Auto merge of #142814 - tgross35:rollup-fioob6s, r=tgross35

Rollup of 8 pull requests

Successful merges:

 - rust-lang/rust#142384 (Bringing `rustc_rayon_core` in tree as `rustc_thread_pool`)
 - rust-lang/rust#142476 (Insert parentheses around binary operation with attribute)
 - rust-lang/rust#142485 (Marks ADT live if it appears in pattern)
 - rust-lang/rust#142571 (Reason about borrowed classes in CopyProp.)
 - rust-lang/rust#142677 (Add CI check to ensure that rustdoc JSON `FORMAT_VERSION` is correctly updated)
 - rust-lang/rust#142716 (Adjust `with_generic_param_rib`.)
 - rust-lang/rust#142756 (Make `Clone` a `const_trait`)
 - rust-lang/rust#142765 (rustc_target: document public AbiMap-related fn and variants)

r? `@ghost`
`@rustbot` modify labels: rollup

2 files changed, 411 insertions, 0 deletions

diff --git a/compiler/rustc_thread_pool/src/spawn/mod.rs b/compiler/rustc_thread_pool/src/spawn/mod.rs
new file mode 100644
index 00000000000..040a02bfa67
--- /dev/null
+++ b/compiler/rustc_thread_pool/src/spawn/mod.rs
@@ -0,0 +1,165 @@
+use std::mem;
+use std::sync::Arc;
+
+use crate::job::*;
+use crate::registry::Registry;
+use crate::tlv::Tlv;
+use crate::unwind;
+
+/// Puts the task into the Rayon threadpool's job queue in the "static"
+/// or "global" scope. Just like a standard thread, this task is not
+/// tied to the current stack frame, and hence it cannot hold any
+/// references other than those with `'static` lifetime. If you want
+/// to spawn a task that references stack data, use [the `scope()`
+/// function][scope] to create a scope.
+///
+/// [scope]: fn.scope.html
+///
+/// Since tasks spawned with this function cannot hold references into
+/// the enclosing stack frame, you almost certainly want to use a
+/// `move` closure as their argument (otherwise, the closure will
+/// typically hold references to any variables from the enclosing
+/// function that you happen to use).
+///
+/// This API assumes that the closure is executed purely for its
+/// side-effects (i.e., it might send messages, modify data protected
+/// by a mutex, or some such thing).
+///
+/// There is no guaranteed order of execution for spawns, given that
+/// other threads may steal tasks at any time. However, they are
+/// generally prioritized in a LIFO order on the thread from which
+/// they were spawned. Other threads always steal from the other end of
+/// the deque, like FIFO order. The idea is that "recent" tasks are
+/// most likely to be fresh in the local CPU's cache, while other
+/// threads can steal older "stale" tasks. For an alternate approach,
+/// consider [`spawn_fifo()`] instead.
+///
+/// [`spawn_fifo()`]: fn.spawn_fifo.html
+///
+/// # Panic handling
+///
+/// If this closure should panic, the resulting panic will be
+/// propagated to the panic handler registered in the `ThreadPoolBuilder`,
+/// if any. See [`ThreadPoolBuilder::panic_handler()`][ph] for more
+/// details.
+///
+/// [ph]: struct.ThreadPoolBuilder.html#method.panic_handler
+///
+/// # Examples
+///
+/// This code creates a Rayon task that increments a global counter.
+///
+/// ```rust
+/// # use rustc_thread_pool as rayon;
+/// use std::sync::atomic::{AtomicUsize, Ordering, ATOMIC_USIZE_INIT};
+///
+/// static GLOBAL_COUNTER: AtomicUsize = ATOMIC_USIZE_INIT;
+///
+/// rayon::spawn(move || {
+///     GLOBAL_COUNTER.fetch_add(1, Ordering::SeqCst);
+/// });
+/// ```
+pub fn spawn<F>(func: F)
+where
+    F: FnOnce() + Send + 'static,
+{
+    // We assert that current registry has not terminated.
+    unsafe { spawn_in(func, &Registry::current()) }
+}
+
+/// Spawns an asynchronous job in `registry.`
+///
+/// Unsafe because `registry` must not yet have terminated.
+pub(super) unsafe fn spawn_in<F>(func: F, registry: &Arc<Registry>)
+where
+    F: FnOnce() + Send + 'static,
+{
+    // We assert that this does not hold any references (we know
+    // this because of the `'static` bound in the interface);
+    // moreover, we assert that the code below is not supposed to
+    // be able to panic, and hence the data won't leak but will be
+    // enqueued into some deque for later execution.
+    let abort_guard = unwind::AbortIfPanic; // just in case we are wrong, and code CAN panic
+    let job_ref = unsafe { spawn_job(func, registry) };
+    registry.inject_or_push(job_ref);
+    mem::forget(abort_guard);
+}
+
+unsafe fn spawn_job<F>(func: F, registry: &Arc<Registry>) -> JobRef
+where
+    F: FnOnce() + Send + 'static,
+{
+    // Ensure that registry cannot terminate until this job has
+    // executed. This ref is decremented at the (*) below.
+    registry.increment_terminate_count();
+
+    HeapJob::new(Tlv::null(), {
+        let registry = Arc::clone(registry);
+        move || {
+            registry.catch_unwind(func);
+            registry.terminate(); // (*) permit registry to terminate now
+        }
+    })
+    .into_static_job_ref()
+}
+
+/// Fires off a task into the Rayon threadpool in the "static" or
+/// "global" scope. Just like a standard thread, this task is not
+/// tied to the current stack frame, and hence it cannot hold any
+/// references other than those with `'static` lifetime. If you want
+/// to spawn a task that references stack data, use [the `scope_fifo()`
+/// function](fn.scope_fifo.html) to create a scope.
+///
+/// The behavior is essentially the same as [the `spawn`
+/// function](fn.spawn.html), except that calls from the same thread
+/// will be prioritized in FIFO order. This is similar to the now-
+/// deprecated [`breadth_first`] option, except the effect is isolated
+/// to relative `spawn_fifo` calls, not all threadpool tasks.
+///
+/// For more details on this design, see Rayon [RFC #1].
+///
+/// [`breadth_first`]: struct.ThreadPoolBuilder.html#method.breadth_first
+/// [RFC #1]: https://github.com/rayon-rs/rfcs/blob/master/accepted/rfc0001-scope-scheduling.md
+///
+/// # Panic handling
+///
+/// If this closure should panic, the resulting panic will be
+/// propagated to the panic handler registered in the `ThreadPoolBuilder`,
+/// if any. See [`ThreadPoolBuilder::panic_handler()`][ph] for more
+/// details.
+///
+/// [ph]: struct.ThreadPoolBuilder.html#method.panic_handler
+pub fn spawn_fifo<F>(func: F)
+where
+    F: FnOnce() + Send + 'static,
+{
+    // We assert that current registry has not terminated.
+    unsafe { spawn_fifo_in(func, &Registry::current()) }
+}
+
+/// Spawns an asynchronous FIFO job in `registry.`
+///
+/// Unsafe because `registry` must not yet have terminated.
+pub(super) unsafe fn spawn_fifo_in<F>(func: F, registry: &Arc<Registry>)
+where
+    F: FnOnce() + Send + 'static,
+{
+    // We assert that this does not hold any references (we know
+    // this because of the `'static` bound in the interface);
+    // moreover, we assert that the code below is not supposed to
+    // be able to panic, and hence the data won't leak but will be
+    // enqueued into some deque for later execution.
+    let abort_guard = unwind::AbortIfPanic; // just in case we are wrong, and code CAN panic
+    let job_ref = unsafe { spawn_job(func, registry) };
+
+    // If we're in the pool, use our thread's private fifo for this thread to execute
+    // in a locally-FIFO order. Otherwise, just use the pool's global injector.
+    match registry.current_thread() {
+        Some(worker) => unsafe { worker.push_fifo(job_ref) },
+        None => registry.inject(job_ref),
+    }
+    mem::forget(abort_guard);
+}
+
+#[cfg(test)]
+mod tests;
diff --git a/compiler/rustc_thread_pool/src/spawn/tests.rs b/compiler/rustc_thread_pool/src/spawn/tests.rs
new file mode 100644
index 00000000000..8a70d2faf9c
--- /dev/null
+++ b/compiler/rustc_thread_pool/src/spawn/tests.rs
@@ -0,0 +1,246 @@
+use std::any::Any;
+use std::sync::Mutex;
+use std::sync::mpsc::channel;
+
+use super::{spawn, spawn_fifo};
+use crate::{ThreadPoolBuilder, scope};
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn spawn_then_join_in_worker() {
+    let (tx, rx) = channel();
+    scope(move |_| {
+        spawn(move || tx.send(22).unwrap());
+    });
+    assert_eq!(22, rx.recv().unwrap());
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn spawn_then_join_outside_worker() {
+    let (tx, rx) = channel();
+    spawn(move || tx.send(22).unwrap());
+    assert_eq!(22, rx.recv().unwrap());
+}
+
+#[test]
+#[cfg_attr(not(panic = "unwind"), ignore)]
+fn panic_fwd() {
+    let (tx, rx) = channel();
+
+    let tx = Mutex::new(tx);
+    let panic_handler = move |err: Box<dyn Any + Send>| {
+        let tx = tx.lock().unwrap();
+        if let Some(&msg) = err.downcast_ref::<&str>() {
+            if msg == "Hello, world!" {
+                tx.send(1).unwrap();
+            } else {
+                tx.send(2).unwrap();
+            }
+        } else {
+            tx.send(3).unwrap();
+        }
+    };
+
+    let builder = ThreadPoolBuilder::new().panic_handler(panic_handler);
+
+    builder.build().unwrap().spawn(move || panic!("Hello, world!"));
+
+    assert_eq!(1, rx.recv().unwrap());
+}
+
+/// Test what happens when the thread-pool is dropped but there are
+/// still active asynchronous tasks. We expect the thread-pool to stay
+/// alive and executing until those threads are complete.
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn termination_while_things_are_executing() {
+    let (tx0, rx0) = channel();
+    let (tx1, rx1) = channel();
+
+    // Create a thread-pool and spawn some code in it, but then drop
+    // our reference to it.
+    {
+        let thread_pool = ThreadPoolBuilder::new().build().unwrap();
+        thread_pool.spawn(move || {
+            let data = rx0.recv().unwrap();
+
+            // At this point, we know the "main" reference to the
+            // `ThreadPool` has been dropped, but there are still
+            // active threads. Launch one more.
+            spawn(move || {
+                tx1.send(data).unwrap();
+            });
+        });
+    }
+
+    tx0.send(22).unwrap();
+    let v = rx1.recv().unwrap();
+    assert_eq!(v, 22);
+}
+
+#[test]
+#[cfg_attr(not(panic = "unwind"), ignore)]
+fn custom_panic_handler_and_spawn() {
+    let (tx, rx) = channel();
+
+    // Create a parallel closure that will send panics on the
+    // channel; since the closure is potentially executed in parallel
+    // with itself, we have to wrap `tx` in a mutex.
+    let tx = Mutex::new(tx);
+    let panic_handler = move |e: Box<dyn Any + Send>| {
+        tx.lock().unwrap().send(e).unwrap();
+    };
+
+    // Execute an async that will panic.
+    let builder = ThreadPoolBuilder::new().panic_handler(panic_handler);
+    builder.build().unwrap().spawn(move || {
+        panic!("Hello, world!");
+    });
+
+    // Check that we got back the panic we expected.
+    let error = rx.recv().unwrap();
+    if let Some(&msg) = error.downcast_ref::<&str>() {
+        assert_eq!(msg, "Hello, world!");
+    } else {
+        panic!("did not receive a string from panic handler");
+    }
+}
+
+#[test]
+#[cfg_attr(not(panic = "unwind"), ignore)]
+fn custom_panic_handler_and_nested_spawn() {
+    let (tx, rx) = channel();
+
+    // Create a parallel closure that will send panics on the
+    // channel; since the closure is potentially executed in parallel
+    // with itself, we have to wrap `tx` in a mutex.
+    let tx = Mutex::new(tx);
+    let panic_handler = move |e| {
+        tx.lock().unwrap().send(e).unwrap();
+    };
+
+    // Execute an async that will (eventually) panic.
+    const PANICS: usize = 3;
+    let builder = ThreadPoolBuilder::new().panic_handler(panic_handler);
+    builder.build().unwrap().spawn(move || {
+        // launch 3 nested spawn-asyncs; these should be in the same
+        // thread-pool and hence inherit the same panic handler
+        for _ in 0..PANICS {
+            spawn(move || {
+                panic!("Hello, world!");
+            });
+        }
+    });
+
+    // Check that we get back the panics we expected.
+    for _ in 0..PANICS {
+        let error = rx.recv().unwrap();
+        if let Some(&msg) = error.downcast_ref::<&str>() {
+            assert_eq!(msg, "Hello, world!");
+        } else {
+            panic!("did not receive a string from panic handler");
+        }
+    }
+}
+
+macro_rules! test_order {
+    ($outer_spawn:ident, $inner_spawn:ident) => {{
+        let builder = ThreadPoolBuilder::new().num_threads(1);
+        let pool = builder.build().unwrap();
+        let (tx, rx) = channel();
+        pool.install(move || {
+            for i in 0..10 {
+                let tx = tx.clone();
+                $outer_spawn(move || {
+                    for j in 0..10 {
+                        let tx = tx.clone();
+                        $inner_spawn(move || {
+                            tx.send(i * 10 + j).unwrap();
+                        });
+                    }
+                });
+            }
+        });
+        rx.iter().collect::<Vec<i32>>()
+    }};
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn lifo_order() {
+    // In the absence of stealing, `spawn()` jobs on a thread will run in LIFO order.
+    let vec = test_order!(spawn, spawn);
+    let expected: Vec<i32> = (0..100).rev().collect(); // LIFO -> reversed
+    assert_eq!(vec, expected);
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn fifo_order() {
+    // In the absence of stealing, `spawn_fifo()` jobs on a thread will run in FIFO order.
+    let vec = test_order!(spawn_fifo, spawn_fifo);
+    let expected: Vec<i32> = (0..100).collect(); // FIFO -> natural order
+    assert_eq!(vec, expected);
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn lifo_fifo_order() {
+    // LIFO on the outside, FIFO on the inside
+    let vec = test_order!(spawn, spawn_fifo);
+    let expected: Vec<i32> = (0..10).rev().flat_map(|i| (0..10).map(move |j| i * 10 + j)).collect();
+    assert_eq!(vec, expected);
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn fifo_lifo_order() {
+    // FIFO on the outside, LIFO on the inside
+    let vec = test_order!(spawn_fifo, spawn);
+    let expected: Vec<i32> = (0..10).flat_map(|i| (0..10).rev().map(move |j| i * 10 + j)).collect();
+    assert_eq!(vec, expected);
+}
+
+macro_rules! spawn_send {
+    ($spawn:ident, $tx:ident, $i:expr) => {{
+        let tx = $tx.clone();
+        $spawn(move || tx.send($i).unwrap());
+    }};
+}
+
+/// Test mixed spawns pushing a series of numbers, interleaved such
+/// such that negative values are using the second kind of spawn.
+macro_rules! test_mixed_order {
+    ($pos_spawn:ident, $neg_spawn:ident) => {{
+        let builder = ThreadPoolBuilder::new().num_threads(1);
+        let pool = builder.build().unwrap();
+        let (tx, rx) = channel();
+        pool.install(move || {
+            spawn_send!($pos_spawn, tx, 0);
+            spawn_send!($neg_spawn, tx, -1);
+            spawn_send!($pos_spawn, tx, 1);
+            spawn_send!($neg_spawn, tx, -2);
+            spawn_send!($pos_spawn, tx, 2);
+            spawn_send!($neg_spawn, tx, -3);
+            spawn_send!($pos_spawn, tx, 3);
+        });
+        rx.iter().collect::<Vec<i32>>()
+    }};
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn mixed_lifo_fifo_order() {
+    let vec = test_mixed_order!(spawn, spawn_fifo);
+    let expected = vec![3, -1, 2, -2, 1, -3, 0];
+    assert_eq!(vec, expected);
+}
+
+#[test]
+#[cfg_attr(any(target_os = "emscripten", target_family = "wasm"), ignore)]
+fn mixed_fifo_lifo_order() {
+    let vec = test_mixed_order!(spawn_fifo, spawn);
+    let expected = vec![0, -3, 1, -2, 2, -1, 3];
+    assert_eq!(vec, expected);
+}