Import 'rustc-stable-hash' crate
Request Document: go/android-rust-importing-crates
For CL Reviewers: go/android3p#cl-review
Bug: 404806498
Test: m librustc_stable_hash
Change-Id: I19861d1ed3d25f8fefef450caa2fb22080c5a9ec
diff --git a/crates/rustc-stable-hash/.android-checksum.json b/crates/rustc-stable-hash/.android-checksum.json
new file mode 100644
index 0000000..c64f415
--- /dev/null
+++ b/crates/rustc-stable-hash/.android-checksum.json
@@ -0,0 +1 @@
+{"package":null,"files":{".cargo-checksum.json":"7fb461b17c92be5731b0db45437b5de36e467ae889a88a1d522efaa0481ff89a","Android.bp":"fc458b0f6b7dee294525fe386c725cd25f6dcd2dada67fefc4bd2954d465c99e","CHANGELOG.md":"49c5c99ba2fb0f5d33b32240e897caf6dd490ebadf6905b476cefb60a7295881","CODE_OF_CONDUCT.md":"92218933b3f39b8c9edf74a869f7b5afabff99f6a0fcb7818388c3388fc68fd3","Cargo.toml":"d6ca5c0a44a7eb3580797935b1e82f905b4e9813622d494eaa2577f73ecb5715","LICENSE":"50f827348bfd5def2df4f30cb41264072cf9c180bd9ed698437e8d85b2482754","LICENSE-APACHE":"50f827348bfd5def2df4f30cb41264072cf9c180bd9ed698437e8d85b2482754","METADATA":"649cde6cac94834e6b35ae4e1336578fcd5fdfd66b40e9a89dc3ad586e0c41dd","MODULE_LICENSE_APACHE2":"0d6f8afa3940b7f06bebee651376d43bc8b0d5b437337be2696d30377451e93a","README.md":"7ddad36c4e72ff87e517ceb4f96d89af7ab46b7c7a8d01376cef4ca482952251","cargo_embargo.json":"c111f6b6fe8b0956cba97a452d867dc8c2c228ec4fe42ae45c8a6aac3286bd8d","src/int_overflow.rs":"94a4d216af1229bcbf49aa335c84eb7c3b94daed1de52144f8ab8cdfdddb1516","src/lib.rs":"9ba205b7bed93920f689ffc9838180db360665d16db06a4a45867b19b854b4e7","src/sip128.rs":"0098e897851b584a8d1ea98754fc995ea1227c77cca8aaefca1a6b7184531cf1","src/sip128/tests.rs":"19ffe3ce5cf649d3722774e964dad147207a16f94fb9709bbcb295a009e1d1cd","src/stable_hasher.rs":"7165cca5f6062dc4a59b654652a6f74f5fb7bb07cef06a67ebd362d1203318b7","src/stable_hasher/tests.rs":"fb4d8269cfbfd485a761334ec3affeb5827a4aa0e858faa0791df3a8f1221786"}}
\ No newline at end of file
diff --git a/crates/rustc-stable-hash/.cargo-checksum.json b/crates/rustc-stable-hash/.cargo-checksum.json
new file mode 100644
index 0000000..9c8ef0a
--- /dev/null
+++ b/crates/rustc-stable-hash/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"CHANGELOG.md":"d655fa6c105851e32771d64a81578372f15822e3f5e0457d167888f516461c5e","CODE_OF_CONDUCT.md":"3c4d1c4de2e6991695f5dc495f7530ecb188dfafdb1f47a1323ce7159987accd","Cargo.toml":"1fc92d17c00c9ac3bc650ab1ff2db21cfb615a059b259e10df183adb2330207b","LICENSE-APACHE":"62c7a1e35f56406896d7aa7ca52d0cc0d272ac022b5d2796e7d6905db8a3636a","LICENSE-MIT":"23f18e03dc49df91622fe2a76176497404e46ced8a715d9d2b67a7446571cca3","README.md":"89f8b8a1143f5f7bfdb4cb66e662e2b37c56508271674ff8b6762cb4b429d2a1","src/int_overflow.rs":"3a5e3ff4de386defc281622a3f59d3236d38fb42345392e94170dbfb7b226fc9","src/lib.rs":"732f294d3218247ec05d4c97faebbe8216e0c79fb7c713fc795db40ebedbc5c2","src/sip128.rs":"bb161847ce20d12f259f5e8a1be984cb4ddd4010c89836b928a4ab8708cf4e43","src/sip128/tests.rs":"78bbe4215a0017cd83ccb83af636b93c9893a51a88da839eacfc2da2a06dcd0b","src/stable_hasher.rs":"9de0f4d669362dcc2b77d38b45760b285d3db8ed091d3e6a2d4a98cdfc1756b7","src/stable_hasher/tests.rs":"2a169b419aff453a34b0a3bab43a3aa792beb91c19bc07dd741abe5557df5376"},"package":"781442f29170c5c93b7185ad559492601acdc71d5bb0706f5868094f45cfcd08"}
\ No newline at end of file
diff --git a/crates/rustc-stable-hash/Android.bp b/crates/rustc-stable-hash/Android.bp
new file mode 100644
index 0000000..f7f8b47
--- /dev/null
+++ b/crates/rustc-stable-hash/Android.bp
@@ -0,0 +1,31 @@
+// This file is generated by cargo_embargo.
+// Do not modify this file because the changes will be overridden on upgrade.
+
+package {
+ default_applicable_licenses: ["external_rust_crates_rustc-stable-hash_license"],
+ default_team: "trendy_team_android_rust",
+}
+
+license {
+ name: "external_rust_crates_rustc-stable-hash_license",
+ visibility: [":__subpackages__"],
+ license_kinds: ["SPDX-license-identifier-Apache-2.0"],
+ license_text: ["LICENSE"],
+}
+
+rust_library {
+ name: "librustc_stable_hash",
+ host_supported: true,
+ crate_name: "rustc_stable_hash",
+ cargo_env_compat: true,
+ cargo_pkg_version: "0.1.2",
+ crate_root: "src/lib.rs",
+ edition: "2021",
+ apex_available: [
+ "//apex_available:platform",
+ "//apex_available:anyapex",
+ ],
+ product_available: true,
+ vendor_available: true,
+ min_sdk_version: "29",
+}
diff --git a/crates/rustc-stable-hash/CHANGELOG.md b/crates/rustc-stable-hash/CHANGELOG.md
new file mode 100644
index 0000000..7e9254c
--- /dev/null
+++ b/crates/rustc-stable-hash/CHANGELOG.md
@@ -0,0 +1,26 @@
+# Unreleased
+
+# 0.1.2
+
+- Fix `<StableSipHasher128 as Hasher>::finish` not being platform agnostic [#12][pr12]
+
+[pr12]: https://github.com/rust-lang/rustc-stable-hash/pull/12
+
+# 0.1.1
+
+- feat: derive `Clone` for `StableHasher` [#11][pr11]
+
+[pr11]: https://github.com/rust-lang/rustc-stable-hash/pull/11
+
+# 0.1.0
+
+- Rename `StableHasherResult` to `FromStableHash` [#8][pr8]
+- Use new-type for returned-hash of `SipHasher128`(`Hash`) [#8][pr8]
+- Introduce multi hasher support [#8][pr8]
+- `StableHasher::finish` now returns a small hash instead of being fatal [#6][pr6]
+- Remove `StableHasher::finalize` [#4][pr4]
+- Import stable hasher implementation from rustc ([db8aca48129](https://github.com/rust-lang/rust/blob/db8aca48129d86b2623e3ac8cbcf2902d4d313ad/compiler/rustc_data_structures/src/))
+
+[pr8]: https://github.com/rust-lang/rustc-stable-hash/pull/8
+[pr6]: https://github.com/rust-lang/rustc-stable-hash/pull/6
+[pr4]: https://github.com/rust-lang/rustc-stable-hash/pull/4
diff --git a/crates/rustc-stable-hash/CODE_OF_CONDUCT.md b/crates/rustc-stable-hash/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..e3708bc
--- /dev/null
+++ b/crates/rustc-stable-hash/CODE_OF_CONDUCT.md
@@ -0,0 +1,3 @@
+# The Rust Code of Conduct
+
+The Code of Conduct for this repository [can be found online](https://www.rust-lang.org/conduct.html).
diff --git a/crates/rustc-stable-hash/Cargo.toml b/crates/rustc-stable-hash/Cargo.toml
new file mode 100644
index 0000000..8246756
--- /dev/null
+++ b/crates/rustc-stable-hash/Cargo.toml
@@ -0,0 +1,32 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2021"
+name = "rustc-stable-hash"
+version = "0.1.2"
+build = false
+autolib = false
+autobins = false
+autoexamples = false
+autotests = false
+autobenches = false
+description = "A stable hashing algorithm used by rustc"
+readme = "README.md"
+license = "Apache-2.0 OR MIT"
+repository = "https://github.com/rust-lang/rustc-stable-hash"
+
+[features]
+nightly = []
+
+[lib]
+name = "rustc_stable_hash"
+path = "src/lib.rs"
diff --git a/crates/rustc-stable-hash/LICENSE b/crates/rustc-stable-hash/LICENSE
new file mode 120000
index 0000000..6b579aa
--- /dev/null
+++ b/crates/rustc-stable-hash/LICENSE
@@ -0,0 +1 @@
+LICENSE-APACHE
\ No newline at end of file
diff --git a/crates/rustc-stable-hash/LICENSE-APACHE b/crates/rustc-stable-hash/LICENSE-APACHE
new file mode 100644
index 0000000..1b5ec8b
--- /dev/null
+++ b/crates/rustc-stable-hash/LICENSE-APACHE
@@ -0,0 +1,176 @@
+ Apache License
+ Version 2.0, January 2004
+ http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+1. Definitions.
+
+ "License" shall mean the terms and conditions for use, reproduction,
+ and distribution as defined by Sections 1 through 9 of this document.
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+ "You" (or "Your") shall mean an individual or Legal Entity
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+ "Work" shall mean the work of authorship, whether in Source or
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+ "Derivative Works" shall mean any work, whether in Source or Object
+ form, that is based on (or derived from) the Work and for which the
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+ (a) You must give any other recipients of the Work or
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+ (b) You must cause any modified files to carry prominent notices
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+ (c) You must retain, in the Source form of any Derivative Works
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+ (d) If the Work includes a "NOTICE" text file as part of its
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+ of the NOTICE file are for informational purposes only and
+ do not modify the License. You may add Your own attribution
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+ or as an addendum to the NOTICE text from the Work, provided
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+ reproduction, and distribution of the Work otherwise complies with
+ the conditions stated in this License.
+
+5. Submission of Contributions. Unless You explicitly state otherwise,
+ any Contribution intentionally submitted for inclusion in the Work
+ by You to the Licensor shall be under the terms and conditions of
+ this License, without any additional terms or conditions.
+ Notwithstanding the above, nothing herein shall supersede or modify
+ the terms of any separate license agreement you may have executed
+ with Licensor regarding such Contributions.
+
+6. Trademarks. This License does not grant permission to use the trade
+ names, trademarks, service marks, or product names of the Licensor,
+ except as required for reasonable and customary use in describing the
+ origin of the Work and reproducing the content of the NOTICE file.
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+7. Disclaimer of Warranty. Unless required by applicable law or
+ agreed to in writing, Licensor provides the Work (and each
+ Contributor provides its Contributions) on an "AS IS" BASIS,
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+ implied, including, without limitation, any warranties or conditions
+ of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+ PARTICULAR PURPOSE. You are solely responsible for determining the
+ appropriateness of using or redistributing the Work and assume any
+ risks associated with Your exercise of permissions under this License.
+
+8. Limitation of Liability. In no event and under no legal theory,
+ whether in tort (including negligence), contract, or otherwise,
+ unless required by applicable law (such as deliberate and grossly
+ negligent acts) or agreed to in writing, shall any Contributor be
+ liable to You for damages, including any direct, indirect, special,
+ incidental, or consequential damages of any character arising as a
+ result of this License or out of the use or inability to use the
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+9. Accepting Warranty or Additional Liability. While redistributing
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+ on Your own behalf and on Your sole responsibility, not on behalf
+ of any other Contributor, and only if You agree to indemnify,
+ defend, and hold each Contributor harmless for any liability
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+ of your accepting any such warranty or additional liability.
+
+END OF TERMS AND CONDITIONS
diff --git a/crates/rustc-stable-hash/METADATA b/crates/rustc-stable-hash/METADATA
new file mode 100644
index 0000000..930bcb3
--- /dev/null
+++ b/crates/rustc-stable-hash/METADATA
@@ -0,0 +1,17 @@
+name: "rustc-stable-hash"
+description: "A stable hashing algorithm used by rustc"
+third_party {
+ version: "0.1.2"
+ license_type: NOTICE
+ last_upgrade_date {
+ year: 2025
+ month: 3
+ day: 19
+ }
+ homepage: "https://crates.io/crates/rustc-stable-hash"
+ identifier {
+ type: "Archive"
+ value: "https://static.crates.io/crates/rustc-stable-hash/rustc-stable-hash-0.1.2.crate"
+ version: "0.1.2"
+ }
+}
diff --git a/crates/rustc-stable-hash/MODULE_LICENSE_APACHE2 b/crates/rustc-stable-hash/MODULE_LICENSE_APACHE2
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/crates/rustc-stable-hash/MODULE_LICENSE_APACHE2
diff --git a/crates/rustc-stable-hash/README.md b/crates/rustc-stable-hash/README.md
new file mode 100644
index 0000000..548ff21
--- /dev/null
+++ b/crates/rustc-stable-hash/README.md
@@ -0,0 +1,32 @@
+# rustc-stable-hash
+
+[](https://crates.io/crates/rustc-stable-hash)
+[](https://docs.rs/rustc-stable-hash)
+
+A stable hashing algorithm used by `rustc`: cross-platform, deterministic, not secure.
+
+This crate provides facilities with the `StableHasher` structure to create stable hashers over *unstable* hashers by abstracting over them the handling of endian-ness and the target `usize`/`isize` bit size difference.
+
+Currently, this crate provides it's own implementation of 128-bit `SipHasher`: `SipHasher128`; with `StableSipHasher128` for the stable variant.
+
+## Usage
+
+```rust
+use rustc_stable_hash::hashers::{StableSipHasher128, SipHasher128Hash};
+use rustc_stable_hash::FromStableHash;
+use std::hash::Hasher;
+
+struct Hash128([u64; 2]);
+impl FromStableHash for Hash128 {
+ type Hash = SipHasher128Hash;
+
+ fn from(SipHasher128Hash(hash): SipHasher128Hash) -> Hash128 {
+ Hash128(hash)
+ }
+}
+
+let mut hasher = StableSipHasher128::new();
+hasher.write_usize(0xFA);
+
+let hash: Hash128 = hasher.finish();
+```
diff --git a/crates/rustc-stable-hash/cargo_embargo.json b/crates/rustc-stable-hash/cargo_embargo.json
new file mode 100644
index 0000000..b6c35c7
--- /dev/null
+++ b/crates/rustc-stable-hash/cargo_embargo.json
@@ -0,0 +1,4 @@
+{
+ "run_cargo": false,
+ "min_sdk_version": "29"
+}
\ No newline at end of file
diff --git a/crates/rustc-stable-hash/src/int_overflow.rs b/crates/rustc-stable-hash/src/int_overflow.rs
new file mode 100644
index 0000000..716942f
--- /dev/null
+++ b/crates/rustc-stable-hash/src/int_overflow.rs
@@ -0,0 +1,81 @@
+//! Weaker version of `-Coverflow-checks`.
+
+// FIXME: These two traits seems overkill for this crate, we should probably
+// replace these by two simple free floating function instead since we only
+// operate on `usize`.
+
+/// Addition, but only overflow checked when `cfg(debug_assertions)` is set
+/// instead of respecting `-Coverflow-checks`.
+///
+/// This exists for performance reasons, as we ship rustc with overflow checks.
+/// While overflow checks are perf neutral in almost all of the compiler, there
+/// are a few particularly hot areas where we don't want overflow checks in our
+/// dist builds. Overflow is still a bug there, so we want overflow check for
+/// builds with debug assertions.
+///
+/// That's a long way to say that this should be used in areas where overflow
+/// is a bug but overflow checking is too slow.
+pub(crate) trait DebugStrictAdd {
+ /// See [`DebugStrictAdd`].
+ fn debug_strict_add(self, other: Self) -> Self;
+}
+
+macro_rules! impl_debug_strict_add {
+ ($( $ty:ty )*) => {
+ $(
+ impl DebugStrictAdd for $ty {
+ fn debug_strict_add(self, other: Self) -> Self {
+ if cfg!(debug_assertions) {
+ self + other
+ } else {
+ self.wrapping_add(other)
+ }
+ }
+ }
+ )*
+ };
+}
+
+/// See [`DebugStrictAdd`].
+pub(crate) trait DebugStrictSub {
+ /// See [`DebugStrictAdd`].
+ fn debug_strict_sub(self, other: Self) -> Self;
+}
+
+macro_rules! impl_debug_strict_sub {
+ ($( $ty:ty )*) => {
+ $(
+ impl DebugStrictSub for $ty {
+ fn debug_strict_sub(self, other: Self) -> Self {
+ if cfg!(debug_assertions) {
+ self - other
+ } else {
+ self.wrapping_sub(other)
+ }
+ }
+ }
+ )*
+ };
+}
+
+impl_debug_strict_add! {
+ usize
+}
+
+/*
+impl_debug_strict_add! {
+ u8 u16 u32 u64 u128 usize
+ i8 i16 i32 i64 i128 isize
+}
+*/
+
+impl_debug_strict_sub! {
+ usize
+}
+
+/*
+impl_debug_strict_sub! {
+ u8 u16 u32 u64 u128 usize
+ i8 i16 i32 i64 i128 isize
+}
+*/
diff --git a/crates/rustc-stable-hash/src/lib.rs b/crates/rustc-stable-hash/src/lib.rs
new file mode 100644
index 0000000..e68d2d1
--- /dev/null
+++ b/crates/rustc-stable-hash/src/lib.rs
@@ -0,0 +1,35 @@
+//! A stable hashing algorithm used by rustc
+
+#![cfg_attr(feature = "nightly", feature(hasher_prefixfree_extras))]
+#![deny(clippy::missing_safety_doc)]
+#![deny(unsafe_op_in_unsafe_fn)]
+#![deny(unreachable_pub)]
+
+mod int_overflow;
+mod sip128;
+mod stable_hasher;
+
+/// Hashers collection
+pub mod hashers {
+ #[doc(inline)]
+ pub use super::sip128::{SipHasher128, SipHasher128Hash};
+
+ /// Stable 128-bits Sip Hasher
+ ///
+ /// [`StableHasher`] version of [`SipHasher128`].
+ ///
+ /// [`StableHasher`]: super::StableHasher
+ pub type StableSipHasher128 = super::StableHasher<SipHasher128>;
+}
+
+#[doc(inline)]
+pub use stable_hasher::StableHasher;
+
+#[doc(inline)]
+pub use stable_hasher::FromStableHash;
+
+#[doc(inline)]
+pub use stable_hasher::ExtendedHasher;
+
+#[doc(inline)]
+pub use hashers::{SipHasher128Hash, StableSipHasher128};
diff --git a/crates/rustc-stable-hash/src/sip128.rs b/crates/rustc-stable-hash/src/sip128.rs
new file mode 100644
index 0000000..6b5d79b
--- /dev/null
+++ b/crates/rustc-stable-hash/src/sip128.rs
@@ -0,0 +1,551 @@
+//! This is a copy of `core::hash::sip` adapted to providing 128 bit hashes.
+
+// This code is very hot and uses lots of arithmetic, avoid overflow checks for performance.
+// See https://github.com/rust-lang/rust/pull/119440#issuecomment-1874255727
+use crate::int_overflow::{DebugStrictAdd, DebugStrictSub};
+use crate::ExtendedHasher;
+
+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;
+
+/// Hashing result of [`SipHasher128`]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct SipHasher128Hash(pub [u64; 2]);
+
+#[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);
+ $v2 = $v2.wrapping_add($v3);
+ $v1 = $v1.rotate_left(13);
+ $v1 ^= $v0;
+ $v3 = $v3.rotate_left(16);
+ $v3 ^= $v2;
+ $v0 = $v0.rotate_left(32);
+
+ $v2 = $v2.wrapping_add($v1);
+ $v0 = $v0.wrapping_add($v3);
+ $v1 = $v1.rotate_left(17);
+ $v1 ^= $v2;
+ $v3 = $v3.rotate_left(21);
+ $v3 ^= $v0;
+ $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);
+
+ unsafe {
+ if count == 8 {
+ ptr::copy_nonoverlapping(src, dst, 8);
+ return;
+ }
+
+ let mut i = 0;
+ if i.debug_strict_add(3) < count {
+ ptr::copy_nonoverlapping(src.add(i), dst.add(i), 4);
+ i = i.debug_strict_add(4);
+ }
+
+ if i.debug_strict_add(1) < count {
+ ptr::copy_nonoverlapping(src.add(i), dst.add(i), 2);
+ i = i.debug_strict_add(2)
+ }
+
+ if i < count {
+ *dst.add(i) = *src.add(i);
+ i = i.debug_strict_add(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,
+ // HACK: Manual MaybeUninit::uninit_array, use inline const with Rust 1.79
+ buf: unsafe {
+ MaybeUninit::<[MaybeUninit<_>; BUFFER_WITH_SPILL_CAPACITY]>::uninit().assume_init()
+ },
+ 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
+ }
+
+ // 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]) {
+ unsafe {
+ 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;
+ Sip13Rounds::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.debug_strict_add(LEN).debug_strict_sub(BUFFER_SIZE)
+ };
+ self.processed = self.processed.debug_strict_add(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.debug_strict_add(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.debug_strict_add(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]) {
+ unsafe {
+ 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.debug_strict_sub(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).debug_strict_add(1);
+
+ for i in 0..last {
+ let elem = self.buf.get_unchecked(i).assume_init().to_le();
+ self.state.v3 ^= elem;
+ Sip13Rounds::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.debug_strict_sub(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;
+ Sip13Rounds::c_rounds(&mut self.state);
+ self.state.v0 ^= elem;
+ processed = processed.debug_strict_add(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 = self
+ .processed
+ .debug_strict_add(nbuf.debug_strict_add(processed));
+ }
+ }
+
+ // A function for finishing the hashing.
+ //
+ // SAFETY: `buf` must be initialized up to the byte offset `nbuf`.
+ #[inline]
+ unsafe fn finish128_inner(
+ nbuf: usize,
+ buf: &mut [MaybeUninit<u64>; BUFFER_WITH_SPILL_CAPACITY],
+ mut state: State,
+ processed: usize,
+ ) -> [u64; 2] {
+ debug_assert!(nbuf < BUFFER_SIZE);
+
+ // Process full elements in buffer.
+ let last = nbuf / ELEM_SIZE;
+
+ for i in 0..last {
+ let elem = unsafe { buf.get_unchecked(i).assume_init().to_le() };
+ state.v3 ^= elem;
+ Sip13Rounds::c_rounds(&mut state);
+ state.v0 ^= elem;
+ }
+
+ // Get remaining partial element.
+ let elem = if 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 = (buf.as_mut_ptr() as *mut u8).add(nbuf);
+ ptr::write_bytes(dst, 0, ELEM_SIZE - 1);
+ buf.get_unchecked(last).assume_init().to_le()
+ }
+ } else {
+ 0
+ };
+
+ // Finalize the hash.
+ let length = processed.debug_strict_add(nbuf);
+ let b: u64 = ((length as u64 & 0xff) << 56) | elem;
+
+ state.v3 ^= b;
+ Sip13Rounds::c_rounds(&mut state);
+ state.v0 ^= b;
+
+ state.v2 ^= 0xee;
+ Sip13Rounds::d_rounds(&mut state);
+ let l = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
+
+ state.v1 ^= 0xdd;
+ Sip13Rounds::d_rounds(&mut state);
+ let h = state.v0 ^ state.v1 ^ state.v2 ^ state.v3;
+
+ [l, h]
+ }
+}
+
+impl Default for SipHasher128 {
+ fn default() -> SipHasher128 {
+ SipHasher128::new_with_keys(0, 0)
+ }
+}
+
+impl ExtendedHasher for SipHasher128 {
+ type Hash = SipHasher128Hash;
+
+ #[inline]
+ 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.debug_strict_add(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.debug_strict_add(LEN);
+
+ return;
+ }
+
+ unsafe { self.short_write_process_buffer(bytes) }
+ }
+
+ #[inline(always)]
+ fn finish(mut self) -> SipHasher128Hash {
+ SipHasher128Hash(unsafe {
+ SipHasher128::finish128_inner(self.nbuf, &mut self.buf, self.state, self.processed)
+ })
+ }
+}
+
+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);
+ }
+
+ #[cfg(feature = "nightly")]
+ #[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 {
+ let mut buf = self.buf;
+ let [a, b] = unsafe {
+ SipHasher128::finish128_inner(self.nbuf, &mut buf, self.state, self.processed)
+ };
+
+ // Combining the two halves makes sure we get a good quality hash.
+ a.wrapping_mul(3).wrapping_add(b)
+ }
+}
+
+#[derive(Debug, Clone, Default)]
+struct Sip13Rounds;
+
+impl Sip13Rounds {
+ #[inline]
+ fn c_rounds(state: &mut State) {
+ compress!(state);
+ }
+
+ #[inline]
+ fn d_rounds(state: &mut State) {
+ compress!(state);
+ compress!(state);
+ compress!(state);
+ }
+}
diff --git a/crates/rustc-stable-hash/src/sip128/tests.rs b/crates/rustc-stable-hash/src/sip128/tests.rs
new file mode 100644
index 0000000..6be4b12
--- /dev/null
+++ b/crates/rustc-stable-hash/src/sip128/tests.rs
@@ -0,0 +1,320 @@
+use super::*;
+
+use std::hash::Hash;
+
+// Hash just the bytes of the slice, without length prefix
+struct Bytes<'a>(&'a [u8]);
+
+impl<'a> Hash for Bytes<'a> {
+ #[allow(unused_must_use)]
+ fn hash<H: Hasher>(&self, state: &mut H) {
+ for byte in self.0 {
+ state.write_u8(*byte);
+ }
+ }
+}
+
+fn hash_with<T: Hash>(mut st: SipHasher128, x: &T) -> SipHasher128Hash {
+ x.hash(&mut st);
+ st.finish()
+}
+
+fn hash<T: Hash>(x: &T) -> SipHasher128Hash {
+ hash_with(SipHasher128::new_with_keys(0, 0), x)
+}
+
+#[rustfmt::skip]
+const TEST_VECTOR: [[u8; 16]; 64] = [
+ [0xe7, 0x7e, 0xbc, 0xb2, 0x27, 0x88, 0xa5, 0xbe, 0xfd, 0x62, 0xdb, 0x6a, 0xdd, 0x30, 0x30, 0x01],
+ [0xfc, 0x6f, 0x37, 0x04, 0x60, 0xd3, 0xed, 0xa8, 0x5e, 0x05, 0x73, 0xcc, 0x2b, 0x2f, 0xf0, 0x63],
+ [0x75, 0x78, 0x7f, 0x09, 0x05, 0x69, 0x83, 0x9b, 0x85, 0x5b, 0xc9, 0x54, 0x8c, 0x6a, 0xea, 0x95],
+ [0x6b, 0xc5, 0xcc, 0xfa, 0x1e, 0xdc, 0xf7, 0x9f, 0x48, 0x23, 0x18, 0x77, 0x12, 0xeb, 0xd7, 0x43],
+ [0x0c, 0x78, 0x4e, 0x71, 0xac, 0x2b, 0x28, 0x5a, 0x9f, 0x8e, 0x92, 0xe7, 0x8f, 0xbf, 0x2c, 0x25],
+ [0xf3, 0x28, 0xdb, 0x89, 0x34, 0x5b, 0x62, 0x0c, 0x79, 0x52, 0x29, 0xa4, 0x26, 0x95, 0x84, 0x3e],
+ [0xdc, 0xd0, 0x3d, 0x29, 0xf7, 0x43, 0xe7, 0x10, 0x09, 0x51, 0xb0, 0xe8, 0x39, 0x85, 0xa6, 0xf8],
+ [0x10, 0x84, 0xb9, 0x23, 0xf2, 0xaa, 0xe0, 0xc3, 0xa6, 0x2f, 0x2e, 0xc8, 0x08, 0x48, 0xab, 0x77],
+ [0xaa, 0x12, 0xfe, 0xe1, 0xd5, 0xe3, 0xda, 0xb4, 0x72, 0x4f, 0x16, 0xab, 0x35, 0xf9, 0xc7, 0x99],
+ [0x81, 0xdd, 0xb8, 0x04, 0x2c, 0xf3, 0x39, 0x94, 0xf4, 0x72, 0x0e, 0x00, 0x94, 0x13, 0x7c, 0x42],
+ [0x4f, 0xaa, 0x54, 0x1d, 0x5d, 0x49, 0x8e, 0x89, 0xba, 0x0e, 0xa4, 0xc3, 0x87, 0xb2, 0x2f, 0xb4],
+ [0x72, 0x3b, 0x9a, 0xf3, 0x55, 0x44, 0x91, 0xdb, 0xb1, 0xd6, 0x63, 0x3d, 0xfc, 0x6e, 0x0c, 0x4e],
+ [0xe5, 0x3f, 0x92, 0x85, 0x9e, 0x48, 0x19, 0xa8, 0xdc, 0x06, 0x95, 0x73, 0x9f, 0xea, 0x8c, 0x65],
+ [0xb2, 0xf8, 0x58, 0xc7, 0xc9, 0xea, 0x80, 0x1d, 0x53, 0xd6, 0x03, 0x59, 0x6d, 0x65, 0x78, 0x44],
+ [0x87, 0xe7, 0x62, 0x68, 0xdb, 0xc9, 0x22, 0x72, 0x26, 0xb0, 0xca, 0x66, 0x5f, 0x64, 0xe3, 0x78],
+ [0xc1, 0x7e, 0x55, 0x05, 0xb2, 0xbd, 0x52, 0x6c, 0x29, 0x21, 0xcd, 0xec, 0x1e, 0x7e, 0x01, 0x09],
+ [0xd0, 0xa8, 0xd9, 0x57, 0x15, 0x51, 0x8e, 0xeb, 0xb5, 0x13, 0xb0, 0xf8, 0x3d, 0x9e, 0x17, 0x93],
+ [0x23, 0x41, 0x26, 0xf9, 0x3f, 0xbb, 0x66, 0x8d, 0x97, 0x51, 0x12, 0xe8, 0xfe, 0xbd, 0xf7, 0xec],
+ [0xef, 0x42, 0xf0, 0x3d, 0xb7, 0x8f, 0x70, 0x4d, 0x02, 0x3c, 0x44, 0x9f, 0x16, 0xb7, 0x09, 0x2b],
+ [0xab, 0xf7, 0x62, 0x38, 0xc2, 0x0a, 0xf1, 0x61, 0xb2, 0x31, 0x4b, 0x4d, 0x55, 0x26, 0xbc, 0xe9],
+ [0x3c, 0x2c, 0x2f, 0x11, 0xbb, 0x90, 0xcf, 0x0b, 0xe3, 0x35, 0xca, 0x9b, 0x2e, 0x91, 0xe9, 0xb7],
+ [0x2a, 0x7a, 0x68, 0x0f, 0x22, 0xa0, 0x2a, 0x92, 0xf4, 0x51, 0x49, 0xd2, 0x0f, 0xec, 0xe0, 0xef],
+ [0xc9, 0xa8, 0xd1, 0x30, 0x23, 0x1d, 0xd4, 0x3e, 0x42, 0xe6, 0x45, 0x69, 0x57, 0xf8, 0x37, 0x79],
+ [0x1d, 0x12, 0x7b, 0x84, 0x40, 0x5c, 0xea, 0xb9, 0x9f, 0xd8, 0x77, 0x5a, 0x9b, 0xe6, 0xc5, 0x59],
+ [0x9e, 0x4b, 0xf8, 0x37, 0xbc, 0xfd, 0x92, 0xca, 0xce, 0x09, 0xd2, 0x06, 0x1a, 0x84, 0xd0, 0x4a],
+ [0x39, 0x03, 0x1a, 0x96, 0x5d, 0x73, 0xb4, 0xaf, 0x5a, 0x27, 0x4d, 0x18, 0xf9, 0x73, 0xb1, 0xd2],
+ [0x7f, 0x4d, 0x0a, 0x12, 0x09, 0xd6, 0x7e, 0x4e, 0xd0, 0x6f, 0x75, 0x38, 0xe1, 0xcf, 0xad, 0x64],
+ [0xe6, 0x1e, 0xe2, 0x40, 0xfb, 0xdc, 0xce, 0x38, 0x96, 0x9f, 0x4c, 0xd2, 0x49, 0x27, 0xdd, 0x93],
+ [0x4c, 0x3b, 0xa2, 0xb3, 0x7b, 0x0f, 0xdd, 0x8c, 0xfa, 0x5e, 0x95, 0xc1, 0x89, 0xb2, 0x94, 0x14],
+ [0xe0, 0x6f, 0xd4, 0xca, 0x06, 0x6f, 0xec, 0xdd, 0x54, 0x06, 0x8a, 0x5a, 0xd8, 0x89, 0x6f, 0x86],
+ [0x5c, 0xa8, 0x4c, 0x34, 0x13, 0x9c, 0x65, 0x80, 0xa8, 0x8a, 0xf2, 0x49, 0x90, 0x72, 0x07, 0x06],
+ [0x42, 0xea, 0x96, 0x1c, 0x5b, 0x3c, 0x85, 0x8b, 0x17, 0xc3, 0xe5, 0x50, 0xdf, 0xa7, 0x90, 0x10],
+ [0x40, 0x6c, 0x44, 0xde, 0xe6, 0x78, 0x57, 0xb2, 0x94, 0x31, 0x60, 0xf3, 0x0c, 0x74, 0x17, 0xd3],
+ [0xc5, 0xf5, 0x7b, 0xae, 0x13, 0x20, 0xfc, 0xf4, 0xb4, 0xe8, 0x68, 0xe7, 0x1d, 0x56, 0xc6, 0x6b],
+ [0x04, 0xbf, 0x73, 0x7a, 0x5b, 0x67, 0x6b, 0xe7, 0xc3, 0xde, 0x05, 0x01, 0x7d, 0xf4, 0xbf, 0xf9],
+ [0x51, 0x63, 0xc9, 0xc0, 0x3f, 0x19, 0x07, 0xea, 0x10, 0x44, 0xed, 0x5c, 0x30, 0x72, 0x7b, 0x4f],
+ [0x37, 0xa1, 0x10, 0xf0, 0x02, 0x71, 0x8e, 0xda, 0xd2, 0x4b, 0x3f, 0x9e, 0xe4, 0x53, 0xf1, 0x40],
+ [0xb9, 0x87, 0x7e, 0x38, 0x1a, 0xed, 0xd3, 0xda, 0x08, 0xc3, 0x3e, 0x75, 0xff, 0x23, 0xac, 0x10],
+ [0x7c, 0x50, 0x04, 0x00, 0x5e, 0xc5, 0xda, 0x4c, 0x5a, 0xc9, 0x44, 0x0e, 0x5c, 0x72, 0x31, 0x93],
+ [0x81, 0xb8, 0x24, 0x37, 0x83, 0xdb, 0xc6, 0x46, 0xca, 0x9d, 0x0c, 0xd8, 0x2a, 0xbd, 0xb4, 0x6c],
+ [0x50, 0x57, 0x20, 0x54, 0x3e, 0xb9, 0xb4, 0x13, 0xd5, 0x0b, 0x3c, 0xfa, 0xd9, 0xee, 0xf9, 0x38],
+ [0x94, 0x5f, 0x59, 0x4d, 0xe7, 0x24, 0x11, 0xe4, 0xd3, 0x35, 0xbe, 0x87, 0x44, 0x56, 0xd8, 0xf3],
+ [0x37, 0x92, 0x3b, 0x3e, 0x37, 0x17, 0x77, 0xb2, 0x11, 0x70, 0xbf, 0x9d, 0x7e, 0x62, 0xf6, 0x02],
+ [0x3a, 0xd4, 0xe7, 0xc8, 0x57, 0x64, 0x96, 0x46, 0x11, 0xeb, 0x0a, 0x6c, 0x4d, 0x62, 0xde, 0x56],
+ [0xcd, 0x91, 0x39, 0x6c, 0x44, 0xaf, 0x4f, 0x51, 0x85, 0x57, 0x8d, 0x9d, 0xd9, 0x80, 0x3f, 0x0a],
+ [0xfe, 0x28, 0x15, 0x8e, 0x72, 0x7b, 0x86, 0x8f, 0x39, 0x03, 0xc9, 0xac, 0xda, 0x64, 0xa2, 0x58],
+ [0x40, 0xcc, 0x10, 0xb8, 0x28, 0x8c, 0xe5, 0xf0, 0xbc, 0x3a, 0xc0, 0xb6, 0x8a, 0x0e, 0xeb, 0xc8],
+ [0x6f, 0x14, 0x90, 0xf5, 0x40, 0x69, 0x9a, 0x3c, 0xd4, 0x97, 0x44, 0x20, 0xec, 0xc9, 0x27, 0x37],
+ [0xd5, 0x05, 0xf1, 0xb7, 0x5e, 0x1a, 0x84, 0xa6, 0x03, 0xc4, 0x35, 0x83, 0xb2, 0xed, 0x03, 0x08],
+ [0x49, 0x15, 0x73, 0xcf, 0xd7, 0x2b, 0xb4, 0x68, 0x2b, 0x7c, 0xa5, 0x88, 0x0e, 0x1c, 0x8d, 0x6f],
+ [0x3e, 0xd6, 0x9c, 0xfe, 0x45, 0xab, 0x40, 0x3f, 0x2f, 0xd2, 0xad, 0x95, 0x9b, 0xa2, 0x76, 0x66],
+ [0x8b, 0xe8, 0x39, 0xef, 0x1b, 0x20, 0xb5, 0x7c, 0x83, 0xba, 0x7e, 0xb6, 0xa8, 0xc2, 0x2b, 0x6a],
+ [0x14, 0x09, 0x18, 0x6a, 0xb4, 0x22, 0x31, 0xfe, 0xde, 0xe1, 0x81, 0x62, 0xcf, 0x1c, 0xb4, 0xca],
+ [0x2b, 0xf3, 0xcc, 0xc2, 0x4a, 0xb6, 0x72, 0xcf, 0x15, 0x1f, 0xb8, 0xd2, 0xf3, 0xf3, 0x06, 0x9b],
+ [0xb9, 0xb9, 0x3a, 0x28, 0x82, 0xd6, 0x02, 0x5c, 0xdb, 0x8c, 0x56, 0xfa, 0x13, 0xf7, 0x53, 0x7b],
+ [0xd9, 0x7c, 0xca, 0x36, 0x94, 0xfb, 0x20, 0x6d, 0xb8, 0xbd, 0x1f, 0x36, 0x50, 0xc3, 0x33, 0x22],
+ [0x94, 0xec, 0x2e, 0x19, 0xa4, 0x0b, 0xe4, 0x1a, 0xf3, 0x94, 0x0d, 0x6b, 0x30, 0xc4, 0x93, 0x84],
+ [0x4b, 0x41, 0x60, 0x3f, 0x20, 0x9a, 0x04, 0x5b, 0xe1, 0x40, 0xa3, 0x41, 0xa3, 0xdf, 0xfe, 0x10],
+ [0x23, 0xfb, 0xcb, 0x30, 0x9f, 0x1c, 0xf0, 0x94, 0x89, 0x07, 0x55, 0xab, 0x1b, 0x42, 0x65, 0x69],
+ [0xe7, 0xd9, 0xb6, 0x56, 0x90, 0x91, 0x8a, 0x2b, 0x23, 0x2f, 0x2f, 0x5c, 0x12, 0xc8, 0x30, 0x0e],
+ [0xad, 0xe8, 0x3c, 0xf7, 0xe7, 0xf3, 0x84, 0x7b, 0x36, 0xfa, 0x4b, 0x54, 0xb0, 0x0d, 0xce, 0x61],
+ [0x06, 0x10, 0xc5, 0xf2, 0xee, 0x57, 0x1c, 0x8a, 0xc8, 0x0c, 0xbf, 0xe5, 0x38, 0xbd, 0xf1, 0xc7],
+ [0x27, 0x1d, 0x5d, 0x00, 0xfb, 0xdb, 0x5d, 0x15, 0x5d, 0x9d, 0xce, 0xa9, 0x7c, 0xb4, 0x02, 0x18],
+ [0x4c, 0x58, 0x00, 0xe3, 0x4e, 0xfe, 0x42, 0x6f, 0x07, 0x9f, 0x6b, 0x0a, 0xa7, 0x52, 0x60, 0xad],
+];
+
+#[test]
+fn test_siphash_1_3_test_vector() {
+ let k0 = 0x_07_06_05_04_03_02_01_00;
+ let k1 = 0x_0f_0e_0d_0c_0b_0a_09_08;
+
+ let mut input: Vec<u8> = Vec::new();
+
+ #[allow(clippy::identity_op)]
+ for (i, v) in TEST_VECTOR.iter().enumerate() {
+ let out = hash_with(SipHasher128::new_with_keys(k0, k1), &Bytes(&input[..]));
+ let expected = [
+ ((v[0] as u64) << 0)
+ | ((v[1] as u64) << 8)
+ | ((v[2] as u64) << 16)
+ | ((v[3] as u64) << 24)
+ | ((v[4] as u64) << 32)
+ | ((v[5] as u64) << 40)
+ | ((v[6] as u64) << 48)
+ | ((v[7] as u64) << 56),
+ ((v[8] as u64) << 0)
+ | ((v[9] as u64) << 8)
+ | ((v[10] as u64) << 16)
+ | ((v[11] as u64) << 24)
+ | ((v[12] as u64) << 32)
+ | ((v[13] as u64) << 40)
+ | ((v[14] as u64) << 48)
+ | ((v[15] as u64) << 56),
+ ];
+
+ assert_eq!(out.0, expected);
+ input.push(i as u8);
+ }
+}
+
+#[test]
+#[cfg(target_arch = "arm")]
+fn test_hash_usize() {
+ let val = 0xdeadbeef_deadbeef_u64;
+ assert!(hash(&val) != hash(&(val as usize)));
+ assert_eq!(hash(&(val as u32)), hash(&(val as usize)));
+}
+#[test]
+#[cfg(target_arch = "x86_64")]
+fn test_hash_usize() {
+ let val = 0xdeadbeef_deadbeef_u64;
+ assert_eq!(hash(&val), hash(&(val as usize)));
+ assert!(hash(&(val as u32)) != hash(&(val as usize)));
+}
+#[test]
+#[cfg(target_arch = "x86")]
+fn test_hash_usize() {
+ let val = 0xdeadbeef_deadbeef_u64;
+ assert!(hash(&val) != hash(&(val as usize)));
+ assert_eq!(hash(&(val as u32)), hash(&(val as usize)));
+}
+
+#[test]
+fn test_hash_idempotent() {
+ let val64 = 0xdeadbeef_deadbeef_u64;
+ assert_eq!(hash(&val64), hash(&val64));
+ let val32 = 0xdeadbeef_u32;
+ assert_eq!(hash(&val32), hash(&val32));
+}
+
+#[test]
+fn test_hash_no_bytes_dropped_64() {
+ let val = 0xdeadbeef_deadbeef_u64;
+
+ assert!(hash(&val) != hash(&zero_byte(val, 0)));
+ assert!(hash(&val) != hash(&zero_byte(val, 1)));
+ assert!(hash(&val) != hash(&zero_byte(val, 2)));
+ assert!(hash(&val) != hash(&zero_byte(val, 3)));
+ assert!(hash(&val) != hash(&zero_byte(val, 4)));
+ assert!(hash(&val) != hash(&zero_byte(val, 5)));
+ assert!(hash(&val) != hash(&zero_byte(val, 6)));
+ assert!(hash(&val) != hash(&zero_byte(val, 7)));
+
+ fn zero_byte(val: u64, byte: usize) -> u64 {
+ assert!(byte < 8);
+ val & !(0xff << (byte * 8))
+ }
+}
+
+#[test]
+fn test_hash_no_bytes_dropped_32() {
+ let val = 0xdeadbeef_u32;
+
+ assert!(hash(&val) != hash(&zero_byte(val, 0)));
+ assert!(hash(&val) != hash(&zero_byte(val, 1)));
+ assert!(hash(&val) != hash(&zero_byte(val, 2)));
+ assert!(hash(&val) != hash(&zero_byte(val, 3)));
+
+ fn zero_byte(val: u32, byte: usize) -> u32 {
+ assert!(byte < 4);
+ val & !(0xff << (byte * 8))
+ }
+}
+
+#[test]
+fn test_hash_no_concat_alias() {
+ let s = ("aa", "bb");
+ let t = ("aabb", "");
+ let u = ("a", "abb");
+
+ assert!(s != t && t != u);
+ assert!(hash(&s) != hash(&t) && hash(&s) != hash(&u));
+
+ let u = [1, 0, 0, 0];
+ let v = (&u[..1], &u[1..3], &u[3..]);
+ let w = (&u[..], &u[4..4], &u[4..4]);
+
+ assert!(v != w);
+ assert!(hash(&v) != hash(&w));
+}
+
+#[test]
+fn test_short_write_works() {
+ let test_u8 = 0xFF_u8;
+ let test_u16 = 0x1122_u16;
+ let test_u32 = 0x22334455_u32;
+ let test_u64 = 0x33445566_778899AA_u64;
+ let test_u128 = 0x11223344_55667788_99AABBCC_DDEEFF77_u128;
+ let test_usize = 0xD0C0B0A0_usize;
+
+ let test_i8 = -1_i8;
+ let test_i16 = -2_i16;
+ let test_i32 = -3_i32;
+ let test_i64 = -4_i64;
+ let test_i128 = -5_i128;
+ let test_isize = -6_isize;
+
+ let mut h1 = SipHasher128::new_with_keys(0, 0);
+ h1.write(b"bytes");
+ h1.write(b"string");
+ h1.write_u8(test_u8);
+ h1.write_u16(test_u16);
+ h1.write_u32(test_u32);
+ h1.write_u64(test_u64);
+ h1.write_u128(test_u128);
+ h1.write_usize(test_usize);
+ h1.write_i8(test_i8);
+ h1.write_i16(test_i16);
+ h1.write_i32(test_i32);
+ h1.write_i64(test_i64);
+ h1.write_i128(test_i128);
+ h1.write_isize(test_isize);
+
+ let mut h2 = SipHasher128::new_with_keys(0, 0);
+ h2.write(b"bytes");
+ h2.write(b"string");
+ h2.write(&test_u8.to_ne_bytes());
+ h2.write(&test_u16.to_ne_bytes());
+ h2.write(&test_u32.to_ne_bytes());
+ h2.write(&test_u64.to_ne_bytes());
+ h2.write(&test_u128.to_ne_bytes());
+ h2.write(&test_usize.to_ne_bytes());
+ h2.write(&test_i8.to_ne_bytes());
+ h2.write(&test_i16.to_ne_bytes());
+ h2.write(&test_i32.to_ne_bytes());
+ h2.write(&test_i64.to_ne_bytes());
+ h2.write(&test_i128.to_ne_bytes());
+ h2.write(&test_isize.to_ne_bytes());
+
+ let h1_hash = h1.finish();
+ let h2_hash = h2.finish();
+
+ assert_eq!(h1_hash, h2_hash);
+}
+
+macro_rules! test_fill_buffer {
+ ($type:ty, $write_method:ident) => {{
+ // Test filling and overfilling the buffer from all possible offsets
+ // for a given integer type and its corresponding write method.
+ const SIZE: usize = std::mem::size_of::<$type>();
+ let input = [42; BUFFER_SIZE];
+ let x = 0x01234567_89ABCDEF_76543210_FEDCBA98_u128 as $type;
+ let x_bytes = &x.to_ne_bytes();
+
+ for i in 1..=SIZE {
+ let s = &input[..BUFFER_SIZE - i];
+
+ let mut h1 = SipHasher128::new_with_keys(7, 13);
+ h1.write(s);
+ h1.$write_method(x);
+
+ let mut h2 = SipHasher128::new_with_keys(7, 13);
+ h2.write(s);
+ h2.write(x_bytes);
+
+ let h1_hash = h1.finish();
+ let h2_hash = h2.finish();
+
+ assert_eq!(h1_hash, h2_hash);
+ }
+ }};
+}
+
+#[test]
+fn test_fill_buffer() {
+ test_fill_buffer!(u8, write_u8);
+ test_fill_buffer!(u16, write_u16);
+ test_fill_buffer!(u32, write_u32);
+ test_fill_buffer!(u64, write_u64);
+ test_fill_buffer!(u128, write_u128);
+ test_fill_buffer!(usize, write_usize);
+
+ test_fill_buffer!(i8, write_i8);
+ test_fill_buffer!(i16, write_i16);
+ test_fill_buffer!(i32, write_i32);
+ test_fill_buffer!(i64, write_i64);
+ test_fill_buffer!(i128, write_i128);
+ test_fill_buffer!(isize, write_isize);
+}
+
+#[test]
+fn test_finish() {
+ fn hash<H: Hasher>(h: &H) -> u64 {
+ h.finish()
+ }
+
+ let mut hasher = SipHasher128::new_with_keys(0, 0);
+
+ hasher.write_isize(0xF0);
+ hasher.write_isize(0xF0010);
+
+ assert_eq!(hash(&hasher), hash(&hasher));
+}
diff --git a/crates/rustc-stable-hash/src/stable_hasher.rs b/crates/rustc-stable-hash/src/stable_hasher.rs
new file mode 100644
index 0000000..bc5f9d9
--- /dev/null
+++ b/crates/rustc-stable-hash/src/stable_hasher.rs
@@ -0,0 +1,299 @@
+//! Stable hasher adapted for cross-platform independent hash.
+
+use std::fmt;
+use std::hash::Hasher;
+
+#[cfg(test)]
+mod tests;
+
+/// Extended [`Hasher`] trait for use with [`StableHasher`].
+///
+/// It permits returning an arbitrary type as the [`Self::Hash`] type
+/// contrary to the [`Hasher`] trait which can only return `u64`. This
+/// is useful when the hasher uses a different representation.
+///
+/// # Example
+///
+/// ```
+/// use std::hash::Hasher;
+/// use rustc_stable_hash::ExtendedHasher;
+///
+/// struct BogusHasher(u128);
+///
+/// impl Hasher for BogusHasher {
+/// fn write(&mut self, a: &[u8]) {
+/// # self.0 = a.iter().fold(0u128, |acc, a| acc + (*a as u128)) + self.0;
+/// // ...
+/// }
+///
+/// fn finish(&self) -> u64 {
+/// self.0 as u64 // really bogus
+/// }
+/// }
+///
+/// impl ExtendedHasher for BogusHasher {
+/// type Hash = u128;
+///
+/// fn short_write<const LEN: usize>(&mut self, bytes: [u8; LEN]) {
+/// self.write(&bytes)
+/// }
+///
+/// fn finish(self) -> Self::Hash {
+/// self.0
+/// }
+/// }
+/// ```
+pub trait ExtendedHasher: Hasher {
+ /// Type returned by the hasher.
+ type Hash;
+
+ /// Optimized version of [`Hasher::write`] but for small write.
+ fn short_write<const LEN: usize>(&mut self, bytes: [u8; LEN]) {
+ self.write(&bytes);
+ }
+
+ /// Finalization method of the hasher to return the [`Hash`].
+ fn finish(self) -> Self::Hash;
+}
+
+/// A Stable Hasher adapted for cross-platform independent hash.
+///
+/// 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.
+///
+/// # Example
+///
+/// ```
+/// use rustc_stable_hash::hashers::{StableSipHasher128, SipHasher128Hash};
+/// use rustc_stable_hash::{StableHasher, FromStableHash};
+/// use std::hash::Hasher;
+///
+/// struct Hash128([u64; 2]);
+/// impl FromStableHash for Hash128 {
+/// type Hash = SipHasher128Hash;
+///
+/// fn from(SipHasher128Hash(hash): SipHasher128Hash) -> Hash128 {
+/// Hash128(hash)
+/// }
+/// }
+///
+/// let mut hasher = StableSipHasher128::new();
+/// hasher.write_usize(0xFA);
+///
+/// let hash: Hash128 = hasher.finish();
+/// ```
+#[must_use]
+#[derive(Clone)]
+pub struct StableHasher<H: ExtendedHasher> {
+ state: H,
+}
+
+/// Trait for processing the result of the stable hashing operation.
+///
+/// # Example
+///
+/// ```
+/// use rustc_stable_hash::{StableHasher, FromStableHash};
+///
+/// struct Hash128(u128);
+///
+/// impl FromStableHash for Hash128 {
+/// type Hash = [u64; 2];
+///
+/// fn from(hash: [u64; 2]) -> Hash128 {
+/// let upper: u128 = hash[0] as u128;
+/// let lower: u128 = hash[1] as u128;
+///
+/// Hash128((upper << 64) | lower)
+/// }
+/// }
+/// ```
+pub trait FromStableHash: Sized {
+ type Hash;
+
+ /// Convert the finalized state of a [`StableHasher`] and construct
+ /// an [`Self`] containing the processed hash.
+ fn from(hash: Self::Hash) -> Self;
+}
+
+impl<H: ExtendedHasher + Default> StableHasher<H> {
+ /// Creates a new [`StableHasher`].
+ ///
+ /// To be used with the [`Hasher`] implementation and [`StableHasher::finish`].
+ #[inline]
+ pub fn new() -> Self {
+ Default::default()
+ }
+}
+
+impl<H: ExtendedHasher + Default> Default for StableHasher<H> {
+ /// Creates a new [`StableHasher`].
+ ///
+ /// To be used with the [`Hasher`] implementation and [`StableHasher::finish`].
+ #[inline]
+ fn default() -> Self {
+ StableHasher {
+ state: Default::default(),
+ }
+ }
+}
+
+impl<H: ExtendedHasher> StableHasher<H> {
+ /// Creates a new [`StableHasher`] from an already created [`ExtendedHasher`].
+ ///
+ /// Useful when wanting to initialize a hasher with different parameters/keys.
+ ///
+ /// **Important**: Any use of the hasher before being given to a [`StableHasher`]
+ /// is not covered by this crate guarentees and will make the resulting hash
+ /// NOT platform independent.
+ #[inline]
+ pub fn with_hasher(state: H) -> Self {
+ StableHasher { state }
+ }
+
+ /// Returns the typed-hash value for the values written.
+ ///
+ /// The resulting typed-hash value is constructed from an
+ /// [`FromStableHash`] implemenation.
+ ///
+ /// To be used in-place of [`Hasher::finish`].
+ #[inline]
+ #[must_use]
+ pub fn finish<W: FromStableHash<Hash = H::Hash>>(self) -> W {
+ W::from(self.state.finish())
+ }
+}
+
+impl<H: ExtendedHasher + fmt::Debug> fmt::Debug for StableHasher<H> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ write!(f, "{:?}", self.state)
+ }
+}
+
+impl<H: ExtendedHasher> Hasher for StableHasher<H> {
+ /// Returns a combined hash.
+ ///
+ /// For greater precision use instead [`StableHasher::finish`].
+ fn finish(&self) -> u64 {
+ Hasher::finish(&self.state)
+ }
+
+ #[inline]
+ fn write(&mut self, bytes: &[u8]) {
+ self.state.write(bytes);
+ }
+
+ #[cfg(feature = "nightly")]
+ #[inline]
+ fn write_str(&mut self, s: &str) {
+ self.state.write_str(s);
+ }
+
+ #[cfg(feature = "nightly")]
+ #[inline]
+ fn write_length_prefix(&mut self, len: usize) {
+ // Our impl for `usize` will extend it if needed.
+ self.write_usize(len);
+ }
+
+ #[inline]
+ fn write_u8(&mut self, i: u8) {
+ self.state.write_u8(i);
+ }
+
+ #[inline]
+ fn write_u16(&mut self, i: u16) {
+ self.state.short_write(i.to_le_bytes());
+ }
+
+ #[inline]
+ fn write_u32(&mut self, i: u32) {
+ self.state.short_write(i.to_le_bytes());
+ }
+
+ #[inline]
+ fn write_u64(&mut self, i: u64) {
+ self.state.short_write(i.to_le_bytes());
+ }
+
+ #[inline]
+ fn write_u128(&mut self, i: u128) {
+ self.write_u64(i as u64);
+ self.write_u64((i >> 64) as u64);
+ }
+
+ #[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.short_write((i as u64).to_le_bytes());
+ }
+
+ #[inline]
+ fn write_i8(&mut self, i: i8) {
+ self.state.write_i8(i);
+ }
+
+ #[inline]
+ fn write_i16(&mut self, i: i16) {
+ self.state.short_write((i as u16).to_le_bytes());
+ }
+
+ #[inline]
+ fn write_i32(&mut self, i: i32) {
+ self.state.short_write((i as u32).to_le_bytes());
+ }
+
+ #[inline]
+ fn write_i64(&mut self, i: i64) {
+ self.state.short_write((i as u64).to_le_bytes());
+ }
+
+ #[inline]
+ fn write_i128(&mut self, i: i128) {
+ self.state.write(&(i as u128).to_le_bytes());
+ }
+
+ #[inline]
+ fn write_isize(&mut self, i: isize) {
+ // Always treat isize as a 64-bit number so we get the same results on 32 and 64 bit
+ // platforms. This is important for symbol hashes when cross compiling,
+ // for example. Sign extending here is preferable as it means that the
+ // same negative number hashes the same on both 32 and 64 bit platforms.
+ let value = i as u64;
+
+ // Cold path
+ #[cold]
+ #[inline(never)]
+ fn hash_value<H: ExtendedHasher>(state: &mut H, value: u64) {
+ state.write_u8(0xFF);
+ state.short_write(value.to_le_bytes());
+ }
+
+ // `isize` values often seem to have a small (positive) numeric value in practice.
+ // To exploit this, if the value is small, we will hash a smaller amount of bytes.
+ // However, we cannot just skip the leading zero bytes, as that would produce the same hash
+ // e.g. if you hash two values that have the same bit pattern when they are swapped.
+ // See https://github.com/rust-lang/rust/pull/93014 for context.
+ //
+ // Therefore, we employ the following strategy:
+ // 1) When we encounter a value that fits within a single byte (the most common case), we
+ // hash just that byte. This is the most common case that is being optimized. However, we do
+ // not do this for the value 0xFF, as that is a reserved prefix (a bit like in UTF-8).
+ // 2) When we encounter a larger value, we hash a "marker" 0xFF and then the corresponding
+ // 8 bytes. Since this prefix cannot occur when we hash a single byte, when we hash two
+ // `isize`s that fit within a different amount of bytes, they should always produce a different
+ // byte stream for the hasher.
+ if value < 0xFF {
+ self.state.write_u8(value as u8);
+ } else {
+ hash_value(&mut self.state, value);
+ }
+ }
+}
diff --git a/crates/rustc-stable-hash/src/stable_hasher/tests.rs b/crates/rustc-stable-hash/src/stable_hasher/tests.rs
new file mode 100644
index 0000000..b2f2946
--- /dev/null
+++ b/crates/rustc-stable-hash/src/stable_hasher/tests.rs
@@ -0,0 +1,155 @@
+use std::hash::Hash;
+
+use super::*;
+use crate::{SipHasher128Hash, StableSipHasher128};
+
+// The tests below compare the computed hashes to particular expected values
+// in order to test that we produce the same results on different platforms,
+// regardless of endianness and `usize` and `isize` size differences (this
+// of course assumes we run these tests on platforms that differ in those
+// ways). The expected values depend on the hashing algorithm used, so they
+// need to be updated whenever StableHasher changes its hashing algorithm.
+
+#[derive(Debug, PartialEq)]
+struct TestHash([u64; 2]);
+
+impl FromStableHash for TestHash {
+ type Hash = SipHasher128Hash;
+
+ fn from(SipHasher128Hash(hash): Self::Hash) -> TestHash {
+ TestHash(hash)
+ }
+}
+
+#[test]
+fn test_hash_integers() {
+ // Test that integers are handled consistently across platforms.
+ let test_u8 = 0xAB_u8;
+ let test_u16 = 0xFFEE_u16;
+ let test_u32 = 0x445577AA_u32;
+ let test_u64 = 0x01234567_13243546_u64;
+ let test_u128 = 0x22114433_66557788_99AACCBB_EEDDFF77_u128;
+ let test_usize = 0xD0C0B0A0_usize;
+
+ let test_i8 = -100_i8;
+ let test_i16 = -200_i16;
+ let test_i32 = -300_i32;
+ let test_i64 = -400_i64;
+ let test_i128 = -500_i128;
+ let test_isize = -600_isize;
+
+ let mut h = StableSipHasher128::new();
+ test_u8.hash(&mut h);
+ test_u16.hash(&mut h);
+ test_u32.hash(&mut h);
+ test_u64.hash(&mut h);
+ test_u128.hash(&mut h);
+ test_usize.hash(&mut h);
+ test_i8.hash(&mut h);
+ test_i16.hash(&mut h);
+ test_i32.hash(&mut h);
+ test_i64.hash(&mut h);
+ test_i128.hash(&mut h);
+ test_isize.hash(&mut h);
+
+ // This depends on the hashing algorithm. See note at top of file.
+ let expected = TestHash([13997337031081104755, 6178945012502239489]);
+
+ assert_eq!(expected, h.finish());
+}
+
+#[test]
+fn test_hash_usize() {
+ // Test that usize specifically is handled consistently across platforms.
+ let test_usize = 0xABCDEF01_usize;
+
+ let mut h = StableSipHasher128::new();
+ test_usize.hash(&mut h);
+
+ // This depends on the hashing algorithm. See note at top of file.
+ let expected = TestHash([12037165114281468837, 3094087741167521712]);
+
+ assert_eq!(expected, h.finish());
+}
+
+#[test]
+fn test_hash_isize() {
+ // Test that isize specifically is handled consistently across platforms.
+ let test_isize = -7_isize;
+
+ let mut h = StableSipHasher128::new();
+ test_isize.hash(&mut h);
+
+ // This depends on the hashing algorithm. See note at top of file.
+ let expected = TestHash([3979067582695659080, 2322428596355037273]);
+
+ assert_eq!(expected, h.finish());
+}
+
+fn hash<T: Hash>(t: &T) -> TestHash {
+ let mut h = StableSipHasher128::new();
+ t.hash(&mut h);
+ h.finish()
+}
+
+// Check that the `isize` hashing optimization does not produce the same hash when permuting two
+// values.
+#[test]
+fn test_isize_compression() {
+ fn check_hash(a: u64, b: u64) {
+ let hash_a = hash(&(a as isize, b as isize));
+ let hash_b = hash(&(b as isize, a as isize));
+ assert_ne!(
+ hash_a, hash_b,
+ "The hash stayed the same when permuting values `{a}` and `{b}`!",
+ );
+ }
+
+ check_hash(0xAA, 0xAAAA);
+ check_hash(0xFF, 0xFFFF);
+ check_hash(0xAAAA, 0xAAAAAA);
+ check_hash(0xAAAAAA, 0xAAAAAAAA);
+ check_hash(0xFF, 0xFFFFFFFFFFFFFFFF);
+ check_hash(u64::MAX /* -1 */, 1);
+}
+
+#[test]
+fn test_cloned_hasher_output() {
+ // Test that integers are handled consistently across platforms.
+ let test_u8 = 0xAB_u8;
+ let test_u16 = 0xFFEE_u16;
+ let test_u32 = 0x445577AA_u32;
+
+ let mut h1 = StableSipHasher128::new();
+ test_u8.hash(&mut h1);
+ test_u16.hash(&mut h1);
+
+ let h2 = h1.clone();
+ let mut h3 = h1.clone();
+ // Make sure the cloned hasher can be fed more values.
+ test_u32.hash(&mut h3);
+
+ let h1_hash: TestHash = h1.finish();
+ assert_eq!(h1_hash, h2.finish());
+ assert_ne!(h1_hash, h3.finish());
+}
+
+#[test]
+fn test_hash_trait_finish() {
+ fn hash<H: Hasher>(h: &H) -> u64 {
+ h.finish()
+ }
+
+ // Test that integers are handled consistently across platforms.
+ let test_u8 = 0xAB_u8;
+ let test_u16 = 0xFFEE_u16;
+ let test_u32 = 0x445577AA_u32;
+
+ let mut h1 = StableSipHasher128::new();
+ test_u8.hash(&mut h1);
+ test_u16.hash(&mut h1);
+ test_u32.hash(&mut h1);
+
+ assert_eq!(hash(&h1), hash(&h1));
+ assert_eq!(hash(&h1), 13655241286414701638);
+}
diff --git a/pseudo_crate/Cargo.lock b/pseudo_crate/Cargo.lock
index f8b10a1..b540bb6 100644
--- a/pseudo_crate/Cargo.lock
+++ b/pseudo_crate/Cargo.lock
@@ -404,6 +404,7 @@
"rustc-demangle",
"rustc-demangle-capi",
"rustc-hash 2.1.1",
+ "rustc-stable-hash",
"rustix",
"rustversion",
"ryu",
@@ -5448,6 +5449,12 @@
checksum = "357703d41365b4b27c590e3ed91eabb1b663f07c4c084095e60cbed4362dff0d"
[[package]]
+name = "rustc-stable-hash"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "781442f29170c5c93b7185ad559492601acdc71d5bb0706f5868094f45cfcd08"
+
+[[package]]
name = "rustc_version"
version = "0.4.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/pseudo_crate/Cargo.toml b/pseudo_crate/Cargo.toml
index 8c41d73..c91e6ba 100644
--- a/pseudo_crate/Cargo.toml
+++ b/pseudo_crate/Cargo.toml
@@ -314,6 +314,7 @@
rustc-demangle = "=0.1.24"
rustc-demangle-capi = "=0.1.0"
rustc-hash = "=2.1.1"
+rustc-stable-hash = "=0.1.2"
rustix = "=0.38.31"
rustversion = "=1.0.20"
ryu = "=1.0.20"
diff --git a/pseudo_crate/crate-list.txt b/pseudo_crate/crate-list.txt
index 5b62edb..5790334 100644
--- a/pseudo_crate/crate-list.txt
+++ b/pseudo_crate/crate-list.txt
@@ -308,6 +308,7 @@
rustc-demangle
rustc-demangle-capi
rustc-hash
+rustc-stable-hash
rustix
rustversion
ryu
