diff --git a/luisa_compute/src/lang.rs b/luisa_compute/src/lang.rs
index c4181d7..c8249b4 100644
--- a/luisa_compute/src/lang.rs
+++ b/luisa_compute/src/lang.rs
@@ -309,7 +309,7 @@ pub(crate) struct FnRecorder {
     pub(crate) block_size: Option<[u32; 3]>,
     pub(crate) building_kernel: bool,
     pub(crate) pools: CArc<ModulePools>,
-    pub(crate) arena: Bump,
+    pub(crate) arena: Rc<Bump>,
     pub(crate) dtors: Vec<(*mut u8, fn(*mut u8))>,
     pub(crate) callable_ret_type: Option<CArc<Type>>,
     pub(crate) const_builder: IrBuilder,
@@ -427,7 +427,9 @@ impl FnRecorder {
             device: None,
             block_size: None,
             pools: pools.clone(),
-            arena: Bump::new(),
+            arena: parent.as_ref()
+                .map(|p| p.borrow().arena.clone())
+                .unwrap_or_else(|| Rc::new(Bump::new())),
             building_kernel: false,
             callable_ret_type: None,
             kernel_id,
diff --git a/luisa_compute/src/lang/functions.rs b/luisa_compute/src/lang/functions.rs
index 89b40f1..bcf9fe8 100644
--- a/luisa_compute/src/lang/functions.rs
+++ b/luisa_compute/src/lang/functions.rs
@@ -184,11 +184,12 @@ pub fn set_block_size(size: [u32; 3]) {
     });
 }
 
-pub fn block_size() -> Expr<Uint3> {
-    with_recorder(|r| {
-        let s = r.block_size.unwrap_or_else(|| panic!("Block size not set"));
-        Uint3::new(s[0], s[1], s[2]).expr()
-    })
+pub fn block_size() -> [u32; 3] {
+    with_recorder(|r| r.block_size.unwrap_or_else(|| panic!("Block size not set")))
+}
+pub fn block_size_expr() -> Expr<Uint3> {
+    let sz = block_size();
+    Uint3::expr(sz[0], sz[1], sz[2])
 }
 
 pub unsafe fn bitcast<From: Value, To: Value>(expr: Expr<From>) -> Expr<To> {
diff --git a/luisa_compute/src/lang/types/shared.rs b/luisa_compute/src/lang/types/shared.rs
index a3a1aab..a8c4dbb 100644
--- a/luisa_compute/src/lang/types/shared.rs
+++ b/luisa_compute/src/lang/types/shared.rs
@@ -41,21 +41,6 @@ impl<T: Value> Shared<T> {
             _ => unreachable!(),
         }
     }
-    pub fn write<I: IntoIndex, V: Into<Expr<T>>>(&self, i: I, value: V) {
-        let i = i.to_u64();
-        let value = value.into();
-
-        if need_runtime_check() {
-            check_index_lt_usize(i, self.len());
-        }
-        let i = i.node().get();
-        let value = value.node().get();
-        let self_node = self.node.get();
-        __current_scope(|b| {
-            let gep = b.call(Func::GetElementPtr, &[self_node, i], T::type_());
-            b.update(gep, value);
-        });
-    }
     pub fn load(&self) -> VLArrayExpr<T> {
         let self_node = self.node.get();
         VLArrayExpr::from_node(
@@ -70,3 +55,40 @@ impl<T: Value> Shared<T> {
         });
     }
 }
+impl<T: Value> IndexRead for Shared<T> {
+    type Element = T;
+    fn read<I: IntoIndex>(&self, i: I) -> Expr<Self::Element> {
+        let i = i.to_u64();
+
+        if need_runtime_check() {
+            check_index_lt_usize(i, self.len());
+        }
+        let i = i.node().get();
+        let self_node = self.node.get();
+        Expr::from_node(
+            __current_scope(|b| {
+                let gep = b.call(Func::GetElementPtr, &[self_node, i], T::type_());
+                b.load(gep)
+            })
+            .into(),
+        )
+    }
+}
+
+impl<T: Value> IndexWrite for Shared<T> {
+    fn write<I: IntoIndex, V: AsExpr<Value = Self::Element>>(&self, i: I, value: V) {
+        let i = i.to_u64();
+        let value = value.as_expr();
+
+        if need_runtime_check() {
+            check_index_lt_usize(i, self.len());
+        }
+        let i = i.node().get();
+        let value = value.node().get();
+        let self_node = self.node.get();
+        __current_scope(|b| {
+            let gep = b.call(Func::GetElementPtr, &[self_node, i], T::type_());
+            b.update(gep, value);
+        });
+    }
+}