build(rust): vendor rnix parser crate

third_party/crates/hashbrown-0.14.5/src/raw/sse2.rs

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+use super::bitmask::BitMask;
+use super::EMPTY;
+use core::mem;
+use core::num::NonZeroU16;
+
+#[cfg(target_arch = "x86")]
+use core::arch::x86;
+#[cfg(target_arch = "x86_64")]
+use core::arch::x86_64 as x86;
+
+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 bytes which can be scanned in
+/// parallel.
+///
+/// This implementation uses a 128-bit SSE value.
+#[derive(Copy, Clone)]
+pub(crate) struct Group(x86::__m128i);
+
+// 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 bytes, 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 [u8; Group::WIDTH] {
+        #[repr(C)]
+        struct AlignedBytes {
+            _align: [Group; 0],
+            bytes: [u8; Group::WIDTH],
+        }
+        const ALIGNED_BYTES: AlignedBytes = AlignedBytes {
+            _align: [],
+            bytes: [EMPTY; Group::WIDTH],
+        };
+        &ALIGNED_BYTES.bytes
+    }
+
+    /// Loads a group of bytes starting at the given address.
+    #[inline]
+    #[allow(clippy::cast_ptr_alignment)] // unaligned load
+    pub(crate) unsafe fn load(ptr: *const u8) -> Self {
+        Group(x86::_mm_loadu_si128(ptr.cast()))
+    }
+
+    /// Loads a group of bytes 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 u8) -> Self {
+        // FIXME: use align_offset once it stabilizes
+        debug_assert_eq!(ptr as usize & (mem::align_of::<Self>() - 1), 0);
+        Group(x86::_mm_load_si128(ptr.cast()))
+    }
+
+    /// Stores the group of bytes 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 u8) {
+        // FIXME: use align_offset once it stabilizes
+        debug_assert_eq!(ptr as usize & (mem::align_of::<Self>() - 1), 0);
+        x86::_mm_store_si128(ptr.cast(), self.0);
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which have
+    /// the given value.
+    #[inline]
+    pub(crate) fn match_byte(self, byte: u8) -> BitMask {
+        #[allow(
+            clippy::cast_possible_wrap, // byte: u8 as i8
+            // byte: i32 as u16
+            //   note: _mm_movemask_epi8 returns a 16-bit mask in a i32, the
+            //   upper 16-bits of the i32 are zeroed:
+            clippy::cast_sign_loss,
+            clippy::cast_possible_truncation
+        )]
+        unsafe {
+            let cmp = x86::_mm_cmpeq_epi8(self.0, x86::_mm_set1_epi8(byte as i8));
+            BitMask(x86::_mm_movemask_epi8(cmp) as u16)
+        }
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are
+    /// `EMPTY`.
+    #[inline]
+    pub(crate) fn match_empty(self) -> BitMask {
+        self.match_byte(EMPTY)
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are
+    /// `EMPTY` or `DELETED`.
+    #[inline]
+    pub(crate) fn match_empty_or_deleted(self) -> BitMask {
+        #[allow(
+            // byte: i32 as u16
+            //   note: _mm_movemask_epi8 returns a 16-bit mask in a i32, the
+            //   upper 16-bits of the i32 are zeroed:
+            clippy::cast_sign_loss,
+            clippy::cast_possible_truncation
+        )]
+        unsafe {
+            // A byte is EMPTY or DELETED iff the high bit is set
+            BitMask(x86::_mm_movemask_epi8(self.0) as u16)
+        }
+    }
+
+    /// Returns a `BitMask` indicating all bytes in the group which are full.
+    #[inline]
+    pub(crate) fn match_full(&self) -> BitMask {
+        self.match_empty_or_deleted().invert()
+    }
+
+    /// Performs the following transformation on all bytes 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 > byte = 1111_1111 (true) or 0000_0000 (false)
+        //   1111_1111 | 1000_0000 = 1111_1111
+        //   0000_0000 | 1000_0000 = 1000_0000
+        #[allow(
+            clippy::cast_possible_wrap, // byte: 0x80_u8 as i8
+        )]
+        unsafe {
+            let zero = x86::_mm_setzero_si128();
+            let special = x86::_mm_cmpgt_epi8(zero, self.0);
+            Group(x86::_mm_or_si128(
+                special,
+                x86::_mm_set1_epi8(0x80_u8 as i8),
+            ))
+        }
+    }
+}