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Remove uses of autocfg
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Detect platforms that do not support AtomicU64 by using the same way.
AFAIK, this is more robust than the current way that uses autocfg.
See also rust-lang/futures-rs#2294.
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@taiki-e
taiki-e committed May 27, 2021
1 parent 7e6c097 commit c385325
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Showing 8 changed files with 104 additions and 72 deletions.
25 changes: 25 additions & 0 deletions ci/no_atomic.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,31 @@ for target in $(rustc --print target-list); do
done
echo "];" >>"$file"

{
# Only crossbeam-utils actually uses this const.
echo "#[allow(dead_code)]"
echo "const NO_ATOMIC_64: &[&str] = &["
} >>"$file"
for target in $(rustc --print target-list); do
res=$(rustc --print target-spec-json -Z unstable-options --target "$target" \
| jq -r "select(.\"max-atomic-width\" == 32)")
[[ -z "$res" ]] || echo " \"$target\"," >>"$file"
done
# It is not clear exactly what `"max-atomic-width" == null` means, but they
# actually seem to have the same max-atomic-width as the target-pointer-width.
# The targets currently included in this group are "mipsel-sony-psp",
# "thumbv4t-none-eabi", "thumbv6m-none-eabi", all of which are
# `"target-pointer-width" == "32"`, so assuming them `"max-atomic-width" == 32`
# for now.
for target in $(rustc --print target-list); do
res=$(rustc --print target-spec-json -Z unstable-options --target "$target" \
| jq -r "select(.\"max-atomic-width\" == null)")
[[ -z "$res" ]] || echo " \"$target\"," >>"$file"
done
echo "];" >>"$file"

# There is no `"max-atomic-width" == 16` or `"max-atomic-width" == 8` targets.

# `"max-atomic-width" == 0` means that atomic is not supported at all.
{
# Only crossbeam-utils actually uses this const.
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3 changes: 0 additions & 3 deletions crossbeam-utils/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -42,8 +42,5 @@ lazy_static = { version = "1.4.0", optional = true }
[target.'cfg(crossbeam_loom)'.dependencies]
loom = { version = "0.5", optional = true }

[build-dependencies]
autocfg = "1.0.0"

[dev-dependencies]
rand = "0.8"
25 changes: 5 additions & 20 deletions crossbeam-utils/build.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,6 @@

use std::env;

use autocfg::AutoCfg;

include!("no_atomic.rs");

// The rustc-cfg strings below are *not* public API. Please let us know by
Expand Down Expand Up @@ -31,25 +29,12 @@ fn main() {
}
if NO_ATOMIC.contains(&&*target) {
println!("cargo:rustc-cfg=crossbeam_no_atomic");
println!("cargo:rustc-cfg=crossbeam_no_atomic_64");
} else if NO_ATOMIC_64.contains(&&*target) {
println!("cargo:rustc-cfg=crossbeam_no_atomic_64");
} else {
// Otherwise, assuming `"max-atomic-width" == 64`.
}

let cfg = match AutoCfg::new() {
Ok(cfg) => cfg,
Err(e) => {
println!(
"cargo:warning={}: unable to determine rustc version: {}",
env!("CARGO_PKG_NAME"),
e
);
return;
}
};

cfg.emit_type_cfg("core::sync::atomic::AtomicU8", "has_atomic_u8");
cfg.emit_type_cfg("core::sync::atomic::AtomicU16", "has_atomic_u16");
cfg.emit_type_cfg("core::sync::atomic::AtomicU32", "has_atomic_u32");
cfg.emit_type_cfg("core::sync::atomic::AtomicU64", "has_atomic_u64");
cfg.emit_type_cfg("core::sync::atomic::AtomicU128", "has_atomic_u128");

println!("cargo:rerun-if-changed=no_atomic.rs");
}
44 changes: 16 additions & 28 deletions crossbeam-utils/src/atomic/atomic_cell.rs
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Expand Up @@ -497,26 +497,19 @@ macro_rules! impl_arithmetic {
};
}

#[cfg(has_atomic_u8)]
impl_arithmetic!(u8, atomic::AtomicU8, "let a = AtomicCell::new(7u8);");
#[cfg(all(has_atomic_u8, not(crossbeam_loom)))]
impl_arithmetic!(i8, atomic::AtomicI8, "let a = AtomicCell::new(7i8);");
#[cfg(has_atomic_u16)]
impl_arithmetic!(u16, atomic::AtomicU16, "let a = AtomicCell::new(7u16);");
#[cfg(all(has_atomic_u16, not(crossbeam_loom)))]
impl_arithmetic!(i16, atomic::AtomicI16, "let a = AtomicCell::new(7i16);");
#[cfg(has_atomic_u32)]
impl_arithmetic!(u32, atomic::AtomicU32, "let a = AtomicCell::new(7u32);");
#[cfg(all(has_atomic_u32, not(crossbeam_loom)))]
impl_arithmetic!(i32, atomic::AtomicI32, "let a = AtomicCell::new(7i32);");
#[cfg(has_atomic_u64)]
#[cfg(not(crossbeam_no_atomic_64))]
impl_arithmetic!(u64, atomic::AtomicU64, "let a = AtomicCell::new(7u64);");
#[cfg(all(has_atomic_u64, not(crossbeam_loom)))]
#[cfg(not(crossbeam_no_atomic_64))]
impl_arithmetic!(i64, atomic::AtomicI64, "let a = AtomicCell::new(7i64);");
#[cfg(all(has_atomic_u128, not(crossbeam_loom)))]
impl_arithmetic!(u128, atomic::AtomicU128, "let a = AtomicCell::new(7u128);");
#[cfg(all(has_atomic_u128, not(crossbeam_loom)))]
impl_arithmetic!(i128, atomic::AtomicI128, "let a = AtomicCell::new(7i128);");
// TODO: AtomicU128 is unstable
// impl_arithmetic!(u128, atomic::AtomicU128, "let a = AtomicCell::new(7u128);");
// impl_arithmetic!(i128, atomic::AtomicI128, "let a = AtomicCell::new(7i128);");

impl_arithmetic!(
usize,
Expand Down Expand Up @@ -809,16 +802,13 @@ macro_rules! atomic {
atomic!(@check, $t, AtomicUnit, $a, $atomic_op);
atomic!(@check, $t, atomic::AtomicUsize, $a, $atomic_op);

#[cfg(has_atomic_u8)]
atomic!(@check, $t, atomic::AtomicU8, $a, $atomic_op);
#[cfg(has_atomic_u16)]
atomic!(@check, $t, atomic::AtomicU16, $a, $atomic_op);
#[cfg(has_atomic_u32)]
atomic!(@check, $t, atomic::AtomicU32, $a, $atomic_op);
#[cfg(has_atomic_u64)]
#[cfg(not(crossbeam_no_atomic_64))]
atomic!(@check, $t, atomic::AtomicU64, $a, $atomic_op);
#[cfg(has_atomic_u128)]
atomic!(@check, $t, atomic::AtomicU128, $a, $atomic_op);
// TODO: AtomicU128 is unstable
// atomic!(@check, $t, atomic::AtomicU128, $a, $atomic_op);

#[cfg(crossbeam_loom)]
unimplemented!("loom does not support non-atomic atomic ops");
Expand All @@ -831,17 +821,15 @@ macro_rules! atomic {
/// Returns `true` if operations on `AtomicCell<T>` are lock-free.
const fn atomic_is_lock_free<T>() -> bool {
// HACK(taiki-e): This is equivalent to `atomic! { T, _a, true, false }`, but can be used in const fn even in Rust 1.36.
let is_lock_free = can_transmute::<T, AtomicUnit>() | can_transmute::<T, atomic::AtomicUsize>();
#[cfg(has_atomic_u8)]
let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU8>();
#[cfg(has_atomic_u16)]
let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU16>();
#[cfg(has_atomic_u32)]
let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU32>();
#[cfg(has_atomic_u64)]
let is_lock_free = can_transmute::<T, AtomicUnit>()
| can_transmute::<T, atomic::AtomicUsize>()
| can_transmute::<T, atomic::AtomicU8>()
| can_transmute::<T, atomic::AtomicU16>()
| can_transmute::<T, atomic::AtomicU32>();
#[cfg(not(crossbeam_no_atomic_64))]
let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU64>();
#[cfg(has_atomic_u128)]
let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU128>();
// TODO: AtomicU128 is unstable
// let is_lock_free = is_lock_free | can_transmute::<T, atomic::AtomicU128>();
is_lock_free
}

Expand Down
10 changes: 2 additions & 8 deletions crossbeam-utils/src/atomic/consume.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -68,21 +68,15 @@ macro_rules! impl_atomic {
impl_atomic!(AtomicBool, bool);
impl_atomic!(AtomicUsize, usize);
impl_atomic!(AtomicIsize, isize);
#[cfg(has_atomic_u8)]
impl_atomic!(AtomicU8, u8);
#[cfg(has_atomic_u8)]
impl_atomic!(AtomicI8, i8);
#[cfg(has_atomic_u16)]
impl_atomic!(AtomicU16, u16);
#[cfg(has_atomic_u16)]
impl_atomic!(AtomicI16, i16);
#[cfg(has_atomic_u32)]
impl_atomic!(AtomicU32, u32);
#[cfg(has_atomic_u32)]
impl_atomic!(AtomicI32, i32);
#[cfg(has_atomic_u64)]
#[cfg(not(crossbeam_no_atomic_64))]
impl_atomic!(AtomicU64, u64);
#[cfg(has_atomic_u64)]
#[cfg(not(crossbeam_no_atomic_64))]
impl_atomic!(AtomicI64, i64);

#[cfg(not(crossbeam_no_atomic))]
Expand Down
6 changes: 1 addition & 5 deletions crossbeam-utils/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -72,16 +72,12 @@ mod primitive {
#[cfg(not(crossbeam_no_atomic))]
pub(crate) use core::sync::atomic::{AtomicBool, AtomicIsize, AtomicUsize};
#[cfg(not(crossbeam_no_atomic))]
#[cfg(has_atomic_u16)]
pub(crate) use core::sync::atomic::{AtomicI16, AtomicU16};
#[cfg(not(crossbeam_no_atomic))]
#[cfg(has_atomic_u32)]
pub(crate) use core::sync::atomic::{AtomicI32, AtomicU32};
#[cfg(not(crossbeam_no_atomic))]
#[cfg(has_atomic_u64)]
#[cfg(not(crossbeam_no_atomic_64))]
pub(crate) use core::sync::atomic::{AtomicI64, AtomicU64};
#[cfg(not(crossbeam_no_atomic))]
#[cfg(has_atomic_u8)]
pub(crate) use core::sync::atomic::{AtomicI8, AtomicU8};
}

Expand Down
22 changes: 14 additions & 8 deletions crossbeam-utils/tests/atomic_cell.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,17 +9,23 @@ fn is_lock_free() {
struct U8Wrap(bool);
struct I16Wrap(i16);

assert_eq!(AtomicCell::<usize>::is_lock_free(), true);
assert_eq!(AtomicCell::<isize>::is_lock_free(), true);
assert_eq!(AtomicCell::<UsizeWrap>::is_lock_free(), true);
assert!(AtomicCell::<usize>::is_lock_free());
assert!(AtomicCell::<isize>::is_lock_free());
assert!(AtomicCell::<UsizeWrap>::is_lock_free());

assert_eq!(AtomicCell::<u8>::is_lock_free(), cfg!(has_atomic_u8));
assert_eq!(AtomicCell::<bool>::is_lock_free(), cfg!(has_atomic_u8));
assert_eq!(AtomicCell::<U8Wrap>::is_lock_free(), cfg!(has_atomic_u8));
assert!(AtomicCell::<u8>::is_lock_free());
assert!(AtomicCell::<bool>::is_lock_free());
assert!(AtomicCell::<U8Wrap>::is_lock_free());

assert_eq!(AtomicCell::<I16Wrap>::is_lock_free(), cfg!(has_atomic_u16));
assert!(AtomicCell::<I16Wrap>::is_lock_free());

assert_eq!(AtomicCell::<u128>::is_lock_free(), cfg!(has_atomic_u128));
assert_eq!(
AtomicCell::<u64>::is_lock_free(),
cfg!(not(crossbeam_no_atomic_64))
);

// AtomicU128 is unstable
assert!(!AtomicCell::<u128>::is_lock_free());
}

#[test]
Expand Down
41 changes: 41 additions & 0 deletions no_atomic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,47 @@ const NO_ATOMIC_CAS: &[&str] = &[
"thumbv6m-none-eabi",
];
#[allow(dead_code)]
const NO_ATOMIC_64: &[&str] = &[
"arm-linux-androideabi",
"armebv7r-none-eabi",
"armebv7r-none-eabihf",
"armv4t-unknown-linux-gnueabi",
"armv5te-unknown-linux-gnueabi",
"armv5te-unknown-linux-musleabi",
"armv5te-unknown-linux-uclibceabi",
"armv7r-none-eabi",
"armv7r-none-eabihf",
"hexagon-unknown-linux-musl",
"mips-unknown-linux-gnu",
"mips-unknown-linux-musl",
"mips-unknown-linux-uclibc",
"mipsel-unknown-linux-gnu",
"mipsel-unknown-linux-musl",
"mipsel-unknown-linux-uclibc",
"mipsel-unknown-none",
"mipsisa32r6-unknown-linux-gnu",
"mipsisa32r6el-unknown-linux-gnu",
"powerpc-unknown-linux-gnu",
"powerpc-unknown-linux-gnuspe",
"powerpc-unknown-linux-musl",
"powerpc-unknown-netbsd",
"powerpc-unknown-openbsd",
"powerpc-wrs-vxworks",
"powerpc-wrs-vxworks-spe",
"riscv32gc-unknown-linux-gnu",
"riscv32gc-unknown-linux-musl",
"riscv32imac-unknown-none-elf",
"thumbv7em-none-eabi",
"thumbv7em-none-eabihf",
"thumbv7m-none-eabi",
"thumbv8m.base-none-eabi",
"thumbv8m.main-none-eabi",
"thumbv8m.main-none-eabihf",
"mipsel-sony-psp",
"thumbv4t-none-eabi",
"thumbv6m-none-eabi",
];
#[allow(dead_code)]
const NO_ATOMIC: &[&str] = &[
"avr-unknown-gnu-atmega328",
"msp430-none-elf",
Expand Down

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