diff --git a/CURRENT_TASK.md b/CURRENT_TASK.md
index 83001214..45f64a12 100644
--- a/CURRENT_TASK.md
+++ b/CURRENT_TASK.md
@@ -43,6 +43,9 @@ Clone() Reduction — Phase 1 (Arc/str)
   - `TypeBox.type_parameters: Vec<String>` → `Vec<Arc<str>>`.
   - Adjusted builder/registry and `full_name()` accordingly; public behavior unchanged.
   - Rationale: share-on-clone for frequently copied identifiers, reduce String allocations.
+ - TypeRegistry
+   - `types: HashMap<String, Arc<TypeBox>>` → `HashMap<Arc<str>, Arc<TypeBox>>`（内部型名の共有化）。
+   - API互換（`get_type(&str)` は Borrow によりそのまま利用可能）。
 
 Refactor Plan (next 1–2 weeks)
 1) Split parse_box_declaration (667 lines) in src/parser/declarations/box_definition.rs
diff --git a/src/parser/declarations/box_definition.rs b/src/parser/declarations/box_definition.rs
index a2a50ca8..02e90a29 100644
--- a/src/parser/declarations/box_definition.rs
+++ b/src/parser/declarations/box_definition.rs
@@ -13,6 +13,78 @@ use crate::tokenizer::TokenType;
 use std::collections::HashMap;
 
 impl NyashParser {
+    /// Validate that birth_once properties do not have cyclic dependencies via me.<prop> references
+    fn validate_birth_once_cycles(
+        &mut self,
+        methods: &HashMap<String, ASTNode>,
+    ) -> Result<(), ParseError> {
+        if !crate::config::env::unified_members() {
+            return Ok(());
+        }
+        use std::collections::{HashMap, HashSet};
+        // Collect birth_once compute bodies
+        let mut birth_bodies: HashMap<String, Vec<ASTNode>> = HashMap::new();
+        for (mname, mast) in methods {
+            if let Some(prop) = mname.strip_prefix("__compute_birth_") {
+                if let ASTNode::FunctionDeclaration { body, .. } = mast {
+                    birth_bodies.insert(prop.to_string(), body.clone());
+                }
+            }
+        }
+        if birth_bodies.is_empty() {
+            return Ok(());
+        }
+        // Build dependency graph: A -> {B | me.B used inside A}
+        let mut deps: HashMap<String, HashSet<String>> = HashMap::new();
+        let props: HashSet<String> = birth_bodies.keys().cloned().collect();
+        for (p, body) in &birth_bodies {
+            let used = self.ast_collect_me_fields(body);
+            let mut set = HashSet::new();
+            for u in used {
+                if props.contains(&u) && u != *p {
+                    set.insert(u);
+                }
+            }
+            deps.insert(p.clone(), set);
+        }
+        // Detect cycle via DFS
+        fn has_cycle(
+            node: &str,
+            deps: &HashMap<String, HashSet<String>>,
+            temp: &mut HashSet<String>,
+            perm: &mut HashSet<String>,
+        ) -> bool {
+            if perm.contains(node) {
+                return false;
+            }
+            if !temp.insert(node.to_string()) {
+                return true; // back-edge
+            }
+            if let Some(ns) = deps.get(node) {
+                for n in ns {
+                    if has_cycle(n, deps, temp, perm) {
+                        return true;
+                    }
+                }
+            }
+            temp.remove(node);
+            perm.insert(node.to_string());
+            false
+        }
+        let mut perm = HashSet::new();
+        let mut temp = HashSet::new();
+        for p in deps.keys() {
+            if has_cycle(p, &deps, &mut temp, &mut perm) {
+                let line = self.current_token().line;
+                return Err(ParseError::UnexpectedToken {
+                    found: self.current_token().token_type.clone(),
+                    expected: "birth_once declarations must not have cyclic dependencies".to_string(),
+                    line,
+                });
+            }
+        }
+        Ok(())
+    }
     /// Extracted: parse block-first unified member: `{ body } as [once|birth_once]? name : Type [postfix]`
     /// Returns true if a member was parsed and emitted into `methods`.
     fn parse_unified_member_block_first(
@@ -565,67 +637,7 @@ impl NyashParser {
         }
 
         // birth_once 相互依存の簡易検出（宣言間の循環）
-        if crate::config::env::unified_members() {
-            // Collect birth_once compute bodies
-            use std::collections::{HashMap, HashSet};
-            let mut birth_bodies: HashMap<String, Vec<ASTNode>> = HashMap::new();
-            for (mname, mast) in &methods {
-                if let Some(prop) = mname.strip_prefix("__compute_birth_") {
-                    if let ASTNode::FunctionDeclaration { body, .. } = mast {
-                        birth_bodies.insert(prop.to_string(), body.clone());
-                    }
-                }
-            }
-            // Build dependency graph: A -> {B | me.B used inside A}
-            let mut deps: HashMap<String, HashSet<String>> = HashMap::new();
-            let props: HashSet<String> = birth_bodies.keys().cloned().collect();
-            for (p, body) in &birth_bodies {
-                let used = self.ast_collect_me_fields(body);
-                let mut set = HashSet::new();
-                for u in used {
-                    if props.contains(&u) && u != *p {
-                        set.insert(u);
-                    }
-                }
-                deps.insert(p.clone(), set);
-            }
-            // Detect cycle via DFS
-            fn has_cycle(
-                node: &str,
-                deps: &HashMap<String, HashSet<String>>,
-                temp: &mut HashSet<String>,
-                perm: &mut HashSet<String>,
-            ) -> bool {
-                if perm.contains(node) {
-                    return false;
-                }
-                if !temp.insert(node.to_string()) {
-                    return true; // back-edge
-                }
-                if let Some(ns) = deps.get(node) {
-                    for n in ns {
-                        if has_cycle(n, deps, temp, perm) {
-                            return true;
-                        }
-                    }
-                }
-                temp.remove(node);
-                perm.insert(node.to_string());
-                false
-            }
-            let mut perm = HashSet::new();
-            let mut temp = HashSet::new();
-            for p in deps.keys() {
-                if has_cycle(p, &deps, &mut temp, &mut perm) {
-                    let line = self.current_token().line;
-                    return Err(ParseError::UnexpectedToken {
-                        found: self.current_token().token_type.clone(),
-                        expected: "birth_once declarations must not have cyclic dependencies".to_string(),
-                        line,
-                    });
-                }
-            }
-        }
+        self.validate_birth_once_cycles(&methods)?;
 
         Ok(ASTNode::BoxDeclaration {
             name,
diff --git a/src/type_box.rs b/src/type_box.rs
index bd765340..3282e1f0 100644
--- a/src/type_box.rs
+++ b/src/type_box.rs
@@ -14,7 +14,7 @@ use std::sync::Arc;
 /// メソッドシグニチャ情報
 #[derive(Debug, Clone)]
 pub struct MethodSignature {
-    pub name: String,
+    pub name: Arc<str>,
     pub parameters: Vec<String>,
     pub parameter_types: Vec<Arc<TypeBox>>,
     pub return_type: Arc<TypeBox>,
@@ -22,9 +22,9 @@ pub struct MethodSignature {
 }
 
 impl MethodSignature {
-    pub fn new(name: String, parameters: Vec<String>) -> Self {
+    pub fn new<N: Into<Arc<str>>>(name: N, parameters: Vec<String>) -> Self {
         Self {
-            name,
+            name: name.into(),
             parameters,
             parameter_types: Vec::new(),
             return_type: Arc::new(TypeBox::void_type()),
@@ -32,14 +32,14 @@ impl MethodSignature {
         }
     }
 
-    pub fn with_types(
-        name: String,
+    pub fn with_types<N: Into<Arc<str>>>(
+        name: N,
         parameters: Vec<String>,
         parameter_types: Vec<Arc<TypeBox>>,
         return_type: Arc<TypeBox>,
     ) -> Self {
         Self {
-            name,
+            name: name.into(),
             parameters,
             parameter_types,
             return_type,
@@ -58,7 +58,7 @@ pub struct TypeBox {
     pub fields: HashMap<String, Arc<TypeBox>>,
 
     /// メソッドシグニチャ情報
-    pub methods: HashMap<String, MethodSignature>,
+    pub methods: HashMap<Arc<str>, MethodSignature>,
 
     /// 親型（継承）
     pub parent_type: Option<Arc<TypeBox>>,
@@ -295,7 +295,7 @@ impl Display for TypeBox {
 #[derive(Debug)]
 pub struct TypeRegistry {
     /// 登録済み型
-    types: HashMap<String, Arc<TypeBox>>,
+    types: HashMap<Arc<str>, Arc<TypeBox>>,
 
     /// 継承チェーン情報（高速化用）
     inheritance_chains: HashMap<String, Vec<String>>,
@@ -342,7 +342,7 @@ impl TypeRegistry {
         }
 
         self.inheritance_chains.insert(name_s.clone(), chain);
-        self.types.insert(name_s, type_box);
+        self.types.insert(type_box.name.clone(), type_box);
     }
 
     /// 型を取得
@@ -365,7 +365,7 @@ impl TypeRegistry {
 
     /// すべての型名を取得
     pub fn get_all_type_names(&self) -> Vec<String> {
-        self.types.keys().cloned().collect()
+        self.types.keys().map(|k| k.as_ref().to_string()).collect()
     }
 
     /// ジェネリクス型をインスタンス化
diff --git a/tools/test/smoke/llvm/ir_phi_empty_check_all.sh b/tools/test/smoke/llvm/ir_phi_empty_check_all.sh
new file mode 100644
index 00000000..eaad9e45
--- /dev/null
+++ b/tools/test/smoke/llvm/ir_phi_empty_check_all.sh
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Run empty-PHI checker across a curated set of test cases
+CASES=(
+  apps/tests/hello_simple_llvm.nyash
+  apps/tests/loop_if_phi.nyash
+  apps/tests/llvm_phi_mix.nyash
+  apps/tests/llvm_phi_heavy_mix.nyash
+  apps/tests/llvm_phi_try_mix.nyash
+)
+
+DIR="tools/test/smoke/llvm"
+
+for c in "${CASES[@]}"; do
+  echo "[phi-empty-check-all] -> $c"
+  bash "$DIR/ir_phi_empty_check.sh" "$c"
+done
+
+echo "[phi-empty-check-all] OK: all cases passed"