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Add cfg(target_has_atomic_equal_alignment) and use it for Atomic::from_mut. #76965

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Merged
merged 8 commits into from
Sep 24, 2020
Merged

Add cfg(target_has_atomic_equal_alignment) and use it for Atomic::from_mut. #76965

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db74e1f
Add cfg(target_has_atomic_equal_alignment).
m-ou-se Sep 20, 2020
9e3f94d
Don't unwrap but report a fatal error for TargetDataLayout::parse.
m-ou-se Sep 20, 2020
af56ad7
Add feature gate ui test for cfg(target_has_atomic_load_store).
m-ou-se Sep 20, 2020
54fdf54
Add feature gate ui test for cfg(target_has_atomic_equal_alignment).
m-ou-se Sep 20, 2020
668225d
Revert "Revert adding Atomic::from_mut."
m-ou-se Sep 21, 2020
7a04ff6
Gate Atomic::from_mut on cfg(target_has_atomic_equal_alignment).
m-ou-se Sep 20, 2020
5d6f1a1
Move `use align_of` in atomic.rs into the places where it is used.
m-ou-se Sep 21, 2020
bcc1d56
Test that AtomicU64::from_mut is not available on x86 linux.
m-ou-se Sep 21, 2020
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Gate Atomic::from_mut on cfg(target_has_atomic_equal_alignment). 
Instead of a few hardcoded cfg(target_arch = ..) like before.
  • Loading branch information
@m-ou-se
m-ou-se committed Sep 21, 2020
commit 7a04ff6c33c8bc9b8b1012e12a9920df52956e2f
27 changes: 19 additions & 8 deletions library/core/src/sync/atomic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -110,6 +110,8 @@ use self::Ordering::*;
use crate::cell::UnsafeCell;
use crate::fmt;
use crate::intrinsics;

#[allow(unused_imports)]
use crate::mem::align_of;

use crate::hint::spin_loop;
Expand Down Expand Up @@ -342,6 +344,7 @@ impl AtomicBool {
/// assert_eq!(some_bool, false);
/// ```
#[inline]
#[cfg(target_has_atomic_equal_alignment = "8")]
#[unstable(feature = "atomic_from_mut", issue = "76314")]
pub fn from_mut(v: &mut bool) -> &Self {
// SAFETY: the mutable reference guarantees unique ownership, and
Expand Down Expand Up @@ -855,6 +858,7 @@ impl<T> AtomicPtr<T> {
/// assert_eq!(unsafe { *some_ptr }, 456);
/// ```
#[inline]
#[cfg(target_has_atomic_equal_alignment = "ptr")]
#[unstable(feature = "atomic_from_mut", issue = "76314")]
pub fn from_mut(v: &mut *mut T) -> &Self {
let [] = [(); align_of::<AtomicPtr<()>>() - align_of::<*mut ()>()];
Expand Down Expand Up @@ -1159,6 +1163,7 @@ macro_rules! if_not_8_bit {
#[cfg(target_has_atomic_load_store = "8")]
macro_rules! atomic_int {
($cfg_cas:meta,
$cfg_align:meta,
$stable:meta,
$stable_cxchg:meta,
$stable_debug:meta,
Expand All @@ -1167,7 +1172,6 @@ macro_rules! atomic_int {
$stable_nand:meta,
$const_stable:meta,
$stable_init_const:meta,
$(from_mut: cfg($from_mut_cfg:meta),)?
$s_int_type:literal, $int_ref:expr,
$extra_feature:expr,
$min_fn:ident, $max_fn:ident,
Expand Down Expand Up @@ -1304,15 +1308,14 @@ assert_eq!(some_int, 100);
```
"),
#[inline]
$(#[cfg($from_mut_cfg)])?
#[$cfg_align]
#[unstable(feature = "atomic_from_mut", issue = "76314")]
pub fn from_mut(v: &mut $int_type) -> &Self {
let [] = [(); align_of::<Self>() - align_of::<$int_type>()];
// SAFETY:
// - the mutable reference guarantees unique ownership.
// - the alignment of `$int_type` and `Self` is the
// same on all platforms enabled by `$from_mut_cfg`
// as verified above.
// same, as promised by $cfg_align and verified above.
unsafe { &*(v as *mut $int_type as *mut Self) }
}
}
Expand Down Expand Up @@ -1959,6 +1962,7 @@ let mut atomic = ", stringify!($atomic_type), "::new(1);
#[cfg(target_has_atomic_load_store = "8")]
atomic_int! {
cfg(target_has_atomic = "8"),
cfg(target_has_atomic_equal_alignment = "8"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
Expand All @@ -1977,6 +1981,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "8")]
atomic_int! {
cfg(target_has_atomic = "8"),
cfg(target_has_atomic_equal_alignment = "8"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
Expand All @@ -1995,6 +2000,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "16")]
atomic_int! {
cfg(target_has_atomic = "16"),
cfg(target_has_atomic_equal_alignment = "16"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
Expand All @@ -2013,6 +2019,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "16")]
atomic_int! {
cfg(target_has_atomic = "16"),
cfg(target_has_atomic_equal_alignment = "16"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
Expand All @@ -2031,6 +2038,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "32")]
atomic_int! {
cfg(target_has_atomic = "32"),
cfg(target_has_atomic_equal_alignment = "32"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
Expand All @@ -2049,6 +2057,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "32")]
atomic_int! {
cfg(target_has_atomic = "32"),
cfg(target_has_atomic_equal_alignment = "32"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
Expand All @@ -2067,6 +2076,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "64")]
atomic_int! {
cfg(target_has_atomic = "64"),
cfg(target_has_atomic_equal_alignment = "64"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
Expand All @@ -2075,7 +2085,6 @@ atomic_int! {
stable(feature = "integer_atomics_stable", since = "1.34.0"),
rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
unstable(feature = "integer_atomics", issue = "32976"),
from_mut: cfg(not(target_arch = "x86")),
"i64", "../../../std/primitive.i64.html",
"",
atomic_min, atomic_max,
Expand All @@ -2086,6 +2095,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "64")]
atomic_int! {
cfg(target_has_atomic = "64"),
cfg(target_has_atomic_equal_alignment = "64"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
stable(feature = "integer_atomics_stable", since = "1.34.0"),
Expand All @@ -2094,7 +2104,6 @@ atomic_int! {
stable(feature = "integer_atomics_stable", since = "1.34.0"),
rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
unstable(feature = "integer_atomics", issue = "32976"),
from_mut: cfg(not(target_arch = "x86")),
"u64", "../../../std/primitive.u64.html",
"",
atomic_umin, atomic_umax,
Expand All @@ -2105,6 +2114,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "128")]
atomic_int! {
cfg(target_has_atomic = "128"),
cfg(target_has_atomic_equal_alignment = "128"),
unstable(feature = "integer_atomics", issue = "32976"),
unstable(feature = "integer_atomics", issue = "32976"),
unstable(feature = "integer_atomics", issue = "32976"),
Expand All @@ -2113,7 +2123,6 @@ atomic_int! {
unstable(feature = "integer_atomics", issue = "32976"),
rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
unstable(feature = "integer_atomics", issue = "32976"),
from_mut: cfg(not(target_arch = "x86_64")),
"i128", "../../../std/primitive.i128.html",
"#![feature(integer_atomics)]\n\n",
atomic_min, atomic_max,
Expand All @@ -2124,6 +2133,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "128")]
atomic_int! {
cfg(target_has_atomic = "128"),
cfg(target_has_atomic_equal_alignment = "128"),
unstable(feature = "integer_atomics", issue = "32976"),
unstable(feature = "integer_atomics", issue = "32976"),
unstable(feature = "integer_atomics", issue = "32976"),
Expand All @@ -2132,7 +2142,6 @@ atomic_int! {
unstable(feature = "integer_atomics", issue = "32976"),
rustc_const_stable(feature = "const_integer_atomics", since = "1.34.0"),
unstable(feature = "integer_atomics", issue = "32976"),
from_mut: cfg(not(target_arch = "x86_64")),
"u128", "../../../std/primitive.u128.html",
"#![feature(integer_atomics)]\n\n",
atomic_umin, atomic_umax,
Expand Down Expand Up @@ -2164,6 +2173,7 @@ macro_rules! ptr_width {
#[cfg(target_has_atomic_load_store = "ptr")]
atomic_int! {
cfg(target_has_atomic = "ptr"),
cfg(target_has_atomic_equal_alignment = "ptr"),
stable(feature = "rust1", since = "1.0.0"),
stable(feature = "extended_compare_and_swap", since = "1.10.0"),
stable(feature = "atomic_debug", since = "1.3.0"),
Expand All @@ -2182,6 +2192,7 @@ atomic_int! {
#[cfg(target_has_atomic_load_store = "ptr")]
atomic_int! {
cfg(target_has_atomic = "ptr"),
cfg(target_has_atomic_equal_alignment = "ptr"),
stable(feature = "rust1", since = "1.0.0"),
stable(feature = "extended_compare_and_swap", since = "1.10.0"),
stable(feature = "atomic_debug", since = "1.3.0"),
Expand Down