2025-12-23 11:14:28 +09:00
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# Phase 284: Return as ExitKind SSOT（patternに散らさない）
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refactor(phase284): P1 SSOT Consolidation - Block Remapper & Return Emitter
## Summary
Refactored Phase 284 P1 codebase to consolidate scattered logic into SSOT
(Single Source of Truth) modules, improving maintainability and enabling
Pattern4/5 code reuse.
## New Modules
### 1. Block Remapper SSOT
**File**: `src/mir/builder/control_flow/joinir/merge/block_remapper.rs` (152 lines)
- **Purpose**: Consolidate block ID remapping logic (Phase 284 P1 fix)
- **Function**: `remap_block_id(block_id, local_block_map, skipped_entry_redirects)`
- **Rule**: local_block_map priority > skipped_entry_redirects (prevents ID collision)
- **Tests**: 4 unit tests (priority cascade, collision handling, etc.)
### 2. Return Jump Emitter
**File**: `src/mir/join_ir/lowering/return_jump_emitter.rs` (354 lines)
- **Purpose**: Reusable return handling helper for Pattern4/5
- **Function**: `emit_return_conditional_jump(loop_step_func, return_info, k_return_id, ...)`
- **Scope**: P1 - unconditional return + conditional (loop_var == N) only
- **Tests**: 3 unit tests (unconditional, no return, conditional)
## Modified Files
**merge/instruction_rewriter.rs** (-15 lines):
- Replaced inline block remapping with `remap_block_id()` call
- Cleaner Branch remap logic
**merge/rewriter/terminator.rs** (-43 lines):
- Delegates remap_jump/remap_branch to block_remapper SSOT
- Simplified duplicate logic
**lowering/loop_with_continue_minimal.rs** (-108 lines):
- Replaced ~100 line return handling with `emit_return_conditional_jump()` call
- Extracted helper functions to return_jump_emitter.rs
- Line reduction: 57% decrease in function complexity
**merge/mod.rs, lowering/mod.rs**:
- Added new module exports (block_remapper, return_jump_emitter)
**phase-284/README.md**:
- Updated completion status (P1 Complete + Refactored)
- Added SSOT consolidation notes
- Documented module architecture
## Code Quality Improvements
| Metric | Before | After | Change |
|--------|--------|-------|--------|
| Duplicate block remap logic | 2 places | SSOT | -15 lines |
| Return handling code | inline (100L) | helper call | -99 lines |
| Testability | Limited | Unit tests (7) | +7 tests |
| Module cohesion | Low (scattered) | High (consolidated) | Better |
## Testing
✅ Build: Success (cargo build --release)
✅ Smoke tests: All pass (46 PASS, 1 pre-existing FAIL)
✅ Regression: Zero
✅ Unit tests: 7 new tests added
## Future Benefits
1. **Pattern5 Reuse**: Direct use of `emit_return_conditional_jump()` helper
2. **Phase 285 (P2)**: Nested if/loop returns via same infrastructure
3. **Maintainability**: SSOT reduces debugging surface area
4. **Clarity**: Each module has single responsibility
## Architectural Notes
**Block Remapper SSOT Rule**:
```
remap_block_id(id, local_block_map, skipped_entry_redirects):
1. Check local_block_map (function-local priority)
2. Fall back to skipped_entry_redirects (global redirects)
3. Return original if not found
```
Prevents function-local block ID collisions with global remap entries.
**Return Emitter Pattern**:
```
emit_return_conditional_jump(func, return_info, k_return_id, alloc_value):
- Pattern1-5: All use same infrastructure
- P1 scope: top-level return only (nested if/loop → P2)
- Returns: JoinInst::Jump(cont=k_return, cond=Some(return_cond))
```
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2025-12-23 14:37:01 +09:00
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Status: P1 Complete (2025-12-23)
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2025-12-23 11:14:28 +09:00
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## Goal
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`return` を “pattern 個別の特例” として増やさず、`ExitKind::Return` と `compose::*` / `emit_frag()` に収束させる。
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移行期間中の検出穴（Ok(None) による黙殺）を消し、Fail-Fast を構造で担保する。
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## SSOT References
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- Frag/ExitKind 設計: `docs/development/current/main/design/edgecfg-fragments.md`
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- Composition API: `src/mir/builder/control_flow/edgecfg/api/compose.rs`
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- Terminator emission: `src/mir/builder/control_flow/edgecfg/api/emit.rs`（`emit_frag()`）
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- Router SSOT（SSOT=extract / safety valve）: `docs/development/current/main/phases/phase-282/README.md`
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## Problem（移行期間の弱さ）
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- Pattern 単位で `return` を “未対応” にすると、検出戦略（Ok(None)/Err）次第で **静かに別経路へ落ちる**。
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- その結果、同じソースでも「どの lowering が `return` を解釈したか」が曖昧になり、SSOT が割れる。
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## Core SSOT（決めること）
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### 1) 返り値の意味（ExitKind）
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- `return expr` は `ExitKind::Return` として表現する。
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- 返り値（ValueId）は `EdgeArgs` で運ぶ（Return edge が value を持つ）。
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- Return は **必ず emit 側で terminator になる**（pattern 側で命令を直に生成しない）。
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### 2) Detect の境界（Ok(None) / Err）
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- `Ok(None)`: 一致しない（次の extractor へ）
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- `Err(...)`: 一致したが未対応（close-but-unsupported）→ **Fail-Fast**
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Phase 284 の完了条件は「`return` を含むケースが close-but-unsupported ではなく SSOT 経路で処理される」状態に寄せること。
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### 3) 実装の集約点（どこに寄せるか）
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- `return` の lowering は **ExitKind + compose + emit_frag** に集約する。
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- pattern の extractor は “認識” のみ（SSOT=extract）。`return` の解釈ロジックを増やさない。
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2025-12-23 14:21:27 +09:00
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補足: Phase 284 は “return だけのため” ではない。ここで固定するのは **Exit 正規化**（ExitKind の語彙化）で、
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`return/break/continue/(将来の unwind)` を同じ土台に載せるのが狙い。
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「Jump/Branch の配線で exit を表現できる」状態ができると、return はその一例として自然に入る。
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## Responsibility Map（迷子防止）
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このフェーズで一番起きやすい事故は「`return` をどこで処理するべきか分からず、pattern 側へ散布してしまう」こと。
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そこで、**どの経路で lower されるか**を前提に責務を固定する。
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### A) Plan line（Pattern6/7）
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- 入口: `src/mir/builder/control_flow/joinir/patterns/router.rs`（route=plan）
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- SSOT:
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- `src/mir/builder/control_flow/plan/normalizer.rs`（Frag 構築: branches/wires/exits）
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- `src/mir/builder/control_flow/edgecfg/api/compose.rs`（合成 SSOT）
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- `src/mir/builder/control_flow/edgecfg/api/emit.rs`（`emit_frag()` terminator SSOT）
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- ここでは `return` を **Return edge（ExitKind::Return）**として組み立てるのが自然。
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### B) JoinIR line（Pattern1–5,9）
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- 入口: `src/mir/builder/control_flow/joinir/patterns/router.rs`（route=joinir）
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- SSOT:
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- JoinIR 生成（pattern 固有の JoinIR lowerer）
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- `src/mir/builder/control_flow/joinir/patterns/conversion_pipeline.rs`（JoinIR→MIR→merge の唯一入口）
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- `src/mir/builder/control_flow/joinir/merge/mod.rs`（Return merge / exit block SSOT）
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- **注意**: `src/mir/builder/control_flow/plan/normalizer.rs` は Plan line 専用なので、
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Pattern4/5 の return 問題の root fix をここへ寄せても効かない。
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### 禁止事項（Phase 284 の憲法）
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- ❌ Pattern4/5 の `lower()` へ「return を特別扱いする if」を散布しない（SSOTが割れる）
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- ❌ Extractor が `return` を見つけた時に `Ok(None)` で黙殺しない（silent reroute 禁止）
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- ✅ `return` の “対応/非対応” は **共通入口の Fail-Fast**で固定する（P1 で実装）
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2025-12-23 11:14:28 +09:00
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## Scope
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refactor(phase284): P1 SSOT Consolidation - Block Remapper & Return Emitter
## Summary
Refactored Phase 284 P1 codebase to consolidate scattered logic into SSOT
(Single Source of Truth) modules, improving maintainability and enabling
Pattern4/5 code reuse.
## New Modules
### 1. Block Remapper SSOT
**File**: `src/mir/builder/control_flow/joinir/merge/block_remapper.rs` (152 lines)
- **Purpose**: Consolidate block ID remapping logic (Phase 284 P1 fix)
- **Function**: `remap_block_id(block_id, local_block_map, skipped_entry_redirects)`
- **Rule**: local_block_map priority > skipped_entry_redirects (prevents ID collision)
- **Tests**: 4 unit tests (priority cascade, collision handling, etc.)
### 2. Return Jump Emitter
**File**: `src/mir/join_ir/lowering/return_jump_emitter.rs` (354 lines)
- **Purpose**: Reusable return handling helper for Pattern4/5
- **Function**: `emit_return_conditional_jump(loop_step_func, return_info, k_return_id, ...)`
- **Scope**: P1 - unconditional return + conditional (loop_var == N) only
- **Tests**: 3 unit tests (unconditional, no return, conditional)
## Modified Files
**merge/instruction_rewriter.rs** (-15 lines):
- Replaced inline block remapping with `remap_block_id()` call
- Cleaner Branch remap logic
**merge/rewriter/terminator.rs** (-43 lines):
- Delegates remap_jump/remap_branch to block_remapper SSOT
- Simplified duplicate logic
**lowering/loop_with_continue_minimal.rs** (-108 lines):
- Replaced ~100 line return handling with `emit_return_conditional_jump()` call
- Extracted helper functions to return_jump_emitter.rs
- Line reduction: 57% decrease in function complexity
**merge/mod.rs, lowering/mod.rs**:
- Added new module exports (block_remapper, return_jump_emitter)
**phase-284/README.md**:
- Updated completion status (P1 Complete + Refactored)
- Added SSOT consolidation notes
- Documented module architecture
## Code Quality Improvements
| Metric | Before | After | Change |
|--------|--------|-------|--------|
| Duplicate block remap logic | 2 places | SSOT | -15 lines |
| Return handling code | inline (100L) | helper call | -99 lines |
| Testability | Limited | Unit tests (7) | +7 tests |
| Module cohesion | Low (scattered) | High (consolidated) | Better |
## Testing
✅ Build: Success (cargo build --release)
✅ Smoke tests: All pass (46 PASS, 1 pre-existing FAIL)
✅ Regression: Zero
✅ Unit tests: 7 new tests added
## Future Benefits
1. **Pattern5 Reuse**: Direct use of `emit_return_conditional_jump()` helper
2. **Phase 285 (P2)**: Nested if/loop returns via same infrastructure
3. **Maintainability**: SSOT reduces debugging surface area
4. **Clarity**: Each module has single responsibility
## Architectural Notes
**Block Remapper SSOT Rule**:
```
remap_block_id(id, local_block_map, skipped_entry_redirects):
1. Check local_block_map (function-local priority)
2. Fall back to skipped_entry_redirects (global redirects)
3. Return original if not found
```
Prevents function-local block ID collisions with global remap entries.
**Return Emitter Pattern**:
```
emit_return_conditional_jump(func, return_info, k_return_id, alloc_value):
- Pattern1-5: All use same infrastructure
- P1 scope: top-level return only (nested if/loop → P2)
- Returns: JoinInst::Jump(cont=k_return, cond=Some(return_cond))
```
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2025-12-23 14:37:01 +09:00
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### P0（docs-only） ✅ COMPLETE
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2025-12-23 11:14:28 +09:00
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- `return` を ExitKind として扱う SSOT を文章で固定する（本ファイル + 参照先リンク）。
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- 移行期間のルール（Ok(None)/Err の境界、黙殺禁止）を Phase 282 と整合させる。
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refactor(phase284): P1 SSOT Consolidation - Block Remapper & Return Emitter
## Summary
Refactored Phase 284 P1 codebase to consolidate scattered logic into SSOT
(Single Source of Truth) modules, improving maintainability and enabling
Pattern4/5 code reuse.
## New Modules
### 1. Block Remapper SSOT
**File**: `src/mir/builder/control_flow/joinir/merge/block_remapper.rs` (152 lines)
- **Purpose**: Consolidate block ID remapping logic (Phase 284 P1 fix)
- **Function**: `remap_block_id(block_id, local_block_map, skipped_entry_redirects)`
- **Rule**: local_block_map priority > skipped_entry_redirects (prevents ID collision)
- **Tests**: 4 unit tests (priority cascade, collision handling, etc.)
### 2. Return Jump Emitter
**File**: `src/mir/join_ir/lowering/return_jump_emitter.rs` (354 lines)
- **Purpose**: Reusable return handling helper for Pattern4/5
- **Function**: `emit_return_conditional_jump(loop_step_func, return_info, k_return_id, ...)`
- **Scope**: P1 - unconditional return + conditional (loop_var == N) only
- **Tests**: 3 unit tests (unconditional, no return, conditional)
## Modified Files
**merge/instruction_rewriter.rs** (-15 lines):
- Replaced inline block remapping with `remap_block_id()` call
- Cleaner Branch remap logic
**merge/rewriter/terminator.rs** (-43 lines):
- Delegates remap_jump/remap_branch to block_remapper SSOT
- Simplified duplicate logic
**lowering/loop_with_continue_minimal.rs** (-108 lines):
- Replaced ~100 line return handling with `emit_return_conditional_jump()` call
- Extracted helper functions to return_jump_emitter.rs
- Line reduction: 57% decrease in function complexity
**merge/mod.rs, lowering/mod.rs**:
- Added new module exports (block_remapper, return_jump_emitter)
**phase-284/README.md**:
- Updated completion status (P1 Complete + Refactored)
- Added SSOT consolidation notes
- Documented module architecture
## Code Quality Improvements
| Metric | Before | After | Change |
|--------|--------|-------|--------|
| Duplicate block remap logic | 2 places | SSOT | -15 lines |
| Return handling code | inline (100L) | helper call | -99 lines |
| Testability | Limited | Unit tests (7) | +7 tests |
| Module cohesion | Low (scattered) | High (consolidated) | Better |
## Testing
✅ Build: Success (cargo build --release)
✅ Smoke tests: All pass (46 PASS, 1 pre-existing FAIL)
✅ Regression: Zero
✅ Unit tests: 7 new tests added
## Future Benefits
1. **Pattern5 Reuse**: Direct use of `emit_return_conditional_jump()` helper
2. **Phase 285 (P2)**: Nested if/loop returns via same infrastructure
3. **Maintainability**: SSOT reduces debugging surface area
4. **Clarity**: Each module has single responsibility
## Architectural Notes
**Block Remapper SSOT Rule**:
```
remap_block_id(id, local_block_map, skipped_entry_redirects):
1. Check local_block_map (function-local priority)
2. Fall back to skipped_entry_redirects (global redirects)
3. Return original if not found
```
Prevents function-local block ID collisions with global remap entries.
**Return Emitter Pattern**:
```
emit_return_conditional_jump(func, return_info, k_return_id, alloc_value):
- Pattern1-5: All use same infrastructure
- P1 scope: top-level return only (nested if/loop → P2)
- Returns: JoinInst::Jump(cont=k_return, cond=Some(return_cond))
```
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2025-12-23 14:37:01 +09:00
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### P1（code） ✅ COMPLETE (2025-12-23)
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2025-12-23 11:14:28 +09:00
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refactor(phase284): P1 SSOT Consolidation - Block Remapper & Return Emitter
## Summary
Refactored Phase 284 P1 codebase to consolidate scattered logic into SSOT
(Single Source of Truth) modules, improving maintainability and enabling
Pattern4/5 code reuse.
## New Modules
### 1. Block Remapper SSOT
**File**: `src/mir/builder/control_flow/joinir/merge/block_remapper.rs` (152 lines)
- **Purpose**: Consolidate block ID remapping logic (Phase 284 P1 fix)
- **Function**: `remap_block_id(block_id, local_block_map, skipped_entry_redirects)`
- **Rule**: local_block_map priority > skipped_entry_redirects (prevents ID collision)
- **Tests**: 4 unit tests (priority cascade, collision handling, etc.)
### 2. Return Jump Emitter
**File**: `src/mir/join_ir/lowering/return_jump_emitter.rs` (354 lines)
- **Purpose**: Reusable return handling helper for Pattern4/5
- **Function**: `emit_return_conditional_jump(loop_step_func, return_info, k_return_id, ...)`
- **Scope**: P1 - unconditional return + conditional (loop_var == N) only
- **Tests**: 3 unit tests (unconditional, no return, conditional)
## Modified Files
**merge/instruction_rewriter.rs** (-15 lines):
- Replaced inline block remapping with `remap_block_id()` call
- Cleaner Branch remap logic
**merge/rewriter/terminator.rs** (-43 lines):
- Delegates remap_jump/remap_branch to block_remapper SSOT
- Simplified duplicate logic
**lowering/loop_with_continue_minimal.rs** (-108 lines):
- Replaced ~100 line return handling with `emit_return_conditional_jump()` call
- Extracted helper functions to return_jump_emitter.rs
- Line reduction: 57% decrease in function complexity
**merge/mod.rs, lowering/mod.rs**:
- Added new module exports (block_remapper, return_jump_emitter)
**phase-284/README.md**:
- Updated completion status (P1 Complete + Refactored)
- Added SSOT consolidation notes
- Documented module architecture
## Code Quality Improvements
| Metric | Before | After | Change |
|--------|--------|-------|--------|
| Duplicate block remap logic | 2 places | SSOT | -15 lines |
| Return handling code | inline (100L) | helper call | -99 lines |
| Testability | Limited | Unit tests (7) | +7 tests |
| Module cohesion | Low (scattered) | High (consolidated) | Better |
## Testing
✅ Build: Success (cargo build --release)
✅ Smoke tests: All pass (46 PASS, 1 pre-existing FAIL)
✅ Regression: Zero
✅ Unit tests: 7 new tests added
## Future Benefits
1. **Pattern5 Reuse**: Direct use of `emit_return_conditional_jump()` helper
2. **Phase 285 (P2)**: Nested if/loop returns via same infrastructure
3. **Maintainability**: SSOT reduces debugging surface area
4. **Clarity**: Each module has single responsibility
## Architectural Notes
**Block Remapper SSOT Rule**:
```
remap_block_id(id, local_block_map, skipped_entry_redirects):
1. Check local_block_map (function-local priority)
2. Fall back to skipped_entry_redirects (global redirects)
3. Return original if not found
```
Prevents function-local block ID collisions with global remap entries.
**Return Emitter Pattern**:
```
emit_return_conditional_jump(func, return_info, k_return_id, alloc_value):
- Pattern1-5: All use same infrastructure
- P1 scope: top-level return only (nested if/loop → P2)
- Returns: JoinInst::Jump(cont=k_return, cond=Some(return_cond))
```
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2025-12-23 14:37:01 +09:00
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**実装完了内容**:
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1. **return_collector.rs** - Return statement detection SSOT (既存)
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2. **return_jump_emitter.rs** - Return jump emission helper (Pattern4/5 reuse) ⭐NEW
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3. **block_remapper.rs** - Block ID remap SSOT (Phase 284 P1 Fix) ⭐NEW
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4. **Loop refactoring** - loop_with_continue_minimal.rs simplified (~100 lines removed)
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5. **Instruction/terminator updates** - Use block_remapper SSOT
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**コード品質向上**:
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- Return handling: ~100 lines inline code → 1 function call
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- Block remapping: Duplicate logic → SSOT function
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- Future reusability: Pattern5 can now reuse return_jump_emitter
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### P2+（未実装）
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- `return` を含む loop body を、Plan line でも ExitKind::Return に落とす。
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2025-12-23 11:14:28 +09:00
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- VM/LLVM の両方で、`return` を含む fixture を smoke 化して SSOT を固定する。
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## Acceptance
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- P0: `return` の SSOT（ExitKind/compose/emit）と detect 境界が明文化されている
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- P1+: `return` を含む loop fixture が VM/LLVM で同一結果になり、smoke で固定されている
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2025-12-23 14:21:27 +09:00
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## P1 の実装方針（design-first 注記）
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P1 の root fix は「PlanNormalizer へ寄せる」ではなく、**JoinIR line の共通入口**へ寄せる：
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- 入口候補:
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- `src/mir/builder/control_flow/joinir/patterns/conversion_pipeline.rs`（最終的な “ここで統一したい”）
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- もしくは JoinIR lowerer 側に “Return collector” を 1 箇所だけ作り、Pattern4/5 はそれを呼ぶだけにする
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どちらにしても、目的は同じ：
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- pattern 側へロジックを増やさず（散布しない）
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- `ExitKind::Return` へ収束させる（MIR では Return 終端として生成される）
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