## Phase 254: Pattern 6 (ScanWithInit) Detection & JoinIR Lowering
Pattern 6 detects index_of/find/contains-style loops:
- Loop condition: i < x.length()
- Loop body: if with method call condition + early return
- Step: i = i + 1
- Post-loop: return not-found value (-1)
Key features:
- Minimal lowering: main/loop_step/k_exit functions
- substring hoisted to init-time BoxCall
- Two k_exit jumps (found: i, not found: -1)
- Tests: phase254_p0_index_of_min.hako
## Phase 255 P0: Multi-param Loop CarrierInfo
Implemented CarrierInfo architecture for Pattern 6's 3-variable loop (s, ch, i):
- i: LoopState (header PHI + exit PHI)
- s, ch: ConditionOnly (header PHI only)
- Alphabetical ordering for determinism
- All 3 PHI nodes created correctly
- Eliminates "undefined ValueId" errors
## Phase 255 P1: Exit PHI DCE Fix
Prevents exit PHI from being deleted by DCE:
- PostLoopEarlyReturnStepBox emits post-loop guard
- if (i != -1) { return i } forces exit PHI usage
- Proven pattern from Pattern 2 (balanced_depth_scan)
- VM/LLVM backends working
## Test Results
✅ pattern254_p0_index_of_vm.sh: PASS (exit code 1)
✅ pattern254_p0_index_of_llvm_exe.sh: PASS (mock)
✅ Quick profile: json_lint_vm PASS (progresses past index_of)
✅ Pattern 1-5: No regressions
## Files Added
- src/mir/builder/control_flow/joinir/patterns/pattern6_scan_with_init.rs
- src/mir/join_ir/lowering/scan_with_init_minimal.rs
- apps/tests/phase254_p0_index_of_min.hako
- docs/development/current/main/phases/phase-254/README.md
- docs/development/current/main/phases/phase-255/README.md
🧠 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Nyash Development Documentation 🔧
開発者向けの進行中タスクと開発計画ドキュメントです。
📂 ディレクトリ構造
current/
CURRENT_TASK.md- 現在進行中のタスク- アクティブな開発作業の詳細
- 最新の実装状況
roadmap/
- phases/ - フェーズ別開発計画
- phase-8/ - AST→MIR変換
- phase-9/ - VM/JIT実装
- phase-10/ - AOT最適化
- native-plan/ - ネイティブビルド計画
- 実行バックエンド統合
- パフォーマンス目標
proposals/
- RFC(Request for Comments)
- 新機能提案
- 設計ディスカッション
🎯 重要な参照先
- 進行状況:
current/CURRENT_TASK.md - 開発計画:
roadmap/phases/ - 技術提案:
proposals/ - ドキュメントのステータス/入口ポリシー:
doc-status-policy.md - JoinIR / Selfhost の入口:
current/main/01-JoinIR-Selfhost-INDEX.md
📝 注意事項
このディレクトリの内容は開発中であり、頻繁に変更されます。
安定した仕様はreference/を参照してください。