From b48511f4b86516d6bde370e689bd5ba96723f078 Mon Sep 17 00:00:00 2001
From: Taiki Endo <te316e89@gmail.com>
Date: Thu, 7 Nov 2019 14:50:47 +0900
Subject: [PATCH] Use AtomicCell<u64> on targets with target_has_atomic less
 than 64

---
 .github/workflows/ci.yml | 33 +++++++++++++++++++++++++++++++++
 Cargo.toml               |  6 +++---
 src/sync/atomic.rs       | 37 +++++++++++++++++++++++++++++++++++++
 src/sync/mod.rs          |  1 +
 src/task/task_id.rs      |  4 +++-
 5 files changed, 77 insertions(+), 4 deletions(-)
 create mode 100644 src/sync/atomic.rs

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 031ffc96f..f83ea2264 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -52,6 +52,39 @@ jobs:
         command: test
         args: --all --features unstable
 
+  cross:
+    name: Cross compile
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target:
+          - i686-unknown-linux-gnu
+          - powerpc-unknown-linux-gnu
+          - powerpc64-unknown-linux-gnu
+          - mips-unknown-linux-gnu
+          - arm-linux-androideabi
+
+    steps:
+    - uses: actions/checkout@master
+
+    - name: Install nightly
+      uses: actions-rs/toolchain@v1
+      with:
+        toolchain: nightly
+        override: true
+
+    - name: Install cross
+      run: cargo install cross
+
+    - name: check
+      run: cross check --all --target ${{ matrix.target }}
+
+    - name: check unstable
+      run: cross check --all --features unstable --target ${{ matrix.target }}
+
+    - name: test
+      run: cross test --all --features unstable --target ${{ matrix.target }}
+
   check_fmt_and_docs:
     name: Checking fmt and docs
     runs-on: ubuntu-latest
diff --git a/Cargo.toml b/Cargo.toml
index 48b7d0b61..8aae7b1c8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -53,9 +53,9 @@ async-attributes = { version = "1.1.0", optional = true }
 async-macros = { version = "1.0.0", optional = true }
 async-task = { version = "1.0.0", optional = true }
 broadcaster = { version = "0.2.6", optional = true, default-features = false, features = ["default-channels"] }
-crossbeam-channel = { version = "0.3.9", optional = true }
-crossbeam-deque = { version = "0.7.1", optional = true }
-crossbeam-utils = { version = "0.6.6", optional = true }
+crossbeam-channel = { version = "0.4.0", optional = true }
+crossbeam-deque = { version = "0.7.2", optional = true }
+crossbeam-utils = { version = "0.7.0", optional = true }
 futures-core = { version = "0.3.0", optional = true }
 futures-io = { version = "0.3.0", optional = true }
 futures-timer = { version = "1.0.2", optional = true }
diff --git a/src/sync/atomic.rs b/src/sync/atomic.rs
new file mode 100644
index 000000000..d0b6b1ca3
--- /dev/null
+++ b/src/sync/atomic.rs
@@ -0,0 +1,37 @@
+pub(crate) use self::imp::AtomicU64;
+
+// `AtomicU64` can only be used on targets with `target_has_atomic` is 64 or greater.
+// Once `cfg_target_has_atomic` feature is stable, we can replace it with
+// `#[cfg(target_has_atomic = "64")]`.
+// Refs: https://github.com/rust-lang/rust/tree/master/src/librustc_target
+#[cfg(not(any(target_arch = "arm", target_arch = "mips", target_arch = "powerpc")))]
+mod imp {
+    pub(crate) use std::sync::atomic::AtomicU64;
+}
+
+#[cfg(any(target_arch = "arm", target_arch = "mips", target_arch = "powerpc"))]
+mod imp {
+    use std::sync::atomic::Ordering;
+
+    use crossbeam_utils::atomic::AtomicCell;
+
+    pub(crate) struct AtomicU64(AtomicCell<u64>);
+
+    impl AtomicU64 {
+        pub(crate) const fn new(val: u64) -> Self {
+            Self(AtomicCell::new(val))
+        }
+
+        pub(crate) fn load(&self, _: Ordering) -> u64 {
+            self.0.load()
+        }
+
+        pub(crate) fn fetch_add(&self, val: u64, _: Ordering) -> u64 {
+            self.0.fetch_add(val)
+        }
+
+        pub(crate) fn fetch_sub(&self, val: u64, _: Ordering) -> u64 {
+            self.0.fetch_sub(val)
+        }
+    }
+}
diff --git a/src/sync/mod.rs b/src/sync/mod.rs
index fdeb48c35..0bfeea124 100644
--- a/src/sync/mod.rs
+++ b/src/sync/mod.rs
@@ -181,6 +181,7 @@ pub use std::sync::{Arc, Weak};
 pub use mutex::{Mutex, MutexGuard};
 pub use rwlock::{RwLock, RwLockReadGuard, RwLockWriteGuard};
 
+pub(crate) mod atomic;
 mod mutex;
 mod rwlock;
 
diff --git a/src/task/task_id.rs b/src/task/task_id.rs
index 67eee154b..d73419c5f 100644
--- a/src/task/task_id.rs
+++ b/src/task/task_id.rs
@@ -1,5 +1,7 @@
 use std::fmt;
-use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::atomic::Ordering;
+
+use crate::sync::atomic::AtomicU64;
 
 /// A unique identifier for a task.
 ///