Update CURRENT_TASK: Phase 3 D2 Complete (NO-GO, -1.44% regression)

CURRENT_TASK.md

@@ -1,6 +1,6 @@
 # 本線タスク（現在）
 
-## 更新メモ（2025-12-13 Phase 1-2 Complete）
+## 更新メモ（2025-12-13 Phase 3 D2 Complete - NO-GO）
 
 ### Phase 1 Quick Wins: FREE 昇格 + 観測税ゼロ化
 - ✅ **A1（FREE 昇格）**: `MIXED_TINYV3_C7_SAFE` で `HAKMEM_FREE_TINY_FAST_HOTCOLD=1` をデフォルト化
@@ -33,7 +33,12 @@
 - Implementation: Already in place (lines 252-267 in malloc_tiny_fast.h), now enabled by default
 - Profile updates: Added `bench_setenv_default("HAKMEM_TINY_ALLOC_ROUTE_SHAPE", "1")` to both profiles
 
-## 現在地: B3 採用完了 ✅ (Mixed +2.89%, C6-heavy +9.13%)
+## 現在地: Phase 3 D2 Complete ❌ NO-GO (Mixed -1.44%, wrapper env cache regression)
+
+**Summary**:
+- Phase 3 D2 (Wrapper Env Cache): -1.44% regression → **FROZEN as research box**
+- Lesson: TLS caching not always beneficial - simple global access can be faster
+- Cumulative gains: B3 +2.89%, B4 +1.47%, C3 +2.20%, D1 +1.06% (opt-in) → **~7.2%**
 
 ### Phase ALLOC-GATE-SSOT-1 + ALLOC-TINY-FAST-DUALHOT-2: COMPLETED
 
@@ -286,6 +291,44 @@
 
 **Commit**: `f059c0ec8`
 
+#### Phase 3 D2: Wrapper Env Cache ❌ NO-GO (-1.44%)
+
+**設計メモ**: `docs/analysis/PHASE3_D2_WRAPPER_ENV_CACHE_1_DESIGN.md`
+
+**狙い**: malloc/free wrapper 入口の `wrapper_env_cfg()` 呼び出しオーバーヘッドを削減
+
+**実装完了** ✅:
+- `core/box/wrapper_env_cache_env_box.h` (ENV gate: HAKMEM_WRAP_ENV_CACHE)
+- `core/box/wrapper_env_cache_box.h` (TLS cache: wrapper_env_cfg_fast)
+- `core/box/hak_wrappers.inc.h` (lines 174, 553) - malloc/free hot paths で wrapper_env_cfg_fast() 使用
+- Strategy: Fast pointer cache (TLS caches const wrapper_env_cfg_t*)
+- ENV gate: `HAKMEM_WRAP_ENV_CACHE=0/1` (default OFF)
+
+**A/B テスト結果** ❌ NO-GO:
+- Mixed (10-run, 20M iters):
+  - Baseline (D2=0): 46,516,538 ops/s (avg), 46,467,988 ops/s (median)
+  - Optimized (D2=1): 45,846,933 ops/s (avg), 45,978,185 ops/s (median)
+  - **Average gain: -1.44%**, **Median gain: -1.05%**
+- **Decision: NO-GO** (regression below -1.0% threshold)
+- Action: FREEZE as research box (default OFF, regression confirmed)
+
+**Analysis**:
+- Regression cause: TLS cache adds overhead (branch + TLS access cost)
+- wrapper_env_cfg() is already minimal (pointer return after simple check in g_wrapper_env.inited)
+- Adding TLS caching layer makes it worse, not better
+- Branch prediction penalty for wrap_env_cache_enabled() check outweighs any savings
+- Lesson: Not all caching helps - simple global access can be faster than TLS cache
+
+**Current Cumulative Gain** (Phase 2-3):
+- B3 (Routing shape): +2.89%
+- B4 (Wrapper split): +1.47%
+- C3 (Static routing): +2.20%
+- D1 (Free route cache): +1.06% (opt-in)
+- D2 (Wrapper env cache): -1.44% (NO-GO, frozen)
+- **Total: ~7.2%** (excluding D2, D1 is opt-in ENV)
+
+**Commit**: `19056282b`
+
 #### Phase 3 C4: MIXED MID_V3 Routing Fix ✅ ADOPT
 
 **要点**: `MIXED_TINYV3_C7_SAFE` では `HAKMEM_MID_V3_ENABLED=1` が大きく遅くなるため、**プリセットのデフォルトを OFF に変更**。