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## Phase 18 v2: Next Phase Direction After Phase 18 v1 failure (layout optimization caused I-cache regression), shift to instruction count reduction via compile-time removal: - Stats collection (FRONT_FASTLANE_STAT_INC → no-op) - Environment checks (runtime lookup → constant) - Debug logging (conditional compilation) Expected impact: Instructions -30-40%, Throughput +10-20% ## Success Criteria (STRICT) GO (must have ALL): - Throughput: +5% minimum (+8% preferred) - Instructions: -15% minimum (smoking gun) - I-cache: automatic improvement from smaller footprint NEUTRAL: throughput ±3%, instructions -5% to -15% NO-GO: throughput < -2%, instructions < -5% Key: If instructions do not drop -15%+, allocator is not the bottleneck and this phase should be abandoned. ## Implementation Strategy 1. Makefile knob: BENCH_MINIMAL=0/1 (default OFF, production-safe) 2. Conditional removal: - Stats: #if !HAKMEM_BENCH_MINIMAL - ENV checks: constant propagation - Debug: conditional includes 3. A/B test with perf stat (must measure instruction reduction) ## Files New: - docs/analysis/PHASE18_HOT_TEXT_ISOLATION_2_DESIGN.md (detailed design) - docs/analysis/PHASE18_HOT_TEXT_ISOLATION_2_NEXT_INSTRUCTIONS.md (step-by-step) Modified: - CURRENT_TASK.md (Phase 18 v1/v2 status) ## Key Learning from Phase 18 v1 Failure Layout optimization is extremely fragile without strong ordering guarantees. Section splitting alone (without symbol ordering, PGO, or linker script) destroyed code locality and increased I-cache misses 91%. Switching to direct instruction removal is safer and more predictable. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Docs Overview
このフォルダは hakmem の設計・計測・運用メモを体系化して管理する場所です。
- INDEX.md: 目次（各ドキュメントへのリンク）
- benchmarks/: ベンチマーク手順とスイープ結果の保存先
- specs/: 現在の仕様（SACS‑3/HW/ENV）を集約
- roadmap/: これからの実装計画・優先度・タスク
運用ルール（提案）
- 1つの変更/計測のまとまりにつき1ファイル（or 1フォルダ）
- 再現コマンド・環境変数・ハード構成は必ず記載
- 大きな連続出力はファイルへ保存し、本文からは抜粋/要約を記載