From b8223554317627fd44d4131f69baf86cb94b930c Mon Sep 17 00:00:00 2001
From: nyash-codex <codex@nyash.local>
Date: Thu, 18 Dec 2025 07:20:46 +0900
Subject: [PATCH] docs: Phase 129 progress report (P0-P3 complete)
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## Completed ✅

P0: LLVM EXE smoke test for Phase 128
- VM+LLVM parity verified
- Regression tests pass (phase103, phase118, phase128)

P2: Post-if return var fixture + VM smoke
- phase129_if_only_post_if_return_var_min.hako
- Tests join_k env merge pattern
- Currently passes via fallback (non-Normalized)

P3: Documentation complete
- README.md: Goal, design, scope
- P1-implementation-plan.md: Detailed refactoring plan
- PROGRESS.md: This report

## In Progress 🔄

P1: Materialize join_k continuation
- Status: Analysis complete, awaiting user decision
- Options:
  - A: In-place (fast, risky)
  - B: Phased (recommended, safe)

## Test Results ✅

- cargo test --lib: 1165 passed
- phase128 VM: PASS
- phase128 LLVM EXE: PASS
- phase129 VM: PASS (fallback path)
- Regression: ALL PASS

## Feedback

Box-First:
- JoinKBuilder module proposed (join_k generation)
- EnvBuilder future consideration

Fail-Fast:
- verify_normalized_structure proposed
- verify_branch_is_return_literal too restrictive

Legacy:
- Phase 123-124 lower_if_node incomplete
- Placeholder logic in lhs_vid resolution

## Next Steps

Awaiting user/ChatGPT decision on Option A vs B
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+# Phase 129 Progress Report
+
+## Status: P0-P3 Complete, P1 Requires User Decision
+
+### Completed Tasks ✅
+
+#### P0: LLVM EXE Smoke Test (Commit: e7ad3d31b)
+- ✅ Created `phase128_if_only_partial_assign_normalized_llvm_exe.sh`
+- ✅ VM+LLVM parity verified for Phase 128
+- ✅ Regression tests pass:
+  - phase103_if_only_llvm_exe.sh: PASS
+  - phase118_loop_nested_if_merge_llvm_exe.sh: PASS
+  - phase128_if_only_partial_assign_normalized_vm.sh: PASS
+
+#### P2: Post-If Return Var Fixture (Commit: 083be9921)
+- ✅ Created `apps/tests/phase129_if_only_post_if_return_var_min.hako`
+  - Pattern: `x=1; if flag==1 { x=2 }; print(x)`
+  - Tests join_k env merge concept
+- ✅ Created `phase129_if_only_post_if_return_var_vm.sh`
+  - Expected output: 2
+  - Currently PASSES via fallback path (non-Normalized)
+
+#### P3: Documentation (Commits: 083be9921, 0d2eafd78)
+- ✅ Phase 129 README (`README.md`)
+  - Goal, design, scope, acceptance criteria
+  - join_k continuation pattern explanation
+  - Structural verification requirements
+- ✅ P1 Implementation Plan (`P1-implementation-plan.md`)
+  - Current state analysis
+  - Required changes detailed
+  - Implementation options (A vs B)
+  - Testing strategy
+  - Risk assessment
+  - Open questions
+
+### In-Progress Task 🔄
+
+#### P1: Materialize join_k Continuation
+
+**Current State**: Analysis complete, awaiting user decision
+
+**Key Findings**:
+1. Current `lower_if_node` is Phase 123-124 minimal (incomplete)
+   - Only processes then branch
+   - No join_k generation
+   - No branching structure
+2. Requires substantial refactoring:
+   - Create JoinKBuilder helper module
+   - Refactor lower_if_node signature (affects call chain)
+   - Add env snapshot/merge logic
+   - Process post-if statements in join_k body
+
+**Implementation Options**:
+
+**Option A: In-Place Modification**
+- Pros: Direct, fast (1 commit)
+- Cons: High risk, harder to test incrementally
+
+**Option B: Phased Approach (Recommended)**
+- Phase 129-A: JoinKBuilder foundation + helpers
+- Phase 129-B: Branch lowering to join_k
+- Phase 129-C: Post-if statement support
+- Pros: Incremental testing, clear rollback points
+- Cons: More commits (3), slightly slower
+
+**Decision Needed**: User/ChatGPT should choose Option A or B
+
+## Test Results Summary
+
+### Library Tests
+```bash
+cargo test --lib
+```
+✅ Result: **1165 passed; 0 failed; 56 ignored**
+
+### Smoke Tests
+```bash
+# Phase 128 VM
+phase128_if_only_partial_assign_normalized_vm.sh
+```
+✅ Result: **PASS** (output: 2)
+
+```bash
+# Phase 128 LLVM EXE
+phase128_if_only_partial_assign_normalized_llvm_exe.sh
+```
+✅ Result: **PASS** (output: 2)
+
+```bash
+# Phase 129 VM
+phase129_if_only_post_if_return_var_vm.sh
+```
+✅ Result: **PASS** (output: 2)
+⚠️ Note: Currently via fallback path (non-Normalized)
+
+```bash
+# Regression
+phase103_if_only_llvm_exe.sh
+phase118_loop_nested_if_merge_llvm_exe.sh
+```
+✅ Result: **ALL PASS**
+
+## Feedback (Box-First / Fail-Fast / Legacy)
+
+### Box-First Modularization
+- ✅ **Proposed**: JoinKBuilder module for join_k generation
+  - Single responsibility: join_k function creation
+  - Separate file: `join_k_builder.rs`
+  - Testable in isolation
+- 📋 **Future**: Consider extracting env management to EnvBuilder
+
+### Fail-Fast Opportunities
+- ✅ **Proposed**: `verify_normalized_structure` function
+  - Early detection of malformed Normalized modules
+  - Checks: join_k exists if If exists, no PHI instructions
+  - Returns structured errors with hints
+- 📋 **Current**: `verify_branch_is_return_literal` too restrictive
+  - Should allow Assign statements (Phase 128 already supports)
+  - Should verify tail-call structure (not just Return)
+
+### Legacy Findings
+- ⚠️ **Phase 123-124 Legacy**: `lower_if_node` incomplete implementation
+  - Only processes then branch (line 463)
+  - Verification too restrictive for Phase 128+
+  - No branching structure generated
+  - **Recommendation**: Mark as Phase 123-124 legacy, replace in Phase 129
+- ⚠️ **Placeholder Logic**: lhs_vid uses Const(0) placeholder (line 431-434)
+  - **Recommendation**: Phase 129 should use actual variable resolution
+
+## Open Questions for User/ChatGPT
+
+1. **Implementation Strategy**: Choose Option A or B?
+   - Option A: Fast, risky (in-place modification)
+   - Option B: Safe, incremental (3-phase rollout)
+
+2. **Function ID Allocation**: Where should `next_func_id` come from?
+   - Add to `lower_if_only_to_normalized` parameters?
+   - Module tracks max ID?
+
+3. **Post-If Statement Detection**: How to parse post-if nodes?
+   - StepTree structure provides this?
+   - Need lookahead logic?
+
+4. **join_k Naming Convention**:
+   - `join_k_<func_id>`?
+   - `k_join_<line_number>`?
+   - Auto-increment `join_k_0`, `join_k_1`, ...?
+
+5. **env Parameter Passing**: Representation?
+   - Vec<ValueId> (ordered by env_layout)?
+   - Future: Tuple unpacking?
+
+## Next Steps
+
+### If Option B (Recommended)
+
+**Phase 129-A: Foundation**
+1. Create `src/mir/control_tree/normalized_shadow/join_k_builder.rs`
+2. Implement JoinKBuilder with:
+   - `create_join_k_function`
+   - `snapshot_env`
+   - `generate_tail_call`
+3. Unit tests for JoinKBuilder
+4. Commit: "feat(control_tree): Phase 129-A - JoinKBuilder foundation"
+
+**Phase 129-B: Branch Lowering**
+1. Refactor `lower_if_node` to use JoinKBuilder
+2. Generate then/else tail-calls to join_k
+3. Test with simple fixture (no post-if)
+4. Commit: "feat(control_tree): Phase 129-B - branch lowering to join_k"
+
+**Phase 129-C: Post-If Support**
+1. Process post-if statements in join_k body
+2. Test with Phase 129 fixture
+3. Add `verify_normalized_structure` checks
+4. Commit: "feat(control_tree): Phase 129-C - post-if support + verification"
+
+**Final**
+- Update 10-Now.md, INDEX, Backlog
+- Commit: "docs: Phase 129 DONE"
+
+### If Option A (Fast Track)
+
+**Single Commit**
+1. Implement all changes in one go
+2. Extensive testing required before commit
+3. Higher rollback risk
+4. Commit: "feat(control_tree): Phase 129 - materialize join_k continuation"
+
+## Commits (Current Session)
+
+1. **e7ad3d31b**: test(joinir): Phase 129 P0 - add LLVM EXE smoke for Phase 128
+2. **083be9921**: test(joinir): Phase 129 P2 - add post-if return var fixture + VM smoke
+3. **0d2eafd78**: docs: Phase 129 P1 implementation plan (join_k materialization)
+
+## Acceptance Status
+
+### P0 ✅ DONE
+- [x] Phase 128 LLVM EXE smoke passes
+- [x] Regression tests pass
+
+### P1 🔄 AWAITING DECISION
+- [ ] JoinKBuilder module created
+- [ ] join_k materialized in builder.rs
+- [ ] verify_normalized_structure implemented
+- [ ] Unit tests pass
+
+### P2 ✅ DONE
+- [x] Phase 129 fixture created
+- [x] VM smoke test created and passing
+- [x] Note: Currently fallback path
+
+### P3 ✅ DONE
+- [x] README.md documentation
+- [x] P1 implementation plan
+- [x] Progress report (this file)
+
+## Summary
+
+**Phase 129 Status**: P0, P2, P3 complete. P1 awaiting user decision on implementation strategy.
+
+**Recommendation**: Choose **Option B (Phased Approach)** for safer, incremental implementation with clear rollback points.
+
+**Key Achievement**: VM+LLVM parity for Phase 128 baseline established. Phase 129 foundation (tests, docs, fixtures) ready for P1 implementation.
+
+**Next Action**: User/ChatGPT decides on Option A vs B, then implement P1 accordingly.