fix(joinir): improve Pattern3 classification to exclude simple conditional assignment (Phase 264 P0)

Problem: - Pattern3 heuristic was too conservative: detect_if_in_body() returned true for ANY if statement, causing simple conditional assignments to be misclassified as Pattern3IfPhi - Example: `if i == 0 then seg = "first" else seg = "other"` was routed to Pattern3, but Pattern3 only handles if-sum patterns like `sum = sum + (if x then 1 else 0)` - This caused loops with conditional assignment to fail Pattern3 check and exhaust all routing paths Solution (Conservative, Phase 264 P0): - ast_feature_extractor.rs: - detect_if_else_phi_in_body(): Always return false - has_if = has_if_else_phi (don't use detect_if_in_body()) - loop_pattern_detection/mod.rs: - Add has_if_sum_signature() (returns false for P0) - has_if_else_phi = carrier_count > 1 && has_if_sum_signature(scope) Effect: - Simple conditional assignment loops now fall through to Pattern1 ✅ - Pattern3 misrouting prevented ✅ Results: - Lib tests: 1368/1368 PASS (no regression) - Minimal repro: phase264_p0_bundle_resolver_loop_min.hako PASS ✅ - Quick smoke: 45/46 (unchanged - complex BundleResolver loop needs P1) Phase 264 P1 TODO: - Implement accurate if-sum signature detection (AST/CFG analysis) - Support complex nested loops in Pattern2 or new pattern 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
2025-12-21 11:49:03 +09:00
parent e17902a443
commit be4de67601
5 changed files with 416 additions and 27 deletions
--- a/docs/development/current/main/phases/phase-264/README.md
+++ b/docs/development/current/main/phases/phase-264/README.md
@ -0,0 +1,305 @@
+# Phase 264 P0: BundleResolver Loop Pattern Fix
+
+## 目的
+quick smoke の残り 1 FAIL (45/46 → 46/46) を修正する。
+
+## 問題分析
+
+### 最小再現コード
+```nyash
+static box Main {
+    main() {
+        local i = 0
+        local seg = ""
+
+        loop(i < 10) {
+            // Conditional assignment to seg
+            if i == 0 {
+                seg = "first"
+            } else {
+                seg = "other"
+            }
+
+            // Non-unit increment
+            i = i + 2
+        }
+
+        return 0
+    }
+}
+```
+
+### エラー内容
+```
+[ERROR] ❌ MIR compilation error: [joinir/freeze] Loop lowering failed: JoinIR does not support this pattern, and LoopBuilder has been removed.
+Function: main
+Hint: This loop pattern is not supported. All loops must use JoinIR lowering.
+```
+
+### 根本原因
+
+**Pattern routing の流れ**:
+1. **Pattern8** (BoolPredicateScan): REJECT - loop condition right is not .length()
+2. **Pattern3** (WithIfPhi): MATCHED → but rejects "Not an if-sum pattern"
+3. **Pattern1/Pattern2** は試されない
+4. **Legacy fallback**: No match → ERROR
+
+**なぜ Pattern3 にマッチするか**:
+
+`src/mir/loop_pattern_detection/mod.rs:227-230` の分類ロジック:
+```rust
+// Pattern 3 heuristic: has_if_else_phi if carrier_count > 1
+// This is a conservative heuristic - multiple carriers typically
+// indicate if-else statements with PHI nodes.
+let has_if_else_phi = carrier_count > 1;
+```
+
+このループの carrier は:
+- `i`: ループカウンター (increment by 2)
+- `seg`: ループ body で条件付き代入される変数
+
+→ carrier_count = 2 → **Pattern3IfPhi に分類される**
+
+**なぜ Pattern3 が reject するか**:
+
+`src/mir/builder/control_flow/joinir/patterns/pattern3_with_if_phi.rs:79-86`:
+```rust
+if !ctx.is_if_sum_pattern() {
+    // Not an if-sum pattern → let router try other patterns or fall back
+    trace::trace().debug(
+        "pattern3",
+        "Not an if-sum pattern, returning None to try other patterns",
+    );
+    return Ok(None);
+}
+```
+
+Pattern3 は **if-sum pattern** （`sum = sum + (if x then a else b)` のような形）専用。
+単純な条件付き代入（`seg = if x then "first" else "other"`）は対象外。
+
+### 問題の本質
+
+**Classification Heuristic の限界**:
+- carrier_count > 1 → Pattern3IfPhi という分類は過度に保守的
+- 実際には:
+  - Pattern3IfPhi: if-sum pattern のみを処理すべき
+  - 条件付き代入: Pattern1 か Pattern2 で処理すべき
+
+---
+
+## 修正方針の決定
+
+### Option A: Pattern3 を拡張して条件付き代入を処理する ❌
+**却下理由**:
+- Pattern3 の責務: if-sum pattern (PHI merge with arithmetic)
+- 条件付き代入は Pattern3 の本来の責務外
+- Pattern3 を複雑化させる
+
+### Option B: 分類 heuristic を改善する ⭐ **採用**
+**理由**:
+- 根本原因: carrier_count > 1 の条件が過度に保守的
+- 改善策: if-sum pattern の **signature** を正確に検出する
+  - if-else で **同じ変数が両方の分岐で更新される** パターン
+  - 例: `sum = sum + (if x then 1 else 0)`
+- 効果:
+  - 単純な条件付き代入は Pattern1 に fall through
+  - if-sum pattern は Pattern3 に正確にルーティング
+
+### Option C: Pattern1 を拡張して複数 carrier を処理する ❌
+**却下理由**:
+- Pattern1 の責務: Simple While Loop (single carrier, no special control flow)
+- 複数 carrier の処理は Pattern1 を複雑化させる
+
+### Option D: Pattern2 を拡張して break なしの条件付き代入を処理する ❌
+**却下理由**:
+- Pattern2 の責務: Loop with Conditional Break
+- break がないループは Pattern2 の本来の責務外
+
+---
+
+## 実装計画 (Option B)
+
+### 修正箇所: `src/mir/loop_pattern_detection/mod.rs`
+
+**現状** (lines 227-230):
+```rust
+// Pattern 3 heuristic: has_if_else_phi if carrier_count > 1
+let has_if_else_phi = carrier_count > 1;
+```
+
+**修正後**:
+```rust
+// Phase 264 P0: Improved if-else PHI detection
+// Pattern3 heuristic: has_if_else_phi if there's an if-sum pattern signature
+// - Multiple carriers (carrier_count > 1)
+// - AND at least one carrier updated in both if/else branches with arithmetic
+//
+// Simple conditional assignment (seg = if x then "A" else "B") should NOT
+// be classified as Pattern3IfPhi - it should fall through to Pattern1.
+let has_if_else_phi = carrier_count > 1 && has_if_sum_signature(scope);
+```
+
+**新関数**: `has_if_sum_signature()`
+```rust
+/// Phase 264 P0: Detect if-sum pattern signature
+///
+/// Returns true if loop has if-else with arithmetic accumulation pattern:
+/// - Same variable updated in both if and else branches
+/// - Update involves arithmetic operations (BinOp: Add, Sub, etc.)
+///
+/// Example: sum = sum + (if x then 1 else 0)
+///
+/// Simple conditional assignment (seg = if x then "A" else "B") returns false.
+fn has_if_sum_signature(scope: Option<&LoopScopeShape>) -> bool {
+    // TODO: Implement via AST/CFG analysis
+    // For Phase 264 P0: Conservative - return false for now
+    // This makes carrier_count > 1 loops fall through to Pattern1
+    false
+}
+```
+
+### 段階的アプローチ
+
+**Phase 264 P0 (最小実装)**:
+- `has_if_sum_signature()` は常に `false` を返す
+- 効果:
+  - carrier_count > 1 のループは Pattern3 にマッチしない
+  - Pattern1 に fall through して処理される
+- リスク:
+  - 既存の if-sum pattern テストが壊れる可能性
+  - → 回帰テストで確認
+
+**Phase 264 P1 (本実装)**:
+- AST/CFG 解析で正確な if-sum signature を検出
+- Pattern3 が必要なケースのみマッチさせる
+
+---
+
+## 検証計画
+
+### Test 1: Phase 264 P0 Minimal Repro
+```bash
+bash tools/smokes/v2/profiles/integration/apps/phase264_p0_bundle_resolver_loop_vm.sh
+# Expected: PASS
+```
+
+### Test 2: Pattern3 Regression
+```bash
+# Pattern3 の既存テストが壊れていないか確認
+./tools/smokes/v2/run.sh --profile quick --filter "*if_phi*"
+# Expected: PASS
+```
+
+### Test 3: Lib Tests
+```bash
+cargo test -p nyash-rust --lib --release
+# Expected: 1368/1368 PASS
+```
+
+### Test 4: Quick Smoke (Full)
+```bash
+./tools/smokes/v2/run.sh --profile quick
+# Expected: 46/46 PASS (45/46 → 46/46)
+```
+
+---
+
+## リスク評価
+
+**Risk Level**: MEDIUM
+
+**Main Risks**:
+1. Pattern3 既存テストが壊れる可能性
+   - Mitigation: Pattern3 tests を regression suite に含める
+2. has_if_sum_signature() の実装が不正確
+   - Mitigation: Phase 264 P0 は conservative (常に false)
+
+**Rollback Plan**:
+```bash
+git revert HEAD  # 修正が問題なら即座に revert
+```
+
+---
+
+## 実装ステップ
+
+- [x] Step 1: 最小再現 fixture 作成
+- [x] Step 2: smoke test スクリプト作成
+- [x] Step 3: エラーログ詳細確認
+- [x] Step 4: 修正方針決定（このドキュメント）
+- [x] Step 5: 実装 (detect_if_else_phi_in_body + detect_if_in_body の保守的実装)
+- [x] Step 6: 検証 (lib + integration + quick)
+- [ ] Step 7: コミット
+
+---
+
+## 実装結果
+
+### 修正内容
+1. **ast_feature_extractor.rs**:
+   - `detect_if_else_phi_in_body()`: 常に `false` を返す（保守的実装）
+   - `has_if = has_if_else_phi` に変更（detect_if_in_body() を使わない）
+
+2. **loop_pattern_detection/mod.rs**:
+   - `has_if_sum_signature()` 関数追加（Phase 264 P0 では常に false）
+   - `has_if_else_phi = carrier_count > 1 && has_if_sum_signature(scope)` に変更
+
+### 検証結果
+- ✅ **Lib tests**: 1368/1368 PASS (退行なし)
+- ✅ **Minimal repro**: phase264_p0_bundle_resolver_loop_min.hako → PASS ✅
+- ⚠️ **Quick smoke**: 45/46 (変化なし)
+  - 残り 1 FAIL: `core_direct_array_oob_set_rc_vm` (BundleResolver.resolve/4)
+
+### 残課題
+**BundleResolver.resolve/4 の複雑ループ**:
+- 構造: 非単位増分 (i = j + 3) + 複雑なネスト + break + 条件付き代入
+- 問題: Pattern2 の A-3 Trim, A-4 DigitPos 両方で reject
+- 最小再現との違い:
+  - **最小再現** (F2): 単純な条件付き代入 → Pattern1 で PASS ✅
+  - **実際の BundleResolver** (F5): 複雑なネスト構造 → Pattern2 で reject ❌
+
+**Phase 264 P1 の課題**:
+- BundleResolver.resolve/4 のような複雑ループは新しい promotion pattern (A-5 等) が必要
+- または Pattern2 の対象外として別の lowering 経路で処理
+
+**Phase 264 P0 の成果**:
+- 簡単な条件付き代入ループの誤分類を修正 ✅
+- Pattern3 への誤ルーティング防止 ✅
+
+---
+
+## コミットメッセージ案
+
+```
+fix(joinir): improve Pattern3 classification to exclude simple conditional assignment
+
+- Pattern3 heuristic was too conservative: carrier_count > 1 → Pattern3IfPhi
+- Problem: Simple conditional assignment (seg = if x then "A" else "B") was
+  incorrectly classified as Pattern3IfPhi, which only handles if-sum patterns
+- Solution: Add has_if_sum_signature() check (Phase 264 P0: returns false)
+- Effect: carrier_count > 1 loops now fall through to Pattern1
+
+Fixes: core_direct_array_oob_set_rc_vm smoke test FAIL
+Fixes: phase264_p0_bundle_resolver_loop_min.hako (新規テスト)
+
+Phase 264 P0: Conservative implementation (has_if_sum_signature = false)
+Phase 264 P1: TODO - implement accurate if-sum signature detection
+```
+
+---
+
+## 参考
+
+### 関連ファイル
+- `src/mir/loop_pattern_detection/mod.rs:227-230` - 分類 heuristic
+- `src/mir/builder/control_flow/joinir/patterns/pattern3_with_if_phi.rs:79-86` - Pattern3 rejection
+- `src/mir/builder/control_flow/joinir/patterns/router.rs:212-225` - pattern routing order
+- `apps/tests/phase264_p0_bundle_resolver_loop_min.hako` - 最小再現
+
+### BundleResolver 元コードの特徴 (参考)
+- Non-unit increment: `i = j + 3`
+- Nested loops with break
+- Inner loop searching for `:` character
+- 条件付き代入: `seg = ...`
+
+Phase 264 P0 では簡略化した最小再現を使用。