mirror of
https://github.com/rust-lang/rust.git
synced 2025-11-18 00:46:17 +00:00
d7b42faaa3
This way if the feature is statically detected then it'll be expanded to `true` Closes #349
75 lines
2.2 KiB
Rust
75 lines
2.2 KiB
Rust
//! Run-time feature detection on ARM Aarch32.
|
|
|
|
use super::bit;
|
|
use super::cache;
|
|
use super::linux;
|
|
|
|
#[macro_export]
|
|
#[unstable(feature = "stdsimd", issue = "0")]
|
|
macro_rules! is_arm_feature_detected {
|
|
("neon") => {
|
|
cfg!(target_feature = "neon") ||
|
|
$crate::arch::detect::check_for($crate::arch::detect::Feature::neon)
|
|
};
|
|
("pmull") => {
|
|
cfg!(target_feature = "pmull") ||
|
|
$crate::arch::detect::check_for($crate::arch::detect::Feature::pmull)
|
|
};
|
|
($t:tt) => { compile_error!(concat!("unknown arm target feature: ", $t)) };
|
|
}
|
|
|
|
/// ARM CPU Feature enum. Each variant denotes a position in a bitset for a
|
|
/// particular feature.
|
|
///
|
|
/// PLEASE: do not use this, it is an implementation detail subject to change.
|
|
#[doc(hidden)]
|
|
#[allow(non_camel_case_types)]
|
|
#[repr(u8)]
|
|
pub enum Feature {
|
|
/// ARM Advanced SIMD (NEON) - Aarch32
|
|
neon,
|
|
/// Polynomial Multiply
|
|
pmull,
|
|
}
|
|
|
|
pub fn detect_features() -> cache::Initializer {
|
|
let mut value = cache::Initializer::default();
|
|
fill_features(&mut value);
|
|
return value
|
|
}
|
|
|
|
fn fill_features(value: &mut cache::Initializer) {
|
|
let mut enable_feature = |f, enable| {
|
|
if enable {
|
|
value.set(f as u32);
|
|
}
|
|
};
|
|
|
|
// The values are part of the platform-specific [asm/hwcap.h][hwcap]
|
|
//
|
|
// [hwcap]: https://github.com/torvalds/linux/blob/master/arch/arm64/include/uapi/asm/hwcap.h
|
|
if let Ok(auxv) = linux::auxv() {
|
|
enable_feature(Feature::neon, bit::test(auxv.hwcap, 12));
|
|
enable_feature(Feature::pmull, bit::test(auxv.hwcap2, 1));
|
|
return
|
|
}
|
|
|
|
if let Ok(c) = linux::CpuInfo::new() {
|
|
enable_feature(Feature::neon, c.field("Features").has("neon") &&
|
|
!has_broken_neon(&c));
|
|
enable_feature(Feature::pmull, c.field("Features").has("pmull"));
|
|
return
|
|
}
|
|
|
|
/// Is the CPU known to have a broken NEON unit?
|
|
///
|
|
/// See https://crbug.com/341598.
|
|
fn has_broken_neon(cpuinfo: &linux::CpuInfo) -> bool {
|
|
cpuinfo.field("CPU implementer") == "0x51"
|
|
&& cpuinfo.field("CPU architecture") == "7"
|
|
&& cpuinfo.field("CPU variant") == "0x1"
|
|
&& cpuinfo.field("CPU part") == "0x04d"
|
|
&& cpuinfo.field("CPU revision") == "0"
|
|
}
|
|
}
|