use portable AtomicU64 for powerPC and MIPS

Cargo.lock

@@ -2982,9 +2982,9 @@ dependencies = [
 
 [[package]]
 name = "portable-atomic"
-version = "1.4.2"
+version = "1.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f32154ba0af3a075eefa1eda8bb414ee928f62303a54ea85b8d6638ff1a6ee9e"
+checksum = "3bccab0e7fd7cc19f820a1c8c91720af652d0c88dc9664dd72aef2614f04af3b"
 
 [[package]]
 name = "ppv-lite86"
@@ -3712,6 +3712,7 @@ dependencies = [
  "measureme",
  "memmap2",
  "parking_lot 0.12.1",
+ "portable-atomic",
  "rustc-hash",
  "rustc-rayon",
  "rustc-rayon-core",

compiler/rustc_data_structures/Cargo.toml

@@ -47,6 +47,9 @@ features = [
 memmap2 = "0.2.1"
 # tidy-alphabetical-end
 
+[target.'cfg(any(target_arch = "powerpc", target_arch = "mips"))'.dependencies]
+portable-atomic = "1.5.1"
+
 [features]
 # tidy-alphabetical-start
 rustc_use_parallel_compiler = ["indexmap/rustc-rayon", "rustc-rayon", "rustc-rayon-core"]

compiler/rustc_data_structures/src/marker.rs

@@ -138,7 +138,6 @@ cfg_match! {
             [std::sync::atomic::AtomicUsize]
             [std::sync::atomic::AtomicU8]
             [std::sync::atomic::AtomicU32]
-            [std::sync::atomic::AtomicU64]
             [std::backtrace::Backtrace]
             [std::io::Error]
             [std::fs::File]
@@ -148,6 +147,18 @@ cfg_match! {
             [crate::owned_slice::OwnedSlice]
         );
 
+        // PowerPC and MIPS platforms with 32-bit pointers do not
+        // have AtomicU64 type.
+        #[cfg(not(any(target_arch = "powerpc", target_arch = "mips")))]
+        already_sync!(
+            [std::sync::atomic::AtomicU64]
+        );
+
+        #[cfg(any(target_arch = "powerpc", target_arch = "mips"))]
+        already_sync!(
+            [portable_atomic::AtomicU64]
+        );
+
         macro_rules! impl_dyn_sync {
             ($($($attr: meta)* [$ty: ty where $($generics2: tt)*])*) => {
                 $(unsafe impl<$($generics2)*> DynSync for $ty {})*

compiler/rustc_data_structures/src/sync.rs

@@ -265,7 +265,15 @@ cfg_match! {
 
         pub use std::sync::OnceLock;
 
-        pub use std::sync::atomic::{AtomicBool, AtomicUsize, AtomicU32, AtomicU64};
+        pub use std::sync::atomic::{AtomicBool, AtomicUsize, AtomicU32};
+
+        // PowerPC and MIPS platforms with 32-bit pointers do not
+        // have AtomicU64 type.
+        #[cfg(not(any(target_arch = "powerpc", target_arch = "mips")))]
+        pub use std::sync::atomic::AtomicU64;
+
+        #[cfg(any(target_arch = "powerpc", target_arch = "mips"))]
+        pub use portable_atomic::AtomicU64;
 
         pub use std::sync::Arc as Lrc;
         pub use std::sync::Weak as Weak;

src/tools/tidy/src/deps.rs

@@ -211,6 +211,7 @@ const PERMITTED_RUSTC_DEPENDENCIES: &[&str] = &[
     "perf-event-open-sys",
     "pin-project-lite",
     "polonius-engine",
+    "portable-atomic", // dependency for platforms doesn't support `AtomicU64` in std
     "ppv-lite86",
     "proc-macro-hack",
     "proc-macro2",