feat(ir): declare per-argument read/write effects on the operator registry

[lyfne123]

First of a five-part series making one place answer "which argument does this
operator write". The follow-ups are open as drafts and each builds on this one;
they are listed at the bottom.

"Which argument does this operator write?" is asked by direction inference,
dependency analysis, the mixed-store diagnostic and orchestration codegen, and
today each of them answers it from its own hand-maintained if-chain. There are
at least 39 such detectors in the tree and roughly thirty independent copies of
the single rule "tile.store writes args_[2]". Every one of them defaults an
operator it does not recognise to read-only, so the failure mode of forgetting
an operator is not a compile error: the write disappears, the parameter keeps
direction In, no RAW edge is emitted, and the program races or deadlocks on
device. That is exactly how pld.system.notify reached #2391.

This commit adds the missing single source of truth. It changes no analysis and
no generated code — the declarations are additive, and nothing reads them yet.

tile.mscatter is the standing proof that the gap is live rather than
historical: it writes a GM output_tensor, declares set_output_reuses_input(2)
so the registry already knew the result is that buffer, and appears in none of
the three direction detectors. Two structurally identical kernels differing only
in their single write op derive different directions today:

pl.store    -> out: Out     (recognised)
pl.mscatter -> out: In      (falls through to the read-only default)

• include/pypto/ir/op_registry.h: adds ArgEffect (Read / Write / ReadWrite),
  WriteChannel (Dma / Scalar) and OpArgEffectSpec, plus the fluent setters
  set_arg_effect(index, effect), set_arg_effect(index, resolver),
  no_arg_writes() and set_write_channel(), and the queries
  GetArgEffect(index, kwargs), HasDeclaredArgEffects(), WritesAnyArg() and
  GetWriteChannel(). Undeclared is std::nullopt rather than "all reads", so
  an analysis can tell "a human decided this writes nothing" apart from "nobody
  has looked at this operator yet" and refuse to guess. GetIntKwarg /
  GetStringKwarg back the resolvers.

  The resolver form exists because two effects are genuinely call-dependent:
  the atomic kwarg on the store family (an accumulate reads the slot it adds
  into, a plain store does not) and the op kwarg on pld.system.notify, whose
  default is atomic-add. Constant declarations cannot express either.

• src/ir/op_registry.cpp, python/bindings/bindings.cpp: adds
  OpRegistry::ValidateArgEffects(), called at import next to the existing
  ValidateTileOps(). An operator declaring set_output_reuses_input(N) updates
  argument N in place — that is what reusing the buffer means — so it must
  classify that argument. It reports every offender with the fix rather than
  failing on first use. Classification is what is required, not a particular
  answer: an operator whose in-place slot is metadata may declare it read-only.

• src/ir/op/**: declares effects on 30 operators. The GM and window-bound
  writers (tile.store, tile.mscatter, tile.mgather's scratch,
  tensor.write, tensor.assemble, the pld.tile.* / pld.tensor.* push and
  pull family, pld.system.notify, system.set_ffts, the composite and host
  collectives) also declare their write channel; the accumulate and
  destination-passing tile operators declare ReadWrite, since the positions
  they do not rewrite flow through to their result. pld.system.wait,
  pld.system.defer_wait and pld.tile.remote_load declare no_arg_writes() —
  a decision on record rather than an omission.

  Partial overwrite stays Write, matching the contract the outliner already
  applies to tile.store: a store landing on a sub-region never reads the
  untouched remainder, and calling it ReadWrite would make the enclosing
  parameter InOut, stage the buffer host->device, and invent a cross-rank
  dependency between ranks writing disjoint rows.

• python/bindings/modules/ir.cpp, python/pypto/pypto_core/ir.pyi: exposes
  ArgEffect, WriteChannel, get_op_arg_effect, op_has_declared_arg_effects
  and get_op_write_channel.

• tests/ut/ir/operators/test_op_registry.py: 35 tests — the Read default and
  the unclassified/declared-read-only distinction, the declared effect of every
  writer, both kwarg-dependent resolvers, the write channels, and a coverage
  test asserting each in-place operator is classified, so a new one fails with
  its own name rather than at import.

• docs/en/dev/ir/05-operators.md, docs/zh/dev/ir/05-operators.md: documents
  the fluent API, why partial overwrite is not a read, why declared-read-only
  differs from unclassified, and the import-time enforcement.

• cmake --build build --parallel 32: exit 0

• python -m pytest tests/ut/ -n 16 -q: exit 0 — 10001 passed, 8 skipped
  (9966 before this change; the 35 new tests are the difference, no regressions)

• tests/lint/check_headers.py, check_english_only.py,
  check_docs_en_zh_parity.py, check_op_name_literals.py,
  check_no_broad_raises.py: exit 0 each

• clang-format --dry-run --Werror on every changed C++ file: exit 0

• ruff check / ruff format --check on the changed Python: exit 0 (local ruff
  is 0.16.0 against the pinned 0.14.8; run with required-version temporarily
  commented out, pyproject.toml restored afterwards)

• Enforcement checked negatively: removing any one in-place declaration makes
  import pypto fail naming that operator.

---

The rest of the series

Each is a draft stacked on the one before it, and each is one commit of new work:

• refactor(ir): derive param directions from registry argument effects #2455 — refactor(ir): drive ConvertTensorToTileOps off these declarations, deleting its two write tables (net −300 lines) and fixing tile.mscatter
• refactor(ir): derive outlined scope param directions from registry effects #2456 — refactor(ir): same for ScopeOutliner, which recognised only tile.store and tensor.assemble
• feat(verifier): warn when a parameter declared In is written by its own body #2457 — feat(verifier): report a parameter declared In that its own body writes
• fix(ir): propagate a callee's write onto a caller parameter reached by a carry #2458 — fix(ir): propagate a callee's write onto a caller parameter reached by a loop carry

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📝 Walkthrough

Walkthrough

The operator registry now supports argument read/write effects and DMA or scalar write-channel metadata. Python bindings expose queries for these declarations. Distributed, memory, synchronization, and in-place operators add classifications. Import-time validation and unit tests enforce coverage.

Changes

Operator effect metadata

Layer / File(s)	Summary
Registry effect contract and validation include/pypto/ir/op_registry.h, src/ir/op_registry.cpp, docs/en/dev/ir/05-operators.md, docs/zh/dev/ir/05-operators.md	Adds ArgEffect, WriteChannel, fixed and kwarg-dependent effect specifications, declaration APIs, write-channel queries, and validation for in-place operators.
Python effect queries python/bindings/modules/ir.cpp, python/pypto/pypto_core/ir.pyi, python/bindings/bindings.cpp	Exposes effect enums, effect queries, write-channel queries, and import-time validation.
Distributed operation declarations src/ir/op/distributed/*, src/ir/op/sync_ops/*	Adds effect and DMA-channel metadata to collective, transfer, notification, wait, and synchronization operations.
Local memory and compute declarations src/ir/op/array_ops/memory.cpp, src/ir/op/tensor_ops/memory.cpp, src/ir/op/tile_ops/*	Classifies stores, gathers, scatters, updates, accumulators, and other in-place operations as Write or ReadWrite, with channel metadata where applicable.
Registry test coverage tests/ut/ir/operators/test_op_registry.py	Tests default and dynamic effects, atomic variants, write channels, unknown operators, and completeness for in-place operators.

Estimated code review effort: 4 (Complex) | ~45 minutes

Merge Risk: 🟡 Moderate · up to 53fa5

The PR introduces effect and write-channel metadata for operators, but the current implementation can misclassify arguments and mode-dependent writes, leading downstream analyses to make incorrect dependency or staging decisions. Merge should wait until these bounded correctness issues are fixed.

Possibly related PRs

• hw-native-sys/pypto#2237: Introduces the tile.matmul_mx and tile.tget_scale_addr registrations updated here.
• hw-native-sys/pypto#2357: Introduces the remote_store registrations updated here.
• hw-native-sys/pypto#2396: Extends tile.store, which receives effect and write-channel metadata here.

Sequence Diagram(s)

sequenceDiagram
  participant PythonImport
  participant OpRegistry
  participant RegisteredOps
  PythonImport->>OpRegistry: ValidateArgEffects()
  OpRegistry->>RegisteredOps: Inspect reused-input declarations
  RegisteredOps-->>OpRegistry: Return declared effects or no-write classification
  OpRegistry-->>PythonImport: Complete validation or ValueError

Loading

Poem

A rabbit hops through buffers bright,
Marking reads and writes just right.
DMA paths and scalar streams,
Keep operators clear in dreams.
In-place checks now guard the way.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 65.12% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description clearly explains the operator effect declarations, validation, bindings, tests, documentation, and scope of the changes.
Title check	✅ Passed	The title clearly and concisely identifies the main change: per-argument read/write effects in the IR operator registry.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Inline comments:
In `@include/pypto/ir/op_registry.h`:
- Around line 194-195: The operator registry currently stores one WriteChannel
for all writes, which misclassifies arguments in composite collectives such as
allreduce. Replace write_channel with per-argument channel metadata, expose
lookup by argument index and kwargs, and update collective registrations plus
all public query consumers to use the argument-specific channel.

In `@src/ir/op/distributed/system.cpp`:
- Around line 228-234: Update the pld.system.notify operator registration near
set_arg_effect to declare WriteChannel::Scalar via set_write_channel, ensuring
GetWriteChannel() classifies this DistributedTensor writer as a scalar write.

In `@src/ir/op/tile_ops/memory.cpp`:
- Around line 1400-1403: Make the tile.mgather argument-2 effect conditional in
DeduceTileMgatherType: return Write with the DMA channel only for Mat
target_memory combined with kElem coalesce, where argument 2 is scratch; return
no write effect for Mat row mode, where it is valid_shape, and Vec mode, where
it is absent. Use a kwargs-based resolver or separate overloads, and add
coverage for all three forms.

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📥 Commits

Reviewing files that changed from the base of the PR and between d2cf77c and 53fa5fe.

📒 Files selected for processing (27)

• docs/en/dev/ir/05-operators.md
• docs/zh/dev/ir/05-operators.md
• include/pypto/ir/op_registry.h
• python/bindings/bindings.cpp
• python/bindings/modules/ir.cpp
• python/pypto/pypto_core/ir.pyi
• src/ir/op/array_ops/memory.cpp
• src/ir/op/distributed/allreduce.cpp
• src/ir/op/distributed/collective.cpp
• src/ir/op/distributed/get.cpp
• src/ir/op/distributed/put.cpp
• src/ir/op/distributed/remote_load.cpp
• src/ir/op/distributed/remote_store.cpp
• src/ir/op/distributed/system.cpp
• src/ir/op/sync_ops/cross_core.cpp
• src/ir/op/sync_ops/sync.cpp
• src/ir/op/tensor_ops/memory.cpp
• src/ir/op/tile_ops/batch_matmul.cpp
• src/ir/op/tile_ops/elementwise.cpp
• src/ir/op/tile_ops/matmul.cpp
• src/ir/op/tile_ops/matmul_mx.cpp
• src/ir/op/tile_ops/memory.cpp
• src/ir/op/tile_ops/paged_gather.cpp
• src/ir/op/tile_ops/scatter.cpp
• src/ir/op/tile_ops/transform.cpp
• src/ir/op_registry.cpp
• tests/ut/ir/operators/test_op_registry.py

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[lyfne123]

Pushed 1fc3a331, folded into the single commit this PR carries.

Fixed

• clang-tidy — both classes it reported. bugprone-unchecked-optional-access (6 sites) is gone structurally rather than by suppression: EnsureArgEffects() now returns the engaged spec by reference, so no setter dereferences the optional at all. misc-include-cleaner is fixed by including pypto/ir/comm.h where AtomicType is used.
• tile.mgather's third operand was declared an unconditional write; it is the GM scratch only in Mat element mode and a read-only valid_shape in Mat row mode. Now a kwarg resolver. This was a real defect in the PR — thanks for catching it.
• tile.write and tile.assemble were unclassified destination-passing writers that the import-time gate could not see (neither declares output_reuses_input). Both now declare ReadWrite.
• The Python effect query rejected enum-valued kwargs (std::bad_cast on target_memory=MemorySpace.Mat). It now uses ConvertKwargsDict, the converter every other kwarg-taking binding already uses — which the tile.mgather resolver above depends on.
• Composite collectives no longer declare a write channel. One operator-level channel cannot describe a collective that updates its data window and its signal through different mechanisms, and claiming Dma could have paired a collective's signal write against a scalar tensor.write on the same buffer and made the mixed-store diagnostic reject a valid program. Declaring none restores exactly the pre-PR behaviour for them.

Deliberately not changed — two threads left open rather than resolved, so you can weigh them:

• A Scalar write channel for pld.system.notify. It emits pto.comm.tnotify, a dedicated comm instruction on neither the MTE3 nor the scalar D-cache path (pto_ops_distributed.cpp:511). Declaring either would be a false claim that makes the mixed-store diagnostic reject valid programs; nullopt means "does not participate", which is correct.
• Per-argument write channels. The general answer, but no case in the tree needs two arguments of one operator distinguished, and the concrete risk it pointed at is fixed above by the narrower change. Both rules are now written down in docs/en|zh/dev/ir/05-operators.md so the next reader does not have to re-derive them.

Test count for the commit goes 35 → 40, covering each fix including the three tile.mgather forms.

[lyfne123]

Pushed 31a7989b, folded into the same commit. All three verified against the code first — thank you, all three were real.

[P1] Collective destinations are pure writes. Confirmed in lower_composite_ops_pass.cpp: the allgather / all_to_all / all_to_all_v rules only push into target (pld.tile.put) and never load from it — a grep for a load of target in the allgather rule returns zero — and all_to_all_v deposits into recv_counts with notify(..., Set), not an accumulate. Now:

• target (argument 1) → Write on pld.tensor.allgather / all_to_all / all_to_all_v and their builtin.tensor.* forms
• all_to_all_v.recv_counts (argument 4) → Write
• every signal stays ReadWrite, and so do allreduce / reduce_scatter targets — their Phase 3 does acc = load(target, ...), so the distinction is per operator, not per family. The table test now pins both sides so the two cannot drift.

Worth flagging: the pre-existing AnalyzeCallAccess table in ConvertTensorToTileOps marked these read+write too, so this corrects behaviour that predates the PR rather than a regression it introduced.

[P2] The gate did not ask about the reused argument. Correct, and per_arg could not have answered it: it is resized to cover the highest declared index, so a slot nobody named is indistinguishable there from one declared Read. OpArgEffectSpec::declared_args now records which arguments a registration actually named, no_arg_writes() names none and counts as a verdict about all of them, and ValidateArgEffects() asks HasDeclaredArgEffect(N).

Checked negatively: mis-declaring tile.mscatter as set_arg_effect(1, ...) while it reuses argument 2 now fails import pypto naming that operator, where the old check passed. Exposed as op_has_declared_arg_effect and covered by test_in_place_gate_asks_about_the_reused_argument.

[P2] system.set_ffts. Agreed, and the split was worse than it looks: the correction existed only from the fourth commit of this series onward, so this PR and the two after it each shipped the wrong declaration. Moved into this commit, where it belongs. The backend emits only pto.set_ffts %ws : !pto.ptr<i64> — a pointer handed to the FFTS unit, with the hardware writing that region on its own schedule — so it is now no_arg_writes() with no channel, not merely a channel removal.

Both rules are written down in docs/en|zh/dev/ir/05-operators.md. Test count for the commit goes 40 → 47.