chore: Phase 25.1 完了 - LoopForm v2/Stage1 CLI/環境変数削減 + Phase 26-D からの変更

Phase 25.1 完了成果:
- ✅ LoopForm v2 テスト・ドキュメント・コメント完備
  - 4ケース（A/B/C/D）完全テストカバレッジ
  - 最小再現ケース作成（SSAバグ調査用）
  - SSOT文書作成（loopform_ssot.md）
  - 全ソースに [LoopForm] コメントタグ追加

- ✅ Stage-1 CLI デバッグ環境構築
  - stage1_cli.hako 実装
  - stage1_bridge.rs ブリッジ実装
  - デバッグツール作成（stage1_debug.sh/stage1_minimal.sh）
  - アーキテクチャ改善提案文書

- ✅ 環境変数削減計画策定
  - 25変数の完全調査・分類
  - 6段階削減ロードマップ（25→5、80%削減）
  - 即時削除可能変数特定（NYASH_CONFIG/NYASH_DEBUG）

Phase 26-D からの累積変更:
- PHI実装改善（ExitPhiBuilder/HeaderPhiBuilder等）
- MIRビルダーリファクタリング
- 型伝播・最適化パス改善
- その他約300ファイルの累積変更

🎯 技術的成果:
- SSAバグ根本原因特定（条件分岐内loop変数変更）
- Region+next_iパターン適用完了（UsingCollectorBox等）
- LoopFormパターン文書化・テスト化完了
- セルフホスティング基盤強化

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: ChatGPT <noreply@openai.com>
Co-Authored-By: Task Assistant <task@anthropic.com>

src/mir/verification/barrier.rs

@@ -69,7 +69,7 @@ pub fn check_weakref_and_barrier(function: &MirFunction) -> Result<(), Vec<Verif
                 | MirInstruction::BarrierWrite { ptr } => {
                     if let Some((_db, _di, def_inst)) = def_map.get(ptr) {
                         if let MirInstruction::Const {
-                    value: crate::mir::ConstValue::Void,
+                            value: crate::mir::ConstValue::Void,
                             ..
                         } = def_inst
                         {

src/mir/verification/cfg.rs

@@ -1,7 +1,7 @@
 use crate::mir::function::MirFunction;
-use crate::mir::{BasicBlockId, ValueId};
-use crate::mir::verification_types::VerificationError;
 use crate::mir::verification::utils;
+use crate::mir::verification_types::VerificationError;
+use crate::mir::{BasicBlockId, ValueId};
 use std::collections::{HashMap, HashSet};
 
 /// Verify CFG references and reachability
@@ -23,12 +23,18 @@ pub fn check_control_flow(function: &MirFunction) -> Result<(), Vec<Verification
     // control flow terminators. This is standard practice (see LLVM's `unreachable`).
     // Dead code elimination pass (TODO) will remove them during optimization.
 
-    if errors.is_empty() { Ok(()) } else { Err(errors) }
+    if errors.is_empty() {
+        Ok(())
+    } else {
+        Err(errors)
+    }
 }
 
 /// Verify that merge blocks do not use predecessor-defined values directly (must go through Phi)
 pub fn check_merge_uses(function: &MirFunction) -> Result<(), Vec<VerificationError>> {
-    if crate::config::env::verify_allow_no_phi() { return Ok(()); }
+    if crate::config::env::verify_allow_no_phi() {
+        return Ok(());
+    }
     let mut errors = Vec::new();
     let preds = utils::compute_predecessors(function);
     let def_block = utils::compute_def_blocks(function);
@@ -37,28 +43,43 @@ pub fn check_merge_uses(function: &MirFunction) -> Result<(), Vec<VerificationEr
     for (bid, block) in &function.blocks {
         let set = phi_dsts_in_block.entry(*bid).or_default();
         for inst in block.all_instructions() {
-            if let crate::mir::MirInstruction::Phi { dst, .. } = inst { set.insert(*dst); }
+            if let crate::mir::MirInstruction::Phi { dst, .. } = inst {
+                set.insert(*dst);
+            }
         }
     }
     for (bid, block) in &function.blocks {
-        let Some(pred_list) = preds.get(bid) else { continue };
-        if pred_list.len() < 2 { continue; }
+        let Some(pred_list) = preds.get(bid) else {
+            continue;
+        };
+        if pred_list.len() < 2 {
+            continue;
+        }
         let phi_dsts = phi_dsts_in_block.get(bid);
         let doms_of_block = dominators.get(bid).unwrap();
         for inst in block.all_instructions() {
-            if let crate::mir::MirInstruction::Phi { .. } = inst { continue; }
+            if let crate::mir::MirInstruction::Phi { .. } = inst {
+                continue;
+            }
             for used in inst.used_values() {
                 if let Some(&db) = def_block.get(&used) {
                     if !doms_of_block.contains(&db) {
                         let is_phi_dst = phi_dsts.map(|s| s.contains(&used)).unwrap_or(false);
                         if !is_phi_dst {
-                            errors.push(VerificationError::MergeUsesPredecessorValue { value: used, merge_block: *bid, pred_block: db });
+                            errors.push(VerificationError::MergeUsesPredecessorValue {
+                                value: used,
+                                merge_block: *bid,
+                                pred_block: db,
+                            });
                         }
                     }
                 }
             }
         }
     }
-    if errors.is_empty() { Ok(()) } else { Err(errors) }
+    if errors.is_empty() {
+        Ok(())
+    } else {
+        Err(errors)
+    }
 }
-

src/mir/verification/dom.rs

@@ -1,16 +1,20 @@
 use crate::mir::function::MirFunction;
-use crate::mir::verification_types::VerificationError;
 use crate::mir::verification::utils;
+use crate::mir::verification_types::VerificationError;
 
 /// Verify dominance: def must dominate use across blocks (Phi inputs excluded)
 pub fn check_dominance(function: &MirFunction) -> Result<(), Vec<VerificationError>> {
-    if crate::config::env::verify_allow_no_phi() { return Ok(()); }
+    if crate::config::env::verify_allow_no_phi() {
+        return Ok(());
+    }
     let mut errors = Vec::new();
     let def_block = utils::compute_def_blocks(function);
     let dominators = utils::compute_dominators(function);
     for (use_block_id, block) in &function.blocks {
         for instruction in block.all_instructions() {
-            if let crate::mir::MirInstruction::Phi { .. } = instruction { continue; }
+            if let crate::mir::MirInstruction::Phi { .. } = instruction {
+                continue;
+            }
             for used_value in instruction.used_values() {
                 if let Some(&def_bb) = def_block.get(&used_value) {
                     if def_bb != *use_block_id {
@@ -27,6 +31,9 @@ pub fn check_dominance(function: &MirFunction) -> Result<(), Vec<VerificationErr
             }
         }
     }
-    if errors.is_empty() { Ok(()) } else { Err(errors) }
+    if errors.is_empty() {
+        Ok(())
+    } else {
+        Err(errors)
+    }
 }
-

src/mir/verification/ssa.rs

@@ -1,6 +1,6 @@
 use crate::mir::function::MirFunction;
-use crate::mir::{ValueId};
 use crate::mir::verification_types::VerificationError;
+use crate::mir::ValueId;
 
 /// Verify SSA form: single assignment and all uses defined
 pub fn check_ssa_form(function: &MirFunction) -> Result<(), Vec<VerificationError>> {
@@ -45,5 +45,9 @@ pub fn check_ssa_form(function: &MirFunction) -> Result<(), Vec<VerificationErro
         }
     }
 
-    if errors.is_empty() { Ok(()) } else { Err(errors) }
+    if errors.is_empty() {
+        Ok(())
+    } else {
+        Err(errors)
+    }
 }