hakorune/docs/development/current/main/phase212-5-implementation-complete.md

Phase 212.5: 実装完了レポート

Date: 2025-12-09 Status: ✅ 完了 (Structural if detection + Pattern 3 routing) Commit: [To be filled after commit]

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🎯 達成した目標

✅ Task 1: 構造ベース if 検出実装

修正ファイル: src/mir/builder/control_flow/joinir/patterns/ast_feature_extractor.rs

変更内容:

1. 新規関数 detect_if_in_body() 追加 (line 120-127)

   • ループ本体に ANY if 文が存在するかを検出
   • if-else だけでなく、単一 if 文も検出

2. extract_features() を修正 (line 81-106)

   • has_if = detect_if_in_body(body) で構造ベース検出
   • 従来の carrier_count ヒューリスティックから脱却

✅ Task 2: Pattern 分類ロジック更新

修正ファイル: src/mir/loop_pattern_detection/mod.rs

変更内容: classify() 関数を更新 (line 270-295)

Before (carrier-count heuristic):

// Pattern 3: If-Else PHI (check before Pattern 1)
if features.has_if_else_phi && !features.has_break && !features.has_continue {
    return LoopPatternKind::Pattern3IfPhi;
}

// Pattern 1: Simple While
if !features.has_break && !features.has_continue && !features.has_if_else_phi {
    return LoopPatternKind::Pattern1SimpleWhile;
}

After (structural if detection):

// Pattern 3: If-PHI
// Phase 212.5: Structural if detection - route to P3 if has_if && carrier_count >= 1
if features.has_if && features.carrier_count >= 1 && !features.has_break && !features.has_continue {
    return LoopPatternKind::Pattern3IfPhi;
}

// Pattern 1: Simple While
// Phase 212.5: Exclude loops with if statements (they go to P3)
if !features.has_break && !features.has_continue && !features.has_if {
    return LoopPatternKind::Pattern1SimpleWhile;
}

重要な変更点:

• Pattern 3 条件: carrier_count > 1 → has_if && carrier_count >= 1
• Pattern 1 条件: !has_if_else_phi → !has_if
• 単一キャリアの if-update パターンも Pattern 3 にルーティング可能に！

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📊 検証結果

Test Case: apps/tests/phase212_if_sum_min.hako

Before (Phase 212):

• Pattern: Pattern 1 (Simple While) ← 誤ルーティング
• MIR: if 文が消失
• Carriers: i のみ (sum 消失)
• Output: RC=0 (期待: RC=2)

After (Phase 212.5):

• ✅ Pattern: Pattern 3 (If-Else PHI) ← 正しくルーティング！
• ✅ MIR: PHI ノード生成成功
• ✅ Carriers: i, sum, count の 3 つ検出
• ✅ if-else merge: %31 = phi [%25, bb9], [%29, bb10] 生成

パターンルーティングログ:

[joinir/pattern3] Generated JoinIR for Loop with If-Else PHI (Phase 195: multi-carrier)
[joinir/pattern3] Functions: main, loop_step, k_exit
[joinir/pattern3] Carriers: i (counter), sum (accumulator), count (counter) [Phase 195]
[joinir/pattern3] If-Else PHI in loop body:
[joinir/pattern3]   sum_new = (i % 2 == 1) ? sum+i : sum+0

生成された MIR (抜粋):

bb8:
    1: %24 = icmp Eq %22, %23  ; if condition
    1: %25 = %9 Add %8         ; then branch
    1: %29 = %9 Add %28        ; else branch
    1: br %24, label bb9, label bb10

bb11:
    1: %31 = phi [%25, bb9], [%29, bb10]  ; ← PHI merge!

---

🔍 発見した制約 (Pattern 3 Lowerer)

現状の Pattern 3 実装について

Pattern 3 lowerer (lower_loop_with_if_phi_pattern) はテスト専用のハードコード実装:

Hardcoded elements:

1. Loop condition: i <= 5 (固定値)
2. If condition: i % 2 == 1 (modulo 演算固定)
3. Update logic: sum = sum + i / count = count + 1

Why RC=0 instead of RC=2?

phase212_if_sum_min.hako の実際の条件:

loop(i < 3) {           // Expected: i < 3
    if i > 0 {          // Expected: i > 0
        sum = sum + 1   // Expected: sum + 1
    }
}

Pattern 3 lowerer が生成した MIR:

loop(i <= 5) {          // Actual: i <= 5 (hardcoded)
    if i % 2 == 1 {     // Actual: i % 2 == 1 (hardcoded)
        sum = sum + i   // Actual: sum + i (hardcoded)
    }
}

Conclusion: Pattern 3 lowerer is not AST-based, it's a hardcoded test pattern generator.

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🎉 Phase 212.5 の価値

✅ 達成したこと

1. 構造ベース if 検出の実装

   • Carrier count ヒューリスティック脱却
   • 単一キャリアの if-update パターンサポート

2. Pattern routing の修正

   • if 文を含むループが Pattern 3 に正しくルーティング
   • Pattern 1 からの誤った分類を解消

3. MIR PHI 生成の確認

   • Pattern 3 lowerer が if-else PHI を正常生成
   • JoinIR → MIR 変換パイプライン正常動作

4. アーキテクチャの理解深化

   • AST feature extraction → LoopFeatures → classify → routing の流れ確認
   • Pattern 3 lowerer の現状制約を文書化

📝 残タスク (Phase 212 継続)

To enable full if-sum support:

1. Pattern 3 lowerer を AST-based に書き換え

   • lower_loop_with_if_phi_pattern() の汎用化
   • AST if condition の動的読み込み
   • AST update expression の動的読み込み

2. Or: Pattern 5/6 で汎用 if-sum lowerer を実装

   • Phase 212 の本来の目標
   • Pattern 3 は test-only のまま残す選択肢

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🚀 Next Steps

Option A: Pattern 3 を汎用化

• Pros: 既存 Pattern を完全に
• Cons: リファクタ規模大

Option B: Pattern 5/6 で新規実装

• Pros: クリーンな設計
• Cons: 新規 Pattern 追加コスト

Option C: 段階的移行 (推奨)

1. Phase 212.5 完了として記録 ✅
2. Phase 212 で汎用 if-sum pattern (P5?) を設計
3. Pattern 3 は test-only として保持

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📦 Modified Files Summary

1. src/mir/builder/control_flow/joinir/patterns/ast_feature_extractor.rs

   • Added: detect_if_in_body() function
   • Modified: extract_features() to use structural if detection

2. src/mir/loop_pattern_detection/mod.rs

   • Modified: classify() to use has_if && carrier_count >= 1 for Pattern 3
   • Modified: Pattern 1 to exclude loops with if statements

3. docs/development/current/main/phase212-5-implementation-complete.md (this file)

   • Complete implementation report

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✅ Checklist

• Structural if detection implemented (detect_if_in_body)
• AST feature extraction updated (extract_features)
• Pattern classification logic updated (classify)
• Build successful (cargo build --release)
• Test execution successful (phase212_if_sum_min.hako)
• Pattern routing verified (Pattern 3 selected)
• MIR PHI generation verified (bb11: %31 = phi)
• Pattern 3 lowerer constraints documented
• Implementation report created

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🔖 Status Update

Phase 212.5: COMPLETE ✅ (Commit: aeb6282c)

Scope Completed:

• ✅ Structural if detection (detect_if_in_body)
• ✅ Pattern routing logic (classify with has_if && carrier_count >= 1)
• ✅ Test verification (Pattern 3 routing confirmed)
• ✅ MIR PHI generation verified

Out of Scope (Phase 213): Pattern 3 lowerer (lower_loop_with_if_phi_pattern) is currently a test-only PoC implementation with hardcoded conditions and updates. AST-based generalization for if-sum patterns is handled in Phase 213.

Next: Phase 213 will generalize Pattern 3 lowerer to read actual AST conditions and update expressions dynamically.

Phase 212.5: COMPLETE ✅ Status: Active
Scope: If-sum 実装完了メモ（JoinIR v2）