diff options
| -rw-r--r-- | Cargo.lock | 1 | ||||
| -rw-r--r-- | compiler/rustc_typeck/Cargo.toml | 1 | ||||
| -rw-r--r-- | compiler/rustc_typeck/src/check/generator_interior.rs | 224 | ||||
| -rw-r--r-- | src/test/ui/generator/drop-if.rs | 22 |
4 files changed, 220 insertions, 28 deletions
diff --git a/Cargo.lock b/Cargo.lock index 529e17b158f..dfe3db5907a 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -4383,6 +4383,7 @@ dependencies = [ name = "rustc_typeck" version = "0.0.0" dependencies = [ + "itertools 0.9.0", "rustc_arena", "rustc_ast", "rustc_attr", diff --git a/compiler/rustc_typeck/Cargo.toml b/compiler/rustc_typeck/Cargo.toml index 7e570e151c5..1da106d7002 100644 --- a/compiler/rustc_typeck/Cargo.toml +++ b/compiler/rustc_typeck/Cargo.toml @@ -8,6 +8,7 @@ test = false doctest = false [dependencies] +itertools = "0.9" rustc_arena = { path = "../rustc_arena" } tracing = "0.1" rustc_macros = { path = "../rustc_macros" } diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs index 92dea92a0bc..6144cbbd8dd 100644 --- a/compiler/rustc_typeck/src/check/generator_interior.rs +++ b/compiler/rustc_typeck/src/check/generator_interior.rs @@ -3,10 +3,13 @@ //! is calculated in `rustc_const_eval::transform::generator` and may be a subset of the //! types computed here. +use std::mem; + use crate::expr_use_visitor::{self, ExprUseVisitor}; use super::FnCtxt; use hir::{HirIdMap, Node}; +use itertools::Itertools; use rustc_data_structures::fx::{FxHashSet, FxIndexSet}; use rustc_errors::pluralize; use rustc_hir as hir; @@ -24,6 +27,9 @@ use rustc_span::Span; use smallvec::SmallVec; use tracing::debug; +#[cfg(test)] +mod tests; + struct InteriorVisitor<'a, 'tcx> { fcx: &'a FnCtxt<'a, 'tcx>, types: FxIndexSet<ty::GeneratorInteriorTypeCause<'tcx>>, @@ -80,7 +86,9 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> { ); match self.drop_ranges.get(&hir_id) { - Some(range) if range.contains(yield_data.expr_and_pat_count) => { + Some(range) + if range.is_dropped_at(yield_data.expr_and_pat_count) => + { debug!("value is dropped at yield point; not recording"); return false; } @@ -229,7 +237,7 @@ pub fn resolve_interior<'a, 'tcx>( hir: fcx.tcx.hir(), consumed_places: <_>::default(), borrowed_places: <_>::default(), - drop_ranges: vec![<_>::default()], + drop_ranges: <_>::default(), expr_count: 0, }; @@ -254,7 +262,7 @@ pub fn resolve_interior<'a, 'tcx>( guard_bindings: <_>::default(), guard_bindings_set: <_>::default(), linted_values: <_>::default(), - drop_ranges: drop_range_visitor.drop_ranges.pop().unwrap(), + drop_ranges: drop_range_visitor.drop_ranges, } }; intravisit::walk_body(&mut visitor, body); @@ -671,7 +679,7 @@ struct DropRangeVisitor<'tcx> { /// Maps a HirId to a set of HirIds that are dropped by that node. consumed_places: HirIdMap<HirIdSet>, borrowed_places: HirIdSet, - drop_ranges: Vec<HirIdMap<DropRange>>, + drop_ranges: HirIdMap<DropRange>, expr_count: usize, } @@ -684,28 +692,42 @@ impl DropRangeVisitor<'tcx> { } fn record_drop(&mut self, hir_id: HirId) { - let drop_ranges = self.drop_ranges.last_mut().unwrap(); + let drop_ranges = &mut self.drop_ranges; if self.borrowed_places.contains(&hir_id) { debug!("not marking {:?} as dropped because it is borrowed at some point", hir_id); } else { debug!("marking {:?} as dropped at {}", hir_id, self.expr_count); - drop_ranges.insert(hir_id, DropRange { dropped_at: self.expr_count }); + drop_ranges.insert(hir_id, DropRange::new(self.expr_count)); } } - fn push_drop_scope(&mut self) { - self.drop_ranges.push(<_>::default()); + fn swap_drop_ranges(&mut self, mut other: HirIdMap<DropRange>) -> HirIdMap<DropRange> { + mem::swap(&mut self.drop_ranges, &mut other); + other } - fn pop_and_merge_drop_scope(&mut self) { - let mut old_last = self.drop_ranges.pop().unwrap(); - let drop_ranges = self.drop_ranges.last_mut().unwrap(); - for (k, v) in old_last.drain() { - match drop_ranges.get(&k).cloned() { - Some(v2) => drop_ranges.insert(k, v.intersect(&v2)), - None => drop_ranges.insert(k, v), - }; - } + #[allow(dead_code)] + fn fork_drop_ranges(&self) -> HirIdMap<DropRange> { + self.drop_ranges.iter().map(|(k, v)| (*k, v.fork_at(self.expr_count))).collect() + } + + fn intersect_drop_ranges(&mut self, drops: HirIdMap<DropRange>) { + drops.into_iter().for_each(|(k, v)| match self.drop_ranges.get_mut(&k) { + Some(ranges) => *ranges = ranges.intersect(&v), + None => { + self.drop_ranges.insert(k, v); + } + }) + } + + #[allow(dead_code)] + fn merge_drop_ranges(&mut self, drops: HirIdMap<DropRange>) { + drops.into_iter().for_each(|(k, v)| { + if !self.drop_ranges.contains_key(&k) { + self.drop_ranges.insert(k, DropRange { events: vec![] }); + } + self.drop_ranges.get_mut(&k).unwrap().merge_with(&v, self.expr_count); + }); } /// ExprUseVisitor's consume callback doesn't go deep enough for our purposes in all @@ -751,7 +773,10 @@ impl<'tcx> expr_use_visitor::Delegate<'tcx> for DropRangeVisitor<'tcx> { Some(parent) => parent, None => place_with_id.hir_id, }; - debug!("consume {:?}; diag_expr_id={:?}, using parent {:?}", place_with_id, diag_expr_id, parent); + debug!( + "consume {:?}; diag_expr_id={:?}, using parent {:?}", + place_with_id, diag_expr_id, parent + ); self.mark_consumed(parent, place_with_id.hir_id); place_hir_id(&place_with_id.place).map(|place| self.mark_consumed(parent, place)); } @@ -800,7 +825,7 @@ impl<'tcx> Visitor<'tcx> for DropRangeVisitor<'tcx> { self.visit_expr(lhs); self.visit_expr(rhs); - self.push_drop_scope(); + let old_drops = self.swap_drop_ranges(<_>::default()); std::mem::swap(&mut old_count, &mut self.expr_count); self.visit_expr(rhs); self.visit_expr(lhs); @@ -808,7 +833,39 @@ impl<'tcx> Visitor<'tcx> for DropRangeVisitor<'tcx> { // We should have visited the same number of expressions in either order. assert_eq!(old_count, self.expr_count); - self.pop_and_merge_drop_scope(); + self.intersect_drop_ranges(old_drops); + } + ExprKind::If(test, if_true, if_false) => { + self.visit_expr(test); + + match if_false { + Some(if_false) => { + let mut true_ranges = self.fork_drop_ranges(); + let mut false_ranges = self.fork_drop_ranges(); + + true_ranges = self.swap_drop_ranges(true_ranges); + self.visit_expr(if_true); + true_ranges = self.swap_drop_ranges(true_ranges); + + false_ranges = self.swap_drop_ranges(false_ranges); + self.visit_expr(if_false); + false_ranges = self.swap_drop_ranges(false_ranges); + + self.merge_drop_ranges(true_ranges); + self.merge_drop_ranges(false_ranges); + } + None => { + let mut true_ranges = self.fork_drop_ranges(); + debug!("true branch drop range fork: {:?}", true_ranges); + true_ranges = self.swap_drop_ranges(true_ranges); + self.visit_expr(if_true); + true_ranges = self.swap_drop_ranges(true_ranges); + debug!("true branch computed drop_ranges: {:?}", true_ranges); + debug!("drop ranges before merging: {:?}", self.drop_ranges); + self.merge_drop_ranges(true_ranges); + debug!("drop ranges after merging: {:?}", self.drop_ranges); + } + } } _ => intravisit::walk_expr(self, expr), } @@ -825,20 +882,131 @@ impl<'tcx> Visitor<'tcx> for DropRangeVisitor<'tcx> { } } -#[derive(Clone)] +#[derive(Clone, Debug, PartialEq, Eq)] +enum Event { + Drop(usize), + Reinit(usize), +} + +impl Event { + fn location(&self) -> usize { + match *self { + Event::Drop(i) | Event::Reinit(i) => i, + } + } +} + +impl PartialOrd for Event { + fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> { + self.location().partial_cmp(&other.location()) + } +} + +#[derive(Clone, Debug, PartialEq, Eq)] struct DropRange { - /// The post-order id of the point where this expression is dropped. - /// - /// We can consider the value dropped at any post-order id greater than dropped_at. - dropped_at: usize, + events: Vec<Event>, } impl DropRange { + fn new(begin: usize) -> Self { + Self { events: vec![Event::Drop(begin)] } + } + fn intersect(&self, other: &Self) -> Self { - Self { dropped_at: self.dropped_at.max(other.dropped_at) } + let mut events = vec![]; + self.events + .iter() + .merge_join_by(other.events.iter(), |a, b| a.partial_cmp(b).unwrap()) + .fold((false, false), |(left, right), event| match event { + itertools::EitherOrBoth::Both(_, _) => todo!(), + itertools::EitherOrBoth::Left(e) => match e { + Event::Drop(i) => { + if !left && right { + events.push(Event::Drop(*i)); + } + (true, right) + } + Event::Reinit(i) => { + if left && !right { + events.push(Event::Reinit(*i)); + } + (false, right) + } + }, + itertools::EitherOrBoth::Right(e) => match e { + Event::Drop(i) => { + if left && !right { + events.push(Event::Drop(*i)); + } + (left, true) + } + Event::Reinit(i) => { + if !left && right { + events.push(Event::Reinit(*i)); + } + (left, false) + } + }, + }); + Self { events } + } + + fn is_dropped_at(&self, id: usize) -> bool { + match self.events.iter().try_fold(false, |is_dropped, event| { + if event.location() < id { + Ok(match event { + Event::Drop(_) => true, + Event::Reinit(_) => false, + }) + } else { + Err(is_dropped) + } + }) { + Ok(is_dropped) | Err(is_dropped) => is_dropped, + } + } + + #[allow(dead_code)] + fn drop(&mut self, location: usize) { + self.events.push(Event::Drop(location)) + } + + #[allow(dead_code)] + fn reinit(&mut self, location: usize) { + self.events.push(Event::Reinit(location)); + } + + /// Merges another range with this one. Meant to be used at control flow join points. + /// + /// After merging, the value will be dead at the end of the range only if it was dead + /// at the end of both self and other. + /// + /// Assumes that all locations in each range are less than joinpoint + #[allow(dead_code)] + fn merge_with(&mut self, other: &DropRange, join_point: usize) { + let mut events: Vec<_> = + self.events.iter().merge(other.events.iter()).dedup().cloned().collect(); + + events.push(if self.is_dropped_at(join_point) && other.is_dropped_at(join_point) { + Event::Drop(join_point) + } else { + Event::Reinit(join_point) + }); + + self.events = events; } - fn contains(&self, id: usize) -> bool { - id > self.dropped_at + /// Creates a new DropRange from this one at the split point. + /// + /// Used to model branching control flow. + #[allow(dead_code)] + fn fork_at(&self, split_point: usize) -> Self { + Self { + events: vec![if self.is_dropped_at(split_point) { + Event::Drop(split_point) + } else { + Event::Reinit(split_point) + }], + } } } diff --git a/src/test/ui/generator/drop-if.rs b/src/test/ui/generator/drop-if.rs new file mode 100644 index 00000000000..40f01f78662 --- /dev/null +++ b/src/test/ui/generator/drop-if.rs @@ -0,0 +1,22 @@ +// build-pass + +// This test case is reduced from src/test/ui/drop/dynamic-drop-async.rs + +#![feature(generators)] + +struct Ptr; +impl<'a> Drop for Ptr { + fn drop(&mut self) { + } +} + +fn main() { + let arg = true; + let _ = || { + let arr = [Ptr]; + if arg { + drop(arr); + } + yield + }; +} |