From ab1b48ef2ae06fe9cb0d11632255ac0ab9fff528 Mon Sep 17 00:00:00 2001
From: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Date: Fri, 28 Jun 2024 08:06:36 +0200
Subject: [PATCH] rustc_data_structures: Explicitly check for 64-bit atomics
 support

Instead of keeping a list of architectures which have native support
for 64-bit atomics, just use #[cfg(target_has_atomic = "64")] and its
inverted counterpart to determine whether we need to use portable
AtomicU64 on the target architecture.
---
 compiler/rustc_data_structures/Cargo.toml    | 2 +-
 compiler/rustc_data_structures/src/marker.rs | 7 +++----
 compiler/rustc_data_structures/src/sync.rs   | 7 +++----
 3 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/compiler/rustc_data_structures/Cargo.toml b/compiler/rustc_data_structures/Cargo.toml
index f525510030b4a..c4b2e067bbeb4 100644
--- a/compiler/rustc_data_structures/Cargo.toml
+++ b/compiler/rustc_data_structures/Cargo.toml
@@ -50,7 +50,7 @@ libc = "0.2"
 memmap2 = "0.2.1"
 # tidy-alphabetical-end
 
-[target.'cfg(any(target_arch = "mips", target_arch = "powerpc", target_arch = "sparc"))'.dependencies]
+[target.'cfg(not(target_has_atomic = "64"))'.dependencies]
 portable-atomic = "1.5.1"
 
 [features]
diff --git a/compiler/rustc_data_structures/src/marker.rs b/compiler/rustc_data_structures/src/marker.rs
index 32fad0de1aa3e..83fdaff515b03 100644
--- a/compiler/rustc_data_structures/src/marker.rs
+++ b/compiler/rustc_data_structures/src/marker.rs
@@ -147,14 +147,13 @@ cfg_match! {
             [crate::owned_slice::OwnedSlice]
         );
 
-        // MIPS, PowerPC and SPARC platforms with 32-bit pointers do not
-        // have AtomicU64 type.
-        #[cfg(not(any(target_arch = "powerpc", target_arch = "powerpc", target_arch = "sparc")))]
+        // Use portable AtomicU64 for targets without native 64-bit atomics
+        #[cfg(target_has_atomic = "64")]
         already_sync!(
             [std::sync::atomic::AtomicU64]
         );
 
-        #[cfg(any(target_arch = "mips", target_arch = "powerpc", target_arch = "sparc"))]
+        #[cfg(not(target_has_atomic = "64"))]
         already_sync!(
             [portable_atomic::AtomicU64]
         );
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index 5ae79ca988f14..79ceb28abb518 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -270,12 +270,11 @@ cfg_match! {
 
         pub use std::sync::atomic::{AtomicBool, AtomicUsize, AtomicU32};
 
-        // MIPS, PowerPC and SPARC platforms with 32-bit pointers do not
-        // have AtomicU64 type.
-        #[cfg(not(any(target_arch = "mips", target_arch = "powerpc", target_arch = "sparc")))]
+        // Use portable AtomicU64 for targets without native 64-bit atomics
+        #[cfg(target_has_atomic = "64")]
         pub use std::sync::atomic::AtomicU64;
 
-        #[cfg(any(target_arch = "mips", target_arch = "powerpc", target_arch = "sparc"))]
+        #[cfg(not(target_has_atomic = "64"))]
         pub use portable_atomic::AtomicU64;
 
         pub use std::sync::Arc as Lrc;