Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 496 insertions, 0 deletions

diff --git a/compiler/rustc_data_structures/src/sip128.rs b/compiler/rustc_data_structures/src/sip128.rs
new file mode 100644
index 000000000..90793a97e
--- /dev/null
+++ b/compiler/rustc_data_structures/src/sip128.rs
@@ -0,0 +1,496 @@
+//! This is a copy of `core::hash::sip` adapted to providing 128 bit hashes.
+
+use std::hash::Hasher;
+use std::mem::{self, MaybeUninit};
+use std::ptr;
+
+#[cfg(test)]
+mod tests;
+
+// The SipHash algorithm operates on 8-byte chunks.
+const ELEM_SIZE: usize = mem::size_of::<u64>();
+
+// Size of the buffer in number of elements, not including the spill.
+//
+// The selection of this size was guided by rustc-perf benchmark comparisons of
+// different buffer sizes. It should be periodically reevaluated as the compiler
+// implementation and input characteristics change.
+//
+// Using the same-sized buffer for everything we hash is a performance versus
+// complexity tradeoff. The ideal buffer size, and whether buffering should even
+// be used, depends on what is being hashed. It may be worth it to size the
+// buffer appropriately (perhaps by making SipHasher128 generic over the buffer
+// size) or disable buffering depending on what is being hashed. But at this
+// time, we use the same buffer size for everything.
+const BUFFER_CAPACITY: usize = 8;
+
+// Size of the buffer in bytes, not including the spill.
+const BUFFER_SIZE: usize = BUFFER_CAPACITY * ELEM_SIZE;
+
+// Size of the buffer in number of elements, including the spill.
+const BUFFER_WITH_SPILL_CAPACITY: usize = BUFFER_CAPACITY + 1;
+
+// Size of the buffer in bytes, including the spill.
+const BUFFER_WITH_SPILL_SIZE: usize = BUFFER_WITH_SPILL_CAPACITY * ELEM_SIZE;
+
+// Index of the spill element in the buffer.
+const BUFFER_SPILL_INDEX: usize = BUFFER_WITH_SPILL_CAPACITY - 1;
+
+#[derive(Debug, Clone)]
+#[repr(C)]
+pub struct SipHasher128 {
+    // The access pattern during hashing consists of accesses to `nbuf` and
+    // `buf` until the buffer is full, followed by accesses to `state` and
+    // `processed`, and then repetition of that pattern until hashing is done.
+    // This is the basis for the ordering of fields below. However, in practice
+    // the cache miss-rate for data access is extremely low regardless of order.
+    nbuf: usize, // how many bytes in buf are valid
+    buf: [MaybeUninit<u64>; BUFFER_WITH_SPILL_CAPACITY], // unprocessed bytes le
+    state: State, // hash State
+    processed: usize, // how many bytes we've processed
+}
+
+#[derive(Debug, Clone, Copy)]
+#[repr(C)]
+struct State {
+    // v0, v2 and v1, v3 show up in pairs in the algorithm,
+    // and simd implementations of SipHash will use vectors
+    // of v02 and v13. By placing them in this order in the struct,
+    // the compiler can pick up on just a few simd optimizations by itself.
+    v0: u64,
+    v2: u64,
+    v1: u64,
+    v3: u64,
+}
+
+macro_rules! compress {
+    ($state:expr) => {{ compress!($state.v0, $state.v1, $state.v2, $state.v3) }};
+    ($v0:expr, $v1:expr, $v2:expr, $v3:expr) => {{
+        $v0 = $v0.wrapping_add($v1);
+        $v1 = $v1.rotate_left(13);
+        $v1 ^= $v0;
+        $v0 = $v0.rotate_left(32);
+        $v2 = $v2.wrapping_add($v3);
+        $v3 = $v3.rotate_left(16);
+        $v3 ^= $v2;
+        $v0 = $v0.wrapping_add($v3);
+        $v3 = $v3.rotate_left(21);
+        $v3 ^= $v0;
+        $v2 = $v2.wrapping_add($v1);
+        $v1 = $v1.rotate_left(17);
+        $v1 ^= $v2;
+        $v2 = $v2.rotate_left(32);
+    }};
+}
+
+// Copies up to 8 bytes from source to destination. This performs better than
+// `ptr::copy_nonoverlapping` on microbenchmarks and may perform better on real
+// workloads since all of the copies have fixed sizes and avoid calling memcpy.
+//
+// This is specifically designed for copies of up to 8 bytes, because that's the
+// maximum of number bytes needed to fill an 8-byte-sized element on which
+// SipHash operates. Note that for variable-sized copies which are known to be
+// less than 8 bytes, this function will perform more work than necessary unless
+// the compiler is able to optimize the extra work away.
+#[inline]
+unsafe fn copy_nonoverlapping_small(src: *const u8, dst: *mut u8, count: usize) {
+    debug_assert!(count <= 8);
+
+    if count == 8 {
+        ptr::copy_nonoverlapping(src, dst, 8);
+        return;
+    }
+
+    let mut i = 0;
+    if i + 3 < count {
+        ptr::copy_nonoverlapping(src.add(i), dst.add(i), 4);
+        i += 4;
+    }
+
+    if i + 1 < count {
+        ptr::copy_nonoverlapping(src.add(i), dst.add(i), 2);
+        i += 2
+    }
+
+    if i < count {
+        *dst.add(i) = *src.add(i);
+        i += 1;
+    }
+
+    debug_assert_eq!(i, count);
+}
+
+// # Implementation
+//
+// This implementation uses buffering to reduce the hashing cost for inputs
+// consisting of many small integers. Buffering simplifies the integration of
+// integer input--the integer write function typically just appends to the
+// buffer with a statically sized write, updates metadata, and returns.
+//
+// Buffering also prevents alternating between writes that do and do not trigger
+// the hashing process. Only when the entire buffer is full do we transition
+// into hashing. This allows us to keep the hash state in registers for longer,
+// instead of loading and storing it before and after processing each element.
+//
+// When a write fills the buffer, a buffer processing function is invoked to
+// hash all of the buffered input. The buffer processing functions are marked
+// `#[inline(never)]` so that they aren't inlined into the append functions,
+// which ensures the more frequently called append functions remain inlineable
+// and don't include register pushing/popping that would only be made necessary
+// by inclusion of the complex buffer processing path which uses those
+// registers.
+//
+// The buffer includes a "spill"--an extra element at the end--which simplifies
+// the integer write buffer processing path. The value that fills the buffer can
+// be written with a statically sized write that may spill over into the spill.
+// After the buffer is processed, the part of the value that spilled over can be
+// written from the spill to the beginning of the buffer with another statically
+// sized write. This write may copy more bytes than actually spilled over, but
+// we maintain the metadata such that any extra copied bytes will be ignored by
+// subsequent processing. Due to the static sizes, this scheme performs better
+// than copying the exact number of bytes needed into the end and beginning of
+// the buffer.
+//
+// The buffer is uninitialized, which improves performance, but may preclude
+// efficient implementation of alternative approaches. The improvement is not so
+// large that an alternative approach should be disregarded because it cannot be
+// efficiently implemented with an uninitialized buffer. On the other hand, an
+// uninitialized buffer may become more important should a larger one be used.
+//
+// # Platform Dependence
+//
+// The SipHash algorithm operates on byte sequences. It parses the input stream
+// as 8-byte little-endian integers. Therefore, given the same byte sequence, it
+// produces the same result on big- and little-endian hardware.
+//
+// However, the Hasher trait has methods which operate on multi-byte integers.
+// How they are converted into byte sequences can be endian-dependent (by using
+// native byte order) or independent (by consistently using either LE or BE byte
+// order). It can also be `isize` and `usize` size dependent (by using the
+// native size), or independent (by converting to a common size), supposing the
+// values can be represented in 32 bits.
+//
+// In order to make `SipHasher128` consistent with `SipHasher` in libstd, we
+// choose to do the integer to byte sequence conversion in the platform-
+// dependent way. Clients can achieve platform-independent hashing by widening
+// `isize` and `usize` integers to 64 bits on 32-bit systems and byte-swapping
+// integers on big-endian systems before passing them to the writing functions.
+// This causes the input byte sequence to look identical on big- and little-
+// endian systems (supposing `isize` and `usize` values can be represented in 32
+// bits), which ensures platform-independent results.
+impl SipHasher128 {
+    #[inline]
+    pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher128 {
+        let mut hasher = SipHasher128 {
+            nbuf: 0,
+            buf: MaybeUninit::uninit_array(),
+            state: State {
+                v0: key0 ^ 0x736f6d6570736575,
+                // The XOR with 0xee is only done on 128-bit algorithm version.
+                v1: key1 ^ (0x646f72616e646f6d ^ 0xee),
+                v2: key0 ^ 0x6c7967656e657261,
+                v3: key1 ^ 0x7465646279746573,
+            },
+            processed: 0,
+        };
+
+        unsafe {
+            // Initialize spill because we read from it in `short_write_process_buffer`.
+            *hasher.buf.get_unchecked_mut(BUFFER_SPILL_INDEX) = MaybeUninit::zeroed();
+        }
+
+        hasher
+    }
+
+    #[inline]
+    pub fn short_write<const LEN: usize>(&mut self, bytes: [u8; LEN]) {
+        let nbuf = self.nbuf;
+        debug_assert!(LEN <= 8);
+        debug_assert!(nbuf < BUFFER_SIZE);
+        debug_assert!(nbuf + LEN < BUFFER_WITH_SPILL_SIZE);
+
+        if nbuf + LEN < BUFFER_SIZE {
+            unsafe {
+                // The memcpy call is optimized away because the size is known.
+                let dst = (self.buf.as_mut_ptr() as *mut u8).add(nbuf);
+                ptr::copy_nonoverlapping(bytes.as_ptr(), dst, LEN);
+            }
+
+            self.nbuf = nbuf + LEN;
+
+            return;
+        }
+
+        unsafe { self.short_write_process_buffer(bytes) }
+    }
+
+    // A specialized write function for values with size <= 8 that should only
+    // be called when the write would cause the buffer to fill.
+    //
+    // SAFETY: the write of `x` into `self.buf` starting at byte offset
+    // `self.nbuf` must cause `self.buf` to become fully initialized (and not
+    // overflow) if it wasn't already.
+    #[inline(never)]
+    unsafe fn short_write_process_buffer<const LEN: usize>(&mut self, bytes: [u8; LEN]) {
+        let nbuf = self.nbuf;
+        debug_assert!(LEN <= 8);
+        debug_assert!(nbuf < BUFFER_SIZE);
+        debug_assert!(nbuf + LEN >= BUFFER_SIZE);
+        debug_assert!(nbuf + LEN < BUFFER_WITH_SPILL_SIZE);
+
+        // Copy first part of input into end of buffer, possibly into spill
+        // element. The memcpy call is optimized away because the size is known.
+        let dst = (self.buf.as_mut_ptr() as *mut u8).add(nbuf);
+        ptr::copy_nonoverlapping(bytes.as_ptr(), dst, LEN);
+
+        // Process buffer.
+        for i in 0..BUFFER_CAPACITY {
+            let elem = self.buf.get_unchecked(i).assume_init().to_le();
+            self.state.v3 ^= elem;
+            Sip24Rounds::c_rounds(&mut self.state);
+            self.state.v0 ^= elem;
+        }
+
+        // Copy remaining input into start of buffer by copying LEN - 1
+        // elements from spill (at most LEN - 1 bytes could have overflowed
+        // into the spill). The memcpy call is optimized away because the size
+        // is known. And the whole copy is optimized away for LEN == 1.
+        let dst = self.buf.as_mut_ptr() as *mut u8;
+        let src = self.buf.get_unchecked(BUFFER_SPILL_INDEX) as *const _ as *const u8;
+        ptr::copy_nonoverlapping(src, dst, LEN - 1);
+
+        // This function should only be called when the write fills the buffer.
+        // Therefore, when LEN == 1, the new `self.nbuf` must be zero.
+        // LEN is statically known, so the branch is optimized away.
+        self.nbuf = if LEN == 1 { 0 } else { nbuf + LEN - BUFFER_SIZE };
+        self.processed += BUFFER_SIZE;
+    }
+
+    // A write function for byte slices.
+    #[inline]
+    fn slice_write(&mut self, msg: &[u8]) {
+        let length = msg.len();
+        let nbuf = self.nbuf;
+        debug_assert!(nbuf < BUFFER_SIZE);
+
+        if nbuf + length < BUFFER_SIZE {
+            unsafe {
+                let dst = (self.buf.as_mut_ptr() as *mut u8).add(nbuf);
+
+                if length <= 8 {
+                    copy_nonoverlapping_small(msg.as_ptr(), dst, length);
+                } else {
+                    // This memcpy is *not* optimized away.
+                    ptr::copy_nonoverlapping(msg.as_ptr(), dst, length);
+                }
+            }
+
+            self.nbuf = nbuf + length;
+
+            return;
+        }
+
+        unsafe { self.slice_write_process_buffer(msg) }
+    }
+
+    // A write function for byte slices that should only be called when the
+    // write would cause the buffer to fill.
+    //
+    // SAFETY: `self.buf` must be initialized up to the byte offset `self.nbuf`,
+    // and `msg` must contain enough bytes to initialize the rest of the element
+    // containing the byte offset `self.nbuf`.
+    #[inline(never)]
+    unsafe fn slice_write_process_buffer(&mut self, msg: &[u8]) {
+        let length = msg.len();
+        let nbuf = self.nbuf;
+        debug_assert!(nbuf < BUFFER_SIZE);
+        debug_assert!(nbuf + length >= BUFFER_SIZE);
+
+        // Always copy first part of input into current element of buffer.
+        // This function should only be called when the write fills the buffer,
+        // so we know that there is enough input to fill the current element.
+        let valid_in_elem = nbuf % ELEM_SIZE;
+        let needed_in_elem = ELEM_SIZE - valid_in_elem;
+
+        let src = msg.as_ptr();
+        let dst = (self.buf.as_mut_ptr() as *mut u8).add(nbuf);
+        copy_nonoverlapping_small(src, dst, needed_in_elem);
+
+        // Process buffer.
+
+        // Using `nbuf / ELEM_SIZE + 1` rather than `(nbuf + needed_in_elem) /
+        // ELEM_SIZE` to show the compiler that this loop's upper bound is > 0.
+        // We know that is true, because last step ensured we have a full
+        // element in the buffer.
+        let last = nbuf / ELEM_SIZE + 1;
+
+        for i in 0..last {
+            let elem = self.buf.get_unchecked(i).assume_init().to_le();
+            self.state.v3 ^= elem;
+            Sip24Rounds::c_rounds(&mut self.state);
+            self.state.v0 ^= elem;
+        }
+
+        // Process the remaining element-sized chunks of input.
+        let mut processed = needed_in_elem;
+        let input_left = length - processed;
+        let elems_left = input_left / ELEM_SIZE;
+        let extra_bytes_left = input_left % ELEM_SIZE;
+
+        for _ in 0..elems_left {
+            let elem = (msg.as_ptr().add(processed) as *const u64).read_unaligned().to_le();
+            self.state.v3 ^= elem;
+            Sip24Rounds::c_rounds(&mut self.state);
+            self.state.v0 ^= elem;
+            processed += ELEM_SIZE;
+        }
+
+        // Copy remaining input into start of buffer.
+        let src = msg.as_ptr().add(processed);
+        let dst = self.buf.as_mut_ptr() as *mut u8;
+        copy_nonoverlapping_small(src, dst, extra_bytes_left);
+
+        self.nbuf = extra_bytes_left;
+        self.processed += nbuf + processed;
+    }
+
+    #[inline]
+    pub fn finish128(mut self) -> (u64, u64) {
+        debug_assert!(self.nbuf < BUFFER_SIZE);
+
+        // Process full elements in buffer.
+        let last = self.nbuf / ELEM_SIZE;
+
+        // Since we're consuming self, avoid updating members for a potential
+        // performance gain.
+        let mut state = self.state;
+
+        for i in 0..last {
+            let elem = unsafe { self.buf.get_unchecked(i).assume_init().to_le() };
+            state.v3 ^= elem;
+            Sip24Rounds::c_rounds(&mut state);
+            state.v0 ^= elem;
+        }
+
+        // Get remaining partial element.
+        let elem = if self.nbuf % ELEM_SIZE != 0 {
+            unsafe {
+                // Ensure element is initialized by writing zero bytes. At most
+                // `ELEM_SIZE - 1` are required given the above check. It's safe
+                // to write this many because we have the spill and we maintain
+                // `self.nbuf` such that this write will start before the spill.
+                let dst = (self.buf.as_mut_ptr() as *mut u8).add(self.nbuf);
+                ptr::write_bytes(dst, 0, ELEM_SIZE - 1);
+                self.buf.get_unchecked(last).assume_init().to_le()
+            }
+        } else {
+            0
+        };
+
+        // Finalize the hash.
+        let length = self.processed + self.nbuf;
+        let b: u64 = ((length as u64 & 0xff) << 56) | elem;
+
+        state.v3 ^= b;
+        Sip24Rounds::c_rounds(&mut state);
+        state.v0 ^= b;
+
+        state.v2 ^= 0xee;
+        Sip24Rounds::d_rounds(&mut state);
+        let _0 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
+
+        state.v1 ^= 0xdd;
+        Sip24Rounds::d_rounds(&mut state);
+        let _1 = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
+
+        (_0, _1)
+    }
+}
+
+impl Hasher for SipHasher128 {
+    #[inline]
+    fn write_u8(&mut self, i: u8) {
+        self.short_write(i.to_ne_bytes());
+    }
+
+    #[inline]
+    fn write_u16(&mut self, i: u16) {
+        self.short_write(i.to_ne_bytes());
+    }
+
+    #[inline]
+    fn write_u32(&mut self, i: u32) {
+        self.short_write(i.to_ne_bytes());
+    }
+
+    #[inline]
+    fn write_u64(&mut self, i: u64) {
+        self.short_write(i.to_ne_bytes());
+    }
+
+    #[inline]
+    fn write_usize(&mut self, i: usize) {
+        self.short_write(i.to_ne_bytes());
+    }
+
+    #[inline]
+    fn write_i8(&mut self, i: i8) {
+        self.short_write((i as u8).to_ne_bytes());
+    }
+
+    #[inline]
+    fn write_i16(&mut self, i: i16) {
+        self.short_write((i as u16).to_ne_bytes());
+    }
+
+    #[inline]
+    fn write_i32(&mut self, i: i32) {
+        self.short_write((i as u32).to_ne_bytes());
+    }
+
+    #[inline]
+    fn write_i64(&mut self, i: i64) {
+        self.short_write((i as u64).to_ne_bytes());
+    }
+
+    #[inline]
+    fn write_isize(&mut self, i: isize) {
+        self.short_write((i as usize).to_ne_bytes());
+    }
+
+    #[inline]
+    fn write(&mut self, msg: &[u8]) {
+        self.slice_write(msg);
+    }
+
+    #[inline]
+    fn write_str(&mut self, s: &str) {
+        // This hasher works byte-wise, and `0xFF` cannot show up in a `str`,
+        // so just hashing the one extra byte is enough to be prefix-free.
+        self.write(s.as_bytes());
+        self.write_u8(0xFF);
+    }
+
+    fn finish(&self) -> u64 {
+        panic!("SipHasher128 cannot provide valid 64 bit hashes")
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+struct Sip24Rounds;
+
+impl Sip24Rounds {
+    #[inline]
+    fn c_rounds(state: &mut State) {
+        compress!(state);
+        compress!(state);
+    }
+
+    #[inline]
+    fn d_rounds(state: &mut State) {
+        compress!(state);
+        compress!(state);
+        compress!(state);
+        compress!(state);
+    }
+}