics, MMA/TMA paths, vectorization, and architecture-specific lowering; 5. autotuning, profiler, carver, diagnostics, instrumentation, and developer tooling; 6. CMake, packaging, tests, examples, benchmarks, maintenance scripts, and documentation. Start with large or repeated production-code surfaces, not only symbols found by an unused-code tool. ## Prove Consumers And Reachability Use `rg` first, then read every relevant call site. Search the exact C++ or Python symbol, its exported alias, registered string, pass-config key, target name, annotation key, and generated symbol. Classify references as: - **production**: `tilelang/`, `src/`, `cmake/`, `CMakeLists.txt`, packaging metadata, runtime templates, and loader or registration paths; - **coverage and usage evidence**: `testing/`, `examples/`, `benchmark/`, and `maint/`; examples and maintenance programs may be supported smoke paths, so inspect them before dismissing them; - **documentation only**: `README.md` and `docs/`; - **excluded/generated/vendor**: the excluded trees listed above. Static text search is not sufficient for TileLang. Before declaring code dead, check all applicable indirect-use mechanisms: - `TVM_FFI_STATIC_INIT_BLOCK`, `TVM_REGISTER_*`, `TIR_REGISTER_TL_TILE_OP`, reflected object fields, and global function names; - Python `tvm_ffi.register_object`, `_ffi_api` bindings, `__init__.py` re-exports, `__all__`, decorators, and compatibility facades; - `BackendModule` manifests, target predicates, execution compatibility, callback maps, and backend package import side effects; - pass factories referenced by registered names, backend pipeline lists, and `PassContext` configuration strings; - CMake source lists and object files retained for static initialization; - generated runtime-template symbol names, cache keys, serialized artifacts, and codegen-emitted calls. Useful discovery searches include: ```bash rg -n "ExactSymbol|registered.string|config_key" tilelang src cmake \ CMakeLists.txt testing examples benchmark maint docs rg -n "TVM_FFI_STATIC_INIT_BLOCK|TVM_REGISTER_|TIR_REGISTER_TL_TILE_OP|register_object|register_backend|__all__" \ tilelang src ``` Treat static analyzers as inventory aids, not proof; dynamic FFI, registration, and target dispatch routinely hide valid consumers. Absence of an in-tree caller proves only in-tree reachability. Treat exported Python APIs, FFI and reflection names, pass-config and annotation strings, target names, runtime ABI, and cache or serialized formats as externally consumed until documentation, release history, and deprecation policy provide evidence otherwise. Tests describe important cases but are not the sole source of the contract. ## Trace The Compiler Contract For a compiler or language candidate, trace one representative construct from the source API through its TIR/TileOp representation, annotations, selected backend pipeline, lowering passes, host/device split, codegen, and runtime consumption. Name the first stage that requires the surface being considered. Before merging or deleting passes, determine: - which backend pipelines include each pass and in what order; - the preconditions, annotations, and analyses each pass consumes and emits; - whether a pass is a no-op only for the inspected example or architecture; - whether diagnostics or source spans become less useful after moving it; - whether generated source, launch metadata, cache identity, or runtime ABI changes even when final numerical results do not. Do not replace a semantic check with an optimizer assumption, or delete a fallback merely because the optimized path handles common examples. When a new dependency would replace hand-rolled code, prefer the standard library, TVM, or an existing dependency first. Otherwise check supported Python versions and platforms, wheel or native-build availability, license, maintenance, transitive footprint, and net code deletion. A dependency that moves equivalent complexity into adapters, CMake, or wheel packaging is not a simplification. ## Respect Backend And Hardware Boundaries Target backends and execution backends are intentionally separate. Do not collapse CUDA, CuTeDSL, ROCm, CPU, Metal, WebGPU, or their execution adapters solely because implementations currently resemble one another. A shared helper is justified only when ownership is target-neutral and the supported capability differences remain explicit. Absence of a runnable device is not evidence that a path is dead. For every backend-facing candidate, record: - target kinds and architecture predicates that can reach it; - source-only or hardware-independent checks available locally; - hardware and toolchain coverage that would still be required; - intentional unsupported cases and fallback behavior. ## Protect Performance-Sensitive Semantics A simpler compiler implementation can produce slower kernels or slower compilation while remaining numerically correct. Scale evidence to the risk: - for cold Python helpers, imports and focused unit tests may be enough; - for transforms and codegen, compare relevant IR and generated source; - for layout, vectorization, memory movement, synchronization, MMA/TMA, pipeline, or autotuning changes, run the subsystem harness and representative hardware benchmarks when available; - for build, cache, JIT, or runtime changes, verify Build, load, launch, cache hit behavior, and artifact portability that the path claims to support. If hardware validation is unavailable, report the gap. Do not convert missing performance evidence into a claim of equivalence. ## Decide The Candidate Classify each investigated item: - **safe deletion**: internal, unreachable through direct or indirect paths, and not part of a supported compatibility or artifact contract; - **consolidation**: multiple paths implement the same contract and an existing owner can absorb them with less total branching and state; - **behavior or API tradeoff**: simplification changes a public API, FFI name, IR/annotation contract, target capability, generated source, cache format, or performance characteristic; require explicit acceptance; - **unproven or intentional**: keep it and record why the apparent duplication is load-bearing. Use history to understand intent when current code is ambiguous, but judge reachability and contracts from the current tree. Reject a candidate when the proposal forces broad unrelated churn without reducing concepts, ownership boundaries, or supported behavior. ## Report Or Implement For a survey, report each retained candidate with: 1. affected files, symbols, or registered names; 2. current responsibility and production consumers; 3. exact removal or consolidation proposed; 4. compatibility, target, correctness, and performance tradeoffs; 5. validation required and any unavailable hardware; 6. confidence level. Also mention representative rejected candidates when they explain intentional architecture or prevent repeated false positives. For implementation, remove the whole obsolete surface: definitions, declarations, exports, registrations, configuration, CMake/package entries, tests that only pin deleted behavior, and stale documentation. Preserve tests that express the surviving contract, and add a regression test when the new boundary would otherwise be ambiguous. Use the repository formatter on touched files, follow [`../tilelang-build/SKILL.md`](../tilelang-build/SKILL.md) for build and test commands, and always run `git diff --check`. In the final report, state the conceptual surface removed, the supported behavior retained or intentionally given up, the checks run, and hardware or toolchain validation not performed.