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cpufeatures: Support dynamic feature detection on iOS and derivative platforms #848

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merged 1 commit into from
Mar 18, 2023
Merged

cpufeatures: Support dynamic feature detection on iOS and derivative platforms #848

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2 changes: 1 addition & 1 deletion cpufeatures/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@ categories = ["no-std"]
edition = "2018"
readme = "README.md"

[target.aarch64-apple-darwin.dependencies]
[target.'cfg(all(target_arch = "aarch64", target_vendor = "apple"))'.dependencies]
libc = "0.2.95"

[target.'cfg(all(target_arch = "aarch64", target_os = "linux"))'.dependencies]
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42 changes: 7 additions & 35 deletions cpufeatures/src/aarch64.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -37,8 +37,8 @@ pub fn getauxval_hwcap() -> u64 {
unsafe { libc::getauxval(libc::AT_HWCAP) }
}

// MacOS runtime detection of target CPU features using `sysctlbyname`.
#[cfg(target_os = "macos")]
// Apple platform's runtime detection of target CPU features using `sysctlbyname`.
#[cfg(target_vendor = "apple")]
#[macro_export]
#[doc(hidden)]
macro_rules! __detect_target_features {
Expand Down Expand Up @@ -87,7 +87,7 @@ pub mod hwcaps {
pub const SHA3: c_ulong = libc::HWCAP_SHA3 | libc::HWCAP_SHA512;
}

// macOS `check!` macro.
// Apple OS (macOS, iOS, watchOS, and tvOS) `check!` macro.
//
// NOTE: several of these instructions (e.g. `aes`, `sha2`) can be assumed to
// be present on all Apple ARM64 hardware.
Expand All @@ -98,7 +98,7 @@ pub mod hwcaps {
//
// See discussion on this issue for more information:
// <https://github.com/RustCrypto/utils/issues/378>
#[cfg(target_os = "macos")]
#[cfg(target_vendor = "apple")]
#[macro_export]
#[doc(hidden)]
macro_rules! check {
Expand All @@ -117,8 +117,8 @@ macro_rules! check {
};
}

/// macOS helper function for calling `sysctlbyname`.
#[cfg(target_os = "macos")]
/// Apple helper function for calling `sysctlbyname`.
#[cfg(target_vendor = "apple")]
pub unsafe fn sysctlbyname(name: &[u8]) -> bool {
assert_eq!(
name.last().cloned(),
Expand All @@ -143,36 +143,8 @@ pub unsafe fn sysctlbyname(name: &[u8]) -> bool {
value != 0
}

// iOS `check!` macro.
//
// Unfortunately iOS does not provide access to the `sysctl(3)` API which means
// we can only return static values for CPU features which can be assumed to
// be present on all Apple ARM64 hardware.
//
// See discussion on this issue for more information:
// <https://github.com/RustCrypto/utils/issues/378>
#[cfg(target_os = "ios")]
#[macro_export]
#[doc(hidden)]
macro_rules! check {
("aes") => {
true
};
("sha2") => {
true
};
("sha3") => {
false
};
}

// On other targets, runtime CPU feature detection is unavailable
#[cfg(not(any(
target_os = "ios",
target_os = "linux",
target_os = "android",
target_os = "macos"
)))]
#[cfg(not(any(target_vendor = "apple", target_os = "linux", target_os = "android",)))]
#[macro_export]
#[doc(hidden)]
macro_rules! __detect_target_features {
Expand Down