⚡ Keep wide OpenQASM register conditions linear

[simon1hofmann]

🤖 AI text below 🤖

Description

• Recognize complete classical-register equality produced by the frontend and emit direct arbitrary-width OpenQASM conditions.
• Fuse only eligible static measurement destinations and reject partial, duplicate, mixed, dynamic, modified, or stale snapshots.
• Share repeated pure register-condition roots within one unchanged classical snapshot, keeping wide programs linear in IR size.
• Preserve initialized OpenQASM 3 whole-register equality without claiming general arbitrary-width classical-expression support.

Stack

1. ✨ Preserve classical control through target mapping #2179 — classical-control-aware target mapping
2. ⚡ Avoid redundant target-compilation liveness analysis #2180 — target-compilation liveness scaling
3. ⚡ Keep wide OpenQASM register conditions linear #2181 — wide OpenQASM register conditions (this PR)

Overlap

Open pull request #2169 adds compile-time fixed-width OpenQASM angles. It changes related semantics documentation, implementation, and tests. The behavior is independent, but this PR requires a semantic rebase and the full OpenQASM/QC test matrix if #2169 lands first.

Testing

• mqt-core-mlir-unittest-qc-translation: 184 passed.
• mqt-core-mlir-unittest-openqasm-target: 177 passed.
• Type stubs, uvx nox -s lint, and git diff --check: passed on the complete detached stack.

AI assistance: Codex assisted with implementation, review, testing, stack construction, and this description.

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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[github-actions]

Cpp-Linter Report ⚠️

Some files did not pass the configured checks!

clang-tidy (v22.1.8) reports: 1 concern(s)

• mlir/lib/Dialect/QC/Translation/TranslateQCToOpenQASM3.cpp:24:1: warning: [misc-include-cleaner]

  included header DenseSet.h is not used directly

     24 | #include <llvm/ADT/DenseSet.h>
        | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     25 | #include <llvm/ADT/STLExtras.h>

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[codecov]

Codecov Report

❌ Patch coverage is 90.36697% with 42 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
.../Dialect/QC/Translation/TranslateQCToOpenQASM3.cpp	87.8%	40 Missing ⚠️
...lib/Dialect/QC/Translation/OpenQASMToQCEmitter.cpp	98.0%	2 Missing ⚠️

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