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don't uniquify regions when canonicalizing

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This commit is contained in:
lcnr 2023-04-11 10:25:49 +02:00
parent b80ee3969f
commit 171f541470
1 changed files with 11 additions and 14 deletions
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25
compiler/rustc_trait_selection/src/solve/canonicalize.rs
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@ -125,8 +125,9 @@ fn finalize(self) -> (ty::UniverseIndex, CanonicalVarInfos<'tcx>) {
// - var_infos: [E0, U1, E1, U1, E1, E6, U6], curr_compressed_uv: 1, next_orig_uv: 6
// - var_infos: [E0, U1, E1, U1, E1, E2, U2], curr_compressed_uv: 2, next_orig_uv: -
//
// This algorithm runs in `O(n²)` where `n` is the number of different universe
// indices in the input. This should be fine as `n` is expected to be small.
// This algorithm runs in `O(nm)` where `n` is the number of different universe
// indices in the input and `m` is the number of canonical variables.
// This should be fine as both `n` and `m` are expected to be small.
let mut curr_compressed_uv = ty::UniverseIndex::ROOT;
let mut existential_in_new_uv = false;
let mut next_orig_uv = Some(ty::UniverseIndex::ROOT);
@ -245,18 +246,14 @@ fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> {
ty::ReError(_) => return r,
};
let existing_bound_var = match self.canonicalize_mode {
CanonicalizeMode::Input => None,
CanonicalizeMode::Response { .. } => {
self.variables.iter().position(|&v| v == r.into()).map(ty::BoundVar::from)
}
};
let var = existing_bound_var.unwrap_or_else(|| {
let var = ty::BoundVar::from(self.variables.len());
self.variables.push(r.into());
self.primitive_var_infos.push(CanonicalVarInfo { kind });
var
});
let var = ty::BoundVar::from(
self.variables.iter().position(|&v| v == r.into()).unwrap_or_else(|| {
let var = self.variables.len();
self.variables.push(r.into());
self.primitive_var_infos.push(CanonicalVarInfo { kind });
var
}),
);
let br = ty::BoundRegion { var, kind: BrAnon(None) };
self.interner().mk_re_late_bound(self.binder_index, br)
}