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Rollup merge of #104898 - oli-obk:group_all_the_things, r=wesleywiser

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Put all cached values into a central struct instead of just the stable hash

cc `@nnethercote`

this allows re-use of the type for Predicate without duplicating all the logic for the non-hash cached fields
This commit is contained in:
Matthias Krüger 2022-12-06 16:54:52 +01:00 • committed by GitHub
commit db416ea195
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10 changed files with 182 additions and 254 deletions
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83
compiler/rustc_data_structures/src/intern.rs
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@ -4,8 +4,6 @@ use std::hash::{Hash, Hasher};
use std::ops::Deref;
use std::ptr;
use crate::fingerprint::Fingerprint;
mod private {
#[derive(Clone, Copy, Debug)]
pub struct PrivateZst;
@ -110,86 +108,5 @@ where
}
}
/// A helper type that you can wrap round your own type in order to automatically
/// cache the stable hash on creation and not recompute it whenever the stable hash
/// of the type is computed.
/// This is only done in incremental mode. You can also opt out of caching by using
/// StableHash::ZERO for the hash, in which case the hash gets computed each time.
/// This is useful if you have values that you intern but never (can?) use for stable
/// hashing.
#[derive(Copy, Clone)]
pub struct WithStableHash<T> {
pub internee: T,
pub stable_hash: Fingerprint,
}
impl<T: PartialEq> PartialEq for WithStableHash<T> {
#[inline]
fn eq(&self, other: &Self) -> bool {
self.internee.eq(&other.internee)
}
}
impl<T: Eq> Eq for WithStableHash<T> {}
impl<T: Ord> PartialOrd for WithStableHash<T> {
fn partial_cmp(&self, other: &WithStableHash<T>) -> Option<Ordering> {
Some(self.internee.cmp(&other.internee))
}
}
impl<T: Ord> Ord for WithStableHash<T> {
fn cmp(&self, other: &WithStableHash<T>) -> Ordering {
self.internee.cmp(&other.internee)
}
}
impl<T> Deref for WithStableHash<T> {
type Target = T;
#[inline]
fn deref(&self) -> &T {
&self.internee
}
}
impl<T: Hash> Hash for WithStableHash<T> {
#[inline]
fn hash<H: Hasher>(&self, s: &mut H) {
if self.stable_hash != Fingerprint::ZERO {
self.stable_hash.hash(s)
} else {
self.internee.hash(s)
}
}
}
impl<T: HashStable<CTX>, CTX> HashStable<CTX> for WithStableHash<T> {
fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
if self.stable_hash == Fingerprint::ZERO || cfg!(debug_assertions) {
// No cached hash available. This can only mean that incremental is disabled.
// We don't cache stable hashes in non-incremental mode, because they are used
// so rarely that the performance actually suffers.
// We need to build the hash as if we cached it and then hash that hash, as
// otherwise the hashes will differ between cached and non-cached mode.
let stable_hash: Fingerprint = {
let mut hasher = StableHasher::new();
self.internee.hash_stable(hcx, &mut hasher);
hasher.finish()
};
if cfg!(debug_assertions) && self.stable_hash != Fingerprint::ZERO {
assert_eq!(
stable_hash, self.stable_hash,
"cached stable hash does not match freshly computed stable hash"
);
}
stable_hash.hash_stable(hcx, hasher);
} else {
self.stable_hash.hash_stable(hcx, hasher);
}
}
}
#[cfg(test)]
mod tests;