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Auto merge of #114611 - nnethercote:type-system-chess, r=compiler-errors

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Speed up compilation of `type-system-chess`

[`type-system-chess`](https://github.com/rust-lang/rustc-perf/pull/1680) is an unusual program that implements a compile-time chess position solver in the trait system(!)  This PR is about making it compile faster.

r? `@ghost`
This commit is contained in:
bors 2023-08-18 06:29:38 +00:00
commit a1e1dba9cc
2 changed files with 27 additions and 10 deletions
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24
compiler/rustc_infer/src/traits/mod.rs
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@ -9,6 +9,7 @@ mod structural_impls;
pub mod util;
use std::cmp;
use std::hash::{Hash, Hasher};
use hir::def_id::LocalDefId;
use rustc_hir as hir;
@ -36,7 +37,7 @@ pub use rustc_middle::traits::*;
/// either identifying an `impl` (e.g., `impl Eq for i32`) that
/// satisfies the obligation, or else finding a bound that is in
/// scope. The eventual result is usually a `Selection` (defined below).
#[derive(Clone, PartialEq, Eq, Hash)]
#[derive(Clone)]
pub struct Obligation<'tcx, T> {
/// The reason we have to prove this thing.
pub cause: ObligationCause<'tcx>,
@ -55,6 +56,27 @@ pub struct Obligation<'tcx, T> {
pub recursion_depth: usize,
}
impl<'tcx, T: PartialEq> PartialEq<Obligation<'tcx, T>> for Obligation<'tcx, T> {
#[inline]
fn eq(&self, other: &Obligation<'tcx, T>) -> bool {
// Ignore `cause` and `recursion_depth`. This is a small performance
// win for a few crates, and a huge performance win for the crate in
// https://github.com/rust-lang/rustc-perf/pull/1680, which greatly
// stresses the trait system.
self.param_env == other.param_env && self.predicate == other.predicate
}
}
impl<T: Eq> Eq for Obligation<'_, T> {}
impl<T: Hash> Hash for Obligation<'_, T> {
fn hash<H: Hasher>(&self, state: &mut H) -> () {
// See the comment on `Obligation::eq`.
self.param_env.hash(state);
self.predicate.hash(state);
}
}
impl<'tcx, P> From<Obligation<'tcx, P>> for solve::Goal<'tcx, P> {
fn from(value: Obligation<'tcx, P>) -> Self {
solve::Goal { param_env: value.param_env, predicate: value.predicate }