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Simplify ObligationCauseData hash to skip ObligationCauseCode

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selection deduplicates obligations through a hashset at some point, computing the hashes for ObligationCauseCode
appears to dominate the hashing cost. bodyid + span + discriminant hash hopefully will sufficiently unique
unique enough.
This commit is contained in:
The8472 2021-11-14 23:49:57 +01:00
parent ad44239975
commit 78b5f2d2fa
1 changed files with 10 additions and 1 deletions
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11
compiler/rustc_middle/src/traits/mod.rs
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@ -23,6 +23,7 @@ use smallvec::SmallVec;
use std::borrow::Cow;
use std::fmt;
use std::hash::{Hash, Hasher};
use std::ops::Deref;
pub use self::select::{EvaluationCache, EvaluationResult, OverflowError, SelectionCache};
@ -108,7 +109,7 @@ impl Deref for ObligationCause<'tcx> {
}
}
#[derive(Clone, Debug, PartialEq, Eq, Hash, Lift)]
#[derive(Clone, Debug, PartialEq, Eq, Lift)]
pub struct ObligationCauseData<'tcx> {
pub span: Span,
@ -123,6 +124,14 @@ pub struct ObligationCauseData<'tcx> {
pub code: ObligationCauseCode<'tcx>,
}
impl Hash for ObligationCauseData<'_> {
fn hash<H: Hasher>(&self, state: &mut H) {
self.body_id.hash(state);
self.span.hash(state);
std::mem::discriminant(&self.code).hash(state);
}
}
impl<'tcx> ObligationCause<'tcx> {
#[inline]
pub fn new(