fix(ir): stage transpose views after V2C transfer

[high-cloud]

Summary

• stage Vec operands in their natural orientation before V2C transfer
• rebuild tile.transpose_view after the operand reaches Mat, then move it to Left or Right
• add an A5 regression covering the original bidirectional pipe reproducer

Root cause

InferTileMemorySpace previously moved a transposed Vec view directly to the cube operand space. Because transpose_view aliases bytes, the mixed-kernel expansion encoded the transposed logical shape as the V2C NZ payload. On A5 this left the V2C handshake stalled even though the generated DIR_BOTH pipe parameters were valid.

The new lowering transports the source tile as 64x128, pops it into Mat, and only then recreates the 128x64 transpose view for the Right operand.

Testing

• cmake --build build --parallel "$PYPTO_BUILD_JOBS"
• exact issue regression with --platform a5 --codegen-only: passed
• exact issue regression on A5 hardware: passed
• generated PTO verified as TPipe<0, Direction::DIR_BOTH, 16384, 2, 2, true> with natural-orientation V2C push/pop
• clang-format --dry-run --Werror src/ir/transforms/infer_tile_memory_space_pass.cpp

Fixes #2767

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📝 Code Review	✅ Completed 2026-09-15T11:55:05.854275Z	4987d0f	PR opened

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📝 Walkthrough

Walkthrough

The compiler now tracks tile call definitions and stages qualifying Vec transpose views through Mat before Cube consumption. A new runtime test covers the mixed-core transpose-view path with BF16 casting, matmul, ReLU, and output validation.

Changes

Transpose View Staging

Layer / File(s)	Summary
Definition tracking and mutator wiring src/ir/transforms/infer_tile_memory_space_pass.cpp	Collects call-valued assignments and passes the definitions to TileMemorySpaceMutator after Phase 2.
Transpose-view staging and regression coverage src/ir/transforms/infer_tile_memory_space_pass.cpp, tests/st/runtime/cross_core/test_v2c_transpose_view.py	Stages qualifying Vec transpose views through Mat, rebuilds the view, and moves it to Left or Right when required. Adds runtime validation for the cross-core matmul path.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: 🟡 Moderate · up to 4987d

Legal aliased transpose views can still reach the A5 stall path, so alias handling should be fixed before merge.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 10.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 2 files.	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 and concisely summarizes the main change: staging transpose views after V2C transfer.
Description check	✅ Passed	The description directly explains the root cause, implementation, regression test, and verification for the changeset.
Linked Issues check	✅ Passed	The PR addresses issue #2767. infer_tile_memory_space_pass.cpp detects a tile.transpose_view whose source is in Vec, stages the source in Mat, recreates the transpose view after transfer, and …
Out of Scope Changes check	✅ Passed	The changed compiler logic directly implements the mixed-kernel transfer fix from issue #2767. The added test directly covers the reported bidirectional V2C transpose case. No unrelated changes appear…

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_{A rabbit saw a tile turn bright,
From Vec to Mat, then set it right.
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Reviewed commit: 4987d0f3a1

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Inline comments:
In `@src/ir/transforms/infer_tile_memory_space_pass.cpp`:
- Line 628: Update TileDefinitionCollector around the Call definition tracking
to preserve transparent aliases created by bare alias = view assignments,
specifically for tile.transpose_view results. Resolve the alias back to the
original transpose-view definition during lookup so
InsertTransposeViewCubeStaging is selected instead of InsertMoveStmt, and add a
regression case covering the alias consumed by tile.matmul.

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• src/ir/transforms/infer_tile_memory_space_pass.cpp
• tests/st/runtime/cross_core/test_v2c_transpose_view.py

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