BE-223: HashQL: Fix SSA repair to handle existing block parameters

[indietyp]

🌟 What is the purpose of this PR?

Fix SSA repair to handle reassignment of variables in the same block correctly. This PR addresses an issue where the SSA repair pass wasn't properly handling cases where a variable is reassigned within the same block before being used as a block parameter.

🔍 What does this change?

• Added a new Existing variant to FindDefFromTop enum to handle cases where a reaching definition is already present in block parameters
• Modified SsaViolationRepair to check if a local declaration already exists for block parameters before creating a new one
• Updated the visitor implementations to ensure right-hand side expressions are visited before left-hand side in assignments
• Added a new test case reassign_rodeo to verify the fix works correctly

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 new test case reassign_rodeo that specifically tests the fixed behavior
• Existing tests continue to pass with the updated implementation

[indietyp]

• BE-223: HashQL: Fix SSA repair to handle existing block parameters #8136 👈 (View in Graphite)
• BE-221: HashQL: Implement DBE (Dead Block Elimination) #8135
• BE-222: HashQL: Remove span from type environment #8134
• BE-201: HashQL: Implement CFG simplification pass #8133
• BE-220: HashQL: Refactor constant representation with specialized Int type for constant evaluation #8122
• BE-214: HashQL: Implement SSA repair pass for MIR #8093
• BE-218: HashQL: Implement MIR test builder #8092
• BE-217: HashQL: Add PlaceContext for tracking read/write semantics in MIR #8088
• BE-216: HashQL: Implement MIR transform infrastructure #8087
• BE-215: HashQL: Implement dominance frontier and iterated frontier algorithms #8082
• main

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[codecov]

Codecov Report

❌ Patch coverage is 97.05882% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.83%. Comparing base (1b3b01b) to head (aa93afe).

Files with missing lines	Patch %	Lines
...al/hashql/mir/src/pass/transform/ssa_repair/mod.rs	94.44%	2 Missing ⚠️

Additional details and impacted files

@@                  Coverage Diff                   @@
##           graphite-base/8136    #8136      +/-   ##
======================================================
+ Coverage               57.80%   57.83%   +0.02%     
======================================================
  Files                    1166     1166              
  Lines                  109121   109179      +58     
  Branches                 4963     4965       +2     
======================================================
+ Hits                    63081    63139      +58     
- Misses                  45306    45307       +1     
+ Partials                  734      733       -1     

Flag	Coverage Δ
rust.hashql-compiletest	49.36% <ø> (ø)
rust.hashql-mir	83.78% <97.05%> (+0.18%)	⬆️

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[graphite-app]

Merge activity

• Dec 1, 2:18 PM UTC: Graphite rebased this pull request, because this pull request is set to merge when ready.