feat(llvm): Phase 131-13/14 - MIR JSON順序修正 & 2パスsnapshot解決
## Phase 131-13: MIR JSON 命令順序修正 - copy 遅延ロジック削除（~80行） - MIR の def→use 順序をそのまま出力（SSOT） - PHI 先頭集約のみ維持 ## Phase 131-14: jump-only block 2パス snapshot 解決 - Pass A: jump-only block はメタ記録のみ - Pass B: resolve_jump_only_snapshots() で CFG ベース解決 - path compression で連鎖を効率的に解決 - サイクル検出で Fail-Fast ## 結果 - ✅ STRICT モードでエラーなし - ✅ bb7 が bb5 の snapshot を正しく継承 - ✅ ループが正しく動作（1, 2 出力確認） - ⚠️ print/concat で segfault（別問題、次Phase） 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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nyash-codex
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# Phase 131-13: MIR JSON Instruction Order Fix - COMPLETED ✅
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Status: **RESOLVED** (2025-12-14)
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Scope: Rust 側の `MIR → JSON (harness)` 出力で、ブロック内の命令順序が崩れて Python LLVM backend が Fail-Fast する問題。
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Related:
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- SSOT (LLVM棚卸し): `docs/development/current/main/phase131-3-llvm-lowering-inventory.md`
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- Case C: `docs/development/current/main/phase131-11-case-c-summary.md`
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## Problem Summary
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**Issue**: LLVM Stage-3 Case C (loop control) failed with undefined value error
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- Test: `apps/tests/llvm_stage3_loop_only.hako`
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- Symptom: `binop dst=19 lhs=17 rhs=18` used undefined v17 and v18
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- Root cause: JSON emitter reordered instructions, breaking def-use chain
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### Original JSON Order (Broken)
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```json
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{
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"id": 3,
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"instructions": [
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{"op": "const", "dst": 16},
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{"op": "binop", "dst": 19, "lhs": 17, "rhs": 18}, // ❌ Use v17, v18 before def
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{"op": "copy", "dst": 17, "src": 16}, // ⚠️ Define v17 AFTER use
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{"op": "copy", "dst": 18, "src": 1}, // ⚠️ Define v18 AFTER use
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{"op": "copy", "dst": 20, "src": 19}
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]
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}
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```
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## Root Cause Analysis
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`src/runner/mir_json_emit.rs` が "use-before-def copy 回避" を目的に **copy の遅延/再配置**を行っており、
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依存（copy dst を参照する binop 等）まで含めた正しいスケジューリングになっていなかった。
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この層（JSON emitter）は optimizer/scheduler ではないため、順序修正を試みるより **Fail-Fast で upstream を炙り出す**のが筋。
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### Responsible Code (Lines 193-266, 652-710)
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```rust
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// Pre-scan: collect values defined anywhere in this block (to delay use-before-def copies)
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let mut block_defines: std::collections::HashSet<u32> = ...;
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let mut emitted_defs: std::collections::HashSet<u32> = ...;
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let mut delayed_copies: Vec<(u32, u32)> = Vec::new();
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// Delay copies if source will be defined later
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if block_defines.contains(&s) && !emitted_defs.contains(&s) {
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delayed_copies.push((d, s)); // ❌ Reordering!
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}
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// Emit delayed copies after sources should be available
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for (d, s) in delayed_copies {
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insts.push(json!({"op":"copy","dst": d, "src": s}));
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}
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```
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## Solution: SSOT Principle ✅
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**Box Theory Diagnosis**: Responsibility boundary violation
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- **JSON Emitter responsibility**: Output MIR instructions in original order
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- **Builder/Optimizer/Verifier responsibility**: Ensure correct def-use order upstream
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### SSOT: 「順序を直す場所」を固定する
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- ✅ JSON emitter は "順序を変えない"（MIR の命令列をそのまま出力する）
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- ✅ もし MIR 自体に use-before-def があるなら、builder/optimizer/verifier 側で直す（またはそこで Fail-Fast）
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### Fix Implementation
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**P0-1: Remove all reordering logic** (except PHI consolidation)
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```rust
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// Phase 131-13: Emit all instructions in MIR order (SSOT principle)
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// No reordering except PHI consolidation at block start (LLVM constraint)
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// Step 1: Emit all PHI instructions first (LLVM requirement)
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for inst in &bb.instructions {
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if let I::Phi { ... } => { insts.push(phi_inst); }
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}
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// Step 2: Emit all non-PHI instructions in MIR order (no reordering!)
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for inst in &bb.instructions {
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match inst {
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I::Phi { .. } => continue, // Already emitted
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I::Copy { dst, src } => {
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insts.push(json!({"op":"copy","dst": dst.as_u32(), "src": src.as_u32()}));
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}
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// ... other instructions in order
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}
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}
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```
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### Emit 規約 (Updated)
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- ✅ PHI は block の先頭（LLVM 制約）。JSON 側で先頭に集約済み。
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- ✅ 非PHIは MIR の順序を保持して出力する（並べ替えない）。
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- ✅ Terminator は最後。
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**Changes**:
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- ✅ Removed `block_defines` HashSet
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- ✅ Removed `emitted_defs` HashSet
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- ✅ Removed `delayed_copies` Vec
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- ✅ Removed all `emitted_defs.insert()` calls
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- ✅ Removed delayed copy emission loop
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- ✅ Applied fix to both `emit_mir_json_for_harness` (lib) and `emit_mir_json_for_harness_bin` (bin)
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### Fixed JSON Order ✅
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```json
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{
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"id": 3,
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"instructions": [
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{"op": "phi", "dst": 1},
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{"op": "const", "dst": 16},
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{"op": "copy", "dst": 17, "src": 16}, // ✅ Define v17 first
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{"op": "copy", "dst": 18, "src": 1}, // ✅ Define v18 second
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{"op": "binop", "dst": 19, "lhs": 17, "rhs": 18}, // ✅ Use v17, v18 after def
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{"op": "copy", "dst": 20, "src": 19},
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{"op": "mir_call", ...},
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{"op": "const", "dst": 21},
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{"op": "ret"}
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]
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}
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```
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## Verification ✅
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### Test Execution
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```bash
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# Generate fixed JSON
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NYASH_DISABLE_PLUGINS=1 ./target/release/hakorune --backend mir \
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--emit-mir-json /tmp/fixed.json apps/tests/llvm_stage3_loop_only.hako
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# Output: MIR JSON written: /tmp/fixed.json
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# Verify instruction order
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cat /tmp/fixed.json | jq '.functions[] | select(.name == "main") | .blocks[1].instructions'
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# ✅ Correct: copy dst=17, copy dst=18, binop lhs=17 rhs=18
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```
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### Build Status
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```bash
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cargo build --release
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# ✅ 0 errors, 0 warnings
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```
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## Done 条件 ✅
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- ✅ Case C の JSON 出力で def→use 順序が正しい
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- ✅ LLVM harness が正しく型解決できる（use-before-def エラーなし）
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- ✅ ビルド成功（0 errors, 0 warnings）
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## Fail-Fast チェック（Future Work）
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JSON emit 時に、同一ブロック内の use-before-def を検出したら明示エラーにする（"直そうとしない"）。
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**P1: Add use-before-def detector** (NYASH_MIR_STRICT mode) - TODO
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```rust
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fn check_use_before_def(block: &BasicBlock) -> Result<(), String> {
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let mut defined: HashSet<ValueId> = HashSet::new();
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for inst in &block.instructions {
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// Check all operands are defined
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for operand in inst.operands() {
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if !defined.contains(&operand) && !is_phi(inst) && !is_block_param(operand) {
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if strict_mode() {
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return Err(format!("Use-before-def: v{}", operand.as_u32()));
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} else {
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eprintln!("[WARN] Use-before-def: v{}", operand.as_u32());
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}
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}
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}
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if let Some(dst) = inst.dst() {
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defined.insert(dst);
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}
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}
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Ok(())
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}
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```
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## Files Modified
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- `src/runner/mir_json_emit.rs`: Core fix (removed ~80 lines of reordering logic)
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## Box Theory Insights
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**Fail-Fast Principle**: Instead of hiding errors with reordering, expose them early
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- ❌ Old approach: Emitter tries to fix broken MIR (scheduler role)
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- ✅ New approach: Emitter outputs MIR as-is, builder ensures correctness
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**SSOT Boundary**:
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- **Upstream** (builder.rs): Responsible for def-use order
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- **Emitter** (mir_json_emit.rs): Responsible for faithful output
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- **Downstream** (LLVM harness): Expects correct order from JSON
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@ -211,6 +211,11 @@ VM and MIR look correct, but LLVM output does not match expected result for Case
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- `return counter` (no string concat)
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- `print(counter)` (no `"Result: " + ...`)
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- Compare with VM and inspect the IR use-sites.
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**Update (Phase 131-13)**:
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- snapshot-only + strict resolver により、Case C の不一致が “LLVM の値解決バグ” ではなく
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“Rust の MIR→JSON emit が block 内命令順序を崩している” 問題として顕在化した。
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- Investigation note: `docs/development/current/main/investigations/phase131-13-mir-json-instruction-order.md`
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- Add `is_infinite_loop: bool` feature to `LoopFeatures` (detect `loop(true)`).
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- Fix classification so `has_break && has_continue` does not route to Pattern 4.
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- Introduce a dedicated pattern kind + lowerer for **infinite loop + early-exit (+ optional continue)**:
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