BE-269: HashQL: Move PreInline out into Canonicalization pass

[indietyp]

🌟 What is the purpose of this PR?

This PR refactors the MIR optimization pipeline by extracting the canonicalization logic from PreInline into a reusable Canonicalization pass. This improves code organization and enables the same optimization sequence to be used in multiple contexts.

🔍 What does this change?

• Extracts the canonicalization logic from PreInline into a new Canonicalization pass
• Makes PreInline a thin wrapper around Canonicalization with pre-inlining specific configuration
• Improves the Changed enum's implementation with optimized bitwise operations
• Adds a new overlay method to GlobalTransformState to combine results from multiple passes
• Adds a Miri test command for the changed_bitor functionality

Pre-Merge Checklist 🚀

🚢 Has this modified a publishable library?

This PR:

• does not modify any publishable blocks or libraries, or modifications do not need publishing

📜 Does this require a change to the docs?

The changes in this PR:

• are internal and do not require a docs change

🕸️ Does this require a change to the Turbo Graph?

The changes in this PR:

• do not affect the execution graph

🛡 What tests cover this?

• Added a Miri test for the changed_bitor functionality
• Existing MIR optimization tests cover the refactored functionality

[cursor]

PR Summary

Centralizes MIR canonicalization logic and streamlines pre-inlining.

• New transform/canonicalization.rs: fixpoint driver running AR → IS → FS/CP → DSE → CFG with configurable iterations (CanonicalizationConfig)
• PreInline rewritten to delegate to Canonicalization (configured with fewer iterations)
• Changed enum: optimized BitOr using unchecked conversion and #[inline] for faster |= on slices
• GlobalTransformState: new overlay(&DefIdSlice<Changed>) to merge per-pass results
• Exports Canonicalization and config via transform/mod.rs
• Adds test:miri script for changed_bitor

^{Written by Cursor Bugbot for commit 0fd9d8f. This will update automatically on new commits. Configure here.}

[indietyp]

• BE-273: HashQL: Profile and benchmark MIR interpreter #8251
• BE-272: HashQL: Add numeric addition and subtraction operators to MIR #8250
• BE-257: HashQL: Implement MIR interpreter with runtime value representation #8245
• BE-271: HashQL: Implement PostInline pass #8240
• BE-269: HashQL: Move PreInline out into Canonicalization pass #8239 👈 (View in Graphite)
• BE-268: HashQL: Rename PreInlining to PreInline for consistency #8238
• BE-270: HashQL: Optimize empty tuples to unit constants in MIR #8237
• BE-197: Implement MIR inline pass for HashQL #8236
• BE-267: Use bump scopes instead of full resets across transformation passes #8234
• BE-266: HashQL: Implement PreInlining pass for MIR optimization #8233
• BE-265: HashQL: Make CopyPropagation aware of local re-assignments #8231
• BE-264: HashQL: Rename SROA to ForwardSubstitution for better semantic clarity #8230
• BE-263: HashQL: add body! macro for declarative MIR construction in tests #8229
• BE-261: HashQL: Implement Administrative Reduction pass for MIR #8227
• BE-262: HashQL: Do not intern empty slices #8223
• BE-260: HashQL: Switch to bump allocator with scoping support #8218
• BE-259: HashQL: Add benchmarks for type system operations #8216
• BE-227: HashQL: Implement call graph analysis for MIR #8214
• BE-258: HashQL: Add Changed enum to track MIR transformation pass modifications #8210
• BE-255: HashQL: Implement Copy Propagation (CP) pass for MIR #8207
• BE-231: HashQL: Add InstSimplify pass for MIR instruction simplification and constant folding #8206
• BE-254: Add CodSpeed benchmarking for HashQL MIR transformation passes #8204
• main

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[augmentcode]

🤖 Augment PR Summary

Summary: Refactors the HashQL MIR optimization pipeline by extracting the canonicalization fixpoint logic into a reusable pass.

Changes:

• Introduces a new Canonicalization global transform pass with a configurable iteration limit.
• Reworks PreInline into a thin wrapper around Canonicalization (pre-inlining tuned config).
• Optimizes Changed bitwise OR by using an unchecked discriminant conversion for better codegen/vectorization.
• Adds GlobalTransformState::overlay to merge per-pass/per-iteration change tracking into a single state.
• Wires the new module export and adds a test:miri script for the changed_bitor test.

Technical Notes: Canonicalization runs a pre-pass (CP+CFG) and then iterates AR → IS → (FS/CP) → DSE → CFG until fixpoint or max_iterations.

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[augmentcode]

Review completed. 2 suggestions posted.

Comment augment review to trigger a new review at any time.

[codspeed-hq]

Merging this PR will not alter performance

✅ 17 untouched benchmarks

---

_{Comparing bm/be-269-hashql-move-out-most-of-preinline-into-a-canonicalization (0312fee) with main (bdb020e)}

[codecov]

Codecov Report

❌ Patch coverage is 94.85714% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.74%. Comparing base (4655bbd) to head (0fd9d8f).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
.../hashql/mir/src/pass/transform/canonicalization.rs	95.54%	5 Missing and 2 partials ⚠️
libs/@local/hashql/mir/src/pass/mod.rs	81.81%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8239      +/-   ##
==========================================
+ Coverage   59.72%   59.74%   +0.01%     
==========================================
  Files        1214     1215       +1     
  Lines      115245   115312      +67     
  Branches     5062     5066       +4     
==========================================
+ Hits        68832    68894      +62     
- Misses      45611    45615       +4     
- Partials      802      803       +1     

Flag	Coverage Δ
rust.hashql-compiletest	46.65% <ø> (ø)
rust.hashql-mir	89.68% <94.85%> (+0.01%)	⬆️

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Merge activity

• Jan 19, 9:56 AM UTC: Graphite rebased this pull request, because this pull request is set to merge when ready.
• Jan 19, 9:56 AM UTC: Graphite rebased this pull request, because this pull request is set to merge when ready.