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//! Run-time feature detection for LoongArch on Linux.
use core::arch::asm;
use super::auxvec;
use crate::detect::{Feature, bit, cache};
/// Try to read the features from the auxiliary vector.
pub(crate) fn detect_features() -> cache::Initializer {
let mut value = cache::Initializer::default();
let enable_feature = |value: &mut cache::Initializer, feature, enable| {
if enable {
value.set(feature as u32);
}
};
// The values are part of the platform-specific [cpucfg]
//
// [cpucfg]: LoongArch Reference Manual Volume 1: Basic Architecture v1.1
let cpucfg1: usize;
let cpucfg2: usize;
let cpucfg3: usize;
unsafe {
asm!(
"cpucfg {}, {}",
"cpucfg {}, {}",
"cpucfg {}, {}",
out(reg) cpucfg1, in(reg) 1,
out(reg) cpucfg2, in(reg) 2,
out(reg) cpucfg3, in(reg) 3,
options(pure, nomem, preserves_flags, nostack)
);
}
enable_feature(&mut value, Feature::_32s, bit::test(cpucfg1, 0) || bit::test(cpucfg1, 1));
enable_feature(&mut value, Feature::frecipe, bit::test(cpucfg2, 25));
enable_feature(&mut value, Feature::div32, bit::test(cpucfg2, 26));
enable_feature(&mut value, Feature::lam_bh, bit::test(cpucfg2, 27));
enable_feature(&mut value, Feature::lamcas, bit::test(cpucfg2, 28));
enable_feature(&mut value, Feature::scq, bit::test(cpucfg2, 30));
enable_feature(&mut value, Feature::ld_seq_sa, bit::test(cpucfg3, 23));
// The values are part of the platform-specific [asm/hwcap.h][hwcap]
//
// [hwcap]: https://github.com/torvalds/linux/blob/master/arch/loongarch/include/uapi/asm/hwcap.h
if let Ok(auxv) = auxvec::auxv() {
enable_feature(&mut value, Feature::f, bit::test(cpucfg2, 1) && bit::test(auxv.hwcap, 3));
enable_feature(&mut value, Feature::d, bit::test(cpucfg2, 2) && bit::test(auxv.hwcap, 3));
enable_feature(&mut value, Feature::lsx, bit::test(auxv.hwcap, 4));
enable_feature(&mut value, Feature::lasx, bit::test(auxv.hwcap, 5));
enable_feature(
&mut value,
Feature::lbt,
bit::test(auxv.hwcap, 10) && bit::test(auxv.hwcap, 11) && bit::test(auxv.hwcap, 12),
);
enable_feature(&mut value, Feature::lvz, bit::test(auxv.hwcap, 9));
enable_feature(&mut value, Feature::ual, bit::test(auxv.hwcap, 2));
return value;
}
value
}
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