Files
hakorune/docs/development/current/main/phases/phase-286
tomoaki 661bbe1ab7 feat(phase284): P1 Complete - Return in Loop with Block Remap Fix
## Summary

Completed Phase 284 P1: Enable return statements in Pattern4/5 loops via
JoinInst::Ret infrastructure (100% pre-existing, no new infrastructure needed).

**Critical Bug Fix**: Block ID remap priority
- Fixed: local_block_map must take precedence over skipped_entry_redirects
- Root cause: Function-local block IDs can collide with global remap entries
  (example: loop_step:bb4 vs k_exit:bb4 after merge allocation)
- Impact: Conditional Jump else branches were incorrectly redirected to exit
- Solution: Check local_block_map FIRST, then skipped_entry_redirects

## Implementation

### New Files
- `src/mir/join_ir/lowering/return_collector.rs` - Return detection SSOT (top-level only, P1 scope)
- `apps/tests/phase284_p1_return_in_loop_min.hako` - Test fixture (exit code 7)
- Smoke test scripts (VM/LLVM)

### Modified Files
- `loop_with_continue_minimal.rs`: Return condition check + Jump generation
- `pattern4_with_continue.rs`: K_RETURN registration in continuation_funcs
- `canonical_names.rs`: K_RETURN constant
- `instruction_rewriter.rs`: Fixed Branch remap priority (P1 fix)
- `terminator.rs`: Fixed Jump/Branch remap priority (P1 fix)
- `conversion_pipeline.rs`: Return normalization support

## Testing

 VM: exit=7 PASS
 LLVM: exit=7 PASS
 Baseline: 46 PASS, 1 FAIL (pre-existing emit issue)
 Zero regression

## Design Notes

- JoinInst::Ret infrastructure was 100% complete before P1
- Bridge automatically converts JoinInst::Ret → MIR Return terminator
- Pattern4/5 now properly merge k_return as non-skippable continuation
- Correct semantics: true condition → return, false → continue loop

## Next Phase (P2+)

- Refactor: Block remap SSOT (block_remapper.rs)
- Refactor: Return jump emitter extraction
- Scope: Nested if/loop returns, multiple returns
- Design: Standardize early exit pattern (return/break/continue as Jump with cond)

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

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2025-12-23 14:21:27 +09:00
..

Phase 286: JoinIR Line AbsorptionJoinIR→CorePlan/Frag 収束)

Status: Planned (design-first)

Goal

移行期間に残っている「2本の lowering」を、構造で 1 本に収束させる。

  • Plan linePattern6/7: CorePlan → Frag(compose) → emit_frag() が SSOT
  • JoinIR linePattern15,9: JoinIR → bridge → merge が SSOT

Phase 286 では JoinIR line を “第2の lowerer” として放置せず、Plan/Frag SSOT へ吸収する道筋を固定する。

Whyなぜ今

  • return のような「大きな出口語彙」は、責務が分散すると実装場所が揺れて事故りやすい
  • 移行期間の弱点は「同じASTでも経路により意味論が割れる可能性がある」こと
  • pattern を溶かしていく思想の最後の壁が “JoinIR line の残存” になりやすい

SSOTPhase 286 で守る憲法)

  • SSOT=extractPhase 282: 検出は extract の成功でのみ決める。pattern_kind は O(1) safety valve のみ。
  • CFG/terminator SSOTPhase 280/281: Frag + compose::* + emit_frag() が唯一の terminator 生成点。
  • Fail-Fast: close-but-unsupported を Ok(None) で黙殺しないsilent reroute 禁止)。

Responsibility Mapどこを触るか

  • JoinIR line の共通入口(現状):
    • src/mir/builder/control_flow/joinir/patterns/conversion_pipeline.rs
    • src/mir/join_ir_vm_bridge/bridge.rs
    • src/mir/builder/control_flow/joinir/merge/mod.rs
  • Plan/Frag SSOT収束先:
    • src/mir/builder/control_flow/plan/*
    • src/mir/builder/control_flow/edgecfg/api/compose.rs
    • src/mir/builder/control_flow/edgecfg/api/emit.rs

Scope提案

P0docs-only

  • 「JoinIR line をどの粒度で吸収するか」を SSOT として決める
    • 例: JoinIR は DomainPlan 生成の補助へ降格 / JoinIR→MIR merge を段階撤去
  • “禁止事項” を明文化pattern 側への散布、二重 SSOT の再発)

P1investigation

  • JoinIR line が持っている「本当は SSOT に寄せたい責務」を棚卸し
    • return/break/continue の扱い
    • exit phi / boundary の責務
    • optimizer/type propagation の入り口

P2PoC

  • 代表 1 パターン(例: Pattern4を “JoinIR 生成 → CorePlan/Frag” に変換する PoC
    • 目的: merge を通さずに emit_frag() 経由で終端が生成できることの証明

AcceptanceP0

  • 2本の lowering が “設計として” どこで 1 本に収束するかが明文化されている
  • Phase 284Return/ Phase 285GCと矛盾しない