Phase 21.7 normalization: optimization pre-work + bench harness expansion

- Add opt-in optimizations (defaults OFF)
  - Ret purity verifier: NYASH_VERIFY_RET_PURITY=1
  - strlen FAST enhancement for const handles
  - FAST_INT gate for same-BB SSA optimization
  - length cache for string literals in llvmlite
- Expand bench harness (tools/perf/microbench.sh)
  - Add branch/call/stringchain/arraymap/chip8/kilo cases
  - Auto-calculate ratio vs C reference
  - Document in benchmarks/README.md
- Compiler health improvements
  - Unify PHI insertion to insert_phi_at_head()
  - Add NYASH_LLVM_SKIP_BUILD=1 for build reuse
- Runtime & safety enhancements
  - Clarify Rust/Hako ownership boundaries
  - Strengthen receiver localization (LocalSSA/pin/after-PHIs)
  - Stop excessive PluginInvoke→BoxCall rewrites
- Update CURRENT_TASK.md, docs, and canaries

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

docs/development/roadmap/phases/phase-21.5-optimization/README.md

@@ -1,31 +1,33 @@
-# Phase 21.5 — Optimization (ny-llvm crate line)
+# Phase 21.5 — Optimization (AotPrep‑First)
 
-Scope
-- Optimize hot paths for the crate (ny-llvmc) line using Hakorune scripts only.
-- Preserve default behavior; all risky changes behind dev toggles.
-- Measure EXE runtime (build once, run many) to avoid toolchain overhead noise.
+目的
+- .hako 側（AotPrep）で前処理最適化（構造のみ）を行い、LLVM/AOT に渡すIRを軽量にする。
+- 既定は挙動不変（opt‑in）。Return 純化ガードで安全性を担保。
 
-Targets (initial)
-- loop: integer accumulations (no I/O)
-- strlen: FAST=1 path (pointer → nyrt_string_length)
-- box: construct/destroy minimal boxes (String/Integer)
+チェックリスト
+- [x] パス分割（StrlenFold / LoopHoist / ConstDedup / CollectionsHot / BinopCSE）
+- [x] CollectionsHot（Array/Map）導入（既定OFF）
+- [x] Map key モード `NYASH_AOT_MAP_KEY_MODE={h|i64|hh|auto}`
+- [x] LoopHoist v1 / BinopCSE v1（最小）
+- [x] ベンチ `linidx`/`maplin` 追加
+- [ ] LoopHoist v2（+/* 右項 const の連鎖前出し/fix‑point）
+- [ ] BinopCSE v2（線形 `i*n` 共通化の強化）
+- [ ] CollectionsHot v2（array index の共通SSA利用）
+- [ ] Map auto 精緻化（_is_const_or_linear の再帰判定）
+- [ ] Idempotence（置換済みタグで再実行時も不変）
+- [ ] `arraymap`/`matmul` ≤ 125%（C基準）
 
-Methodology
-- Build once via ny-llvmc; time execution only (`--exe` mode).
-- Runs: 3–5; report median and average (target ≥ 100ms per run).
-- Observe NYASH_VM_STATS=1 (inst/compare/branch) where relevant to correlate structure and runtime.
-
-Commands (examples)
-- tools/perf/phase215/bench_loop.sh --runs 5
-- tools/perf/phase215/bench_strlen.sh --runs 5 --fast 1
-- tools/perf/phase215/run_all.sh --runs 5 --timeout 120
-
-Dev Toggles (keep OFF by default)
-- NYASH_LLVM_FAST=1 (strlen FAST)
-- HAKO_MIR_BUILDER_JSONFRAG_NORMALIZE=1 (normalize)
-- HAKO_MIR_BUILDER_NORMALIZE_TAG=1 (tag, test-only)
-
-Exit Criteria
-- Representative microbenches stable (≤ 5% variance) and ≥ 80% of C baselines.
-- No regression in EXE canaries (loop/print/strlen FAST) and VM parity canaries.
+トグル
+- `NYASH_MIR_LOOP_HOIST=1` … StrlenFold/LoopHoist/ConstDedup/BinopCSE を有効化
+- `NYASH_AOT_COLLECTIONS_HOT=1` … CollectionsHot（Array/Map）
+- `NYASH_AOT_MAP_KEY_MODE` … `h|i64|hh|auto`（推奨: `auto`）
+- `NYASH_VERIFY_RET_PURITY=1` … Return 純化ガード（開発時ON）
 
+ベンチ（例）
+```bash
+export NYASH_SKIP_TOML_ENV=1 NYASH_DISABLE_PLUGINS=1 \
+       NYASH_LLVM_SKIP_BUILD=1 NYASH_LLVM_FAST=1 NYASH_LLVM_FAST_INT=1 \
+       NYASH_MIR_LOOP_HOIST=1 NYASH_AOT_COLLECTIONS_HOT=1 NYASH_VERIFY_RET_PURITY=1
+for c in arraymap matmul sieve linidx maplin; do \
+  tools/perf/microbench.sh --case $c --exe --runs 3; echo; done
+```