✨ Add DD buildFunctionality/simulate for static QCO funcs

[simon1hofmann]

🤖 AI text below 🤖

Description

Add QCO-native DD construction so static unitary func.func programs can build a matrix DD / simulate a statevector without round-tripping through qc::QuantumComputation.

• New mlir::qco::buildFunctionality / simulate in DDFunctionality.h
• Sparse path for standard gates / simple ctrl; dense path for inv, compound ctrl, etc., with QCO MSB → DD LSB basis conversion
• Wire mapping via qco.static, or qubit block args 0..n-1 when no static ops (synthesis helpers)
• Rejects measurements and other non-unitary / unsupported ops; gphase and barrier supported
• Unit tests vs classic dd::{buildFunctionality,simulate}; Weyl reconstruction tests reuse the new API

Fixes #1913

AI Assistance

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Checklist

• The pull request only contains commits that are focused and relevant to this change.
• I have added appropriate tests that cover the new/changed functionality.
• I have updated the documentation to reflect these changes.
• I have added entries to the changelog for any noteworthy additions, changes, fixes, or removals.
• I have added migration instructions to the upgrade guide (if needed).
• The changes follow the project's style guidelines and introduce no new warnings.
• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

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✅ All modified and coverable lines are covered by tests.

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[simon1hofmann]

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📝 Walkthrough

Walkthrough

The PR adds DD-based construction and simulation for supported MLIR QCO functions, including qubit mapping, gate and matrix application, validation, build integration, and tests. Weyl decomposition tests now use the new DD functionality API.

Changes

QCO DD functionality

Layer / File(s)	Summary
Public API and build wiring mlir/include/mlir/Dialect/QCO/Utils/DDFunctionality.h, mlir/lib/Dialect/QCO/Utils/CMakeLists.txt, mlir/unittests/Dialect/QCO/**/CMakeLists.txt	Declares buildFunctionality and simulate, and links the required QCO matrix and DD libraries.
DD functionality implementation mlir/lib/Dialect/QCO/Utils/DDFunctionality.cpp	Maps SSA qubits, decodes standard gates, applies matrices and controls, walks single-block functions, and returns DD matrices or vectors with failure handling.
Validation and adoption mlir/unittests/Dialect/QCO/Utils/test_dd_functionality.cpp, mlir/unittests/Dialect/QCO/Transforms/Decomposition/test_weyl_decomposition.cpp, CHANGELOG.md	Adds positive and negative DD tests, updates Weyl decomposition to use DD functionality, and adds the PR changelog reference.

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

Sequence Diagram(s)

sequenceDiagram
  participant QCOFunction
  participant DDFunctionality
  participant DDPackage
  QCOFunction->>DDFunctionality: Provide MLIR function
  DDFunctionality->>DDFunctionality: Prepare mapping and walk operations
  DDFunctionality->>DDPackage: Apply gates or matrices
  DDPackage-->>DDFunctionality: Return DD result

Loading

Suggested labels: feature

Suggested reviewers: burgholzer

Poem

I’m a rabbit with qubits in rows,
DD matrices where each pathway flows.
Gates hop and phases gleam,
Tests chase failures through the dream.
With ears up high, the wires align—
A tidy quantum trail by design!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 9.09% 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
Linked Issues check	✅ Passed	The PR implements direct DD functionality construction and simulation for static QCO func.funcs, matching the goals of #1913.
Out of Scope Changes check	✅ Passed	The touched changelog, build files, and tests all support the new DD functionality and do not indicate unrelated scope creep.
Title check	✅ Passed	The title clearly summarizes the main change: adding DD build and simulate support for static QCO funcs.
Description check	✅ Passed	The description matches the template with a summary, issue reference, AI assistance note, and checklist.

✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch feat/dd-qco-functionality

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@mlir/lib/Dialect/QCO/Utils/DDFunctionality.cpp`:
- Around line 101-147: Add parameterized end-to-end semantic parity tests for
every gate handled by decodeStandardGate’s TypeSwitch, comparing QCO behavior
against QC behavior. Include all single- and multi-parameter mappings,
explicitly covering ROp, U2Op, UOp, XXPlusYYOp, and XXMinusYYOp with parameter
ordering validated. Ensure the cases cover every listed gate branch so enum or
decoding discrepancies are detected.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 10dd01db-048b-4134-aad9-73e61c70d6e6

📥 Commits

Reviewing files that changed from the base of the PR and between faa77a7 and 69354d5.

📒 Files selected for processing (8)

• CHANGELOG.md
• mlir/include/mlir/Dialect/QCO/Utils/DDFunctionality.h
• mlir/lib/Dialect/QCO/Utils/CMakeLists.txt
• mlir/lib/Dialect/QCO/Utils/DDFunctionality.cpp
• mlir/unittests/Dialect/QCO/Transforms/Decomposition/CMakeLists.txt
• mlir/unittests/Dialect/QCO/Transforms/Decomposition/test_weyl_decomposition.cpp
• mlir/unittests/Dialect/QCO/Utils/CMakeLists.txt
• mlir/unittests/Dialect/QCO/Utils/test_dd_functionality.cpp

[simon1hofmann]

@coderabbitai review

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[denialhaag]

Really cool to see this application of the QCO matrices! Thanks, @simon1hofmann! 🙂

This already looks good to me! I only have some minor comments, which you can find below.

[simon1hofmann]

Really cool to see this application of the QCO matrices! Thanks, @simon1hofmann! 🙂

This already looks good to me! I only have some minor comments, which you can find below.

Thanks a lot for the review 🙏
I applied all you suggestions besides one (see the last unresolved comment).

[denialhaag]

Thanks for adressing my comments! 🙂 This LGTM now!

I'll tag @burgholzer for a final review.