Remove use of feature(integer_atomics)

Fixes subtle behavior differences between stable and nightly.
taiki-e · Jun 17, 2022 · 61fe79f · 61fe79f
1 parent b55eed8
commit 61fe79f
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Showing 6 changed files with 15 additions and 105 deletions.
diff --git a/build.rs b/build.rs
@@ -19,15 +19,6 @@ const LATEST_STABLE: Version =
 // Probe if unstable features can be compiled with the expected API.
 // This prevents accidental depends on them if the upstream changes its API.
 // This is the same approach used in autocfg, anyhow, etc.
-// for aarch64 and x86_64 macos
-const PROBE_ATOMIC_128: &str = r#"
-#![no_std]
-#![feature(integer_atomics)]
-fn _probe() {
-    let v = core::sync::atomic::AtomicU128::new(0_u128);
-    let _: u128 = v.swap(1_u128, core::sync::atomic::Ordering::Relaxed);
-}
-"#;
 // for x86_64
 const PROBE_CMPXCHG16B: &str = r#"
 #![no_std]
@@ -172,11 +163,8 @@ fn main() {
         println!("cargo:rustc-cfg=portable_atomic_armv5te");
     }
 
-    let aarch64 = target.starts_with("aarch64");
-    let x86_64 = target.starts_with("x86_64");
-
     // aarch64 macos always support lse and lse2 because it is armv8.6: /~https://github.com/rust-lang/rust/blob/1.61.0/compiler/rustc_target/src/spec/aarch64_apple_darwin.rs#L5
-    if aarch64 && (version.minor >= 59 || version.nightly) {
+    if target.starts_with("aarch64") && (version.minor >= 59 || version.nightly) {
         // aarch64_target_feature stabilized in Rust 1.61.
         if has_target_feature("lse", target == "aarch64-apple-darwin", &version, Some(61), true) {
             println!("cargo:rustc-cfg=portable_atomic_target_feature=\"lse\"");
@@ -189,7 +177,8 @@ fn main() {
     }
 
     // cmpxchg16b is available via asm (1.59+) or stdsimd (nightly).
-    let may_use_cmpxchg16b = x86_64 && (version.minor >= 59 || version.nightly);
+    let may_use_cmpxchg16b =
+        target.starts_with("x86_64") && (version.minor >= 59 || version.nightly);
     let mut has_cmpxchg16b = false;
     if may_use_cmpxchg16b {
         // x86_64 macos always support cmpxchg16b: /~https://github.com/rust-lang/rust/blob/1.61.0/compiler/rustc_target/src/spec/x86_64_apple_darwin.rs#L7
@@ -209,20 +198,13 @@ fn main() {
             println!("cargo:rustc-cfg=sanitize_thread");
         }
 
-        if aarch64 || x86_64 {
-            if HAS_ATOMIC_128.contains(&&*target)
-                && probe(PROBE_ATOMIC_128, &target).unwrap_or(false)
-            {
-                println!("cargo:rustc-cfg=portable_atomic_core_atomic_128");
-            } else if may_use_cmpxchg16b
-                && (has_cmpxchg16b
-                    || cfg!(feature = "fallback") && cfg!(feature = "outline-atomics"))
-                && probe(PROBE_CMPXCHG16B, &target).unwrap_or(false)
-            {
-                println!("cargo:rustc-cfg=portable_atomic_cmpxchg16b_stdsimd");
-                if cfg!(feature = "fallback") && cfg!(feature = "outline-atomics") {
-                    println!("cargo:rustc-cfg=portable_atomic_cmpxchg16b_dynamic");
-                }
+        if may_use_cmpxchg16b
+            && (has_cmpxchg16b || cfg!(feature = "fallback") && cfg!(feature = "outline-atomics"))
+            && probe(PROBE_CMPXCHG16B, &target).unwrap_or(false)
+        {
+            println!("cargo:rustc-cfg=portable_atomic_cmpxchg16b_stdsimd");
+            if cfg!(feature = "fallback") && cfg!(feature = "outline-atomics") {
+                println!("cargo:rustc-cfg=portable_atomic_cmpxchg16b_dynamic");
             }
         } else if target.starts_with("s390x")
             && probe(PROBE_ATOMIC_INTRINSICS, &target).unwrap_or(false)

diff --git a/no_atomic.rs b/no_atomic.rs
@@ -70,29 +70,3 @@ const NO_ATOMIC: &[&str] = &[
     "riscv32im-unknown-none-elf",
     "riscv32imc-unknown-none-elf",
 ];
-
-const HAS_ATOMIC_128: &[&str] = &[
-    "aarch64-apple-darwin",
-    "aarch64-apple-ios",
-    "aarch64-apple-ios-macabi",
-    "aarch64-apple-ios-sim",
-    "aarch64-apple-tvos",
-    "aarch64-apple-watchos-sim",
-    "aarch64-fuchsia",
-    "aarch64-kmc-solid_asp3",
-    "aarch64-linux-android",
-    "aarch64-unknown-freebsd",
-    "aarch64-unknown-hermit",
-    "aarch64-unknown-linux-gnu",
-    "aarch64-unknown-linux-gnu_ilp32",
-    "aarch64-unknown-linux-musl",
-    "aarch64-unknown-netbsd",
-    "aarch64-unknown-none",
-    "aarch64-unknown-none-softfloat",
-    "aarch64-unknown-openbsd",
-    "aarch64-unknown-redox",
-    "aarch64-wrs-vxworks",
-    "aarch64_be-unknown-linux-gnu",
-    "aarch64_be-unknown-linux-gnu_ilp32",
-    "x86_64-apple-darwin",
-];
diff --git a/src/imp/core_atomic.rs b/src/imp/core_atomic.rs
@@ -32,5 +32,3 @@ atomic!(AtomicI32, AtomicU32);
     cfg(any(target_has_atomic = "64", target_pointer_width = "64")) // cfg(target_has_atomic_load_store = "64")
 )]
 atomic!(AtomicI64, AtomicU64);
-#[cfg(portable_atomic_core_atomic_128)]
-atomic!(AtomicI128, AtomicU128);
diff --git a/src/imp/mod.rs b/src/imp/mod.rs
@@ -5,13 +5,11 @@
 #[cfg(not(portable_atomic_no_atomic_load_store))]
 mod core_atomic;
 
-#[cfg(any(test, not(portable_atomic_core_atomic_128)))]
 #[cfg(any(not(portable_atomic_no_asm), portable_atomic_nightly))]
 #[cfg(target_arch = "aarch64")]
 #[path = "atomic128/aarch64.rs"]
 mod aarch64;
 
-#[cfg(any(test, not(portable_atomic_core_atomic_128)))]
 #[cfg(any(not(portable_atomic_no_asm), portable_atomic_nightly))]
 #[cfg(any(
     target_feature = "cmpxchg16b",
@@ -51,15 +49,9 @@ mod riscv;
 #[cfg(any(
     test,
     not(any(
-        portable_atomic_core_atomic_128,
         portable_atomic_s390x_atomic_128,
+        all(any(not(portable_atomic_no_asm), portable_atomic_nightly), target_arch = "aarch64"),
         all(
-            not(portable_atomic_core_atomic_128),
-            any(not(portable_atomic_no_asm), portable_atomic_nightly),
-            target_arch = "aarch64"
-        ),
-        all(
-            not(portable_atomic_core_atomic_128),
             any(not(portable_atomic_no_asm), portable_atomic_nightly),
             any(target_feature = "cmpxchg16b", portable_atomic_target_feature = "cmpxchg16b"),
             target_arch = "x86_64",
@@ -206,18 +198,14 @@ pub(crate) use self::fallback::{AtomicI64, AtomicU64};
 pub(crate) use self::interrupt::{AtomicI64, AtomicU64};
 
 // Atomic{I,U}128
-#[cfg(portable_atomic_core_atomic_128)]
-pub(crate) use self::core_atomic::{AtomicI128, AtomicU128};
 // aarch64 stable
 #[cfg(all(
-    not(portable_atomic_core_atomic_128),
     any(not(portable_atomic_no_asm), portable_atomic_nightly),
     target_arch = "aarch64"
 ))]
 pub(crate) use self::aarch64::{AtomicI128, AtomicU128};
 // no core Atomic{I,U}128 & has cmpxchg16b => use cmpxchg16b
 #[cfg(all(
-    not(portable_atomic_core_atomic_128),
     any(not(portable_atomic_no_asm), portable_atomic_nightly),
     any(
         target_feature = "cmpxchg16b",
@@ -238,15 +226,9 @@ pub(crate) use self::s390x::{AtomicI128, AtomicU128};
 // no core Atomic{I,U}128 & has CAS => use lock-base fallback
 #[cfg(feature = "fallback")]
 #[cfg(not(any(
-    portable_atomic_core_atomic_128,
     portable_atomic_s390x_atomic_128,
+    all(any(not(portable_atomic_no_asm), portable_atomic_nightly), target_arch = "aarch64"),
     all(
-        not(portable_atomic_core_atomic_128),
-        any(not(portable_atomic_no_asm), portable_atomic_nightly),
-        target_arch = "aarch64"
-    ),
-    all(
-        not(portable_atomic_core_atomic_128),
         any(not(portable_atomic_no_asm), portable_atomic_nightly),
         any(
             target_feature = "cmpxchg16b",

diff --git a/src/lib.rs b/src/lib.rs
@@ -108,10 +108,6 @@ On x86_64, when the `outline-atomics` optional feature is not enabled and `cmpxc
     clippy::type_complexity
 )]
 // 128-bit atomic
-#![cfg_attr(
-    any(all(test, portable_atomic_nightly), portable_atomic_core_atomic_128),
-    feature(integer_atomics)
-)]
 #![cfg_attr(
     all(
         target_arch = "x86_64",
@@ -2036,15 +2032,9 @@ atomic_int!(AtomicU64, u64, 8);
 #[cfg_attr(
     not(feature = "fallback"),
     cfg(any(
-        portable_atomic_core_atomic_128,
         portable_atomic_s390x_atomic_128,
+        all(any(not(portable_atomic_no_asm), portable_atomic_nightly), target_arch = "aarch64"),
         all(
-            not(portable_atomic_core_atomic_128),
-            any(not(portable_atomic_no_asm), portable_atomic_nightly),
-            target_arch = "aarch64"
-        ),
-        all(
-            not(portable_atomic_core_atomic_128),
             any(not(portable_atomic_no_asm), portable_atomic_nightly),
             any(
                 target_feature = "cmpxchg16b",
@@ -2072,15 +2062,9 @@ atomic_int!(AtomicI128, i128, 16);
 #[cfg_attr(
     not(feature = "fallback"),
     cfg(any(
-        portable_atomic_core_atomic_128,
         portable_atomic_s390x_atomic_128,
+        all(any(not(portable_atomic_no_asm), portable_atomic_nightly), target_arch = "aarch64"),
         all(
-            not(portable_atomic_core_atomic_128),
-            any(not(portable_atomic_no_asm), portable_atomic_nightly),
-            target_arch = "aarch64"
-        ),
-        all(
-            not(portable_atomic_core_atomic_128),
             any(not(portable_atomic_no_asm), portable_atomic_nightly),
             any(
                 target_feature = "cmpxchg16b",

diff --git a/tools/no_atomic.sh b/tools/no_atomic.sh
@@ -13,7 +13,6 @@ file="no_atomic.rs"
 no_atomic_cas=()
 no_atomic_64=()
 no_atomic=()
-has_atomic_128=()
 for target in $(rustc --print target-list); do
     target_spec=$(rustc --print target-spec-json -Z unstable-options --target "${target}")
     res=$(jq <<<"${target_spec}" -r 'select(."atomic-cas" == false)')
@@ -32,8 +31,7 @@ for target in $(rustc --print target-list); do
             no_atomic_64+=("${target}")
             no_atomic+=("${target}")
             ;;
-        64) ;;
-        128) has_atomic_128+=("${target}") ;;
+        64 | 128) ;;
         # There is no `"max-atomic-width" == 16` or `"max-atomic-width" == 8` targets.
         *) echo "${target}" && exit 1 ;;
     esac
@@ -66,12 +64,4 @@ for target in "${no_atomic[@]}"; do
 done
 cat >>"${file}" <<EOF
 ];
-
-const HAS_ATOMIC_128: &[&str] = &[
-EOF
-for target in "${has_atomic_128[@]}"; do
-    echo "    \"${target}\"," >>"${file}"
-done
-cat >>"${file}" <<EOF
-];
 EOF