hakorune/docs/development/current/main/PHASE_57_SUMMARY.md

Phase 57: OWNERSHIP-ANALYZER-DEV - Summary

Status: ✅ COMPLETED

Date: 2025-12-12 Duration: Single session implementation Test Results: All 946 tests passing (56 ignored)

What Was Implemented

1. Naming SSOT Fix

• Unified naming: owned_vars (code) vs owned_carriers (docs)
• Decision: Keep owned_vars in code (more general - includes read-only owned)
• Updated all documentation to use owned_vars consistently

2. Core Analyzer Implementation

Created /home/tomoaki/git/hakorune-selfhost/src/mir/join_ir/ownership/analyzer.rs:

• OwnershipAnalyzer: Main analysis engine (420+ lines)
• ScopeKind: Function/Loop/Block/If scope types
• ScopeInfo: Internal scope representation with defined/reads/writes/condition_reads

3. Analysis Algorithm

Scope Tree Construction

• Function/Loop/Block/If each get unique ScopeId
• Parent-child relationships tracked via scope hierarchy
• Body-local ownership rule: local in if/block → enclosing Loop/Function owns it

Variable Collection (per scope)

• defined: Variables declared with local in this scope
• reads: All variable reads (including nested scopes)
• writes: All variable writes (including nested scopes)
• condition_reads: Variables read in loop/if conditions

Ownership Assignment

• owned_vars = variables defined in Loop/Function scopes
• Carriers = owned_vars.filter(is_written == true)
• Read-only owned variables are NOT carriers

Plan Generation

• relay_writes = writes - owned (find owner in ancestors)
• captures = reads - owned - writes (read-only captures)
• condition_captures = captures ∩ condition_reads

4. Key Implementation Decisions

Smart Propagation

Fixed issue where parent scopes were trying to relay variables owned by child Loop/Function scopes:

// Only propagate writes that are NOT locally owned by Loop/Function children
if child_kind == ScopeKind::Loop || child_kind == ScopeKind::Function {
    // Don't propagate writes for variables defined in this Loop/Function
    for write in writes {
        if !child_defined.contains(&write) {
            parent.writes.insert(write);
        }
    }
} else {
    // For If/Block, propagate all writes
    parent.writes.extend(writes);
}

Relay Path Construction

• Walk up ancestor chain to find owner
• Collect only Loop scopes in relay_path (skip If/Block)
• Inner loop → Outer loop → Function (relay chain)

Invariant Verification (debug builds only)

• No variable appears in multiple categories (owned/relay/capture)
• All relay_writes have valid owners
• condition_captures ⊆ captures

5. Comprehensive Test Suite

Implemented 4 test cases covering all major scenarios:

1. test_simple_loop_ownership: Basic loop with relay writes to function
2. test_loop_local_carrier: Loop-local variable (owned AND written)
3. test_capture_read_only: Read-only capture in loop condition
4. test_nested_loop_relay: Nested loops with relay chain

All tests pass ✅

6. Documentation Updates

• Updated phase56-ownership-relay-design.md with Phase 57 algorithm section
• Updated mod.rs to reflect Phase 57 completion status
• Clear separation: analyzer = dev-only, not connected to lowering yet

Architecture Highlights

Responsibility Boundary

This module does:

• ✅ Collect reads/writes from AST/ProgramJSON
• ✅ Determine variable ownership (owned/relay/capture)
• ✅ Produce OwnershipPlan for downstream lowering

This module does NOT:

• ❌ Generate MIR instructions
• ❌ Modify JoinIR structures
• ❌ Perform lowering transformations

Core Invariants Enforced

1. Ownership Uniqueness: Each variable has exactly one owner scope
2. Carrier Locality: carriers = writes ∩ owned
3. Relay Propagation: writes to ancestor-owned → relay up
4. Capture Read-Only: captures have no PHI at this scope

Files Changed

New Files

• /home/tomoaki/git/hakorune-selfhost/src/mir/join_ir/ownership/analyzer.rs (420+ lines)

Modified Files

• /home/tomoaki/git/hakorune-selfhost/src/mir/join_ir/ownership/mod.rs (export analyzer)
• /home/tomoaki/git/hakorune-selfhost/docs/development/current/main/phase56-ownership-relay-design.md (algorithm section)

Test Results

running 7 tests
test mir::join_ir::ownership::analyzer::tests::test_capture_read_only ... ok
test mir::join_ir::ownership::types::tests::test_carriers_filter ... ok
test mir::join_ir::ownership::analyzer::tests::test_nested_loop_relay ... ok
test mir::join_ir::ownership::types::tests::test_invariant_verification ... ok
test mir::join_ir::ownership::analyzer::tests::test_loop_local_carrier ... ok
test mir::join_ir::ownership::analyzer::tests::test_simple_loop_ownership ... ok
test mir::join_ir::ownership::types::tests::test_empty_plan ... ok

test result: ok. 7 passed; 0 failed; 0 ignored

Full test suite: 946 tests passed, 0 failed, 56 ignored ✅

Next Steps (Phase 58+)

Phase 58: P2 Plumbing (dev-only)

• Connect analyzer to Pattern 2 lowering
• Generate PHI instructions based on OwnershipPlan
• Test with P2 loops

Phase 59: P3 Plumbing (dev-only)

• Connect analyzer to Pattern 3 lowering
• Handle relay chains in nested loops
• Test with P3 loops

Phase 60: Cleanup Dev Heuristics

• Remove old carrier detection logic
• Switch to OwnershipPlan throughout

Phase 61: Canonical Promotion Decision

• Finalize promotion strategy
• Production rollout

Design Philosophy

"読むのは自由、管理は直下だけ" (Read Freely, Manage Directly)

• Variables can be READ from anywhere (capture)
• Variables can only be WRITTEN by their owner or via relay
• Ownership is determined by definition scope (body-local rule)
• No shadowing complexity - clear ownership hierarchy

Dev-First Approach

• Implemented as pure analysis module first
• Not yet connected to lowering (no behavioral changes)
• Can be tested independently with JSON input
• Safe to merge without affecting existing code paths

References

• Phase 56 Design: phase56-ownership-relay-design.md
• JoinIR Architecture: joinir-architecture-overview.md
• Phase 43/245B: Normalized JoinIR completion
• ChatGPT Discussion: 「読むのは自由、管理は直下だけ」設計

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Implementation Status: ✅ Phase 57 Complete - Ready for Phase 58 plumbing