feat(ir): hoist a Graph region's own allocations out to its call sites by lyfne123 · Pull Request #2619 · hw-native-sys/pypto

lyfne123 · 2026-09-02T06:18:30Z

Summary

LegalizeGraphBoundary collected Step C — the tensors a Graph region allocates
for itself — but BuildPlan never read collector.creates(), so every
pl.create_tensor stayed inside the region and became a recorded
alloc_tensors node. Recording one is correct, but the buffer comes off the
graph heap, and task_allocator.h reclaims nothing there until the run ends
("The whole graph must fit at once; nothing is reclaimed mid-run"), so the live
set grows with the number of submissions instead of staying flat — a Qwen3-14B
decoder layer holding 14 intermediates costs 14 × N over N recorded layers.
simpler's hand-written qwen3_14b_decode scene avoids this by hand, for the
same stated reason.

Step C now moves each top-level allocation to the call site as an InOut
boundary tensor. A Graph that allocated for itself gains one appended InOut
parameter per allocation and its emitted region carries no allocation node;
existing parameters keep their indices, and a Graph that allocates nothing is
unaffected.

The doc previously recorded Step C as deliberately unwired, blocked on the
return-alias mapping. That blocker was real; PR #2618 removed it by
canonicalizing a Graph's param-writeback returns. This PR is rebased on that
and depends on it rather than carrying it.

Changes

src/ir/transforms/legalize_graph_boundary_pass.cpp — Step C wiring. A
top-level tensor.create becomes an appended InOut parameter and is emitted
at the call site. It also becomes its own boundary root, so a view of it faces
the same Step B rule as a view of any other boundary tensor: the
GraphBoundaryLegalized verifier holds every tensor parameter to that rule,
and one left in place with a window that can move would make the pass produce
IR its own verifier rejects.

InOut rather than In because the region writes the buffer — declared In,
codegen emits add_input, the launch never registers as a writer, and a
caller that hoisted the create out of its own loop would get no ordering
between successive launches. Out is unavailable: on a Graph boundary it
means the runtime allocates, which rt_graph_args_cacheable refuses.

Two allocations stay where they are, deliberately: tensor.full (orchestration
codegen has no lowering for it at the call site either, and Step D already
rejects it) and a create under a loop (a fresh buffer per iteration; collapsing
N into one parameter would make iterations alias, and the cross-task edges that
would have to re-serialise them were derived well upstream of this pass).
src/ir/transforms/legalize_graph_boundary_pass.cpp,
src/ir/verifier/verify_graph_functions.cpp — boundary provenance now
crosses an in-place call rebind. tmp = kernel(a, tmp) binds a fresh SSA
name to the same buffer; tracking only bare alias = var assignments lost the
boundary root there, so Step B skipped a view of the rebound name outright —
no hoist and no check — and a call-varying offset stayed in the region with the
first call's window frozen into the recording.

Provenance follows the writeback through ExplicitReturnedParamIndices, the
same return-position → parameter map orchestration codegen aliases a call
result on, so the two cannot disagree about which buffer a result names. It
covers single results and tuple elements (pl.submit / pl.spmd_submit), is
memoized per callee, and bails when args_.size() != params_.size() because a
Submit prefix plus a CommCtx suffix breaks the positional mapping.

The verifier's TrackTensorAlias had the identical blind spot, so nothing
caught this. Fixed alongside, re-derived rather than shared, so the check stays
independent.

This hole predates Step C. It is the tensor_root_ lookup that fails, so a
view of a rebound boundary parameter escaped the same way with no allocation
involved. Both shapes are pinned by tests.
Node counting moved to run on the rewritten program. Step C removes
allocation nodes, so counting the pre-hoist body would reject a Graph that
fits, and would disagree with the verifier, which re-derives the same count
from the rewritten IR.
docs/{en,zh}/dev/passes/45-legalize_graph_boundary.md — Step C rewritten
from "not done, and here is the blocker" to what it now does, plus the two
deliberate exclusions, the new counting position, the provenance rule, and a
narrowed "Not yet handled". The section names PR fix(ir): canonicalize a Graph's param-writeback returns #2618 as the dependency it
relies on rather than claiming it.

26-normalize_return_order.md (both locales) keeps one correction on top of
fix(ir): canonicalize a Graph's param-writeback returns #2618: it still said the pass is "a no-op for any program with no InCore
functions", which stopped being true once Step A0 covered Graph.
Tests. New: Step C parameter/direction/call-site coverage, a view of a hoisted
allocation with a moving window (rejected), a loop-nested allocation (left in
place), the three in-place-rebind cases (allocation, plain parameter, and a
moving window that is now rejected rather than skipped), a guard on the fix(ir): canonicalize a Graph's param-writeback returns #2618
dependency, and a codegen test asserting the emitted region carries no
alloc_tensors while the entry allocates and passes the buffers add_inout.

_legalize_outlined now runs NormalizeReturnOrder. It did not before, which
meant the return→param map was all-nullopt in the harness and a test written
against the rebind fix would have passed for the wrong reason. It also matches
the real pipeline, where that pass runs at 26 and this one at 45.

Updated expectations: test_a_region_local_slice_is_left_alone becomes
test_a_view_of_a_hoisted_allocation_moves_out_with_it — its premise is what
this change reverses. Three node-counting cases and the codegen batching case
put their creates under a two-trip loop so they stay in the region and keep
testing the counting/batching rule; two trips rather than one because
Simplify collapses a single-trip loop into its body. The batching and
launch-count numbers under test are otherwise recomputed, not relaxed.

Verification

cmake --build build --parallel 32: exit 0.
pytest tests/ut -n 16 (via the push transaction's validation runner, bound
to the pushed OID): 11087 passed, 8 skipped, 1 xfailed, 0 failed. One case is
deselected — TestUnifiedSlicePadValue::test_symlinked_import_path_still_names_the_caller
asserts a subprocess resolves pypto through a symlinked PYTHONPATH, which
this machine's editable meta-finder redirects regardless of the change under
test.
Focused suites (test_legalize_graph_boundary, test_orchestration_codegen_graph,
test_graph_boundary_legalized, test_normalize_return_order,
test_orchestration_returned_param_map): exit 0.
The provenance fix is load-bearing, checked by disabling it and rebuilding:
the three rebind regression tests fail without it and pass with it.
clang-format 21.1.0 --dry-run --Werror, clang-tidy 21.1.0
--strict-version --diff-base, ruff 0.14.8 (format --check + check),
markdownlint-cli2 0.20.0, and the ten tests/lint/*.py checks: all clean.
On device: test_graph_execution.py — 13/13 passed on a2a3 in CI,
including test_region_alloc, this change's end-to-end case.

Closes #2604

chatgpt-codex-connector · 2026-09-02T06:18:44Z

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-02T06:25:18.244241Z	`23aac36`	PR opened

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coderabbitai · 2026-09-02T06:19:26Z

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📝 Walkthrough

Walkthrough

Changes

Graph boundary legalization

Layer / File(s)	Summary
Graph return contract `src/ir/transforms/normalize_return_order_pass.cpp`, `src/ir/verifier/verify_return_params_explicit.cpp`, `docs/{en,zh}/dev/passes/00-pass_manager.md`, `docs/{en,zh}/dev/passes/26-normalize_return_order.md`	Graph functions now use explicit parameter references for tensor returns. Graph returns are canonicalized but not reordered.
Top-level allocation hoisting `src/ir/transforms/legalize_graph_boundary_pass.cpp`, `docs/{en,zh}/dev/passes/45-legalize_graph_boundary.md`	Top-level `tensor.create` operations are appended as `InOut` boundaries and emitted at the call site. Related slices use `InOut` direction. Node counting runs after rewriting.
Hoisting and node-count validation `tests/ut/ir/transforms/test_legalize_graph_boundary.py`, `tests/ut/codegen/test_orchestration_codegen_graph.py`	Tests cover allocation hoisting, related views, Graph return naming, loop exclusions, caller allocation, and updated node-count limits.

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

Merge Risk: 🟡 Moderate · up to 23aac

This change moves Graph-owned allocations to caller-managed buffers and expands Graph boundary signatures. Branch-local allocations may become unconditional, while edge-case signature handling may reject valid graphs or register a writable buffer without the required write ordering, creating bounded memory and execution-scheduling risks. Merge should wait for these cases to be fixed or explicitly accepted by the owner.

Sequence Diagram(s)

sequenceDiagram
  participant GraphCaller
  participant LegalizeGraphBoundary
  participant GraphBody
  participant GraphAllocator
  GraphCaller->>LegalizeGraphBoundary: legalize Graph boundary
  LegalizeGraphBoundary->>GraphBody: collect top-level tensor.create
  LegalizeGraphBoundary->>GraphCaller: append InOut boundary tensors
  GraphCaller->>GraphAllocator: allocate hoisted tensors
  GraphCaller->>GraphBody: invoke Graph with boundary tensors

Poem

I’m a rabbit with tensors to stack,
Graph boundaries guide them back.
Scratch buffers hop outside,
InOut ears held open wide.
Returns name the paths they ride.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 42.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 50 functions across 5 files. (6 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: hoisting allocations owned by a Graph region to its call sites.
Description check	✅ Passed	The description directly explains the Step C implementation, prerequisites, exclusions, tests, and verification results.
Linked Issues check	✅ Passed	The changes satisfy issue `#2604` by consuming collected top-level Graph allocations, appending them as InOut parameters, emitting allocation at the call site, preserving loop-nested allocations, and up…
Out of Scope Changes check	✅ Passed	The code, documentation, and tests are aligned with issue `#2604`. The return normalization, verifier, node-counting, and code generation changes support the allocation-hoisting objective.

Full details: Linked Issues check

Explanation

The changes satisfy issue #2604 by consuming collected top-level Graph allocations, appending them as InOut parameters, emitting allocation at the call site, preserving loop-nested allocations, and updating required return handling and node counting.

Full details: Docstring Coverage

Explanation

Docstring coverage is 42.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 50 functions across 5 files. (6 skipped: 6 unsupported.)

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Actionable comments posted: 3

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Inline comments:
In `@docs/en/dev/passes/26-normalize_return_order.md`:
- Around line 25-26: Update the Step B function list and no-op condition in
docs/en/dev/passes/26-normalize_return_order.md at lines 25-26 to include Graph
consistently with Group and Spmd. Apply the same documentation updates in
docs/zh/dev/passes/26-normalize_return_order.md at lines 21-22, keeping both
locales aligned.

In `@docs/en/dev/passes/45-legalize_graph_boundary.md`:
- Around line 16-17: Update the introductions in
docs/en/dev/passes/45-legalize_graph_boundary.md lines 16-17 and
docs/zh/dev/passes/45-legalize_graph_boundary.md lines 13-14 to state four
problem classes, changing “three classes” to “four classes” and “三类问题” to
“四类问题.”

In `@src/ir/transforms/legalize_graph_boundary_pass.cpp`:
- Around line 1257-1258: Move the minimum-boundary validation in
CheckGraphSignature to run after Step C and BuildPlan has processed
collector.creates(). Ensure top-level tensor.create entries can be added as
InOut allocations by BuildPlan before rejecting graphs with no original tensor
parameters, while preserving the existing validation for genuinely empty
boundaries.

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📒 Files selected for processing (11)

docs/en/dev/passes/00-pass_manager.md
docs/en/dev/passes/26-normalize_return_order.md
docs/en/dev/passes/45-legalize_graph_boundary.md
docs/zh/dev/passes/00-pass_manager.md
docs/zh/dev/passes/26-normalize_return_order.md
docs/zh/dev/passes/45-legalize_graph_boundary.md
src/ir/transforms/legalize_graph_boundary_pass.cpp
src/ir/transforms/normalize_return_order_pass.cpp
src/ir/verifier/verify_return_params_explicit.cpp
tests/ut/codegen/test_orchestration_codegen_graph.py
tests/ut/ir/transforms/test_legalize_graph_boundary.py

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## Summary `LegalizeGraphBoundary` collected Step C — the tensors a Graph region allocates for itself — but `BuildPlan` never read `collector.creates()`, so every `pl.create_tensor` stayed inside the region and became a recorded `alloc_tensors` node. Recording one is *correct*, but the buffer comes off the graph heap, and `task_allocator.h` reclaims nothing there until the run ends ("The whole graph must fit at once; nothing is reclaimed mid-run"). The live set therefore grows with the number of submissions instead of staying flat: a Qwen3-14B decoder layer holding 14 intermediates costs 14 x N over N recorded layers. simpler's hand-written `qwen3_14b_decode` scene avoids this by hand, for the same stated reason. Step C now moves each top-level allocation to the call site as an `InOut` boundary tensor, so the buffer comes off the ordinary reclaimable heap and the recorded region carries no allocation node at all. ## What changes - **Step C wiring** (`legalize_graph_boundary_pass.cpp`): a top-level `tensor.create` is appended as an `InOut` parameter and emitted at the call site. It also becomes its own boundary root, so a view of it faces the same Step B rule as a view of any other boundary tensor — the `GraphBoundaryLegalized` verifier holds every tensor parameter to that rule, and one left in place with a moving window would make the pass produce IR its own verifier rejects. - **Left in place, deliberately**: `tensor.full` (orchestration codegen has no lowering for it at the call site either, and Step D already rejects it) and a create under a loop (a fresh buffer per iteration; collapsing N into one parameter would make iterations alias, and the edges that would have to re-serialise them were derived well upstream). - **Boundary provenance crosses an in-place call rebind** (`legalize_graph_boundary_pass.cpp`, `verify_graph_functions.cpp`). `tmp = kernel(a, tmp)` binds a fresh SSA name to the same buffer. Tracking only bare `alias = var` assignments lost the boundary root there, so Step B skipped a view of the rebound name outright — no hoist and no check — and a call-varying offset stayed in the region with the first call's window frozen. Provenance now follows the writeback through `ExplicitReturnedParamIndices`, the same return-position -> parameter map orchestration codegen aliases a call result on, for single results and for tuple elements (so `pl.submit` too). The verifier's `TrackTensorAlias` had the identical blind spot and is fixed alongside, so the independent check is actually independent. This hole predates Step C: it is the `tensor_root_` lookup that fails, so a view of a rebound boundary *parameter* escaped the same way, with no allocation involved. Both shapes are pinned. - **Node counting** moved to run on the rewritten program. Step C *removes* allocation nodes, so counting the pre-hoist body would reject a Graph that fits and disagree with the verifier, which re-derives the same count from the rewritten IR. - **Docs** (EN + ZH): Step C rewritten from "not done, and here is the blocker" to what it now does, plus the two deliberate exclusions, the new counting position, the provenance rule, and a narrowed "Not yet handled". The return-canonicalization this depends on landed separately in PR hw-native-sys#2618; the Step C section names it as a dependency rather than claiming it. One correction is kept on top of it: `26-normalize_return_order.md` still said the pass is "a no-op for any program with no InCore functions", which stopped being true once Step A0 covered Graph. ## Verification - Full UT: 11087 passed, 8 skipped, 1 xfailed, 0 failed. One case is deselected — `test_symlinked_import_path_still_names_the_caller` asserts a subprocess resolves `pypto` through a symlinked `PYTHONPATH`, which this machine's editable meta-finder redirects regardless of the change under test. - Emitted orchestration C++: the graph body carries no `alloc_tensors`, and the entry emits `alloc_tensors(s0_ci, s1_ci)` plus `add_inout(s0)` / `add_inout(s1)`. Pinned by a new codegen test. - The provenance fix is load-bearing, checked by disabling it and rebuilding: the three rebind regression tests fail without it and pass with it. - `test_region_alloc` — this change's end-to-end case — passed on a2a3 hardware in CI. - clang-format 21.1.0, clang-tidy 21.1.0 (`--strict-version`), ruff 0.14.8, markdownlint, and the ten `tests/lint/*.py` checks: all clean. - Rebased onto PR hw-native-sys#2618, which landed the return-canonicalization this change had carried as a prerequisite; those hunks are dropped in favour of the upstream version. Closes hw-native-sys#2604

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Comment thread src/ir/transforms/legalize_graph_boundary_pass.cpp

lyfne123 force-pushed the fix/hoist-graph-region-allocations branch 5 times, most recently from ff0551a to 7dbfad8 Compare September 2, 2026 09:24

lyfne123 force-pushed the fix/hoist-graph-region-allocations branch from 7dbfad8 to 2311ad8 Compare September 3, 2026 03:14

Hzfengsy approved these changes Sep 3, 2026

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Hzfengsy merged commit 24da6a6 into hw-native-sys:main Sep 3, 2026
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feat(ir): hoist a Graph region's own allocations out to its call sites - #2619

feat(ir): hoist a Graph region's own allocations out to its call sites#2619
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