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authorbors <bors@rust-lang.org>2024-03-02 22:59:19 +0000
committerbors <bors@rust-lang.org>2024-03-02 22:59:19 +0000
commit0decdac390cfeedcd7f2f44c45f72c59c70d8143 (patch)
tree373fbe344b85306b4bb3d048b0b9ab1952a25c06 /library/alloc/src/task.rs
parent5119208fd78a77547c705d1695428c88d6791263 (diff)
parent4c65eef26937b4ea9572eb953ebc523a6cab167b (diff)
downloadrust-0decdac390cfeedcd7f2f44c45f72c59c70d8143.tar.gz
rust-0decdac390cfeedcd7f2f44c45f72c59c70d8143.zip
Auto merge of #121914 - Nadrieril:rollup-ol98ncg, r=Nadrieril
Rollup of 5 pull requests

Successful merges:

 - #120761 (Add initial support for DataFlowSanitizer)
 - #121622 (Preserve same vtable pointer when cloning raw waker, to fix Waker::will_wake)
 - #121716 (match lowering: Lower bindings in a predictable order)
 - #121731 (Now that inlining, mir validation and const eval all use reveal-all, we won't be constraining hidden types here anymore)
 - #121841 (`f16` and `f128` step 2: intrinsics)

r? `@ghost`
`@rustbot` modify labels: rollup
Diffstat (limited to 'library/alloc/src/task.rs')
-rw-r--r--library/alloc/src/task.rs13
1 files changed, 13 insertions, 0 deletions
diff --git a/library/alloc/src/task.rs b/library/alloc/src/task.rs
index b214f4946b1..b40768a52b6 100644
--- a/library/alloc/src/task.rs
+++ b/library/alloc/src/task.rs
@@ -136,6 +136,15 @@ impl<W: Wake + Send + Sync + 'static> From<Arc<W>> for RawWaker {
 #[inline(always)]
 fn raw_waker<W: Wake + Send + Sync + 'static>(waker: Arc<W>) -> RawWaker {
     // Increment the reference count of the arc to clone it.
+    //
+    // The #[inline(always)] is to ensure that raw_waker and clone_waker are
+    // always generated in the same code generation unit as one another, and
+    // therefore that the structurally identical const-promoted RawWakerVTable
+    // within both functions is deduplicated at LLVM IR code generation time.
+    // This allows optimizing Waker::will_wake to a single pointer comparison of
+    // the vtable pointers, rather than comparing all four function pointers
+    // within the vtables.
+    #[inline(always)]
     unsafe fn clone_waker<W: Wake + Send + Sync + 'static>(waker: *const ()) -> RawWaker {
         unsafe { Arc::increment_strong_count(waker as *const W) };
         RawWaker::new(
@@ -304,6 +313,10 @@ impl<W: LocalWake + 'static> From<Rc<W>> for RawWaker {
 #[inline(always)]
 fn local_raw_waker<W: LocalWake + 'static>(waker: Rc<W>) -> RawWaker {
     // Increment the reference count of the Rc to clone it.
+    //
+    // Refer to the comment on raw_waker's clone_waker regarding why this is
+    // always inline.
+    #[inline(always)]
     unsafe fn clone_waker<W: LocalWake + 'static>(waker: *const ()) -> RawWaker {
         unsafe { Rc::increment_strong_count(waker as *const W) };
         RawWaker::new(