bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Auto merge of #99232 - lcnr:no-bound-vars-check, r=jackh726

Browse source 
`replace_bound_vars` fast path: check predicates, don't check consts

split out from #98900

`ty::Const` doesn't have precomputed type flags, so
computing `has_vars_bound_at_or_above` for constants
requires us to visit the const and its contained types
and constants. A noop fold should be pretty much equally as
fast so removing it prevents us from walking the constant twice
in case it contains bound vars.

r? `@jackh726`
This commit is contained in:
bors 2022-07-18 13:59:05 +00:00
commit 144227dae9
2 changed files with 10 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

7
compiler/rustc_middle/src/ty/fold.rs
View file

@ -445,10 +445,13 @@ impl<'a, 'tcx> TypeFolder<'tcx> for BoundVarReplacer<'a, 'tcx> {
let ct = (self.fld_c)(bound_const, ct.ty()); let ct = (self.fld_c)(bound_const, ct.ty());
ty::fold::shift_vars(self.tcx, ct, self.current_index.as_u32()) ty::fold::shift_vars(self.tcx, ct, self.current_index.as_u32())
} }
_ if ct.has_vars_bound_at_or_above(self.current_index) => ct.super_fold_with(self), _ => ct.super_fold_with(self),
_ => ct,
} }
} }
fn fold_predicate(&mut self, p: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
if p.has_vars_bound_at_or_above(self.current_index) { p.super_fold_with(self) } else { p }
}
} }
impl<'tcx> TyCtxt<'tcx> { impl<'tcx> TyCtxt<'tcx> {

7
compiler/rustc_trait_selection/src/traits/project.rs
View file

@ -753,10 +753,13 @@ impl<'tcx> TypeFolder<'tcx> for BoundVarReplacer<'_, 'tcx> {
.tcx .tcx
.mk_const(ty::ConstS { kind: ty::ConstKind::Placeholder(p), ty: ct.ty() }) .mk_const(ty::ConstS { kind: ty::ConstKind::Placeholder(p), ty: ct.ty() })
} }
_ if ct.has_vars_bound_at_or_above(self.current_index) => ct.super_fold_with(self), _ => ct.super_fold_with(self),
_ => ct,
} }
} }
fn fold_predicate(&mut self, p: ty::Predicate<'tcx>) -> ty::Predicate<'tcx> {
if p.has_vars_bound_at_or_above(self.current_index) { p.super_fold_with(self) } else { p }
}
} }
// The inverse of `BoundVarReplacer`: replaces placeholders with the bound vars from which they came. // The inverse of `BoundVarReplacer`: replaces placeholders with the bound vars from which they came.