BE-457: HashQL: MIR execution pipeline extensions for postgres compilation

[indietyp]

🌟 What is the purpose of this PR?

Prepares the MIR execution pipeline for consumption by the postgres compiler. The execution analysis now produces a complete IslandGraph (not just a flat island list), the placement solver and island placement accept external allocators, and the traversal system gains the TraversalPathBitMap and as_symbol() APIs that the SQL generator needs. Also adds a backend switch cost to the terminator placement so cross-backend transitions are no longer free.

🔍 What does this change?

Execution analysis (pass/execution/mod.rs):

• run() becomes run_in() with an explicit allocator parameter, returning ExecutionAnalysisResidual (assignment + island graph). The island graph is now constructed as part of the analysis rather than left to the caller.
• Adds run_all_in() which runs the execution analysis over all graph-read bodies in a DefIdSlice.

Traversal system (traversal/mod.rs, traversal/entity.rs):

• TraversalPathBitMap: per-vertex-type collection of TraversalPathBitSets with pointwise lattice operations. The postgres compiler uses this to track which paths each island accesses across all vertex types.
• TraversalPath::as_symbol(): returns a static symbol for each path variant, used as SQL column aliases so the interpreter can locate result columns by name.
• TraversalPathBitSet::vertex(): returns the vertex type for a bitset.
• EntityPath::as_symbol() and EntityPath::column_name(): per-path SQL identifiers.

Terminator placement (terminator_placement/mod.rs):

• TransMatrix gains AddAssign for element-wise saturating addition.
• Adds backend_switch_cost() which encodes a fixed overhead for cross-backend transitions (Postgres to Interpreter: 8, Interpreter to Embedding: 4, etc.). Previously cross-backend transitions had zero inherent cost, so empty blocks were arbitrarily assigned to the interpreter even when staying on postgres was free.

Placement solver (placement/solve/):

• PlacementSolver::run() becomes run_in() with allocator parameter.
• CSP solver internal allocations use the provided allocator.

Island graph (island/graph/mod.rs):

• IslandGraph::new_in() now takes an allocator for its output storage.

Pretty printer (pretty/text.rs):

• TextFormatAnnotations gains annotate_basic_block() and BasicBlockAnnotation associated type, plus a blanket impl for &mut T.

Builder (builder/rvalue.rs):

• Adds RValueBuilder::opaque_entity_uuid() convenience constructor for the common pattern of extracting an entity's UUID.

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

⚠️ Known issues

The backend_switch_cost() values (8, 4, etc.) are hand-tuned heuristics. They correctly prevent the solver from arbitrarily switching backends for empty blocks, but a proper cost model would derive these from measured overhead.

🛡 What tests cover this?

• Updated execution pass end-to-end tests (execution/tests.rs) including entity_uuid_equality, mixed_postgres_embedding_interpreter, projection_and_apply_splits
• Updated statement placement tests for interpret and postgres backends (eq_opaque_entity_uuid)
• Updated terminator placement and island tests
• Placement solver tests updated for allocator API

❓ How to test this?

cargo nextest run -p hashql-mir

[cursor]

PR Summary

Medium Risk
Touches core MIR execution-placement logic (solver APIs, island graph construction, and terminator transition costs), which can change target assignment behavior and query compilation outcomes across backends.

Overview
Updates the MIR execution pipeline to be allocator-parameterized and to return richer outputs: ExecutionAnalysis::run_in now yields an ExecutionAnalysisResidual containing both per-block target assignment and a fully-built IslandGraph, plus a new run_all_in helper to analyze all graph-read bodies.

Extends execution planning data structures for Postgres compilation: islands/graphs gain new query helpers (members/contains/find), traversal paths gain as_symbol() and a new per-vertex TraversalPathBitMap lattice, and the MIR builder/body! macro add support for opaque aggregates (including ~ unary in docs).

Changes placement behavior by introducing a fixed backend switch overhead into terminator transition costs (via TransMatrix +=), and refactors the placement solver and island placement APIs to accept external allocators; tests/snapshots are updated and expanded (notably EntityUuid opaque equality) to reflect the new planning outputs and cost model.

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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-306: HashQL: PostgreSQL translation #8526
• BE-457: HashQL: MIR execution pipeline extensions for postgres compilation #8525 👈 (View in Graphite)
• BE-456: HashQL: Entity type model enrichment and graph store query extensions #8524
• BE-429: HashQL: Add island dependency graph with data requirement resolution #8501
• BE-428: HashQL: Simplify traversal tracking to path recording #8498
• BE-434: HashQL: Refactor entity storage path resolution with centralized schema mapping #8496
• BE-427: Add hashql-macros crate with procedural macros for ID types and symbols #8495
• main

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

[augmentcode]

🤖 Augment PR Summary

Summary: Prepares the HashQL MIR execution pipeline for Postgres compilation by returning a full island dependency graph and exposing traversal/placement APIs needed by the SQL generator.
Key Changes:

• Execution analysis now takes an explicit allocator (run_in) and returns ExecutionAnalysisResidual (assignment + IslandGraph); adds run_all_in for batch analysis.
• Traversal adds TraversalPathBitMap, TraversalPath::as_symbol(), and EntityPath::as_symbol()/column_name() for stable SQL column aliases.
• Placement solver and island placement APIs accept external allocators and route CSP internal allocations through the provided bump allocator.
• Terminator placement introduces a fixed backend_switch_cost() so cross-backend transitions have non-zero overhead (avoids “free” backend flips).
• Island graph gains helper queries (members, contains, find) and is now built/resolved within execution analysis.
• Pretty printer supports per-basic-block annotations; MIR builder gains an opaque aggregate constructor and new tests cover opaque UUID equality.

Tests: Updates/extends execution, statement placement, terminator placement, and allocator-related solver snapshots (incl. entity_uuid_equality). Notes: Backend switch costs are heuristics intended to be refined by a measured cost model.

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[augmentcode]

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[codecov]

Codecov Report

❌ Patch coverage is 64.24581% with 128 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.98%. Comparing base (3ba579f) to head (8d113b2).

Files with missing lines	Patch %	Lines
...cal/hashql/mir/src/pass/execution/traversal/mod.rs	0.00%	44 Missing ⚠️
libs/@local/hashql/mir/src/pretty/text.rs	21.62%	28 Missing and 1 partial ⚠️
.../hashql/mir/src/pass/execution/traversal/entity.rs	0.00%	28 Missing ⚠️
libs/@local/hashql/mir/src/pass/execution/mod.rs	44.00%	14 Missing ⚠️
.../hashql/mir/src/pass/execution/island/graph/mod.rs	35.29%	11 Missing ⚠️
.../mir/src/pass/execution/placement/solve/csp/mod.rs	90.00%	0 Missing and 1 partial ⚠️
libs/@local/hashql/mir/src/pass/execution/tests.rs	99.07%	1 Missing ⚠️

Additional details and impacted files

@@                                           Coverage Diff                                            @@
##           bm/be-456-hashql-entity-type-model-enrichment-and-graph-store-query    #8525       +/-   ##
========================================================================================================
+ Coverage                                                                63.39%   83.98%   +20.58%     
========================================================================================================
  Files                                                                      763      326      -437     
  Lines                                                                    89217    51060    -38157     
  Branches                                                                  2916     1299     -1617     
========================================================================================================
- Hits                                                                     56563    42882    -13681     
+ Misses                                                                   32107     7763    -24344     
+ Partials                                                                   547      415      -132     

Flag	Coverage Δ
apps.hash-api	?
local.hash-isomorphic-utils	?
rust.hash-graph-api	?
rust.hash-graph-postgres-store	?
rust.hashql-compiletest	29.69% <ø> (ø)
rust.hashql-eval	?
rust.hashql-hir	?
rust.hashql-mir	92.08% <64.24%> (-0.37%)	⬇️
rust.hashql-syntax-jexpr	?

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[codspeed-hq]

Merging this PR will not alter performance

✅ 24 untouched benchmarks
⏩ 56 skipped benchmarks¹

---

_{Comparing bm/be-457-hashql-mir-execution-pipeline-extensions-for-postgres (8d113b2) with bm/be-456-hashql-entity-type-model-enrichment-and-graph-store-query (3ba579f)}

Footnotes

1. 56 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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