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## Phase 132: Exit PHI Value Parity Fix ### Problem Pattern 1 (Simple While) returned 0 instead of final loop variable value (3) - VM: RC: 3 ✅ (correct) - LLVM: Result: 0 ❌ (wrong) ### Root Cause (Two Layers) 1. **JoinIR/Boundary**: Missing exit_bindings → ExitLineReconnector not firing 2. **LLVM Python**: block_end_values snapshot dropping PHI values ### Fix **JoinIR** (simple_while_minimal.rs): - Jump(k_exit, [i_param]) passes exit value **Boundary** (pattern1_minimal.rs): - Added LoopExitBinding with carrier_name="i", role=LoopState - Enables ExitLineReconnector to update variable_map **LLVM** (block_lower.py): - Use predeclared_ret_phis for reliable PHI filtering - Protect builder.vmap PHIs from overwrites (SSOT principle) ### Result - ✅ VM: RC: 3 - ✅ LLVM: Result: 3 - ✅ VM/LLVM parity achieved ## Phase 132-Post: Box-First Refactoring ### Rust Side **JoinModule::require_function()** (mod.rs): - Encapsulate function search logic - 10 lines → 1 line (90% reduction) - Reusable for Pattern 2-5 ### Python Side **PhiManager Box** (phi_manager.py - new): - Centralized PHI lifecycle management - 47 lines → 8 lines (83% reduction) - SSOT: builder.vmap owns PHIs - Fail-Fast: No silent overwrites **Integration**: - LLVMBuilder: Added phi_manager - block_lower.py: Delegated to PhiManager - tagging.py: Register PHIs with manager ### Documentation **New Files**: - docs/development/architecture/exit-phi-design.md - docs/development/current/main/investigations/phase132-llvm-exit-phi-wrong-result.md - docs/development/current/main/phases/phase-132/ **Updated**: - docs/development/current/main/10-Now.md - docs/development/current/main/phase131-3-llvm-lowering-inventory.md ### Design Principles - Box-First: Logic encapsulated in classes/methods - SSOT: Single Source of Truth (builder.vmap for PHIs) - Fail-Fast: Early explicit failures, no fallbacks - Separation of Concerns: 3-layer architecture 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
Investigations Folder
This folder contains investigation notes and analysis for debugging sessions.
Active Investigations
Phase 131-12: LLVM Wrong Result (Case C)
Status: ✅ Root cause identified Problem: LLVM backend returns wrong results for loop exit values Root Cause: vmap object identity mismatch between Pass A and Pass C
Key Documents:
- phase131-12-case-c-llvm-wrong-result.md - Initial investigation scope
- phase131-12-p1-vmap-identity-analysis.md - Detailed trace analysis
- phase131-12-p1-trace-summary.md - Executive summary with fix recommendations
Quick Summary:
- Bug: Pass A deletes
_current_vmapbefore Pass C runs - Impact: Terminators use wrong vmap object, missing all Pass A writes
- Fix: Store vmap_cur in deferred_terminators tuple (Option 3)
Next Steps:
- Implement Option 3 fix in block_lower.py
- Add Fail-Fast check in instruction_lower.py
- Verify with NYASH_LLVM_VMAP_TRACE=1
- Run full test suite
Trace Environment Variables
Phase 131-12-P1 Traces
NYASH_LLVM_VMAP_TRACE=1 # Object identity and vmap keys tracing
NYASH_LLVM_USE_HARNESS=1 # Enable llvmlite harness
NYASH_LLVM_DUMP_IR=<path> # Save LLVM IR to file
Investigation Workflow
- Scope - Define problem and test case (phase131-12-case-c-*.md)
- Trace - Add instrumentation and collect data (phase131-12-p1-vmap-identity-*.md)
- Analysis - Identify root cause with evidence (phase131-12-p1-trace-summary.md)
- Fix - Implement solution with validation
- Document - Update investigation notes with results
Archive
Completed investigations are kept for reference and pattern recognition.