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Auto merge of #106976 - tmiasko:borrowck-lazy-dominators, r=cjgillot

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Lazy dominator tree construction in borrowck

Motivated by the observation that sometimes constructed dominator tree was never queried.
This commit is contained in:
bors
2023-01-21 11:02:29 +00:00
parent b22aa57fd5 7fe68571fa
commit 21f6839352
3 changed files with 12 additions and 12 deletions
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16
compiler/rustc_borrowck/src/lib.rs
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@@ -5,6 +5,7 @@
#![feature(let_chains)]
#![feature(min_specialization)]
#![feature(never_type)]
#![feature(once_cell)]
#![feature(rustc_attrs)]
#![feature(stmt_expr_attributes)]
#![feature(trusted_step)]
@@ -39,6 +40,7 @@ use rustc_span::{Span, Symbol};
use either::Either;
use smallvec::SmallVec;
use std::cell::OnceCell;
use std::cell::RefCell;
use std::collections::BTreeMap;
use std::rc::Rc;
@@ -333,7 +335,7 @@ fn do_mir_borrowck<'tcx>(
used_mut: Default::default(),
used_mut_upvars: SmallVec::new(),
borrow_set: Rc::clone(&borrow_set),
dominators: Dominators::dummy(), // not used
dominators: Default::default(),
upvars: Vec::new(),
local_names: IndexVec::from_elem(None, &promoted_body.local_decls),
region_names: RefCell::default(),
@@ -346,8 +348,6 @@ fn do_mir_borrowck<'tcx>(
};
}
let dominators = body.basic_blocks.dominators();
let mut mbcx = MirBorrowckCtxt {
infcx,
param_env,
@@ -364,7 +364,7 @@ fn do_mir_borrowck<'tcx>(
used_mut: Default::default(),
used_mut_upvars: SmallVec::new(),
borrow_set: Rc::clone(&borrow_set),
dominators,
dominators: Default::default(),
upvars,
local_names,
region_names: RefCell::default(),
@@ -534,7 +534,7 @@ struct MirBorrowckCtxt<'cx, 'tcx> {
borrow_set: Rc<BorrowSet<'tcx>>,
/// Dominators for MIR
dominators: Dominators<BasicBlock>,
dominators: OnceCell<Dominators<BasicBlock>>,
/// Information about upvars not necessarily preserved in types or MIR
upvars: Vec<Upvar<'tcx>>,
@@ -1051,7 +1051,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
(Read(kind), BorrowKind::Unique | BorrowKind::Mut { .. }) => {
// Reading from mere reservations of mutable-borrows is OK.
if !is_active(&this.dominators, borrow, location) {
if !is_active(this.dominators(), borrow, location) {
assert!(allow_two_phase_borrow(borrow.kind));
return Control::Continue;
}
@@ -2219,6 +2219,10 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
fn is_upvar_field_projection(&self, place_ref: PlaceRef<'tcx>) -> Option<Field> {
path_utils::is_upvar_field_projection(self.infcx.tcx, &self.upvars, place_ref, self.body())
}
fn dominators(&self) -> &Dominators<BasicBlock> {
self.dominators.get_or_init(|| self.body.basic_blocks.dominators())
}
}
mod error {