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[PERF EXPERIMENTS] Hashmap experiment #120151

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[PERF EXPERIMENTS] Hashmap experiment #120151

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f8cb67c
hashmap experiment
Noratrieb Jan 19, 2024
7836b3b
try ahash for interners
Noratrieb Jan 20, 2024
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14 changes: 8 additions & 6 deletions Cargo.lock
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Original file line number Diff line number Diff line change
Expand Up @@ -37,11 +37,12 @@ dependencies = [

[[package]]
name = "ahash"
version = "0.8.6"
version = "0.8.7"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "91429305e9f0a25f6205c5b8e0d2db09e0708a7a6df0f42212bb56c32c8ac97a"
checksum = "77c3a9648d43b9cd48db467b3f87fdd6e146bcc88ab0180006cef2179fe11d01"
dependencies = [
"cfg-if",
"getrandom",
"once_cell",
"version_check",
"zerocopy",
Expand Down Expand Up @@ -3663,6 +3664,7 @@ dependencies = [
name = "rustc_data_structures"
version = "0.0.0"
dependencies = [
"ahash",
"arrayvec",
"bitflags 2.4.1",
"elsa",
Expand Down Expand Up @@ -6373,18 +6375,18 @@ dependencies = [

[[package]]
name = "zerocopy"
version = "0.7.28"
version = "0.7.32"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "7d6f15f7ade05d2a4935e34a457b936c23dc70a05cc1d97133dc99e7a3fe0f0e"
checksum = "74d4d3961e53fa4c9a25a8637fc2bfaf2595b3d3ae34875568a5cf64787716be"
dependencies = [
"zerocopy-derive",
]

[[package]]
name = "zerocopy-derive"
version = "0.7.28"
version = "0.7.32"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "dbbad221e3f78500350ecbd7dfa4e63ef945c05f4c61cb7f4d3f84cd0bba649b"
checksum = "9ce1b18ccd8e73a9321186f97e46f9f04b778851177567b1975109d26a08d2a6"
dependencies = [
"proc-macro2",
"quote",
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_data_structures/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ version = "0.0.0"
edition = "2021"

[dependencies]
ahash = "0.8.7"
# tidy-alphabetical-start
arrayvec = { version = "0.7", default-features = false }
bitflags = "2.4.1"
Expand Down
7 changes: 3 additions & 4 deletions compiler/rustc_data_structures/src/sharded.rs
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Original file line number Diff line number Diff line change
@@ -1,12 +1,11 @@
use crate::fx::{FxHashMap, FxHasher};
#[cfg(parallel_compiler)]
use crate::sync::{is_dyn_thread_safe, CacheAligned};
use crate::sync::{Lock, LockGuard, Mode};
#[cfg(parallel_compiler)]
use itertools::Either;
use std::borrow::Borrow;
use std::collections::hash_map::RawEntryMut;
use std::hash::{Hash, Hasher};
use std::hash::{Hash, Hasher, BuildHasherDefault};
use std::iter;
use std::mem;

Expand Down Expand Up @@ -158,7 +157,7 @@ pub fn shards() -> usize {
1
}

pub type ShardedHashMap<K, V> = Sharded<FxHashMap<K, V>>;
pub type ShardedHashMap<K, V> = Sharded<ahash::AHashMap<K, V, BuildHasherDefault<ahash::AHasher>>>;

impl<K: Eq, V> ShardedHashMap<K, V> {
pub fn len(&self) -> usize {
Expand Down Expand Up @@ -224,7 +223,7 @@ impl<K: Eq + Hash + Copy + IntoPointer> ShardedHashMap<K, ()> {

#[inline]
pub fn make_hash<K: Hash + ?Sized>(val: &K) -> u64 {
let mut state = FxHasher::default();
let mut state = ahash::AHasher::default();
val.hash(&mut state);
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@bjorn3 bjorn3 Jan 20, 2024 •
edited
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Ahash doesn't guarantee determinism of the hash between platforms and versions. This will likely lead to build artifacts that can't be reproduced unless rustc runs on the exact same architecture and likely lead to diagnostics changing between targets. The latter is something we should fix with more sorting anyway, but the former isn't easily avoidable I think.

state.finish()
}
Expand Down
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