From 3a1ed823f87d6e823763419245d229a0edb09db8 Mon Sep 17 00:00:00 2001
From: Hailey Somerville <hailey@hailey.lol>
Date: Thu, 14 Sep 2023 13:03:38 +1000
Subject: [PATCH 1/2] write to TaskStorage::future via inline(never) fn to
 encourage RVO

---
 embassy-executor/src/raw/mod.rs  | 2 +-
 embassy-executor/src/raw/util.rs | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/embassy-executor/src/raw/mod.rs b/embassy-executor/src/raw/mod.rs
index c1d82e18..6d2c1c18 100644
--- a/embassy-executor/src/raw/mod.rs
+++ b/embassy-executor/src/raw/mod.rs
@@ -203,7 +203,7 @@ impl<F: Future + 'static> AvailableTask<F> {
     fn initialize_impl<S>(self, future: impl FnOnce() -> F) -> SpawnToken<S> {
         unsafe {
             self.task.raw.poll_fn.set(Some(TaskStorage::<F>::poll));
-            self.task.future.write(future());
+            self.task.future.write_in_place(future);
 
             let task = TaskRef::new(self.task);
 
diff --git a/embassy-executor/src/raw/util.rs b/embassy-executor/src/raw/util.rs
index e2e8f4df..c46085e4 100644
--- a/embassy-executor/src/raw/util.rs
+++ b/embassy-executor/src/raw/util.rs
@@ -17,8 +17,9 @@ impl<T> UninitCell<T> {
         &mut *self.as_mut_ptr()
     }
 
-    pub unsafe fn write(&self, val: T) {
-        ptr::write(self.as_mut_ptr(), val)
+    #[inline(never)]
+    pub unsafe fn write_in_place(&self, func: impl FnOnce() -> T) {
+        ptr::write(self.as_mut_ptr(), func())
     }
 
     pub unsafe fn drop_in_place(&self) {

From b9d4b18f14ad477c4b554498282ac467ff9cb823 Mon Sep 17 00:00:00 2001
From: Hailey Somerville <hailey@hailey.lol>
Date: Thu, 14 Sep 2023 13:59:24 +1000
Subject: [PATCH 2/2] update UninitCell::write call in arch::wasm too

---
 embassy-executor/src/arch/wasm.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/embassy-executor/src/arch/wasm.rs b/embassy-executor/src/arch/wasm.rs
index 934fd69e..15aed867 100644
--- a/embassy-executor/src/arch/wasm.rs
+++ b/embassy-executor/src/arch/wasm.rs
@@ -73,9 +73,10 @@ mod thread {
         pub fn start(&'static mut self, init: impl FnOnce(Spawner)) {
             unsafe {
                 let executor = &self.inner;
-                self.ctx.closure.write(Closure::new(move |_| {
+                let future = Closure::new(move |_| {
                     executor.poll();
-                }));
+                });
+                self.ctx.closure.write_in_place(|| future);
                 init(self.inner.spawner());
             }
         }