feat(joinir): Phase 188.3 - Pattern6 (NestedLoopMinimal) 選択ロジック実装
## Phase 188.3 進捗: Phase 2 完了 (6/13 tasks) ### 実装完了 ✅ **Phase 1: Fixture作成** - apps/tests/phase1883_nested_minimal.hako 追加 - Add/Compare のみ（乗算なし） - 期待 exit code: 9 (3×3 nested loops) - 既存 lowering で fallback 動作確認 **Phase 2: 選択ロジック (SSOT)** - LoopPatternContext に step_tree_max_loop_depth フィールド追加 - choose_pattern_kind() に Pattern6 選択ロジック実装: 1. Cheap check (has_inner_loop) 2. StepTree 構築 (max_loop_depth 取得) 3. AST validation (is_pattern6_lowerable) - pattern6_nested_minimal.rs モジュール作成 (stub) - LOOP_PATTERNS に Pattern6 entry 追加 - **検証**: Pattern6 が正しく選択される ✅ ### 設計原則 (確認済み) 1. **Fail-Fast**: Pattern6 選択後は Ok(None) で逃げない 2. **outer 変数 write-back 検出 → validation false** (Phase 188.4+) 3. **最小実装**: inner local だけ、Pattern1 モデル二重化 4. **cfg! 依存なし**: production で動作 ### 検証結果 ``` [choose_pattern_kind] has_inner_loop=true [choose_pattern_kind] max_loop_depth=2 [choose_pattern_kind] is_pattern6_lowerable=true ✅ Pattern6 SELECTED! ``` Stub からの期待エラー: ``` [ERROR] ❌ [Pattern6] Nested loop lowering not yet implemented ``` ### 次: Phase 3 (Lowering 実装 - 推定4時間) 残りタスク: - Phase 3-1: AST 抽出ヘルパー - Phase 3-2: Validation ヘルパー - Phase 3-3: Continuation 生成 (outer_step, inner_step, k_inner_exit) - Phase 3-4: fixture が exit=9 を返すことを検証 ### 変更ファイル **新規**: - apps/tests/phase1883_nested_minimal.hako - src/mir/builder/control_flow/joinir/patterns/pattern6_nested_minimal.rs - docs/development/current/main/phases/phase-188.{1,2,3}/README.md **変更**: - src/mir/builder/control_flow/joinir/routing.rs (Pattern6 選択) - src/mir/builder/control_flow/joinir/patterns/router.rs (Context 拡張) - src/mir/builder/control_flow/joinir/patterns/mod.rs (module 宣言) 🎯 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
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docs/development/current/main/phases/phase-188.1/README.md
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# Phase 188.1: cap_missing/NestedLoop 解除（strict gate unblock）
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**Date**: 2025-12-27
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**Goal**: `cap_missing/NestedLoop` を解除して、`selfhost_minimal` を integration で PASS させる（Fail-Fastを崩さない）
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**Status**: ✅ Capability gate unblock 完了 / ❌ Pattern 6（検出・lowering）は Phase 188.2+ に deferred
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---
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## ⚠️ Implementation Reality (Phase 188.1 Scope)
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### What Phase 188.1 actually did
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- ✅ **StepTree capability gate**: `StepCapability::NestedLoop` を strict allowlist に追加して、`cap_missing/NestedLoop` を解除した
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- ✅ **Integration導線**: `selfhost_minimal` の SKIP を撤去しても integration selfhost が FAIL=0 になることを確認した
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### What Phase 188.1 did NOT do
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- ❌ **Nested loop の自動検出（LoopFormベース）**は未実装
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`loop_pattern_detection::extract_features()` は `max_loop_depth=1` / `has_inner_loops=false` の固定値（TODO）で、Pattern 6 の分岐は到達しない
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- ❌ **Pattern 6 lowering** は未実装
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`src/mir/join_ir/lowering/loop_patterns/nested_minimal.rs` はインフラ（stub）で、現状 `None` を返す
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### Why LoopForm-based nesting detection is impossible (current architecture)
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Nesting depth は **StepTree（AST側）**にはあるが、**LoopForm（MIR側）**には存在しない。
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- ✅ StepTree: `StepTreeFeatures.max_loop_depth`（AST → StepTree 変換時に計算）
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- ❌ LoopForm: `LoopForm = LoopShape` は CFG ブロック参照だけを持ち、親子/深さ情報が無い
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従って、ネスト深さの検査や Pattern 6 の自動検出を **LoopFormレイヤーだけで完結させることはできない**。
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次の実装は Phase 188.2 で「StepTree側を使うか / LoopRegion（親子構造）を実装するか」を docs-first で決める。
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## Pattern 6 Specification: NestedLoop Minimal
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**Note**: このセクションは「目標仕様（design）」であり、Phase 188.1 では gate unblock のみ完了。実装は Phase 188.2+。
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### Supported Forms (ONLY)
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**Pattern**: Outer Pattern 1 + Inner Pattern 1
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```nyash
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// Outer loop: Pattern 1 (simple while, no break/continue)
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loop(outer_cond) {
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// ... outer loop body before inner ...
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// Inner loop: Pattern 1 ONLY (simple while, no break/continue)
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loop(inner_cond) {
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// ... inner loop body ...
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}
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// ... outer loop body after inner ...
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}
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```
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**Requirements**:
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- **Outer loop**: Pattern 1 (Simple While) - no break/continue
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- **Inner loop**: Pattern 1 (Simple While) - no break/continue
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- **Nesting depth**: EXACTLY 1 level (`max_loop_depth == 2`)
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- **No control flow**: No break/continue in either loop
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- **Sequential execution**: Inner loop completes before outer continues
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### Unsupported Forms (Explicit Error)
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**Rejected with明示エラー** (no silent fallback):
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1. **Deeper nesting** (`max_loop_depth > 2`):
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```
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[joinir/nested_loop/depth_exceeded] max_loop_depth=3 exceeds limit (max=2)
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Hint: Refactor to avoid 3+ level nesting, or split into separate functions
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```
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2. **Inner loop with break/continue**:
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```
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[joinir/nested_loop/inner_control_flow] Inner loop has break/continue (not supported)
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Hint: Only simple while loops (Pattern 1) supported as inner loops
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```
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3. **Outer loop with break/continue**:
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```
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[joinir/nested_loop/outer_control_flow] Outer loop has break/continue (not supported)
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Hint: Only simple while loops (Pattern 1) supported as outer loops
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```
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4. **Multiple inner loops** (siblings):
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```
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[joinir/nested_loop/multiple_inner] Multiple inner loops detected (not supported)
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Hint: Only one inner loop per outer loop supported
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```
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---
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## JoinIR Lowering Strategy
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### Example Input (Nyash)
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```nyash
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static box Main {
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main() {
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local outer_i = 0
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loop(outer_i < 3) {
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local inner_j = 0
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loop(inner_j < 2) {
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print(inner_j)
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inner_j = inner_j + 1
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}
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outer_i = outer_i + 1
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}
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return 0
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}
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}
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```
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### Expected Output (JoinIR Pseudocode)
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```text
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fn main():
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Call(outer_step, [0, k_main_exit])
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fn outer_step(outer_i, k_outer_exit):
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// Exit condition check
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exit_cond = !(outer_i < 3)
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Jump(k_outer_exit, [], cond=exit_cond) // Early exit if condition false
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// Initialize inner loop variables
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inner_j = 0
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// Inner loop step function (nested inside outer_step)
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fn inner_step(inner_j, k_inner_exit):
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exit_cond = !(inner_j < 2)
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Jump(k_inner_exit, [], cond=exit_cond)
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print(inner_j)
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inner_j_next = inner_j + 1
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Call(inner_step, [inner_j_next, k_inner_exit]) // Tail recursion
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// k_inner_exit continuation (resume outer loop body after inner completes)
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fn k_inner_exit():
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outer_i_next = outer_i + 1
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Call(outer_step, [outer_i_next, k_outer_exit]) // Outer tail recursion
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// Entry: call inner loop
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Call(inner_step, [inner_j, k_inner_exit])
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fn k_main_exit():
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return 0
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```
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**Key Points**:
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- **Nested functions**: Inner step function is defined inside outer step function
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- **Continuation wiring**: `k_inner_exit` resumes outer loop body after inner completes
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- **Carrier isolation**: Outer carriers (`outer_i`) and inner carriers (`inner_j`) are separate
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- **Same pattern as Pattern 1**: Both loops use tail-recursive step function pattern
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---
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## ⚠️ Implementation Reality (Phase 188.1 Scope)
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### What Was Actually Implemented
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**Phase 188.1 delivered**:
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1. ✅ **StepTree capability gate**: `StepCapability::NestedLoop` added to allowlist
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2. ✅ **Pattern 6 enum**: `Pattern6NestedLoopMinimal` classification added
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3. ✅ **Lowering stub**: `nested_minimal.rs` module created (infrastructure only)
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4. ✅ **Test pass**: selfhost_minimal conditional SKIP removed, 154/154 PASS maintained
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**Phase 188.1 did NOT implement**:
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- ❌ **Automatic nesting detection from LoopForm**: LoopForm (= LoopShape) has NO nesting information
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- ❌ **Pattern 6 lowering logic**: `lower_nested_loop_minimal_to_joinir()` returns `None` (stub)
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- ❌ **LoopRegion integration**: LoopRegion parent/child structure exists but is NOT instantiated
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### Why Automatic Detection Is NOT Possible (Current Architecture)
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**LoopForm Limitation**:
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```rust
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// src/mir/loop_form.rs
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pub type LoopForm = crate::mir::control_form::LoopShape;
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// LoopShape structure (src/mir/control_form.rs):
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pub struct LoopShape {
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pub preheader: BasicBlockId,
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pub header: BasicBlockId,
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pub body: Vec<BasicBlockId>,
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pub latch: BasicBlockId,
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pub exit_blocks: Vec<BasicBlockId>,
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// ❌ NO parent field
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// ❌ NO children field
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// ❌ NO depth field
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}
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```
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**Nesting information exists ONLY in StepTree** (AST level):
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```rust
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// src/mir/control_tree/step_tree.rs (line 17-25)
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pub struct StepTreeFeatures {
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pub max_loop_depth: u32, // ← Detected during AST → StepTree conversion
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// ...
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}
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```
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- ✅ AST parsing time: Nesting depth calculated
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- ❌ MIR lowering time: LoopForm has NO access to this information
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**LoopRegion infrastructure exists but is NOT integrated**:
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```rust
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// src/mir/control_form.rs (line 40-62) - Phase 32 definition
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pub struct LoopRegion {
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pub parent: Option<LoopId>, // ← Structure defined
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pub children: Vec<LoopId>, // ← But NOT instantiated anywhere
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}
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```
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### Where Nesting Depth Checking MUST Happen
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**✅ Possible locations**:
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1. **StepTree level** (before LoopForm creation):
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- Use `StepTreeFeatures.max_loop_depth` during control flow analysis
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- Reject `max_loop_depth > 2` at StepTree → LoopForm conversion time
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2. **LoopRegion level** (if integrated in Phase 188.2+):
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- Use `LoopRegion.parent` to compute actual nesting depth
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- Build LoopRegion tree and check depth constraints
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**❌ Impossible location**:
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- **LoopForm level**: No nesting information available (by design)
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### Phase 188.2 Design Decision Required
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**Choice A: StepTreeFeatures Integration**
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- Pass `StepTreeFeatures` (AST-level) to JoinIR lowering
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- Use `max_loop_depth` from StepTree for Pattern 6 detection
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- Pro: Nesting info already exists
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- Con: AST-level info may not match MIR structure (optimizations)
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**Choice B: LoopRegion Integration**
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- Instantiate `LoopRegion` with parent/child relationships
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- Compute nesting depth from MIR control flow graph
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- Pro: MIR-level truth (accurate after optimizations)
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- Con: Requires implementing LoopRegion builder (Phase 32 infrastructure not yet wired)
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**Decision timeline**: Phase 188.2 planning session (docs-first approach)
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---
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## Implementation Files
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### New Files Created
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1. **`src/mir/join_ir/lowering/loop_patterns/nested_minimal.rs`**
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- Phase 188.1: インフラ（stub）。現状 `lower_nested_loop_minimal_to_joinir()` は `None` を返す
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### Modified Files
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1. **`src/mir/loop_pattern_detection/mod.rs`** (~15 lines)
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- Add `Pattern6NestedLoopMinimal` enum variant
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- Add `max_loop_depth`, `has_inner_loops` to `LoopFeatures`
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- Update `extract_features()`, `classify()`
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2. **`src/mir/join_ir/lowering/loop_patterns/mod.rs`** (~2 lines)
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- Export `nested_minimal` module
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3. **`src/mir/join_ir/lowering/loop_pattern_router.rs`** (~10 lines)
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- Add Pattern 6 routing case
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- Add explicit error for `max_loop_depth > 2`
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4. **`src/mir/builder/control_flow/joinir/control_tree_capability_guard.rs`** (~1 line)
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- Add `StepCapability::NestedLoop` to allowlist
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5. **`tools/smokes/v2/profiles/integration/selfhost/selfhost_minimal.sh`** (~6 lines removed)
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- Remove conditional SKIP for `cap_missing/NestedLoop`
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---
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## Integration Points
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### Detection Pipeline
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1. **AST → StepTree** (`step_tree.rs` lines 461-463):
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```rust
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if features.max_loop_depth > 1 {
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facts.add_capability(StepCapability::NestedLoop);
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}
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```
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2. **StepTree → Contract** (automatic capability contract check)
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3. **Contract → Guard** (`control_tree_capability_guard.rs` line 44):
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```rust
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StepCapability::NestedLoop, // Phase 188.1: Now in allowlist
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```
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4. **LoopForm → Pattern Detection** (`loop_pattern_detection::classify()`):
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```rust
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// Phase 188.1: Pattern 6 enum defined, but detection logic is STUB
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// Currently always returns max_loop_depth = 1 (default)
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// because LoopForm has NO nesting information.
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//
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// TODO (Phase 188.2): Integrate StepTreeFeatures or LoopRegion
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// to enable actual nesting detection.
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if features.max_loop_depth == 2
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&& features.has_inner_loops
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&& !features.has_break
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&& !features.has_continue
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{
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return LoopPatternKind::Pattern6NestedLoopMinimal; // Never reached (stub)
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}
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```
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5. **Pattern → Lowering** (`loop_pattern_router.rs`):
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```rust
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LoopPatternKind::Pattern6NestedLoopMinimal => {
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super::loop_patterns::lower_nested_loop_minimal_to_joinir(loop_form, lowerer)
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}
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```
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---
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## Success Criteria
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### Functional Requirements
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- ✅ `selfhost_minimal.sh`: Remove conditional SKIP, test PASS (or explicit error)
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- ✅ `integration --filter "selfhost_"`: FAIL=0 maintained
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- ✅ `quick`: 154/154 PASS unchanged
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### Quality Requirements
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- ✅ Explicit errors for unsupported forms (no silent `Ok(None)`)
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- ✅ Phase 286 Fail-Fast principle maintained (no silent fallback)
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- ✅ Minimal diff (~180 lines total)
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---
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## Out of Scope (Future Work)
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**Deferred to Phase 188.2+**:
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- Pattern 6 の実装（ネスト検出のSSOT決定 + lowering 実装）
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- break/continue in nested loops (Pattern 2/4 inner/outer combinations)
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- Multiple inner loops (siblings)
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- 2+ level nesting (3+ loop depth)
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- Nested loops with PHI (Pattern 3 inner/outer combinations)
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- Shared carriers between outer/inner loops
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**Rationale**: Phase 188.1 is minimal PoC to unblock selfhost_minimal. Complex patterns deferred to avoid scope creep.
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---
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## References
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- **Phase 188 Overview**: `docs/private/roadmap2/phases/phase-188-joinir-loop-pattern-expansion/README.md`
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- **Pattern Classification**: `docs/private/roadmap2/phases/phase-188-joinir-loop-pattern-expansion/pattern-classification.md`
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- **JoinIR Architecture**: `docs/development/current/main/joinir-architecture-overview.md`
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- **Selfhost Integration Limitations**: `docs/development/current/main/investigations/selfhost-integration-limitations.md`
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---
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## End of Phase 188.1 Documentation
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**Status**: Infrastructure complete, detection logic deferred to Phase 188.2
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**Reality**: Pattern 6 enum exists, but automatic detection is NOT implemented (LoopForm limitation)
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**Total Estimated Effort**: 4-5 hours (infrastructure only)
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**Date Completed**: 2025-12-27
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