mv compiler to compiler/

compiler/rustc_data_structures/src/stable_hasher.rs

@@ -0,0 +1,578 @@
+use crate::sip128::SipHasher128;
+use rustc_index::bit_set;
+use rustc_index::vec;
+use smallvec::SmallVec;
+use std::hash::{BuildHasher, Hash, Hasher};
+use std::mem;
+
+/// When hashing something that ends up affecting properties like symbol names,
+/// we want these symbol names to be calculated independently of other factors
+/// like what architecture you're compiling *from*.
+///
+/// To that end we always convert integers to little-endian format before
+/// hashing and the architecture dependent `isize` and `usize` types are
+/// extended to 64 bits if needed.
+pub struct StableHasher {
+    state: SipHasher128,
+}
+
+impl ::std::fmt::Debug for StableHasher {
+    fn fmt(&self, f: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result {
+        write!(f, "{:?}", self.state)
+    }
+}
+
+pub trait StableHasherResult: Sized {
+    fn finish(hasher: StableHasher) -> Self;
+}
+
+impl StableHasher {
+    #[inline]
+    pub fn new() -> Self {
+        StableHasher { state: SipHasher128::new_with_keys(0, 0) }
+    }
+
+    pub fn finish<W: StableHasherResult>(self) -> W {
+        W::finish(self)
+    }
+}
+
+impl StableHasherResult for u128 {
+    fn finish(hasher: StableHasher) -> Self {
+        let (_0, _1) = hasher.finalize();
+        u128::from(_0) | (u128::from(_1) << 64)
+    }
+}
+
+impl StableHasherResult for u64 {
+    fn finish(hasher: StableHasher) -> Self {
+        hasher.finalize().0
+    }
+}
+
+impl StableHasher {
+    #[inline]
+    pub fn finalize(self) -> (u64, u64) {
+        self.state.finish128()
+    }
+}
+
+impl Hasher for StableHasher {
+    fn finish(&self) -> u64 {
+        panic!("use StableHasher::finalize instead");
+    }
+
+    #[inline]
+    fn write(&mut self, bytes: &[u8]) {
+        self.state.write(bytes);
+    }
+
+    #[inline]
+    fn write_u8(&mut self, i: u8) {
+        self.state.write_u8(i);
+    }
+
+    #[inline]
+    fn write_u16(&mut self, i: u16) {
+        self.state.write_u16(i.to_le());
+    }
+
+    #[inline]
+    fn write_u32(&mut self, i: u32) {
+        self.state.write_u32(i.to_le());
+    }
+
+    #[inline]
+    fn write_u64(&mut self, i: u64) {
+        self.state.write_u64(i.to_le());
+    }
+
+    #[inline]
+    fn write_u128(&mut self, i: u128) {
+        self.state.write_u128(i.to_le());
+    }
+
+    #[inline]
+    fn write_usize(&mut self, i: usize) {
+        // Always treat usize as u64 so we get the same results on 32 and 64 bit
+        // platforms. This is important for symbol hashes when cross compiling,
+        // for example.
+        self.state.write_u64((i as u64).to_le());
+    }
+
+    #[inline]
+    fn write_i8(&mut self, i: i8) {
+        self.state.write_i8(i);
+    }
+
+    #[inline]
+    fn write_i16(&mut self, i: i16) {
+        self.state.write_i16(i.to_le());
+    }
+
+    #[inline]
+    fn write_i32(&mut self, i: i32) {
+        self.state.write_i32(i.to_le());
+    }
+
+    #[inline]
+    fn write_i64(&mut self, i: i64) {
+        self.state.write_i64(i.to_le());
+    }
+
+    #[inline]
+    fn write_i128(&mut self, i: i128) {
+        self.state.write_i128(i.to_le());
+    }
+
+    #[inline]
+    fn write_isize(&mut self, i: isize) {
+        // Always treat isize as i64 so we get the same results on 32 and 64 bit
+        // platforms. This is important for symbol hashes when cross compiling,
+        // for example.
+        self.state.write_i64((i as i64).to_le());
+    }
+}
+
+/// Something that implements `HashStable<CTX>` can be hashed in a way that is
+/// stable across multiple compilation sessions.
+///
+/// Note that `HashStable` imposes rather more strict requirements than usual
+/// hash functions:
+///
+/// - Stable hashes are sometimes used as identifiers. Therefore they must
+///   conform to the corresponding `PartialEq` implementations:
+///
+///     - `x == y` implies `hash_stable(x) == hash_stable(y)`, and
+///     - `x != y` implies `hash_stable(x) != hash_stable(y)`.
+///
+///   That second condition is usually not required for hash functions
+///   (e.g. `Hash`). In practice this means that `hash_stable` must feed any
+///   information into the hasher that a `PartialEq` comparison takes into
+///   account. See [#49300](https://github.com/rust-lang/rust/issues/49300)
+///   for an example where violating this invariant has caused trouble in the
+///   past.
+///
+/// - `hash_stable()` must be independent of the current
+///    compilation session. E.g. they must not hash memory addresses or other
+///    things that are "randomly" assigned per compilation session.
+///
+/// - `hash_stable()` must be independent of the host architecture. The
+///   `StableHasher` takes care of endianness and `isize`/`usize` platform
+///   differences.
+pub trait HashStable<CTX> {
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher);
+}
+
+/// Implement this for types that can be turned into stable keys like, for
+/// example, for DefId that can be converted to a DefPathHash. This is used for
+/// bringing maps into a predictable order before hashing them.
+pub trait ToStableHashKey<HCX> {
+    type KeyType: Ord + Sized + HashStable<HCX>;
+    fn to_stable_hash_key(&self, hcx: &HCX) -> Self::KeyType;
+}
+
+// Implement HashStable by just calling `Hash::hash()`. This works fine for
+// self-contained values that don't depend on the hashing context `CTX`.
+#[macro_export]
+macro_rules! impl_stable_hash_via_hash {
+    ($t:ty) => {
+        impl<CTX> $crate::stable_hasher::HashStable<CTX> for $t {
+            #[inline]
+            fn hash_stable(&self, _: &mut CTX, hasher: &mut $crate::stable_hasher::StableHasher) {
+                ::std::hash::Hash::hash(self, hasher);
+            }
+        }
+    };
+}
+
+impl_stable_hash_via_hash!(i8);
+impl_stable_hash_via_hash!(i16);
+impl_stable_hash_via_hash!(i32);
+impl_stable_hash_via_hash!(i64);
+impl_stable_hash_via_hash!(isize);
+
+impl_stable_hash_via_hash!(u8);
+impl_stable_hash_via_hash!(u16);
+impl_stable_hash_via_hash!(u32);
+impl_stable_hash_via_hash!(u64);
+impl_stable_hash_via_hash!(usize);
+
+impl_stable_hash_via_hash!(u128);
+impl_stable_hash_via_hash!(i128);
+
+impl_stable_hash_via_hash!(char);
+impl_stable_hash_via_hash!(());
+
+impl<CTX> HashStable<CTX> for ::std::num::NonZeroU32 {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        self.get().hash_stable(ctx, hasher)
+    }
+}
+
+impl<CTX> HashStable<CTX> for ::std::num::NonZeroUsize {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        self.get().hash_stable(ctx, hasher)
+    }
+}
+
+impl<CTX> HashStable<CTX> for f32 {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        let val: u32 = unsafe { ::std::mem::transmute(*self) };
+        val.hash_stable(ctx, hasher);
+    }
+}
+
+impl<CTX> HashStable<CTX> for f64 {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        let val: u64 = unsafe { ::std::mem::transmute(*self) };
+        val.hash_stable(ctx, hasher);
+    }
+}
+
+impl<CTX> HashStable<CTX> for ::std::cmp::Ordering {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        (*self as i8).hash_stable(ctx, hasher);
+    }
+}
+
+impl<T1: HashStable<CTX>, CTX> HashStable<CTX> for (T1,) {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        let (ref _0,) = *self;
+        _0.hash_stable(ctx, hasher);
+    }
+}
+
+impl<T1: HashStable<CTX>, T2: HashStable<CTX>, CTX> HashStable<CTX> for (T1, T2) {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        let (ref _0, ref _1) = *self;
+        _0.hash_stable(ctx, hasher);
+        _1.hash_stable(ctx, hasher);
+    }
+}
+
+impl<T1, T2, T3, CTX> HashStable<CTX> for (T1, T2, T3)
+where
+    T1: HashStable<CTX>,
+    T2: HashStable<CTX>,
+    T3: HashStable<CTX>,
+{
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        let (ref _0, ref _1, ref _2) = *self;
+        _0.hash_stable(ctx, hasher);
+        _1.hash_stable(ctx, hasher);
+        _2.hash_stable(ctx, hasher);
+    }
+}
+
+impl<T1, T2, T3, T4, CTX> HashStable<CTX> for (T1, T2, T3, T4)
+where
+    T1: HashStable<CTX>,
+    T2: HashStable<CTX>,
+    T3: HashStable<CTX>,
+    T4: HashStable<CTX>,
+{
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        let (ref _0, ref _1, ref _2, ref _3) = *self;
+        _0.hash_stable(ctx, hasher);
+        _1.hash_stable(ctx, hasher);
+        _2.hash_stable(ctx, hasher);
+        _3.hash_stable(ctx, hasher);
+    }
+}
+
+impl<T: HashStable<CTX>, CTX> HashStable<CTX> for [T] {
+    default fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        self.len().hash_stable(ctx, hasher);
+        for item in self {
+            item.hash_stable(ctx, hasher);
+        }
+    }
+}
+
+impl<T: HashStable<CTX>, CTX> HashStable<CTX> for Vec<T> {
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        (&self[..]).hash_stable(ctx, hasher);
+    }
+}
+
+impl<K, V, R, CTX> HashStable<CTX> for indexmap::IndexMap<K, V, R>
+where
+    K: HashStable<CTX> + Eq + Hash,
+    V: HashStable<CTX>,
+    R: BuildHasher,
+{
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        self.len().hash_stable(ctx, hasher);
+        for kv in self {
+            kv.hash_stable(ctx, hasher);
+        }
+    }
+}
+
+impl<K, R, CTX> HashStable<CTX> for indexmap::IndexSet<K, R>
+where
+    K: HashStable<CTX> + Eq + Hash,
+    R: BuildHasher,
+{
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        self.len().hash_stable(ctx, hasher);
+        for key in self {
+            key.hash_stable(ctx, hasher);
+        }
+    }
+}
+
+impl<A, CTX> HashStable<CTX> for SmallVec<[A; 1]>
+where
+    A: HashStable<CTX>,
+{
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        (&self[..]).hash_stable(ctx, hasher);
+    }
+}
+
+impl<T: ?Sized + HashStable<CTX>, CTX> HashStable<CTX> for Box<T> {
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        (**self).hash_stable(ctx, hasher);
+    }
+}
+
+impl<T: ?Sized + HashStable<CTX>, CTX> HashStable<CTX> for ::std::rc::Rc<T> {
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        (**self).hash_stable(ctx, hasher);
+    }
+}
+
+impl<T: ?Sized + HashStable<CTX>, CTX> HashStable<CTX> for ::std::sync::Arc<T> {
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        (**self).hash_stable(ctx, hasher);
+    }
+}
+
+impl<CTX> HashStable<CTX> for str {
+    #[inline]
+    fn hash_stable(&self, _: &mut CTX, hasher: &mut StableHasher) {
+        self.len().hash(hasher);
+        self.as_bytes().hash(hasher);
+    }
+}
+
+impl<CTX> HashStable<CTX> for String {
+    #[inline]
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        (&self[..]).hash_stable(hcx, hasher);
+    }
+}
+
+impl<HCX> ToStableHashKey<HCX> for String {
+    type KeyType = String;
+    #[inline]
+    fn to_stable_hash_key(&self, _: &HCX) -> Self::KeyType {
+        self.clone()
+    }
+}
+
+impl<CTX> HashStable<CTX> for bool {
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        (if *self { 1u8 } else { 0u8 }).hash_stable(ctx, hasher);
+    }
+}
+
+impl<T, CTX> HashStable<CTX> for Option<T>
+where
+    T: HashStable<CTX>,
+{
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        if let Some(ref value) = *self {
+            1u8.hash_stable(ctx, hasher);
+            value.hash_stable(ctx, hasher);
+        } else {
+            0u8.hash_stable(ctx, hasher);
+        }
+    }
+}
+
+impl<T1, T2, CTX> HashStable<CTX> for Result<T1, T2>
+where
+    T1: HashStable<CTX>,
+    T2: HashStable<CTX>,
+{
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        mem::discriminant(self).hash_stable(ctx, hasher);
+        match *self {
+            Ok(ref x) => x.hash_stable(ctx, hasher),
+            Err(ref x) => x.hash_stable(ctx, hasher),
+        }
+    }
+}
+
+impl<'a, T, CTX> HashStable<CTX> for &'a T
+where
+    T: HashStable<CTX> + ?Sized,
+{
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        (**self).hash_stable(ctx, hasher);
+    }
+}
+
+impl<T, CTX> HashStable<CTX> for ::std::mem::Discriminant<T> {
+    #[inline]
+    fn hash_stable(&self, _: &mut CTX, hasher: &mut StableHasher) {
+        ::std::hash::Hash::hash(self, hasher);
+    }
+}
+
+impl<T, CTX> HashStable<CTX> for ::std::ops::RangeInclusive<T>
+where
+    T: HashStable<CTX>,
+{
+    #[inline]
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        self.start().hash_stable(ctx, hasher);
+        self.end().hash_stable(ctx, hasher);
+    }
+}
+
+impl<I: vec::Idx, T, CTX> HashStable<CTX> for vec::IndexVec<I, T>
+where
+    T: HashStable<CTX>,
+{
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        self.len().hash_stable(ctx, hasher);
+        for v in &self.raw {
+            v.hash_stable(ctx, hasher);
+        }
+    }
+}
+
+impl<I: vec::Idx, CTX> HashStable<CTX> for bit_set::BitSet<I> {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        self.words().hash_stable(ctx, hasher);
+    }
+}
+
+impl<R: vec::Idx, C: vec::Idx, CTX> HashStable<CTX> for bit_set::BitMatrix<R, C> {
+    fn hash_stable(&self, ctx: &mut CTX, hasher: &mut StableHasher) {
+        self.words().hash_stable(ctx, hasher);
+    }
+}
+
+impl<T, CTX> HashStable<CTX> for bit_set::FiniteBitSet<T>
+where
+    T: HashStable<CTX> + bit_set::FiniteBitSetTy,
+{
+    fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
+        self.0.hash_stable(hcx, hasher);
+    }
+}
+
+impl_stable_hash_via_hash!(::std::path::Path);
+impl_stable_hash_via_hash!(::std::path::PathBuf);
+
+impl<K, V, R, HCX> HashStable<HCX> for ::std::collections::HashMap<K, V, R>
+where
+    K: ToStableHashKey<HCX> + Eq,
+    V: HashStable<HCX>,
+    R: BuildHasher,
+{
+    #[inline]
+    fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
+        hash_stable_hashmap(hcx, hasher, self, ToStableHashKey::to_stable_hash_key);
+    }
+}
+
+impl<K, R, HCX> HashStable<HCX> for ::std::collections::HashSet<K, R>
+where
+    K: ToStableHashKey<HCX> + Eq,
+    R: BuildHasher,
+{
+    fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
+        let mut keys: Vec<_> = self.iter().map(|k| k.to_stable_hash_key(hcx)).collect();
+        keys.sort_unstable();
+        keys.hash_stable(hcx, hasher);
+    }
+}
+
+impl<K, V, HCX> HashStable<HCX> for ::std::collections::BTreeMap<K, V>
+where
+    K: ToStableHashKey<HCX>,
+    V: HashStable<HCX>,
+{
+    fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
+        let mut entries: Vec<_> =
+            self.iter().map(|(k, v)| (k.to_stable_hash_key(hcx), v)).collect();
+        entries.sort_unstable_by(|&(ref sk1, _), &(ref sk2, _)| sk1.cmp(sk2));
+        entries.hash_stable(hcx, hasher);
+    }
+}
+
+impl<K, HCX> HashStable<HCX> for ::std::collections::BTreeSet<K>
+where
+    K: ToStableHashKey<HCX>,
+{
+    fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
+        let mut keys: Vec<_> = self.iter().map(|k| k.to_stable_hash_key(hcx)).collect();
+        keys.sort_unstable();
+        keys.hash_stable(hcx, hasher);
+    }
+}
+
+pub fn hash_stable_hashmap<HCX, K, V, R, SK, F>(
+    hcx: &mut HCX,
+    hasher: &mut StableHasher,
+    map: &::std::collections::HashMap<K, V, R>,
+    to_stable_hash_key: F,
+) where
+    K: Eq,
+    V: HashStable<HCX>,
+    R: BuildHasher,
+    SK: HashStable<HCX> + Ord,
+    F: Fn(&K, &HCX) -> SK,
+{
+    let mut entries: Vec<_> = map.iter().map(|(k, v)| (to_stable_hash_key(k, hcx), v)).collect();
+    entries.sort_unstable_by(|&(ref sk1, _), &(ref sk2, _)| sk1.cmp(sk2));
+    entries.hash_stable(hcx, hasher);
+}
+
+/// A vector container that makes sure that its items are hashed in a stable
+/// order.
+pub struct StableVec<T>(Vec<T>);
+
+impl<T> StableVec<T> {
+    pub fn new(v: Vec<T>) -> Self {
+        StableVec(v)
+    }
+}
+
+impl<T> ::std::ops::Deref for StableVec<T> {
+    type Target = Vec<T>;
+
+    fn deref(&self) -> &Vec<T> {
+        &self.0
+    }
+}
+
+impl<T, HCX> HashStable<HCX> for StableVec<T>
+where
+    T: HashStable<HCX> + ToStableHashKey<HCX>,
+{
+    fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
+        let StableVec(ref v) = *self;
+
+        let mut sorted: Vec<_> = v.iter().map(|x| x.to_stable_hash_key(hcx)).collect();
+        sorted.sort_unstable();
+        sorted.hash_stable(hcx, hasher);
+    }
+}