Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 140 insertions, 0 deletions

diff --git a/third_party/rust/cpufeatures/src/lib.rs b/third_party/rust/cpufeatures/src/lib.rs
new file mode 100644
index 0000000000..b6c7c10b24
--- /dev/null
+++ b/third_party/rust/cpufeatures/src/lib.rs
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+//! This crate provides macros for runtime CPU feature detection. It's intended
+//! as a stopgap until Rust [RFC 2725] adding first-class target feature detection
+//! macros to `libcore` is implemented.
+//!
+//! Supported target architectures:
+//! - `aarch64`: Linux and macOS/M4 only (ARM64 does not support OS-independent feature detection)
+//!   - Target features: `aes`, `sha2`, `sha3`
+//! - `x86`/`x86_64`: OS independent and `no_std`-friendly
+//!   - Target features: `adx`, `aes`, `avx`, `avx2`, `bmi1`, `bmi2`, `fma`,
+//!     `mmx`, `pclmulqdq`, `popcnt`, `rdrand`, `rdseed`, `sgx`, `sha`, `sse`,
+//!     `sse2`, `sse3`, `sse4.1`, `sse4.2`, `ssse3`
+//!
+//! If you would like detection support for a target feature which is not on
+//! this list, please [open a GitHub issue][gh].
+//!
+//! # Example
+//! ```
+//! # #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+//! # {
+//! // This macro creates `cpuid_aes_sha` module
+//! cpufeatures::new!(cpuid_aes_sha, "aes", "sha");
+//!
+//! // `token` is a Zero Sized Type (ZST) value, which guarantees
+//! // that underlying static storage got properly initialized,
+//! // which allows to omit initialization branch
+//! let token: cpuid_aes_sha::InitToken = cpuid_aes_sha::init();
+//!
+//! if token.get() {
+//!     println!("CPU supports both SHA and AES extensions");
+//! } else {
+//!     println!("SHA and AES extensions are not supported");
+//! }
+//!
+//! // If stored value needed only once you can get stored value
+//! // omitting the token
+//! let val = cpuid_aes_sha::get();
+//! assert_eq!(val, token.get());
+//!
+//! // Additionally you can get both token and value
+//! let (token, val) = cpuid_aes_sha::init_get();
+//! assert_eq!(val, token.get());
+//! # }
+//! ```
+//!
+//! Note that if all tested target features are enabled via compiler options
+//! (e.g. by using `RUSTFLAGS`), the `get` method will always return `true`
+//! and `init` will not use CPUID instruction. Such behavior allows
+//! compiler to completely eliminate fallback code.
+//!
+//! After first call macro caches result and returns it in subsequent
+//! calls, thus runtime overhead for them is minimal.
+//!
+//! [RFC 2725]: https://github.com/rust-lang/rfcs/pull/2725
+//! [gh]: https://github.com/RustCrypto/utils/issues/new?title=cpufeatures:%20requesting%20support%20for%20CHANGEME%20target%20feature
+
+#![no_std]
+#![doc(
+    html_logo_url = "https://raw.githubusercontent.com/RustCrypto/media/6ee8e381/logo.svg",
+    html_favicon_url = "https://raw.githubusercontent.com/RustCrypto/media/6ee8e381/logo.svg"
+)]
+
+#[cfg(not(miri))]
+#[cfg(all(target_arch = "aarch64"))]
+#[doc(hidden)]
+pub mod aarch64;
+
+#[cfg(not(miri))]
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+mod x86;
+
+#[cfg(miri)]
+mod miri;
+
+#[cfg(not(any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")))]
+compile_error!("This crate works only on `aarch64`, `x86`, and `x86-64` targets.");
+
+/// Create module with CPU feature detection code.
+#[macro_export]
+macro_rules! new {
+    ($mod_name:ident, $($tf:tt),+ $(,)?) => {
+        mod $mod_name {
+            use core::sync::atomic::{AtomicU8, Ordering::Relaxed};
+
+            const UNINIT: u8 = u8::max_value();
+            static STORAGE: AtomicU8 = AtomicU8::new(UNINIT);
+
+            /// Initialization token
+            #[derive(Copy, Clone, Debug)]
+            pub struct InitToken(());
+
+            impl InitToken {
+                /// Get initialized value
+                #[inline(always)]
+                pub fn get(&self) -> bool {
+                    $crate::__unless_target_features! {
+                        $($tf),+ => {
+                            STORAGE.load(Relaxed) == 1
+                        }
+                    }
+                }
+            }
+
+            /// Initialize underlying storage if needed and get
+            /// stored value and initialization token.
+            #[inline]
+            pub fn init_get() -> (InitToken, bool) {
+                let res = $crate::__unless_target_features! {
+                    $($tf),+ => {
+                        // Relaxed ordering is fine, as we only have a single atomic variable.
+                        let val = STORAGE.load(Relaxed);
+
+                        if val == UNINIT {
+                            let res = $crate::__detect_target_features!($($tf),+);
+                            STORAGE.store(res as u8, Relaxed);
+                            res
+                        } else {
+                            val == 1
+                        }
+                    }
+                };
+
+                (InitToken(()), res)
+            }
+
+            /// Initialize underlying storage if needed and get
+            /// initialization token.
+            #[inline]
+            pub fn init() -> InitToken {
+                init_get().0
+            }
+
+            /// Initialize underlying storage if needed and get
+            /// stored value.
+            #[inline]
+            pub fn get() -> bool {
+                init_get().1
+            }
+        }
+    };
+}