Rollup merge of #137095 - saethlin:use-hash64-for-hashes, r=workingjubilee

Replace some u64 hashes with Hash64

I introduced the Hash64 and Hash128 types in https://github.com/rust-lang/rust/pull/110083, essentially as a mechanism to prevent hashes from landing in our leb128 encoding paths. If you just have a u64 or u128 field in a struct then derive Encodable/Decodable, that number gets leb128 encoding. So if you need to store a hash or some other value which behaves very close to a hash, don't store it as a u64.

This reverts part of https://github.com/rust-lang/rust/pull/117603, which turned an encoded Hash64 into a u64.

Based on https://github.com/rust-lang/rust/pull/110083, I don't expect this to be perf-sensitive on its own, though I expect that it may help stabilize some of the small rmeta size fluctuations we currently see in perf reports.

Cargo.lock

@@ -3317,6 +3317,7 @@ dependencies = [
  "rand 0.8.5",
  "rand_xoshiro",
  "rustc_data_structures",
+ "rustc_hashes",
  "rustc_index",
  "rustc_macros",
  "rustc_serialize",
@@ -3544,6 +3545,7 @@ dependencies = [
  "rustc_errors",
  "rustc_fluent_macro",
  "rustc_fs_util",
+ "rustc_hashes",
  "rustc_hir",
  "rustc_index",
  "rustc_llvm",
@@ -3586,6 +3588,7 @@ dependencies = [
  "rustc_errors",
  "rustc_fluent_macro",
  "rustc_fs_util",
+ "rustc_hashes",
  "rustc_hir",
  "rustc_hir_pretty",
  "rustc_incremental",
@@ -3658,6 +3661,7 @@ dependencies = [
  "rustc-stable-hash",
  "rustc_arena",
  "rustc_graphviz",
+ "rustc_hashes",
  "rustc_index",
  "rustc_macros",
  "rustc_serialize",
@@ -3768,6 +3772,7 @@ dependencies = [
  "rustc_error_codes",
  "rustc_error_messages",
  "rustc_fluent_macro",
+ "rustc_hashes",
  "rustc_hir",
  "rustc_index",
  "rustc_lexer",
@@ -3840,6 +3845,13 @@ version = "0.0.0"
 name = "rustc_graphviz"
 version = "0.0.0"
 
+[[package]]
+name = "rustc_hashes"
+version = "0.0.0"
+dependencies = [
+ "rustc-stable-hash",
+]
+
 [[package]]
 name = "rustc_hir"
 version = "0.0.0"
@@ -3849,6 +3861,7 @@ dependencies = [
  "rustc_arena",
  "rustc_ast",
  "rustc_data_structures",
+ "rustc_hashes",
  "rustc_index",
  "rustc_macros",
  "rustc_serialize",
@@ -4169,6 +4182,7 @@ dependencies = [
  "rustc_feature",
  "rustc_fluent_macro",
  "rustc_graphviz",
+ "rustc_hashes",
  "rustc_hir",
  "rustc_hir_pretty",
  "rustc_index",
@@ -4405,6 +4419,7 @@ dependencies = [
  "measureme",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_hashes",
  "rustc_hir",
  "rustc_index",
  "rustc_middle",
@@ -4428,6 +4443,7 @@ dependencies = [
  "rustc_errors",
  "rustc_feature",
  "rustc_fluent_macro",
+ "rustc_hashes",
  "rustc_hir",
  "rustc_index",
  "rustc_macros",
@@ -4488,6 +4504,7 @@ name = "rustc_serialize"
 version = "0.0.0"
 dependencies = [
  "indexmap",
+ "rustc_hashes",
  "rustc_macros",
  "smallvec",
  "tempfile",
@@ -4508,6 +4525,7 @@ dependencies = [
  "rustc_feature",
  "rustc_fluent_macro",
  "rustc_fs_util",
+ "rustc_hashes",
  "rustc_hir",
  "rustc_lint_defs",
  "rustc_macros",
@@ -4549,6 +4567,7 @@ dependencies = [
  "md-5",
  "rustc_arena",
  "rustc_data_structures",
+ "rustc_hashes",
  "rustc_index",
  "rustc_macros",
  "rustc_serialize",
@@ -4568,6 +4587,7 @@ dependencies = [
  "rustc_abi",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_hashes",
  "rustc_hir",
  "rustc_middle",
  "rustc_session",
@@ -4663,6 +4683,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_fluent_macro",
+ "rustc_hashes",
  "rustc_hir",
  "rustc_index",
  "rustc_infer",

compiler/rustc_abi/Cargo.toml

@@ -9,6 +9,7 @@ bitflags = "2.4.1"
 rand = { version = "0.8.4", default-features = false, optional = true }
 rand_xoshiro = { version = "0.6.0", optional = true }
 rustc_data_structures = { path = "../rustc_data_structures", optional = true  }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_index = { path = "../rustc_index", default-features = false }
 rustc_macros = { path = "../rustc_macros", optional = true }
 rustc_serialize = { path = "../rustc_serialize", optional = true  }

compiler/rustc_abi/src/layout.rs

@@ -2,6 +2,7 @@ use std::fmt::{self, Write};
 use std::ops::{Bound, Deref};
 use std::{cmp, iter};
 
+use rustc_hashes::Hash64;
 use rustc_index::Idx;
 use tracing::debug;
 
@@ -133,7 +134,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             size,
             max_repr_align: None,
             unadjusted_abi_align: align.abi,
-            randomization_seed: combined_seed,
+            randomization_seed: Hash64::new(combined_seed),
         }
     }
 
@@ -226,7 +227,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
             size: Size::ZERO,
             max_repr_align: None,
             unadjusted_abi_align: dl.i8_align.abi,
-            randomization_seed: 0,
+            randomization_seed: Hash64::ZERO,
         }
     }
 
@@ -1058,7 +1059,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
         // unsizable tail fields are excluded so that we use the same seed for the sized and unsized layouts.
         let field_seed = fields_excluding_tail
             .iter()
-            .fold(0u64, |acc, f| acc.wrapping_add(f.randomization_seed));
+            .fold(Hash64::ZERO, |acc, f| acc.wrapping_add(f.randomization_seed));
 
         if optimize_field_order && fields.len() > 1 {
             // If `-Z randomize-layout` was enabled for the type definition we can shuffle
@@ -1072,7 +1073,7 @@ impl<Cx: HasDataLayout> LayoutCalculator<Cx> {
                     // `ReprOptions.field_shuffle_seed` is a deterministic seed we can use to randomize field
                     // ordering.
                     let mut rng = rand_xoshiro::Xoshiro128StarStar::seed_from_u64(
-                        field_seed.wrapping_add(repr.field_shuffle_seed),
+                        field_seed.wrapping_add(repr.field_shuffle_seed).as_u64(),
                     );
 
                     // Shuffle the ordering of the fields.

compiler/rustc_abi/src/lib.rs

@@ -50,6 +50,7 @@ use std::str::FromStr;
 use bitflags::bitflags;
 #[cfg(feature = "nightly")]
 use rustc_data_structures::stable_hasher::StableOrd;
+use rustc_hashes::Hash64;
 use rustc_index::{Idx, IndexSlice, IndexVec};
 #[cfg(feature = "nightly")]
 use rustc_macros::{Decodable_Generic, Encodable_Generic, HashStable_Generic};
@@ -140,7 +141,7 @@ pub struct ReprOptions {
     /// hash without loss, but it does pay the price of being larger.
     /// Everything's a tradeoff, a 64-bit seed should be sufficient for our
     /// purposes (primarily `-Z randomize-layout`)
-    pub field_shuffle_seed: u64,
+    pub field_shuffle_seed: Hash64,
 }
 
 impl ReprOptions {
@@ -1727,7 +1728,7 @@ pub struct LayoutData<FieldIdx: Idx, VariantIdx: Idx> {
     /// transmuted to `Foo<U>` we aim to create probalistically distinct seeds so that Foo can choose
     /// to reorder its fields based on that information. The current implementation is a conservative
     /// approximation of this goal.
-    pub randomization_seed: u64,
+    pub randomization_seed: Hash64,
 }
 
 impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
@@ -1781,7 +1782,7 @@ impl<FieldIdx: Idx, VariantIdx: Idx> LayoutData<FieldIdx, VariantIdx> {
             align,
             max_repr_align: None,
             unadjusted_abi_align: align.abi,
-            randomization_seed,
+            randomization_seed: Hash64::new(randomization_seed),
         }
     }
 }

compiler/rustc_codegen_llvm/Cargo.toml

@@ -25,6 +25,7 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_fs_util = { path = "../rustc_fs_util" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
 rustc_llvm = { path = "../rustc_llvm" }

compiler/rustc_codegen_llvm/src/common.rs

@@ -7,7 +7,8 @@ use rustc_abi::{AddressSpace, HasDataLayout};
 use rustc_ast::Mutability;
 use rustc_codegen_ssa::common::TypeKind;
 use rustc_codegen_ssa::traits::*;
-use rustc_data_structures::stable_hasher::{Hash128, HashStable, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_hashes::Hash128;
 use rustc_hir::def_id::DefId;
 use rustc_middle::bug;
 use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar};

compiler/rustc_codegen_ssa/Cargo.toml

@@ -25,6 +25,7 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_fs_util = { path = "../rustc_fs_util" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_hir_pretty = { path = "../rustc_hir_pretty" }
 rustc_incremental = { path = "../rustc_incremental" }

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -15,7 +15,8 @@ use std::fmt::Write;
 
 use rustc_abi::Integer;
 use rustc_data_structures::fx::FxHashSet;
-use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_hashes::Hash64;
 use rustc_hir::def_id::DefId;
 use rustc_hir::definitions::{DefPathData, DefPathDataName, DisambiguatedDefPathData};
 use rustc_hir::{CoroutineDesugaring, CoroutineKind, CoroutineSource, Mutability};

compiler/rustc_data_structures/Cargo.toml

@@ -18,6 +18,7 @@ rustc-rayon = { version = "0.5.1", features = ["indexmap"] }
 rustc-stable-hash = { version = "0.1.0", features = ["nightly"] }
 rustc_arena = { path = "../rustc_arena" }
 rustc_graphviz = { path = "../rustc_graphviz" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_index = { path = "../rustc_index", package = "rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }

compiler/rustc_data_structures/src/fingerprint.rs

@@ -1,10 +1,9 @@
 use std::hash::{Hash, Hasher};
 
+use rustc_hashes::Hash64;
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 
-use crate::stable_hasher::{
-    FromStableHash, Hash64, StableHasherHash, impl_stable_traits_for_trivial_type,
-};
+use crate::stable_hasher::{FromStableHash, StableHasherHash, impl_stable_traits_for_trivial_type};
 
 #[cfg(test)]
 mod tests;

compiler/rustc_data_structures/src/lib.rs

@@ -84,7 +84,6 @@ pub mod vec_cache;
 pub mod work_queue;
 
 mod atomic_ref;
-mod hashes;
 
 /// This calls the passed function while ensuring it won't be inlined into the caller.
 #[inline(never)]

compiler/rustc_data_structures/src/stable_hasher.rs

@@ -10,12 +10,11 @@ use smallvec::SmallVec;
 #[cfg(test)]
 mod tests;
 
+use rustc_hashes::{Hash64, Hash128};
 pub use rustc_stable_hash::{
     FromStableHash, SipHasher128Hash as StableHasherHash, StableSipHasher128 as StableHasher,
 };
 
-pub use crate::hashes::{Hash64, Hash128};
-
 /// Something that implements `HashStable<CTX>` can be hashed in a way that is
 /// stable across multiple compilation sessions.
 ///

compiler/rustc_data_structures/src/tagged_ptr/tests.rs

@@ -1,7 +1,8 @@
 use std::ptr;
 
+use rustc_hashes::Hash128;
+
 use super::*;
-use crate::hashes::Hash128;
 use crate::stable_hasher::{HashStable, StableHasher};
 
 /// A tag type used in [`TaggedRef`] tests.

compiler/rustc_errors/Cargo.toml

@@ -14,6 +14,7 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_error_codes = { path = "../rustc_error_codes" }
 rustc_error_messages = { path = "../rustc_error_messages" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
 rustc_lexer = { path = "../rustc_lexer" }

compiler/rustc_errors/src/lib.rs

@@ -58,12 +58,13 @@ pub use emitter::ColorConfig;
 use emitter::{DynEmitter, Emitter, is_case_difference, is_different};
 use rustc_data_structures::AtomicRef;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
-use rustc_data_structures::stable_hasher::{Hash128, StableHasher};
+use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_data_structures::sync::{DynSend, Lock};
 pub use rustc_error_messages::{
     DiagMessage, FluentBundle, LanguageIdentifier, LazyFallbackBundle, MultiSpan, SpanLabel,
     SubdiagMessage, fallback_fluent_bundle, fluent_bundle,
 };
+use rustc_hashes::Hash128;
 use rustc_lint_defs::LintExpectationId;
 pub use rustc_lint_defs::{Applicability, listify, pluralize};
 use rustc_macros::{Decodable, Encodable};

compiler/rustc_hashes/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "rustc_hashes"
+version = "0.0.0"
+edition = "2021"
+
+[dependencies]
+# tidy-alphabetical-start
+rustc-stable-hash = { version = "0.1.0" }
+# tidy-alphabetical-end

compiler/rustc_hashes/src/lib.rs

@@ -1,6 +1,8 @@
 //! rustc encodes a lot of hashes. If hashes are stored as `u64` or `u128`, a `derive(Encodable)`
 //! will apply varint encoding to the hashes, which is less efficient than directly encoding the 8
-//! or 16 bytes of the hash.
+//! or 16 bytes of the hash. And if that hash depends on the `StableCrateHash` (which most in rustc
+//! do), the varint encoding will make the number of bytes encoded fluctuate between compiler
+//! versions.
 //!
 //! The types in this module represent 64-bit or 128-bit hashes produced by a `StableHasher`.
 //! `Hash64` and `Hash128` expose some utility functions to encourage users to not extract the inner
@@ -14,10 +16,9 @@
 use std::fmt;
 use std::ops::BitXorAssign;
 
-use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
-
-use crate::stable_hasher::{FromStableHash, StableHasherHash};
+use rustc_stable_hash::{FromStableHash, SipHasher128Hash as StableHasherHash};
 
+/// A `u64` but encoded with a fixed size; for hashes this encoding is more compact than `u64`.
 #[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord, Default)]
 pub struct Hash64 {
     inner: u64,
@@ -35,6 +36,11 @@ impl Hash64 {
     pub fn as_u64(self) -> u64 {
         self.inner
     }
+
+    #[inline]
+    pub fn wrapping_add(self, other: Self) -> Self {
+        Self { inner: self.inner.wrapping_add(other.inner) }
+    }
 }
 
 impl BitXorAssign<u64> for Hash64 {
@@ -44,20 +50,6 @@ impl BitXorAssign<u64> for Hash64 {
     }
 }
 
-impl<S: Encoder> Encodable<S> for Hash64 {
-    #[inline]
-    fn encode(&self, s: &mut S) {
-        s.emit_raw_bytes(&self.inner.to_le_bytes());
-    }
-}
-
-impl<D: Decoder> Decodable<D> for Hash64 {
-    #[inline]
-    fn decode(d: &mut D) -> Self {
-        Self { inner: u64::from_le_bytes(d.read_raw_bytes(8).try_into().unwrap()) }
-    }
-}
-
 impl FromStableHash for Hash64 {
     type Hash = StableHasherHash;
 
@@ -79,6 +71,7 @@ impl fmt::LowerHex for Hash64 {
     }
 }
 
+/// A `u128` but encoded with a fixed size; for hashes this encoding is more compact than `u128`.
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Default)]
 pub struct Hash128 {
     inner: u128,
@@ -95,6 +88,11 @@ impl std::hash::Hash for Hash128 {
 }
 
 impl Hash128 {
+    #[inline]
+    pub fn new(n: u128) -> Self {
+        Self { inner: n }
+    }
+
     #[inline]
     pub fn truncate(self) -> Hash64 {
         Hash64 { inner: self.inner as u64 }
@@ -111,20 +109,6 @@ impl Hash128 {
     }
 }
 
-impl<S: Encoder> Encodable<S> for Hash128 {
-    #[inline]
-    fn encode(&self, s: &mut S) {
-        s.emit_raw_bytes(&self.inner.to_le_bytes());
-    }
-}
-
-impl<D: Decoder> Decodable<D> for Hash128 {
-    #[inline]
-    fn decode(d: &mut D) -> Self {
-        Self { inner: u128::from_le_bytes(d.read_raw_bytes(16).try_into().unwrap()) }
-    }
-}
-
 impl FromStableHash for Hash128 {
     type Hash = StableHasherHash;
 

compiler/rustc_hir/Cargo.toml

@@ -10,6 +10,7 @@ rustc_abi = { path = "../rustc_abi" }
 rustc_arena = { path = "../rustc_arena" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }

compiler/rustc_hir/src/def_path_hash_map.rs

@@ -1,4 +1,4 @@
-use rustc_data_structures::stable_hasher::Hash64;
+use rustc_hashes::Hash64;
 use rustc_span::def_id::DefIndex;
 
 #[derive(Clone, Default)]

compiler/rustc_hir/src/definitions.rs

@@ -7,8 +7,9 @@
 use std::fmt::{self, Write};
 use std::hash::Hash;
 
-use rustc_data_structures::stable_hasher::{Hash64, StableHasher};
+use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_data_structures::unord::UnordMap;
+use rustc_hashes::Hash64;
 use rustc_index::IndexVec;
 use rustc_macros::{Decodable, Encodable};
 use rustc_span::{Symbol, kw, sym};

compiler/rustc_hir/src/tests.rs

@@ -1,6 +1,6 @@
 #![allow(rustc::symbol_intern_string_literal)]
 
-use rustc_data_structures::stable_hasher::Hash64;
+use rustc_hashes::Hash64;
 use rustc_span::def_id::{DefPathHash, StableCrateId};
 use rustc_span::edition::Edition;
 use rustc_span::{Symbol, create_session_globals_then};

compiler/rustc_middle/Cargo.toml

@@ -22,6 +22,7 @@ rustc_errors = { path = "../rustc_errors" }
 rustc_feature = { path = "../rustc_feature" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_graphviz = { path = "../rustc_graphviz" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_hir_pretty = { path = "../rustc_hir_pretty" }
 rustc_index = { path = "../rustc_index" }

compiler/rustc_middle/src/mir/mono.rs

@@ -6,8 +6,9 @@ use rustc_attr_parsing::InlineAttr;
 use rustc_data_structures::base_n::{BaseNString, CASE_INSENSITIVE, ToBaseN};
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_data_structures::stable_hasher::{Hash128, HashStable, StableHasher, ToStableHashKey};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
 use rustc_data_structures::unord::UnordMap;
+use rustc_hashes::Hash128;
 use rustc_hir::ItemId;
 use rustc_hir::def_id::{CrateNum, DefId, DefIdSet, LOCAL_CRATE};
 use rustc_index::Idx;

compiler/rustc_middle/src/ty/layout.rs

@@ -11,6 +11,7 @@ use rustc_error_messages::DiagMessage;
 use rustc_errors::{
     Diag, DiagArgValue, DiagCtxtHandle, Diagnostic, EmissionGuarantee, IntoDiagArg, Level,
 };
+use rustc_hashes::Hash64;
 use rustc_hir::LangItem;
 use rustc_hir::def_id::DefId;
 use rustc_index::IndexVec;
@@ -778,7 +779,7 @@ where
                     size: Size::ZERO,
                     max_repr_align: None,
                     unadjusted_abi_align: tcx.data_layout.i8_align.abi,
-                    randomization_seed: 0,
+                    randomization_seed: Hash64::ZERO,
                 })
             }
 

compiler/rustc_middle/src/ty/mod.rs

@@ -1487,8 +1487,7 @@ impl<'tcx> TyCtxt<'tcx> {
 
         // Generate a deterministically-derived seed from the item's path hash
         // to allow for cross-crate compilation to actually work
-        let mut field_shuffle_seed =
-            self.def_path_hash(did.to_def_id()).0.to_smaller_hash().as_u64();
+        let mut field_shuffle_seed = self.def_path_hash(did.to_def_id()).0.to_smaller_hash();
 
         // If the user defined a custom seed for layout randomization, xor the item's
         // path hash with the user defined seed, this will allowing determinism while

compiler/rustc_middle/src/ty/util.rs

@@ -5,9 +5,10 @@ use std::{fmt, iter};
 use rustc_abi::{ExternAbi, Float, Integer, IntegerType, Size};
 use rustc_apfloat::Float as _;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_data_structures::stable_hasher::{Hash128, HashStable, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::ErrorGuaranteed;
+use rustc_hashes::Hash128;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId};

compiler/rustc_query_impl/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2021"
 measureme = "11"
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
 rustc_middle = { path = "../rustc_middle" }

compiler/rustc_query_impl/src/plumbing.rs

@@ -4,10 +4,11 @@
 
 use std::num::NonZero;
 
-use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lock;
 use rustc_data_structures::unord::UnordMap;
 use rustc_errors::DiagInner;
+use rustc_hashes::Hash64;
 use rustc_index::Idx;
 use rustc_middle::bug;
 use rustc_middle::dep_graph::{

compiler/rustc_query_system/Cargo.toml

@@ -13,6 +13,7 @@ rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_feature = { path = "../rustc_feature" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }

compiler/rustc_query_system/src/query/mod.rs

@@ -11,9 +11,9 @@ mod caches;
 pub use self::caches::{DefIdCache, DefaultCache, QueryCache, SingleCache, VecCache};
 
 mod config;
-use rustc_data_structures::stable_hasher::Hash64;
 use rustc_data_structures::sync::Lock;
 use rustc_errors::DiagInner;
+use rustc_hashes::Hash64;
 use rustc_hir::def::DefKind;
 use rustc_macros::{Decodable, Encodable};
 use rustc_span::Span;

compiler/rustc_serialize/Cargo.toml

@@ -6,6 +6,7 @@ edition = "2021"
 [dependencies]
 # tidy-alphabetical-start
 indexmap = "2.0.0"
+rustc_hashes = { path = "../rustc_hashes" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
 thin-vec = "0.2.12"
 # tidy-alphabetical-end

compiler/rustc_serialize/src/serialize.rs

@@ -10,6 +10,7 @@ use std::path;
 use std::rc::Rc;
 use std::sync::Arc;
 
+use rustc_hashes::{Hash64, Hash128};
 use smallvec::{Array, SmallVec};
 use thin_vec::ThinVec;
 
@@ -716,3 +717,31 @@ impl<D: Decoder, T: Decodable<D>> Decodable<D> for Arc<[T]> {
         vec.into()
     }
 }
+
+impl<S: Encoder> Encodable<S> for Hash64 {
+    #[inline]
+    fn encode(&self, s: &mut S) {
+        s.emit_raw_bytes(&self.as_u64().to_le_bytes());
+    }
+}
+
+impl<S: Encoder> Encodable<S> for Hash128 {
+    #[inline]
+    fn encode(&self, s: &mut S) {
+        s.emit_raw_bytes(&self.as_u128().to_le_bytes());
+    }
+}
+
+impl<D: Decoder> Decodable<D> for Hash64 {
+    #[inline]
+    fn decode(d: &mut D) -> Self {
+        Self::new(u64::from_le_bytes(d.read_raw_bytes(8).try_into().unwrap()))
+    }
+}
+
+impl<D: Decoder> Decodable<D> for Hash128 {
+    #[inline]
+    fn decode(d: &mut D) -> Self {
+        Self::new(u128::from_le_bytes(d.read_raw_bytes(16).try_into().unwrap()))
+    }
+}

compiler/rustc_session/Cargo.toml

@@ -14,6 +14,7 @@ rustc_errors = { path = "../rustc_errors" }
 rustc_feature = { path = "../rustc_feature" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_fs_util = { path = "../rustc_fs_util" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_lint_defs = { path = "../rustc_lint_defs" }
 rustc_macros = { path = "../rustc_macros" }

compiler/rustc_session/src/config.rs

@@ -2934,9 +2934,9 @@ pub(crate) mod dep_tracking {
 
     use rustc_abi::Align;
     use rustc_data_structures::fx::FxIndexMap;
-    use rustc_data_structures::stable_hasher::Hash64;
     use rustc_errors::LanguageIdentifier;
     use rustc_feature::UnstableFeatures;
+    use rustc_hashes::Hash64;
     use rustc_span::RealFileName;
     use rustc_span::edition::Edition;
     use rustc_target::spec::{

compiler/rustc_session/src/options.rs

@@ -7,9 +7,9 @@ use std::str;
 use rustc_abi::Align;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::profiling::TimePassesFormat;
-use rustc_data_structures::stable_hasher::Hash64;
 use rustc_errors::{ColorConfig, LanguageIdentifier, TerminalUrl};
 use rustc_feature::UnstableFeatures;
+use rustc_hashes::Hash64;
 use rustc_macros::{Decodable, Encodable};
 use rustc_span::edition::Edition;
 use rustc_span::{RealFileName, SourceFileHashAlgorithm};

compiler/rustc_span/Cargo.toml

@@ -12,6 +12,7 @@ itoa = "1.0"
 md5 = { package = "md-5", version = "0.10.0" }
 rustc_arena = { path = "../rustc_arena" }
 rustc_data_structures = { path = "../rustc_data_structures" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }

compiler/rustc_span/src/def_id.rs

@@ -3,10 +3,9 @@ use std::hash::{BuildHasherDefault, Hash, Hasher};
 
 use rustc_data_structures::AtomicRef;
 use rustc_data_structures::fingerprint::Fingerprint;
-use rustc_data_structures::stable_hasher::{
-    Hash64, HashStable, StableHasher, StableOrd, ToStableHashKey,
-};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher, StableOrd, ToStableHashKey};
 use rustc_data_structures::unhash::Unhasher;
+use rustc_hashes::Hash64;
 use rustc_index::Idx;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_serialize::{Decodable, Encodable};

compiler/rustc_span/src/hygiene.rs

@@ -33,9 +33,10 @@ use std::sync::Arc;
 
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_data_structures::stable_hasher::{Hash64, HashStable, HashingControls, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, HashingControls, StableHasher};
 use rustc_data_structures::sync::{Lock, WorkerLocal};
 use rustc_data_structures::unhash::UnhashMap;
+use rustc_hashes::Hash64;
 use rustc_index::IndexVec;
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};

compiler/rustc_span/src/lib.rs

@@ -87,9 +87,10 @@ use std::sync::Arc;
 use std::{fmt, iter};
 
 use md5::{Digest, Md5};
-use rustc_data_structures::stable_hasher::{Hash64, Hash128, HashStable, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::{FreezeLock, FreezeWriteGuard, Lock};
 use rustc_data_structures::unord::UnordMap;
+use rustc_hashes::{Hash64, Hash128};
 use sha1::Sha1;
 use sha2::Sha256;
 

compiler/rustc_symbol_mangling/Cargo.toml

@@ -11,6 +11,7 @@ rustc-demangle = "0.1.21"
 rustc_abi = { path = "../rustc_abi" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_middle = { path = "../rustc_middle" }
 rustc_session = { path = "../rustc_session" }

compiler/rustc_symbol_mangling/src/hashed.rs

@@ -1,6 +1,7 @@
 use std::fmt::Write;
 
-use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_hashes::Hash64;
 use rustc_hir::def_id::CrateNum;
 use rustc_middle::ty::{Instance, TyCtxt};
 

compiler/rustc_symbol_mangling/src/legacy.rs

@@ -1,7 +1,8 @@
 use std::fmt::{self, Write};
 use std::mem::{self, discriminant};
 
-use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher};
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
+use rustc_hashes::Hash64;
 use rustc_hir::def_id::{CrateNum, DefId};
 use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
 use rustc_middle::bug;

compiler/rustc_ty_utils/Cargo.toml

@@ -11,6 +11,7 @@ rustc_ast_ir = { path = "../rustc_ast_ir" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
+rustc_hashes = { path = "../rustc_hashes" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }
 rustc_infer = { path = "../rustc_infer" }

compiler/rustc_ty_utils/src/layout.rs

@@ -9,6 +9,7 @@ use rustc_abi::{
     HasDataLayout, Layout, LayoutCalculatorError, LayoutData, Niche, ReprOptions, Scalar, Size,
     StructKind, TagEncoding, VariantIdx, Variants, WrappingRange,
 };
+use rustc_hashes::Hash64;
 use rustc_index::bit_set::DenseBitSet;
 use rustc_index::{IndexSlice, IndexVec};
 use rustc_middle::bug;
@@ -380,7 +381,7 @@ fn layout_of_uncached<'tcx>(
                 size,
                 max_repr_align: None,
                 unadjusted_abi_align: element.align.abi,
-                randomization_seed: element.randomization_seed.wrapping_add(count),
+                randomization_seed: element.randomization_seed.wrapping_add(Hash64::new(count)),
             })
         }
         ty::Slice(element) => {
@@ -395,7 +396,9 @@ fn layout_of_uncached<'tcx>(
                 max_repr_align: None,
                 unadjusted_abi_align: element.align.abi,
                 // adding a randomly chosen value to distinguish slices
-                randomization_seed: element.randomization_seed.wrapping_add(0x2dcba99c39784102),
+                randomization_seed: element
+                    .randomization_seed
+                    .wrapping_add(Hash64::new(0x2dcba99c39784102)),
             })
         }
         ty::Str => tcx.mk_layout(LayoutData {
@@ -408,7 +411,7 @@ fn layout_of_uncached<'tcx>(
             max_repr_align: None,
             unadjusted_abi_align: dl.i8_align.abi,
             // another random value
-            randomization_seed: 0xc1325f37d127be22,
+            randomization_seed: Hash64::new(0xc1325f37d127be22),
         }),
 
         // Odd unit types.
@@ -585,7 +588,7 @@ fn layout_of_uncached<'tcx>(
                 align,
                 max_repr_align: None,
                 unadjusted_abi_align: align.abi,
-                randomization_seed: e_ly.randomization_seed.wrapping_add(e_len),
+                randomization_seed: e_ly.randomization_seed.wrapping_add(Hash64::new(e_len)),
             })
         }
 
@@ -1051,7 +1054,7 @@ fn coroutine_layout<'tcx>(
     };
 
     // this is similar to how ReprOptions populates its field_shuffle_seed
-    let def_hash = tcx.def_path_hash(def_id).0.to_smaller_hash().as_u64();
+    let def_hash = tcx.def_path_hash(def_id).0.to_smaller_hash();
 
     let layout = tcx.mk_layout(LayoutData {
         variants: Variants::Multiple {

compiler/rustc_type_ir/src/ty_kind.rs

@@ -14,6 +14,7 @@ use rustc_type_ir_macros::{Lift_Generic, TypeFoldable_Generic, TypeVisitable_Gen
 use self::TyKind::*;
 pub use self::closure::*;
 use crate::inherent::*;
+#[cfg(feature = "nightly")]
 use crate::visit::TypeVisitable;
 use crate::{self as ty, DebruijnIndex, Interner};
 

src/tools/rust-analyzer/crates/hir-def/src/data/adt.rs

@@ -9,6 +9,7 @@ use hir_expand::name::Name;
 use intern::sym;
 use la_arena::Arena;
 use rustc_abi::{Align, Integer, IntegerType, ReprFlags, ReprOptions};
+use rustc_hashes::Hash64;
 use triomphe::Arc;
 use tt::iter::TtElement;
 
@@ -172,7 +173,7 @@ fn parse_repr_tt(tt: &TopSubtree) -> Option<ReprOptions> {
         }
     }
 
-    Some(ReprOptions { int, align: max_align, pack: min_pack, flags, field_shuffle_seed: 0 })
+    Some(ReprOptions { int, align: max_align, pack: min_pack, flags, field_shuffle_seed: Hash64::ZERO })
 }
 
 impl StructData {

src/tools/rust-analyzer/crates/hir-def/src/lib.rs

@@ -18,9 +18,15 @@ extern crate ra_ap_rustc_parse_format as rustc_parse_format;
 #[cfg(feature = "in-rust-tree")]
 extern crate rustc_abi;
 
+#[cfg(feature = "in-rust-tree")]
+extern crate rustc_hashes;
+
 #[cfg(not(feature = "in-rust-tree"))]
 extern crate ra_ap_rustc_abi as rustc_abi;
 
+#[cfg(not(feature = "in-rust-tree"))]
+extern crate ra_ap_rustc_hashes as rustc_hashes;
+
 pub mod db;
 
 pub mod attr;

src/tools/rust-analyzer/crates/hir-ty/src/layout.rs

@@ -15,6 +15,7 @@ use hir_def::{
 use la_arena::{Idx, RawIdx};
 use rustc_abi::AddressSpace;
 use rustc_index::{IndexSlice, IndexVec};
+use rustc_hashes::Hash64;
 
 use triomphe::Arc;
 
@@ -197,7 +198,7 @@ fn layout_of_simd_ty(
         align,
         max_repr_align: None,
         unadjusted_abi_align: align.abi,
-        randomization_seed: 0,
+        randomization_seed: Hash64::ZERO,
     }))
 }
 
@@ -314,7 +315,7 @@ pub fn layout_of_ty_query(
                 size,
                 max_repr_align: None,
                 unadjusted_abi_align: element.align.abi,
-                randomization_seed: 0,
+                randomization_seed: Hash64::ZERO,
             }
         }
         TyKind::Slice(element) => {
@@ -328,7 +329,7 @@ pub fn layout_of_ty_query(
                 size: Size::ZERO,
                 max_repr_align: None,
                 unadjusted_abi_align: element.align.abi,
-                randomization_seed: 0,
+                randomization_seed: Hash64::ZERO,
             }
         }
         TyKind::Str => Layout {
@@ -340,7 +341,7 @@ pub fn layout_of_ty_query(
             size: Size::ZERO,
             max_repr_align: None,
             unadjusted_abi_align: dl.i8_align.abi,
-            randomization_seed: 0,
+            randomization_seed: Hash64::ZERO,
         },
         // Potentially-wide pointers.
         TyKind::Ref(_, _, pointee) | TyKind::Raw(_, pointee) => {

src/tools/rust-analyzer/crates/hir-ty/src/lib.rs

@@ -12,6 +12,9 @@ extern crate ra_ap_rustc_index as rustc_index;
 #[cfg(feature = "in-rust-tree")]
 extern crate rustc_abi;
 
+#[cfg(feature = "in-rust-tree")]
+extern crate rustc_hashes;
+
 #[cfg(not(feature = "in-rust-tree"))]
 extern crate ra_ap_rustc_abi as rustc_abi;
 
@@ -21,6 +24,9 @@ extern crate rustc_pattern_analysis;
 #[cfg(not(feature = "in-rust-tree"))]
 extern crate ra_ap_rustc_pattern_analysis as rustc_pattern_analysis;
 
+#[cfg(not(feature = "in-rust-tree"))]
+extern crate ra_ap_rustc_hashes as rustc_hashes;
+
 mod builder;
 mod chalk_db;
 mod chalk_ext;

tests/run-make/rustc-crates-on-stable/rmake.rs

@@ -35,6 +35,8 @@ fn main() {
             "rustc_abi",
             "-p",
             "rustc_parse_format",
+            "-p",
+            "rustc_hashes",
         ])
         .run();
 }

tests/ui-fulldeps/missing-rustc-driver-error.stderr

@@ -2,5 +2,13 @@ error: crate `rustc_serialize` required to be available in rlib format, but was
    |
    = help: try adding `extern crate rustc_driver;` at the top level of this crate
 
+error: crate `rustc_hashes` required to be available in rlib format, but was not found in this form
+   |
+   = help: try adding `extern crate rustc_driver;` at the top level of this crate
+
+error: crate `rustc_stable_hash` required to be available in rlib format, but was not found in this form
+   |
+   = help: try adding `extern crate rustc_driver;` at the top level of this crate
+
 error: aborting due to NUMBER previous errors