138 lines
4.8 KiB
Rust
138 lines
4.8 KiB
Rust
use super::super::{BitMask, Tag};
|
|
use core::mem;
|
|
use core::num::NonZeroU16;
|
|
|
|
use core::arch::loongarch64::*;
|
|
use mem::transmute;
|
|
|
|
pub(crate) type BitMaskWord = u16;
|
|
pub(crate) type NonZeroBitMaskWord = NonZeroU16;
|
|
pub(crate) const BITMASK_STRIDE: usize = 1;
|
|
pub(crate) const BITMASK_MASK: BitMaskWord = 0xffff;
|
|
pub(crate) const BITMASK_ITER_MASK: BitMaskWord = !0;
|
|
|
|
/// Abstraction over a group of control tags which can be scanned in
|
|
/// parallel.
|
|
///
|
|
/// This implementation uses a 128-bit LSX value.
|
|
#[derive(Copy, Clone)]
|
|
pub(crate) struct Group(v16i8);
|
|
|
|
// FIXME: https://github.com/rust-lang/rust-clippy/issues/3859
|
|
#[allow(clippy::use_self)]
|
|
impl Group {
|
|
/// Number of bytes in the group.
|
|
pub(crate) const WIDTH: usize = mem::size_of::<Self>();
|
|
|
|
/// Returns a full group of empty tags, suitable for use as the initial
|
|
/// value for an empty hash table.
|
|
///
|
|
/// This is guaranteed to be aligned to the group size.
|
|
#[inline]
|
|
#[allow(clippy::items_after_statements)]
|
|
pub(crate) const fn static_empty() -> &'static [Tag; Group::WIDTH] {
|
|
#[repr(C)]
|
|
struct AlignedTags {
|
|
_align: [Group; 0],
|
|
tags: [Tag; Group::WIDTH],
|
|
}
|
|
const ALIGNED_TAGS: AlignedTags = AlignedTags {
|
|
_align: [],
|
|
tags: [Tag::EMPTY; Group::WIDTH],
|
|
};
|
|
&ALIGNED_TAGS.tags
|
|
}
|
|
|
|
/// Loads a group of tags starting at the given address.
|
|
#[inline]
|
|
#[allow(clippy::cast_ptr_alignment)] // unaligned load
|
|
pub(crate) unsafe fn load(ptr: *const Tag) -> Self {
|
|
Group(lsx_vld::<0>(ptr.cast()))
|
|
}
|
|
|
|
/// Loads a group of tags starting at the given address, which must be
|
|
/// aligned to `mem::align_of::<Group>()`.
|
|
#[inline]
|
|
#[allow(clippy::cast_ptr_alignment)]
|
|
pub(crate) unsafe fn load_aligned(ptr: *const Tag) -> Self {
|
|
debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
|
|
Group(lsx_vld::<0>(ptr.cast()))
|
|
}
|
|
|
|
/// Stores the group of tags to the given address, which must be
|
|
/// aligned to `mem::align_of::<Group>()`.
|
|
#[inline]
|
|
#[allow(clippy::cast_ptr_alignment)]
|
|
pub(crate) unsafe fn store_aligned(self, ptr: *mut Tag) {
|
|
debug_assert_eq!(ptr.align_offset(mem::align_of::<Self>()), 0);
|
|
lsx_vst::<0>(self.0, ptr.cast());
|
|
}
|
|
|
|
/// Returns a `BitMask` indicating all tags in the group which have
|
|
/// the given value.
|
|
#[inline]
|
|
pub(crate) fn match_tag(self, tag: Tag) -> BitMask {
|
|
#[allow(clippy::missing_transmute_annotations)]
|
|
unsafe {
|
|
let cmp = lsx_vseq_b(self.0, lsx_vreplgr2vr_b(tag.0 as i32));
|
|
BitMask(lsx_vpickve2gr_hu::<0>(transmute(lsx_vmskltz_b(cmp))) as u16)
|
|
}
|
|
}
|
|
|
|
/// Returns a `BitMask` indicating all tags in the group which are
|
|
/// `EMPTY`.
|
|
#[inline]
|
|
pub(crate) fn match_empty(self) -> BitMask {
|
|
#[allow(clippy::missing_transmute_annotations)]
|
|
unsafe {
|
|
let cmp = lsx_vseqi_b::<{ Tag::EMPTY.0 as i8 as i32 }>(self.0);
|
|
BitMask(lsx_vpickve2gr_hu::<0>(transmute(lsx_vmskltz_b(cmp))) as u16)
|
|
}
|
|
}
|
|
|
|
/// Returns a `BitMask` indicating all tags in the group which are
|
|
/// `EMPTY` or `DELETED`.
|
|
#[inline]
|
|
pub(crate) fn match_empty_or_deleted(self) -> BitMask {
|
|
#[allow(clippy::missing_transmute_annotations)]
|
|
unsafe {
|
|
// A tag is EMPTY or DELETED iff the high bit is set
|
|
BitMask(lsx_vpickve2gr_hu::<0>(transmute(lsx_vmskltz_b(self.0))) as u16)
|
|
}
|
|
}
|
|
|
|
/// Returns a `BitMask` indicating all tags in the group which are full.
|
|
#[inline]
|
|
pub(crate) fn match_full(&self) -> BitMask {
|
|
#[allow(clippy::missing_transmute_annotations)]
|
|
unsafe {
|
|
// A tag is EMPTY or DELETED iff the high bit is set
|
|
BitMask(lsx_vpickve2gr_hu::<0>(transmute(lsx_vmskgez_b(self.0))) as u16)
|
|
}
|
|
}
|
|
|
|
/// Performs the following transformation on all tags in the group:
|
|
/// - `EMPTY => EMPTY`
|
|
/// - `DELETED => EMPTY`
|
|
/// - `FULL => DELETED`
|
|
#[inline]
|
|
pub(crate) fn convert_special_to_empty_and_full_to_deleted(self) -> Self {
|
|
// Map high_bit = 1 (EMPTY or DELETED) to 1111_1111
|
|
// and high_bit = 0 (FULL) to 1000_0000
|
|
//
|
|
// Here's this logic expanded to concrete values:
|
|
// let special = 0 > tag = 1111_1111 (true) or 0000_0000 (false)
|
|
// 1111_1111 | 1000_0000 = 1111_1111
|
|
// 0000_0000 | 1000_0000 = 1000_0000
|
|
#[allow(clippy::missing_transmute_annotations)]
|
|
unsafe {
|
|
let zero = lsx_vreplgr2vr_b(0);
|
|
let special = lsx_vslt_b(self.0, zero);
|
|
Group(transmute(lsx_vor_v(
|
|
transmute(special),
|
|
transmute(lsx_vreplgr2vr_b(Tag::DELETED.0 as i32)),
|
|
)))
|
|
}
|
|
}
|
|
}
|