Remove old nightly-specific optimizations

This only removes optimizations that are only used in old nightly. Most of them were only used in old nightly releases about 3 and a half to about 2 years ago.
taiki-e · Sep 24, 2023 · dea4dbe · dea4dbe
1 parent 287ef3d
commit dea4dbe
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Showing 9 changed files with 22 additions and 36 deletions.
diff --git a/build.rs b/build.rs
@@ -133,20 +133,16 @@ fn main() {
         println!("cargo:rustc-cfg=portable_atomic_llvm_16");
     }
     if version.nightly {
+        // For Miri and ThreadSanitizer.
         // https://github.com/rust-lang/rust/pull/97423 merged in Rust 1.64 (nightly-2022-06-30).
-        if version.probe(64, 2022, 6, 29) {
+        if target_arch == "aarch64" && version.probe(64, 2022, 6, 29) {
             println!("cargo:rustc-cfg=portable_atomic_new_atomic_intrinsics");
         }
-        // https://github.com/rust-lang/rust/pull/100911 (includes https://github.com/rust-lang/stdarch/pull/1315) merged in Rust 1.65 (nightly-2022-08-26).
-        if target_arch == "x86_64" && !version.probe(65, 2022, 8, 25) {
-            println!(
-                "cargo:rustc-cfg=portable_atomic_no_cmpxchg16b_intrinsic_stronger_failure_ordering"
-            );
-        }
         // feature(isa_attribute) stabilized in Rust 1.67 (nightly-2022-11-06): https://github.com/rust-lang/rust/pull/102458
         if target_arch == "arm" && !version.probe(67, 2022, 11, 5) {
             println!("cargo:rustc-cfg=portable_atomic_unstable_isa_attribute");
         }
+        // For Miri and ThreadSanitizer.
         // https://github.com/rust-lang/rust/pull/109359 (includes https://github.com/rust-lang/stdarch/pull/1358) merged in Rust 1.70 (nightly-2023-03-24).
         if target_arch == "x86_64" && !version.probe(70, 2023, 3, 23) {
             println!("cargo:rustc-cfg=portable_atomic_unstable_cmpxchg16b_intrinsic");
@@ -176,8 +172,8 @@ fn main() {
         }
     }
 
-    let is_apple =
-        target_os == "macos" || target_os == "ios" || target_os == "tvos" || target_os == "watchos";
+    let is_macos = target_os == "macos";
+    let is_apple = is_macos || target_os == "ios" || target_os == "tvos" || target_os == "watchos";
     match target_arch {
         "x86_64" => {
             // cmpxchg16b_target_feature stabilized in Rust 1.69 (nightly-2023-03-01): https://github.com/rust-lang/rust/pull/106774
@@ -221,7 +217,6 @@ fn main() {
 
             // aarch64 macOS always supports FEAT_LSE and FEAT_LSE2 because it is armv8.5-a:
             // https://github.com/llvm/llvm-project/blob/llvmorg-17.0.0-rc2/llvm/include/llvm/TargetParser/AArch64TargetParser.h#L494
-            let is_macos = target_os == "macos";
             let mut has_lse = is_macos;
             // FEAT_LSE2 doesn't imply FEAT_LSE. FEAT_LSE128 implies FEAT_LSE but not FEAT_LSE2.
             // As of rustc 1.70, target_feature "lse2"/"lse128"/"rcpc3" is not available on rustc side:

diff --git a/src/imp/arm_linux.rs b/src/imp/arm_linux.rs
@@ -16,9 +16,7 @@
 #[path = "fallback/outline_atomics.rs"]
 mod fallback;
 
-#[cfg(not(portable_atomic_no_asm))]
-use core::arch::asm;
-use core::{cell::UnsafeCell, mem, sync::atomic::Ordering};
+use core::{arch::asm, cell::UnsafeCell, mem, sync::atomic::Ordering};
 
 use crate::utils::{Pair, U64};
 

diff --git a/src/imp/atomic128/intrinsics.rs b/src/imp/atomic128/intrinsics.rs
@@ -134,7 +134,9 @@ unsafe fn atomic_compare_exchange(
             let prev = unsafe { core::arch::x86_64::cmpxchg16b(dst, old, new, success, failure) };
             (prev, prev == old)
         }
-        #[cfg(portable_atomic_no_cmpxchg16b_intrinsic_stronger_failure_ordering)]
+        // The stronger failure ordering in cmpxchg16b_intrinsic is actually supported
+        // before stabilization, but we do not have a specific cfg for it.
+        #[cfg(portable_atomic_unstable_cmpxchg16b_intrinsic)]
         let success = crate::utils::upgrade_success_ordering(success, failure);
         #[cfg(target_feature = "cmpxchg16b")]
         // SAFETY: the caller must guarantee that `dst` is valid for both writes and

diff --git a/src/imp/core_atomic.rs b/src/imp/core_atomic.rs
@@ -140,7 +140,7 @@ macro_rules! atomic_int {
         #[cfg(not(all(
             any(target_arch = "x86", target_arch = "x86_64"),
             not(any(miri, portable_atomic_sanitize_thread)),
-            any(not(portable_atomic_no_asm), portable_atomic_unstable_asm),
+            not(portable_atomic_no_asm),
         )))]
         #[cfg_attr(
             portable_atomic_no_cfg_target_has_atomic,
@@ -376,7 +376,7 @@ macro_rules! atomic_int {
             #[cfg(not(all(
                 any(target_arch = "x86", target_arch = "x86_64"),
                 not(any(miri, portable_atomic_sanitize_thread)),
-                any(not(portable_atomic_no_asm), portable_atomic_unstable_asm),
+                not(portable_atomic_no_asm),
             )))]
             #[inline]
             #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces
@@ -391,7 +391,7 @@ macro_rules! atomic_int {
             #[cfg(not(all(
                 any(target_arch = "x86", target_arch = "x86_64"),
                 not(any(miri, portable_atomic_sanitize_thread)),
-                any(not(portable_atomic_no_asm), portable_atomic_unstable_asm),
+                not(portable_atomic_no_asm),
             )))]
             #[inline]
             #[cfg_attr(miri, track_caller)] // even without panics, this helps for Miri backtraces

diff --git a/src/imp/fallback/mod.rs b/src/imp/fallback/mod.rs
@@ -43,7 +43,7 @@
         ),
         all(
             target_arch = "arm",
-            any(not(portable_atomic_no_asm), portable_atomic_unstable_asm),
+            not(portable_atomic_no_asm),
             any(target_os = "linux", target_os = "android"),
             not(portable_atomic_no_outline_atomics),
         ),

diff --git a/src/imp/mod.rs b/src/imp/mod.rs
@@ -108,14 +108,8 @@ mod powerpc64;
 // s390x 128-bit atomics
 #[cfg(all(target_arch = "s390x", portable_atomic_unstable_asm_experimental_arch))]
 // Use intrinsics.rs on Miri and Sanitizer that do not support inline assembly.
-#[cfg_attr(
-    all(any(miri, portable_atomic_sanitize_thread), portable_atomic_new_atomic_intrinsics),
-    path = "atomic128/intrinsics.rs"
-)]
-#[cfg_attr(
-    not(all(any(miri, portable_atomic_sanitize_thread), portable_atomic_new_atomic_intrinsics)),
-    path = "atomic128/s390x.rs"
-)]
+#[cfg_attr(any(miri, portable_atomic_sanitize_thread), path = "atomic128/intrinsics.rs")]
+#[cfg_attr(not(any(miri, portable_atomic_sanitize_thread)), path = "atomic128/s390x.rs")]
 mod s390x;
 
 // pre-v6 ARM Linux 64-bit atomics
@@ -124,7 +118,7 @@ mod s390x;
 #[cfg(all(
     target_arch = "arm",
     not(any(miri, portable_atomic_sanitize_thread)),
-    any(not(portable_atomic_no_asm), portable_atomic_unstable_asm),
+    not(portable_atomic_no_asm),
     any(target_os = "linux", target_os = "android"),
     not(any(target_feature = "v6", portable_atomic_target_feature = "v6")),
     not(portable_atomic_no_outline_atomics),
@@ -152,7 +146,7 @@ mod riscv;
 #[cfg(all(
     any(target_arch = "x86", target_arch = "x86_64"),
     not(any(miri, portable_atomic_sanitize_thread)),
-    any(not(portable_atomic_no_asm), portable_atomic_unstable_asm),
+    not(portable_atomic_no_asm),
 ))]
 mod x86;
 
@@ -320,7 +314,7 @@ items! {
     #[cfg(not(all(
         target_arch = "arm",
         not(any(miri, portable_atomic_sanitize_thread)),
-        any(not(portable_atomic_no_asm), portable_atomic_unstable_asm),
+        not(portable_atomic_no_asm),
         any(target_os = "linux", target_os = "android"),
         not(any(target_feature = "v6", portable_atomic_target_feature = "v6")),
         not(portable_atomic_no_outline_atomics),
@@ -387,7 +381,7 @@ items! {
 #[cfg(all(
     target_arch = "arm",
     not(any(miri, portable_atomic_sanitize_thread)),
-    any(not(portable_atomic_no_asm), portable_atomic_unstable_asm),
+    not(portable_atomic_no_asm),
     any(target_os = "linux", target_os = "android"),
     not(any(target_feature = "v6", portable_atomic_target_feature = "v6")),
     not(portable_atomic_no_outline_atomics),

diff --git a/src/imp/x86.rs b/src/imp/x86.rs
@@ -14,9 +14,7 @@
 // Generated asm:
 // - x86_64 https://godbolt.org/z/8fve4YP1G
 
-#[cfg(not(portable_atomic_no_asm))]
-use core::arch::asm;
-use core::sync::atomic::Ordering;
+use core::{arch::asm, sync::atomic::Ordering};
 
 use super::core_atomic::{
     AtomicI16, AtomicI32, AtomicI64, AtomicI8, AtomicIsize, AtomicU16, AtomicU32, AtomicU64,

diff --git a/src/lib.rs b/src/lib.rs
@@ -260,7 +260,7 @@ RUSTFLAGS="--cfg portable_atomic_no_outline_atomics" cargo ...
 // - cfg(target_has_atomic)
 // - #[target_feature(enable = "lse")] on AArch64
 // - #[target_feature(enable = "cmpxchg16b")] on x86_64
-// - asm! on ARM, AArch64, RISC-V, x86, x86_64
+// - asm! on ARM, AArch64, RISC-V, x86_64
 // - llvm_asm! on AVR (tier 3) and MSP430 (tier 3)
 // - #[instruction_set] on non-Linux pre-v6 ARM (tier 3)
 #![cfg_attr(portable_atomic_unstable_cfg_target_has_atomic, feature(cfg_target_has_atomic))]
@@ -290,7 +290,6 @@ RUSTFLAGS="--cfg portable_atomic_no_outline_atomics" cargo ...
             target_arch = "arm",
             target_arch = "riscv32",
             target_arch = "riscv64",
-            target_arch = "x86",
             target_arch = "x86_64",
         ),
     ),

diff --git a/src/tests/mod.rs b/src/tests/mod.rs
@@ -84,7 +84,7 @@ fn test_is_lock_free() {
             feature = "fallback",
             target_arch = "arm",
             not(any(miri, portable_atomic_sanitize_thread)),
-            any(not(portable_atomic_no_asm), portable_atomic_unstable_asm),
+            not(portable_atomic_no_asm),
             any(target_os = "linux", target_os = "android"),
             not(any(target_feature = "v6", portable_atomic_target_feature = "v6")),
             not(portable_atomic_no_outline_atomics),