BE-227: HashQL: Implement call graph analysis for MIR

[indietyp]

Add call graph analysis for MIR

🌟 What is the purpose of this PR?

This PR adds a call graph analysis pass for MIR that tracks function call relationships between definitions. The call graph can be used for call site enumeration, reachability analysis, and optimization decisions.

🔍 What does this change?

• Adds CallGraph to represent function call relationships between DefIds
• Implements CallGraphAnalysis pass to populate the graph from MIR bodies
• Adds CallKind enum to distinguish between direct function calls, filter functions, and other references
• Adds id field to Body struct to track the definition ID of each body
• Implements Display for Location and GraphReadLocation to improve debugging
• Includes comprehensive tests with snapshots to verify call graph construction

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?

• Comprehensive unit tests for various call patterns:
  • Direct function calls
  • Function arguments containing DefIds
  • Multiple calls from the same body
  • Call chains across multiple bodies
  • Recursive calls
  • Indirect calls via locals

[cursor]

PR Summary

Introduces inter-procedural call graph construction and related infrastructure.

• Call graph: Adds CallGraph, CallGraphAnalysis, and CallKind (tracks Apply, Filter, and Opaque references) with Display output
• Body identification: Adds Body.id: DefId; builder.finish initializes it and reification now assigns IDs via push_with; visitors ignore id
• Location formatting: Implements Display for Location and GraphReadLocation for clearer diagnostics
• Exports/tests: Re-exports analysis in analysis::mod; adds snapshot tests covering direct/indirect, multiple, chained, and recursive calls

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[indietyp]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• 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 👈 (View in Graphite)
• 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

This stack of pull requests is managed by Graphite. Learn more about stacking.

[augmentcode]

🤖 Augment PR Summary

Summary: Adds an inter-procedural call graph analysis pass for HashQL MIR to track cross-definition references and call sites.

Changes:

• Introduce CallGraph (backed by LinkedGraph) keyed by DefId nodes and CallKind-annotated edges.
• Add CallGraphAnalysis visitor pass that walks MIR bodies and records Apply, graph-read Filter, and Opaque references.
• Extend Body with id: DefId and plumb assignment through lowering via push_with.
• Implement Display for Location and GraphReadLocation to improve debugging / snapshots.
• Expose call graph analysis from pass::analysis.
• Add snapshot-based unit tests covering direct calls, call chains, recursion, argument references, and indirect calls via locals.

Technical Notes: Direct call edges are only emitted when the callee is syntactically a DefId (indirect calls via locals are treated as Opaque until later lowering/SROA removes most indirections).

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[augmentcode]

Review completed. 1 suggestions posted.

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

[codecov]

Codecov Report

❌ Patch coverage is 91.93548% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.37%. Comparing base (3d60ecf) to head (964c8b2).

Files with missing lines	Patch %	Lines
...ocal/hashql/mir/src/pass/analysis/callgraph/mod.rs	73.91%	18 Missing ⚠️
...ibs/@local/hashql/mir/src/body/terminator/graph.rs	0.00%	6 Missing ⚠️
libs/@local/hashql/mir/src/visit/mut.rs	50.00%	1 Missing ⚠️

Additional details and impacted files

@@                                         Coverage Diff                                         @@
##           bm/be-258-hashql-implement-transformationpass-changed-detection    #8214      +/-   ##
===================================================================================================
+ Coverage                                                            59.27%   59.37%   +0.10%     
===================================================================================================
  Files                                                                 1191     1195       +4     
  Lines                                                               113489   113796     +307     
  Branches                                                              4986     4986              
===================================================================================================
+ Hits                                                                 67275    67572     +297     
- Misses                                                               45438    45448      +10     
  Partials                                                               776      776              

Flag	Coverage Δ
rust.hashql-compiletest	46.65% <ø> (ø)
rust.hashql-mir	88.51% <91.93%> (+0.27%)	⬆️

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[codspeed-hq]

CodSpeed Performance Report

Merging #8214 will not alter performance

_{Comparing bm/be-227-hashql-implement-call-graph (964c8b2) with bm/be-258-hashql-implement-transformationpass-changed-detection (65c3381)¹}

Summary

✅ 17 untouched

Footnotes

1. No successful run was found on bm/be-258-hashql-implement-transformationpass-changed-detection (3d60ecf) during the generation of this report, so 762b28b was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩