diff --git a/luisa_compute/examples/custom_op.rs b/luisa_compute/examples/custom_op.rs
index 1513bfe..6383550 100644
--- a/luisa_compute/examples/custom_op.rs
+++ b/luisa_compute/examples/custom_op.rs
@@ -1,6 +1,6 @@
 use std::env::current_exe;
 
-use luisa::lang::debug::CpuFn;
+use luisa::lang::external::CpuFn;
 use luisa::prelude::*;
 use luisa_compute as luisa;
 #[derive(Clone, Copy, Value, Debug)]
diff --git a/luisa_compute/src/lang.rs b/luisa_compute/src/lang.rs
index 61e87fe..cd071fe 100644
--- a/luisa_compute/src/lang.rs
+++ b/luisa_compute/src/lang.rs
@@ -35,6 +35,7 @@ pub mod ops;
 pub mod poly;
 pub mod soa;
 pub mod types;
+pub mod external;
 
 pub(crate) trait CallFuncTrait {
     fn call<T: Value, S: Value>(self, x: Expr<T>) -> Expr<S>;
diff --git a/luisa_compute/src/lang/debug.rs b/luisa_compute/src/lang/debug.rs
index 5b8f5da..20e2c4c 100644
--- a/luisa_compute/src/lang/debug.rs
+++ b/luisa_compute/src/lang/debug.rs
@@ -1,85 +1,8 @@
-use ir::CpuCustomOp;
 use std::ffi::CString;
 use std::fmt::Debug;
-use std::sync::Arc;
 
 use crate::internal_prelude::*;
 
-pub struct CpuFn<T: Value> {
-    op: CArc<CpuCustomOp>,
-    _marker: PhantomData<T>,
-}
-
-/*
-Interestingly, Box::into_raw(Box<Closure>) does not give a valid pointer.
-*/
-struct ClosureContainer<T> {
-    f: Arc<dyn Fn(&mut T) + 'static + Send + Sync>,
-}
-
-impl<T: Value> CpuFn<T> {
-    pub fn new<F: Fn(&mut T) + 'static + Send + Sync>(f: F) -> Self {
-        let f_ptr = Box::into_raw(Box::new(ClosureContainer::<T> { f: Arc::new(f) }));
-        let op = CpuCustomOp {
-            data: f_ptr as *mut u8,
-            func: _trampoline::<T, F>,
-            destructor: _drop::<F>,
-            arg_type: T::type_(),
-        };
-        Self {
-            op: CArc::new(op),
-            _marker: PhantomData,
-        }
-    }
-    pub fn call(&self, arg: impl AsExpr<Value = T>) -> Expr<T> {
-        RECORDER.with(|r| {
-            let mut r = r.borrow_mut();
-            assert!(r.lock);
-            assert_eq!(
-                r.device
-                    .as_ref()
-                    .unwrap()
-                    .upgrade()
-                    .unwrap()
-                    .inner
-                    .query("device_name")
-                    .unwrap(),
-                "cpu",
-                "CpuFn can only be used in cpu backend"
-            );
-            let addr = CArc::as_ptr(&self.op) as u64;
-            if let Some((_, op)) = r.cpu_custom_ops.get(&addr) {
-                assert_eq!(CArc::as_ptr(op), CArc::as_ptr(&self.op));
-            } else {
-                let i = r.cpu_custom_ops.len();
-                r.cpu_custom_ops.insert(addr, (i, self.op.clone()));
-            }
-        });
-        Expr::<T>::from_node(__current_scope(|b| {
-            b.call(
-                Func::CpuCustomOp(self.op.clone()),
-                &[arg.as_expr().node()],
-                T::type_(),
-            )
-        }))
-    }
-}
-
-extern "C" fn _trampoline<T, F: FnMut(&mut T)>(data: *mut u8, args: *mut u8) {
-    unsafe {
-        let container = &*(data as *const ClosureContainer<T>);
-        let f = &container.f;
-        let args = &mut *(args as *mut T);
-        f(args);
-    }
-}
-
-extern "C" fn _drop<T>(data: *mut u8) {
-    unsafe {
-        let _ = Box::from_raw(data as *mut T);
-    }
-}
-
 #[macro_export]
 macro_rules! cpu_dbg {
     ($arg:expr) => {{
diff --git a/luisa_compute/src/lang/external.rs b/luisa_compute/src/lang/external.rs
new file mode 100644
index 0000000..c26b138
--- /dev/null
+++ b/luisa_compute/src/lang/external.rs
@@ -0,0 +1,80 @@
+use std::sync::Arc;
+
+use luisa_compute_ir::ir::CpuCustomOp;
+
+use crate::internal_prelude::*;
+pub struct CpuFn<T: Value> {
+    op: CArc<CpuCustomOp>,
+    _marker: PhantomData<T>,
+}
+
+/*
+Interestingly, Box::into_raw(Box<Closure>) does not give a valid pointer.
+*/
+struct ClosureContainer<T> {
+    f: Arc<dyn Fn(&mut T) + 'static + Send + Sync>,
+}
+
+/// A custom function that can be called inside a cpu kernel
+impl<T: Value> CpuFn<T> {
+    pub fn new<F: Fn(&mut T) + 'static + Send + Sync>(f: F) -> Self {
+        let f_ptr = Box::into_raw(Box::new(ClosureContainer::<T> { f: Arc::new(f) }));
+        let op = CpuCustomOp {
+            data: f_ptr as *mut u8,
+            func: _trampoline::<T, F>,
+            destructor: _drop::<F>,
+            arg_type: T::type_(),
+        };
+        Self {
+            op: CArc::new(op),
+            _marker: PhantomData,
+        }
+    }
+    pub fn call(&self, arg: impl AsExpr<Value = T>) -> Expr<T> {
+        RECORDER.with(|r| {
+            let mut r = r.borrow_mut();
+            assert!(r.lock);
+            assert_eq!(
+                r.device
+                    .as_ref()
+                    .unwrap()
+                    .upgrade()
+                    .unwrap()
+                    .inner
+                    .query("device_name")
+                    .unwrap(),
+                "cpu",
+                "CpuFn can only be used in cpu backend"
+            );
+            let addr = CArc::as_ptr(&self.op) as u64;
+            if let Some((_, op)) = r.cpu_custom_ops.get(&addr) {
+                assert_eq!(CArc::as_ptr(op), CArc::as_ptr(&self.op));
+            } else {
+                let i = r.cpu_custom_ops.len();
+                r.cpu_custom_ops.insert(addr, (i, self.op.clone()));
+            }
+        });
+        Expr::<T>::from_node(__current_scope(|b| {
+            b.call(
+                Func::CpuCustomOp(self.op.clone()),
+                &[arg.as_expr().node()],
+                T::type_(),
+            )
+        }))
+    }
+}
+
+extern "C" fn _trampoline<T, F: FnMut(&mut T)>(data: *mut u8, args: *mut u8) {
+    unsafe {
+        let container = &*(data as *const ClosureContainer<T>);
+        let f = &container.f;
+        let args = &mut *(args as *mut T);
+        f(args);
+    }
+}
+
+extern "C" fn _drop<T>(data: *mut u8) {
+    unsafe {
+        let _ = Box::from_raw(data as *mut T);
+    }
+}
diff --git a/luisa_compute/src/lib.rs b/luisa_compute/src/lib.rs
index ade93e6..86a89ae 100644
--- a/luisa_compute/src/lib.rs
+++ b/luisa_compute/src/lib.rs
@@ -35,7 +35,7 @@ pub mod prelude {
     };
     pub use crate::lang::types::vector::swizzle::*;
     pub use crate::lang::types::vector::VectorExprProxy;
-    pub use crate::lang::types::{AsExpr, Expr, Value, Var, SoaValue};
+    pub use crate::lang::types::{AsExpr, Expr, SoaValue, Value, Var};
     pub use crate::lang::Aggregate;
     pub use crate::resource::{IoTexel, StorageTexel, *};
     pub use crate::runtime::api::StreamTag;
@@ -52,7 +52,8 @@ pub mod prelude {
 }
 
 mod internal_prelude {
-    pub(crate) use crate::lang::debug::{__env_need_backtrace, is_cpu_backend, CpuFn};
+    pub(crate) use crate::lang::debug::{__env_need_backtrace, is_cpu_backend};
+    pub(crate) use crate::lang::external::CpuFn;
     pub(crate) use crate::lang::ir::ffi::*;
     pub(crate) use crate::lang::ir::{
         new_node, register_type, BasicBlock, Const, Func, Instruction, IrBuilder, Node,
@@ -60,7 +61,7 @@ mod internal_prelude {
     };
     pub(crate) use crate::lang::ops::Linear;
     pub(crate) use crate::lang::types::vector::alias::*;
-    pub(crate) use crate::lang::types::{SoaBufferProxy, vector::*};
+    pub(crate) use crate::lang::types::{vector::*, SoaBufferProxy};
     #[allow(unused_imports)]
     pub(crate) use crate::lang::{
         check_index_lt_usize, ir, CallFuncTrait, Recorder, __compose, __extract, __insert,
diff --git a/luisa_compute_sys/LuisaCompute b/luisa_compute_sys/LuisaCompute
index ecc1268..3015047 160000
--- a/luisa_compute_sys/LuisaCompute
+++ b/luisa_compute_sys/LuisaCompute
@@ -1 +1 @@
-Subproject commit ecc1268f1a294b90becb7222f00256232fc7e140
+Subproject commit 30150473b3f772d59f416cb2fb5cd3e796c085a9