Refactor drop_ranges
Splits drop_ranges into drop_ranges::record_consumed_borrow, drop_ranges::cfg_build, and drop_ranges::cfg_propagate. The top level drop_ranges module has an entry point that does all the coordination of the other three phases, using code original in generator_interior.
This commit is contained in:
Eric Holk
parent
30e1b1e92e
commit
f5f98d7ee4
6 changed files with 455 additions and 410 deletions
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@ -3,9 +3,8 @@
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//! is calculated in `rustc_const_eval::transform::generator` and may be a subset of the
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//! is calculated in `rustc_const_eval::transform::generator` and may be a subset of the
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//! types computed here.
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//! types computed here.
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use self::drop_ranges::{DropRangeVisitor, DropRanges, ExprUseDelegate};
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use self::drop_ranges::DropRanges;
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use super::FnCtxt;
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use super::FnCtxt;
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use crate::expr_use_visitor::ExprUseVisitor;
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use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
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use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
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use rustc_errors::pluralize;
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use rustc_errors::pluralize;
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use rustc_hir as hir;
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use rustc_hir as hir;
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@ -187,42 +186,17 @@ pub fn resolve_interior<'a, 'tcx>(
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kind: hir::GeneratorKind,
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kind: hir::GeneratorKind,
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) {
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) {
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let body = fcx.tcx.hir().body(body_id);
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let body = fcx.tcx.hir().body(body_id);
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let mut visitor = InteriorVisitor {
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let mut visitor = {
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let mut expr_use_visitor = ExprUseDelegate::new(fcx.tcx.hir());
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// Run ExprUseVisitor to find where values are consumed.
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ExprUseVisitor::new(
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&mut expr_use_visitor,
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&fcx.infcx,
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def_id.expect_local(),
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fcx.param_env,
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&fcx.typeck_results.borrow(),
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)
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.consume_body(body);
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let region_scope_tree = fcx.tcx.region_scope_tree(def_id);
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let mut drop_range_visitor = DropRangeVisitor::from_uses(
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expr_use_visitor,
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region_scope_tree.body_expr_count(body.id()).unwrap_or(0),
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);
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intravisit::walk_body(&mut drop_range_visitor, body);
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let mut drop_ranges = drop_range_visitor.into_drop_ranges();
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drop_ranges.propagate_to_fixpoint();
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InteriorVisitor {
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fcx,
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fcx,
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types: FxIndexSet::default(),
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types: FxIndexSet::default(),
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region_scope_tree,
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region_scope_tree: fcx.tcx.region_scope_tree(def_id),
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expr_count: 0,
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expr_count: 0,
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kind,
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kind,
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prev_unresolved_span: None,
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prev_unresolved_span: None,
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guard_bindings: <_>::default(),
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guard_bindings: <_>::default(),
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guard_bindings_set: <_>::default(),
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guard_bindings_set: <_>::default(),
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linted_values: <_>::default(),
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linted_values: <_>::default(),
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drop_ranges: drop_ranges,
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drop_ranges: drop_ranges::compute_drop_ranges(fcx, def_id, body),
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}
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};
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};
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intravisit::walk_body(&mut visitor, body);
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intravisit::walk_body(&mut visitor, body);
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@ -12,180 +12,42 @@
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//! The end result is a data structure that maps the post-order index of each node in the HIR tree
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//! The end result is a data structure that maps the post-order index of each node in the HIR tree
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//! to a set of values that are known to be dropped at that location.
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//! to a set of values that are known to be dropped at that location.
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use std::collections::BTreeMap;
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use self::cfg_build::DropRangeVisitor;
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use std::fmt::Debug;
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use self::record_consumed_borrow::ExprUseDelegate;
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use std::mem::swap;
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use crate::check::FnCtxt;
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use hir::def_id::DefId;
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use hir::intravisit::{self, NestedVisitorMap, Visitor};
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use hir::{Body, HirId, HirIdMap, Node, intravisit};
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use hir::{Expr, ExprKind, Guard, HirId, HirIdMap, HirIdSet, Node};
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use rustc_graphviz as dot;
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use rustc_hir as hir;
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use rustc_hir as hir;
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use rustc_index::bit_set::BitSet;
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use rustc_index::bit_set::BitSet;
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use rustc_index::vec::IndexVec;
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use rustc_index::vec::IndexVec;
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use rustc_middle::hir::map::Map;
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use rustc_middle::hir::map::Map;
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use rustc_middle::hir::place::{Place, PlaceBase};
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use std::collections::BTreeMap;
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use rustc_middle::ty;
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use std::fmt::Debug;
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use std::mem::swap;
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use crate::expr_use_visitor;
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mod cfg_build;
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mod record_consumed_borrow;
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mod cfg_propagate;
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mod cfg_visualize;
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/// Works with ExprUseVisitor to find interesting values for the drop range analysis.
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pub fn compute_drop_ranges<'a, 'tcx>(
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///
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fcx: &'a FnCtxt<'a, 'tcx>,
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/// Interesting values are those that are either dropped or borrowed. For dropped values, we also
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def_id: DefId,
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/// record the parent expression, which is the point where the drop actually takes place.
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body: &'tcx Body<'tcx>,
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pub struct ExprUseDelegate<'tcx> {
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) -> DropRanges {
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hir: Map<'tcx>,
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let mut expr_use_visitor = ExprUseDelegate::new(fcx.tcx.hir());
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/// Records the variables/expressions that are dropped by a given expression.
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expr_use_visitor.consume_body(fcx, def_id, body);
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///
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/// The key is the hir-id of the expression, and the value is a set or hir-ids for variables
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/// or values that are consumed by that expression.
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///
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/// Note that this set excludes "partial drops" -- for example, a statement like `drop(x.y)` is
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/// not considered a drop of `x`, although it would be a drop of `x.y`.
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consumed_places: HirIdMap<HirIdSet>,
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/// A set of hir-ids of values or variables that are borrowed at some point within the body.
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borrowed_places: HirIdSet,
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}
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impl<'tcx> ExprUseDelegate<'tcx> {
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let mut drop_range_visitor = DropRangeVisitor::from_uses(
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pub fn new(hir: Map<'tcx>) -> Self {
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expr_use_visitor,
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Self { hir, consumed_places: <_>::default(), borrowed_places: <_>::default() }
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fcx.tcx.region_scope_tree(def_id).body_expr_count(body.id()).unwrap_or(0),
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}
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fn mark_consumed(&mut self, consumer: HirId, target: HirId) {
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if !self.consumed_places.contains_key(&consumer) {
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self.consumed_places.insert(consumer, <_>::default());
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}
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self.consumed_places.get_mut(&consumer).map(|places| places.insert(target));
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}
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}
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impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> {
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fn consume(
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&mut self,
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place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
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diag_expr_id: hir::HirId,
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) {
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let parent = match self.hir.find_parent_node(place_with_id.hir_id) {
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Some(parent) => parent,
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None => place_with_id.hir_id,
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};
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debug!(
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"consume {:?}; diag_expr_id={:?}, using parent {:?}",
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place_with_id, diag_expr_id, parent
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);
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);
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self.mark_consumed(parent, place_with_id.hir_id);
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intravisit::walk_body(&mut drop_range_visitor, body);
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place_hir_id(&place_with_id.place).map(|place| self.mark_consumed(parent, place));
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}
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fn borrow(
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let mut drop_ranges = drop_range_visitor.into_drop_ranges();
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&mut self,
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drop_ranges.propagate_to_fixpoint();
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place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
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_diag_expr_id: hir::HirId,
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_bk: rustc_middle::ty::BorrowKind,
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) {
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place_hir_id(&place_with_id.place).map(|place| self.borrowed_places.insert(place));
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}
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fn mutate(
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drop_ranges
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&mut self,
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_assignee_place: &expr_use_visitor::PlaceWithHirId<'tcx>,
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_diag_expr_id: hir::HirId,
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) {
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}
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fn fake_read(
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&mut self,
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_place: expr_use_visitor::Place<'tcx>,
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_cause: rustc_middle::mir::FakeReadCause,
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_diag_expr_id: hir::HirId,
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) {
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}
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}
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/// Gives the hir_id associated with a place if one exists. This is the hir_id that we want to
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/// track for a value in the drop range analysis.
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fn place_hir_id(place: &Place<'_>) -> Option<HirId> {
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match place.base {
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PlaceBase::Rvalue | PlaceBase::StaticItem => None,
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PlaceBase::Local(hir_id)
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| PlaceBase::Upvar(ty::UpvarId { var_path: ty::UpvarPath { hir_id }, .. }) => Some(hir_id),
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}
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}
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/// This struct is used to gather the information for `DropRanges` to determine the regions of the
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/// HIR tree for which a value is dropped.
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///
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/// We are interested in points where a variables is dropped or initialized, and the control flow
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/// of the code. We identify locations in code by their post-order traversal index, so it is
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/// important for this traversal to match that in `RegionResolutionVisitor` and `InteriorVisitor`.
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pub struct DropRangeVisitor<'tcx> {
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hir: Map<'tcx>,
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/// Maps a HirId to a set of HirIds that are dropped by that node.
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///
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/// See also the more detailed comment on `ExprUseDelegate.consumed_places`.
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consumed_places: HirIdMap<HirIdSet>,
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borrowed_places: HirIdSet,
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drop_ranges: DropRanges,
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expr_count: usize,
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}
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impl<'tcx> DropRangeVisitor<'tcx> {
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pub fn from_uses(uses: ExprUseDelegate<'tcx>, num_exprs: usize) -> Self {
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debug!("consumed_places: {:?}", uses.consumed_places);
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let drop_ranges = DropRanges::new(
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uses.consumed_places.iter().flat_map(|(_, places)| places.iter().copied()),
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&uses.hir,
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num_exprs,
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);
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Self {
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hir: uses.hir,
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consumed_places: uses.consumed_places,
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borrowed_places: uses.borrowed_places,
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drop_ranges,
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expr_count: 0,
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}
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}
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pub fn into_drop_ranges(self) -> DropRanges {
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self.drop_ranges
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}
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fn record_drop(&mut self, hir_id: HirId) {
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if self.borrowed_places.contains(&hir_id) {
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debug!("not marking {:?} as dropped because it is borrowed at some point", hir_id);
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} else {
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debug!("marking {:?} as dropped at {}", hir_id, self.expr_count);
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let count = self.expr_count;
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self.drop_ranges.drop_at(hir_id, count);
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}
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}
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/// ExprUseVisitor's consume callback doesn't go deep enough for our purposes in all
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/// expressions. This method consumes a little deeper into the expression when needed.
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fn consume_expr(&mut self, expr: &hir::Expr<'_>) {
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debug!("consuming expr {:?}, count={}", expr.hir_id, self.expr_count);
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let places = self
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.consumed_places
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.get(&expr.hir_id)
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.map_or(vec![], |places| places.iter().cloned().collect());
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for place in places {
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for_each_consumable(place, self.hir.find(place), |hir_id| self.record_drop(hir_id));
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}
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}
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fn reinit_expr(&mut self, expr: &hir::Expr<'_>) {
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if let ExprKind::Path(hir::QPath::Resolved(
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_,
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hir::Path { res: hir::def::Res::Local(hir_id), .. },
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)) = expr.kind
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{
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let location = self.expr_count;
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debug!("reinitializing {:?} at {}", hir_id, location);
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self.drop_ranges.reinit_at(*hir_id, location);
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} else {
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debug!("reinitializing {:?} is not supported", expr);
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}
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}
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}
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}
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/// Applies `f` to consumable portion of a HIR node.
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/// Applies `f` to consumable portion of a HIR node.
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@ -206,92 +68,6 @@ fn for_each_consumable(place: HirId, node: Option<Node<'_>>, mut f: impl FnMut(H
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}
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}
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}
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}
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impl<'tcx> Visitor<'tcx> for DropRangeVisitor<'tcx> {
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type Map = intravisit::ErasedMap<'tcx>;
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fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
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NestedVisitorMap::None
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}
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fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
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let mut reinit = None;
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match expr.kind {
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ExprKind::If(test, if_true, if_false) => {
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self.visit_expr(test);
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let fork = self.expr_count;
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self.drop_ranges.add_control_edge(fork, self.expr_count + 1);
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self.visit_expr(if_true);
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let true_end = self.expr_count;
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self.drop_ranges.add_control_edge(fork, self.expr_count + 1);
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if let Some(if_false) = if_false {
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self.visit_expr(if_false);
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}
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self.drop_ranges.add_control_edge(true_end, self.expr_count + 1);
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}
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ExprKind::Assign(lhs, rhs, _) => {
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self.visit_expr(lhs);
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self.visit_expr(rhs);
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reinit = Some(lhs);
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}
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ExprKind::Loop(body, ..) => {
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let loop_begin = self.expr_count + 1;
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self.visit_block(body);
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self.drop_ranges.add_control_edge(self.expr_count, loop_begin);
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}
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ExprKind::Match(scrutinee, arms, ..) => {
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self.visit_expr(scrutinee);
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let fork = self.expr_count;
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let arm_end_ids = arms
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.iter()
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.map(|hir::Arm { pat, body, guard, .. }| {
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self.drop_ranges.add_control_edge(fork, self.expr_count + 1);
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self.visit_pat(pat);
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match guard {
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Some(Guard::If(expr)) => self.visit_expr(expr),
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Some(Guard::IfLet(pat, expr)) => {
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self.visit_pat(pat);
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self.visit_expr(expr);
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}
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None => (),
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}
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self.visit_expr(body);
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self.expr_count
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})
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.collect::<Vec<_>>();
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arm_end_ids.into_iter().for_each(|arm_end| {
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self.drop_ranges.add_control_edge(arm_end, self.expr_count + 1)
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});
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}
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ExprKind::Break(hir::Destination { target_id: Ok(target), .. }, ..)
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| ExprKind::Continue(hir::Destination { target_id: Ok(target), .. }, ..) => {
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self.drop_ranges.add_control_edge_hir_id(self.expr_count, target);
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}
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_ => intravisit::walk_expr(self, expr),
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}
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self.expr_count += 1;
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self.drop_ranges.add_node_mapping(expr.hir_id, self.expr_count);
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self.consume_expr(expr);
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if let Some(expr) = reinit {
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self.reinit_expr(expr);
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}
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}
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|
||||||
fn visit_pat(&mut self, pat: &'tcx hir::Pat<'tcx>) {
|
|
||||||
intravisit::walk_pat(self, pat);
|
|
||||||
|
|
||||||
// Increment expr_count here to match what InteriorVisitor expects.
|
|
||||||
self.expr_count += 1;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
rustc_index::newtype_index! {
|
rustc_index::newtype_index! {
|
||||||
pub struct PostOrderId {
|
pub struct PostOrderId {
|
||||||
DEBUG_FORMAT = "id({})",
|
DEBUG_FORMAT = "id({})",
|
||||||
|
|
@ -426,127 +202,6 @@ impl DropRanges {
|
||||||
self.node_mut(location.into()).reinits.push(value);
|
self.node_mut(location.into()).reinits.push(value);
|
||||||
}
|
}
|
||||||
|
|
||||||
pub fn propagate_to_fixpoint(&mut self) {
|
|
||||||
trace!("before fixpoint: {:#?}", self);
|
|
||||||
self.process_deferred_edges();
|
|
||||||
let preds = self.compute_predecessors();
|
|
||||||
|
|
||||||
trace!("predecessors: {:#?}", preds.iter_enumerated().collect::<BTreeMap<_, _>>());
|
|
||||||
|
|
||||||
let mut propagate = || {
|
|
||||||
let mut changed = false;
|
|
||||||
for id in self.nodes.indices() {
|
|
||||||
let old_state = self.nodes[id].drop_state.clone();
|
|
||||||
let mut new_state = if id.index() == 0 {
|
|
||||||
BitSet::new_empty(self.num_values())
|
|
||||||
} else {
|
|
||||||
// If we are not the start node and we have no predecessors, treat
|
|
||||||
// everything as dropped because there's no way to get here anyway.
|
|
||||||
BitSet::new_filled(self.num_values())
|
|
||||||
};
|
|
||||||
|
|
||||||
for pred in &preds[id] {
|
|
||||||
let state = &self.nodes[*pred].drop_state;
|
|
||||||
new_state.intersect(state);
|
|
||||||
}
|
|
||||||
|
|
||||||
for drop in &self.nodes[id].drops {
|
|
||||||
new_state.insert(*drop);
|
|
||||||
}
|
|
||||||
|
|
||||||
for reinit in &self.nodes[id].reinits {
|
|
||||||
new_state.remove(*reinit);
|
|
||||||
}
|
|
||||||
|
|
||||||
changed |= old_state != new_state;
|
|
||||||
self.nodes[id].drop_state = new_state;
|
|
||||||
}
|
|
||||||
|
|
||||||
changed
|
|
||||||
};
|
|
||||||
|
|
||||||
while propagate() {
|
|
||||||
trace!("drop_state changed, re-running propagation");
|
|
||||||
}
|
|
||||||
|
|
||||||
trace!("after fixpoint: {:#?}", self);
|
|
||||||
}
|
|
||||||
|
|
||||||
fn compute_predecessors(&self) -> IndexVec<PostOrderId, Vec<PostOrderId>> {
|
|
||||||
let mut preds = IndexVec::from_fn_n(|_| vec![], self.nodes.len());
|
|
||||||
for (id, node) in self.nodes.iter_enumerated() {
|
|
||||||
if node.successors.len() == 0 && id.index() != self.nodes.len() - 1 {
|
|
||||||
preds[id + 1].push(id);
|
|
||||||
} else {
|
|
||||||
for succ in &node.successors {
|
|
||||||
preds[*succ].push(id);
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
preds
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
impl<'a> dot::GraphWalk<'a> for DropRanges {
|
|
||||||
type Node = PostOrderId;
|
|
||||||
|
|
||||||
type Edge = (PostOrderId, PostOrderId);
|
|
||||||
|
|
||||||
fn nodes(&'a self) -> dot::Nodes<'a, Self::Node> {
|
|
||||||
self.nodes.iter_enumerated().map(|(i, _)| i).collect()
|
|
||||||
}
|
|
||||||
|
|
||||||
fn edges(&'a self) -> dot::Edges<'a, Self::Edge> {
|
|
||||||
self.nodes
|
|
||||||
.iter_enumerated()
|
|
||||||
.flat_map(|(i, node)| {
|
|
||||||
if node.successors.len() == 0 {
|
|
||||||
vec![(i, i + 1)]
|
|
||||||
} else {
|
|
||||||
node.successors.iter().map(move |&s| (i, s)).collect()
|
|
||||||
}
|
|
||||||
})
|
|
||||||
.collect()
|
|
||||||
}
|
|
||||||
|
|
||||||
fn source(&'a self, edge: &Self::Edge) -> Self::Node {
|
|
||||||
edge.0
|
|
||||||
}
|
|
||||||
|
|
||||||
fn target(&'a self, edge: &Self::Edge) -> Self::Node {
|
|
||||||
edge.1
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
impl<'a> dot::Labeller<'a> for DropRanges {
|
|
||||||
type Node = PostOrderId;
|
|
||||||
|
|
||||||
type Edge = (PostOrderId, PostOrderId);
|
|
||||||
|
|
||||||
fn graph_id(&'a self) -> dot::Id<'a> {
|
|
||||||
dot::Id::new("drop_ranges").unwrap()
|
|
||||||
}
|
|
||||||
|
|
||||||
fn node_id(&'a self, n: &Self::Node) -> dot::Id<'a> {
|
|
||||||
dot::Id::new(format!("id{}", n.index())).unwrap()
|
|
||||||
}
|
|
||||||
|
|
||||||
fn node_label(&'a self, n: &Self::Node) -> dot::LabelText<'a> {
|
|
||||||
dot::LabelText::LabelStr(
|
|
||||||
format!(
|
|
||||||
"{:?}, local_id: {}",
|
|
||||||
n,
|
|
||||||
self.post_order_map
|
|
||||||
.iter()
|
|
||||||
.find(|(_hir_id, &post_order_id)| post_order_id == n.index())
|
|
||||||
.map_or("<unknown>".into(), |(hir_id, _)| format!(
|
|
||||||
"{}",
|
|
||||||
hir_id.local_id.index()
|
|
||||||
))
|
|
||||||
)
|
|
||||||
.into(),
|
|
||||||
)
|
|
||||||
}
|
|
||||||
}
|
}
|
||||||
|
|
||||||
#[derive(Debug)]
|
#[derive(Debug)]
|
||||||
|
|
|
||||||
|
|
@ -0,0 +1,169 @@
|
||||||
|
use super::{for_each_consumable, record_consumed_borrow::ExprUseDelegate, DropRanges};
|
||||||
|
use hir::{
|
||||||
|
intravisit::{self, NestedVisitorMap, Visitor},
|
||||||
|
Expr, ExprKind, Guard, HirId, HirIdMap, HirIdSet,
|
||||||
|
};
|
||||||
|
use rustc_hir as hir;
|
||||||
|
use rustc_middle::hir::map::Map;
|
||||||
|
|
||||||
|
/// This struct is used to gather the information for `DropRanges` to determine the regions of the
|
||||||
|
/// HIR tree for which a value is dropped.
|
||||||
|
///
|
||||||
|
/// We are interested in points where a variables is dropped or initialized, and the control flow
|
||||||
|
/// of the code. We identify locations in code by their post-order traversal index, so it is
|
||||||
|
/// important for this traversal to match that in `RegionResolutionVisitor` and `InteriorVisitor`.
|
||||||
|
pub struct DropRangeVisitor<'tcx> {
|
||||||
|
hir: Map<'tcx>,
|
||||||
|
/// Maps a HirId to a set of HirIds that are dropped by that node.
|
||||||
|
///
|
||||||
|
/// See also the more detailed comment on `ExprUseDelegate.consumed_places`.
|
||||||
|
consumed_places: HirIdMap<HirIdSet>,
|
||||||
|
borrowed_places: HirIdSet,
|
||||||
|
drop_ranges: DropRanges,
|
||||||
|
expr_count: usize,
|
||||||
|
}
|
||||||
|
|
||||||
|
impl<'tcx> DropRangeVisitor<'tcx> {
|
||||||
|
pub fn from_uses(uses: ExprUseDelegate<'tcx>, num_exprs: usize) -> Self {
|
||||||
|
debug!("consumed_places: {:?}", uses.consumed_places);
|
||||||
|
let drop_ranges = DropRanges::new(
|
||||||
|
uses.consumed_places.iter().flat_map(|(_, places)| places.iter().copied()),
|
||||||
|
&uses.hir,
|
||||||
|
num_exprs,
|
||||||
|
);
|
||||||
|
Self {
|
||||||
|
hir: uses.hir,
|
||||||
|
consumed_places: uses.consumed_places,
|
||||||
|
borrowed_places: uses.borrowed_places,
|
||||||
|
drop_ranges,
|
||||||
|
expr_count: 0,
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
pub fn into_drop_ranges(self) -> DropRanges {
|
||||||
|
self.drop_ranges
|
||||||
|
}
|
||||||
|
|
||||||
|
fn record_drop(&mut self, hir_id: HirId) {
|
||||||
|
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);
|
||||||
|
let count = self.expr_count;
|
||||||
|
self.drop_ranges.drop_at(hir_id, count);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
/// ExprUseVisitor's consume callback doesn't go deep enough for our purposes in all
|
||||||
|
/// expressions. This method consumes a little deeper into the expression when needed.
|
||||||
|
fn consume_expr(&mut self, expr: &hir::Expr<'_>) {
|
||||||
|
debug!("consuming expr {:?}, count={}", expr.hir_id, self.expr_count);
|
||||||
|
let places = self
|
||||||
|
.consumed_places
|
||||||
|
.get(&expr.hir_id)
|
||||||
|
.map_or(vec![], |places| places.iter().cloned().collect());
|
||||||
|
for place in places {
|
||||||
|
for_each_consumable(place, self.hir.find(place), |hir_id| self.record_drop(hir_id));
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
fn reinit_expr(&mut self, expr: &hir::Expr<'_>) {
|
||||||
|
if let ExprKind::Path(hir::QPath::Resolved(
|
||||||
|
_,
|
||||||
|
hir::Path { res: hir::def::Res::Local(hir_id), .. },
|
||||||
|
)) = expr.kind
|
||||||
|
{
|
||||||
|
let location = self.expr_count;
|
||||||
|
debug!("reinitializing {:?} at {}", hir_id, location);
|
||||||
|
self.drop_ranges.reinit_at(*hir_id, location);
|
||||||
|
} else {
|
||||||
|
debug!("reinitializing {:?} is not supported", expr);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
impl<'tcx> Visitor<'tcx> for DropRangeVisitor<'tcx> {
|
||||||
|
type Map = intravisit::ErasedMap<'tcx>;
|
||||||
|
|
||||||
|
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
|
||||||
|
NestedVisitorMap::None
|
||||||
|
}
|
||||||
|
|
||||||
|
fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
|
||||||
|
let mut reinit = None;
|
||||||
|
match expr.kind {
|
||||||
|
ExprKind::If(test, if_true, if_false) => {
|
||||||
|
self.visit_expr(test);
|
||||||
|
|
||||||
|
let fork = self.expr_count;
|
||||||
|
|
||||||
|
self.drop_ranges.add_control_edge(fork, self.expr_count + 1);
|
||||||
|
self.visit_expr(if_true);
|
||||||
|
let true_end = self.expr_count;
|
||||||
|
|
||||||
|
self.drop_ranges.add_control_edge(fork, self.expr_count + 1);
|
||||||
|
if let Some(if_false) = if_false {
|
||||||
|
self.visit_expr(if_false);
|
||||||
|
}
|
||||||
|
|
||||||
|
self.drop_ranges.add_control_edge(true_end, self.expr_count + 1);
|
||||||
|
}
|
||||||
|
ExprKind::Assign(lhs, rhs, _) => {
|
||||||
|
self.visit_expr(lhs);
|
||||||
|
self.visit_expr(rhs);
|
||||||
|
|
||||||
|
reinit = Some(lhs);
|
||||||
|
}
|
||||||
|
ExprKind::Loop(body, ..) => {
|
||||||
|
let loop_begin = self.expr_count + 1;
|
||||||
|
self.visit_block(body);
|
||||||
|
self.drop_ranges.add_control_edge(self.expr_count, loop_begin);
|
||||||
|
}
|
||||||
|
ExprKind::Match(scrutinee, arms, ..) => {
|
||||||
|
self.visit_expr(scrutinee);
|
||||||
|
|
||||||
|
let fork = self.expr_count;
|
||||||
|
let arm_end_ids = arms
|
||||||
|
.iter()
|
||||||
|
.map(|hir::Arm { pat, body, guard, .. }| {
|
||||||
|
self.drop_ranges.add_control_edge(fork, self.expr_count + 1);
|
||||||
|
self.visit_pat(pat);
|
||||||
|
match guard {
|
||||||
|
Some(Guard::If(expr)) => self.visit_expr(expr),
|
||||||
|
Some(Guard::IfLet(pat, expr)) => {
|
||||||
|
self.visit_pat(pat);
|
||||||
|
self.visit_expr(expr);
|
||||||
|
}
|
||||||
|
None => (),
|
||||||
|
}
|
||||||
|
self.visit_expr(body);
|
||||||
|
self.expr_count
|
||||||
|
})
|
||||||
|
.collect::<Vec<_>>();
|
||||||
|
arm_end_ids.into_iter().for_each(|arm_end| {
|
||||||
|
self.drop_ranges.add_control_edge(arm_end, self.expr_count + 1)
|
||||||
|
});
|
||||||
|
}
|
||||||
|
ExprKind::Break(hir::Destination { target_id: Ok(target), .. }, ..)
|
||||||
|
| ExprKind::Continue(hir::Destination { target_id: Ok(target), .. }, ..) => {
|
||||||
|
self.drop_ranges.add_control_edge_hir_id(self.expr_count, target);
|
||||||
|
}
|
||||||
|
|
||||||
|
_ => intravisit::walk_expr(self, expr),
|
||||||
|
}
|
||||||
|
|
||||||
|
self.expr_count += 1;
|
||||||
|
self.drop_ranges.add_node_mapping(expr.hir_id, self.expr_count);
|
||||||
|
self.consume_expr(expr);
|
||||||
|
if let Some(expr) = reinit {
|
||||||
|
self.reinit_expr(expr);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
fn visit_pat(&mut self, pat: &'tcx hir::Pat<'tcx>) {
|
||||||
|
intravisit::walk_pat(self, pat);
|
||||||
|
|
||||||
|
// Increment expr_count here to match what InteriorVisitor expects.
|
||||||
|
self.expr_count += 1;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
@ -0,0 +1,67 @@
|
||||||
|
use std::collections::BTreeMap;
|
||||||
|
|
||||||
|
use rustc_index::{bit_set::BitSet, vec::IndexVec};
|
||||||
|
|
||||||
|
use super::{DropRanges, PostOrderId};
|
||||||
|
|
||||||
|
impl DropRanges {
|
||||||
|
pub fn propagate_to_fixpoint(&mut self) {
|
||||||
|
trace!("before fixpoint: {:#?}", self);
|
||||||
|
self.process_deferred_edges();
|
||||||
|
let preds = self.compute_predecessors();
|
||||||
|
|
||||||
|
trace!("predecessors: {:#?}", preds.iter_enumerated().collect::<BTreeMap<_, _>>());
|
||||||
|
|
||||||
|
let mut propagate = || {
|
||||||
|
let mut changed = false;
|
||||||
|
for id in self.nodes.indices() {
|
||||||
|
let old_state = self.nodes[id].drop_state.clone();
|
||||||
|
let mut new_state = if id.index() == 0 {
|
||||||
|
BitSet::new_empty(self.num_values())
|
||||||
|
} else {
|
||||||
|
// If we are not the start node and we have no predecessors, treat
|
||||||
|
// everything as dropped because there's no way to get here anyway.
|
||||||
|
BitSet::new_filled(self.num_values())
|
||||||
|
};
|
||||||
|
|
||||||
|
for pred in &preds[id] {
|
||||||
|
let state = &self.nodes[*pred].drop_state;
|
||||||
|
new_state.intersect(state);
|
||||||
|
}
|
||||||
|
|
||||||
|
for drop in &self.nodes[id].drops {
|
||||||
|
new_state.insert(*drop);
|
||||||
|
}
|
||||||
|
|
||||||
|
for reinit in &self.nodes[id].reinits {
|
||||||
|
new_state.remove(*reinit);
|
||||||
|
}
|
||||||
|
|
||||||
|
changed |= old_state != new_state;
|
||||||
|
self.nodes[id].drop_state = new_state;
|
||||||
|
}
|
||||||
|
|
||||||
|
changed
|
||||||
|
};
|
||||||
|
|
||||||
|
while propagate() {
|
||||||
|
trace!("drop_state changed, re-running propagation");
|
||||||
|
}
|
||||||
|
|
||||||
|
trace!("after fixpoint: {:#?}", self);
|
||||||
|
}
|
||||||
|
|
||||||
|
fn compute_predecessors(&self) -> IndexVec<PostOrderId, Vec<PostOrderId>> {
|
||||||
|
let mut preds = IndexVec::from_fn_n(|_| vec![], self.nodes.len());
|
||||||
|
for (id, node) in self.nodes.iter_enumerated() {
|
||||||
|
if node.successors.len() == 0 && id.index() != self.nodes.len() - 1 {
|
||||||
|
preds[id + 1].push(id);
|
||||||
|
} else {
|
||||||
|
for succ in &node.successors {
|
||||||
|
preds[*succ].push(id);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
preds
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
@ -0,0 +1,68 @@
|
||||||
|
//! Implementation of GraphWalk for DropRanges so we can visualize the control
|
||||||
|
//! flow graph when needed for debugging.
|
||||||
|
|
||||||
|
use rustc_graphviz as dot;
|
||||||
|
|
||||||
|
use super::{DropRanges, PostOrderId};
|
||||||
|
|
||||||
|
impl<'a> dot::GraphWalk<'a> for DropRanges {
|
||||||
|
type Node = PostOrderId;
|
||||||
|
|
||||||
|
type Edge = (PostOrderId, PostOrderId);
|
||||||
|
|
||||||
|
fn nodes(&'a self) -> dot::Nodes<'a, Self::Node> {
|
||||||
|
self.nodes.iter_enumerated().map(|(i, _)| i).collect()
|
||||||
|
}
|
||||||
|
|
||||||
|
fn edges(&'a self) -> dot::Edges<'a, Self::Edge> {
|
||||||
|
self.nodes
|
||||||
|
.iter_enumerated()
|
||||||
|
.flat_map(|(i, node)| {
|
||||||
|
if node.successors.len() == 0 {
|
||||||
|
vec![(i, i + 1)]
|
||||||
|
} else {
|
||||||
|
node.successors.iter().map(move |&s| (i, s)).collect()
|
||||||
|
}
|
||||||
|
})
|
||||||
|
.collect()
|
||||||
|
}
|
||||||
|
|
||||||
|
fn source(&'a self, edge: &Self::Edge) -> Self::Node {
|
||||||
|
edge.0
|
||||||
|
}
|
||||||
|
|
||||||
|
fn target(&'a self, edge: &Self::Edge) -> Self::Node {
|
||||||
|
edge.1
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
impl<'a> dot::Labeller<'a> for DropRanges {
|
||||||
|
type Node = PostOrderId;
|
||||||
|
|
||||||
|
type Edge = (PostOrderId, PostOrderId);
|
||||||
|
|
||||||
|
fn graph_id(&'a self) -> dot::Id<'a> {
|
||||||
|
dot::Id::new("drop_ranges").unwrap()
|
||||||
|
}
|
||||||
|
|
||||||
|
fn node_id(&'a self, n: &Self::Node) -> dot::Id<'a> {
|
||||||
|
dot::Id::new(format!("id{}", n.index())).unwrap()
|
||||||
|
}
|
||||||
|
|
||||||
|
fn node_label(&'a self, n: &Self::Node) -> dot::LabelText<'a> {
|
||||||
|
dot::LabelText::LabelStr(
|
||||||
|
format!(
|
||||||
|
"{:?}, local_id: {}",
|
||||||
|
n,
|
||||||
|
self.post_order_map
|
||||||
|
.iter()
|
||||||
|
.find(|(_hir_id, &post_order_id)| post_order_id == n.index())
|
||||||
|
.map_or("<unknown>".into(), |(hir_id, _)| format!(
|
||||||
|
"{}",
|
||||||
|
hir_id.local_id.index()
|
||||||
|
))
|
||||||
|
)
|
||||||
|
.into(),
|
||||||
|
)
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
@ -0,0 +1,112 @@
|
||||||
|
use crate::{
|
||||||
|
check::FnCtxt,
|
||||||
|
expr_use_visitor::{self, ExprUseVisitor},
|
||||||
|
};
|
||||||
|
use hir::{HirId, HirIdMap, HirIdSet, Body, def_id::DefId};
|
||||||
|
use rustc_hir as hir;
|
||||||
|
use rustc_middle::hir::{
|
||||||
|
map::Map,
|
||||||
|
place::{Place, PlaceBase},
|
||||||
|
};
|
||||||
|
use rustc_middle::ty;
|
||||||
|
|
||||||
|
/// Works with ExprUseVisitor to find interesting values for the drop range analysis.
|
||||||
|
///
|
||||||
|
/// Interesting values are those that are either dropped or borrowed. For dropped values, we also
|
||||||
|
/// record the parent expression, which is the point where the drop actually takes place.
|
||||||
|
pub struct ExprUseDelegate<'tcx> {
|
||||||
|
pub(super) hir: Map<'tcx>,
|
||||||
|
/// Records the variables/expressions that are dropped by a given expression.
|
||||||
|
///
|
||||||
|
/// The key is the hir-id of the expression, and the value is a set or hir-ids for variables
|
||||||
|
/// or values that are consumed by that expression.
|
||||||
|
///
|
||||||
|
/// Note that this set excludes "partial drops" -- for example, a statement like `drop(x.y)` is
|
||||||
|
/// not considered a drop of `x`, although it would be a drop of `x.y`.
|
||||||
|
pub(super) consumed_places: HirIdMap<HirIdSet>,
|
||||||
|
/// A set of hir-ids of values or variables that are borrowed at some point within the body.
|
||||||
|
pub(super) borrowed_places: HirIdSet,
|
||||||
|
}
|
||||||
|
|
||||||
|
impl<'tcx> ExprUseDelegate<'tcx> {
|
||||||
|
pub fn new(hir: Map<'tcx>) -> Self {
|
||||||
|
Self { hir, consumed_places: <_>::default(), borrowed_places: <_>::default() }
|
||||||
|
}
|
||||||
|
|
||||||
|
pub fn consume_body(
|
||||||
|
&mut self,
|
||||||
|
fcx: &'_ FnCtxt<'_, 'tcx>,
|
||||||
|
def_id: DefId,
|
||||||
|
body: &'tcx Body<'tcx>,
|
||||||
|
) {
|
||||||
|
// Run ExprUseVisitor to find where values are consumed.
|
||||||
|
ExprUseVisitor::new(
|
||||||
|
self,
|
||||||
|
&fcx.infcx,
|
||||||
|
def_id.expect_local(),
|
||||||
|
fcx.param_env,
|
||||||
|
&fcx.typeck_results.borrow(),
|
||||||
|
)
|
||||||
|
.consume_body(body);
|
||||||
|
}
|
||||||
|
|
||||||
|
fn mark_consumed(&mut self, consumer: HirId, target: HirId) {
|
||||||
|
if !self.consumed_places.contains_key(&consumer) {
|
||||||
|
self.consumed_places.insert(consumer, <_>::default());
|
||||||
|
}
|
||||||
|
self.consumed_places.get_mut(&consumer).map(|places| places.insert(target));
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> {
|
||||||
|
fn consume(
|
||||||
|
&mut self,
|
||||||
|
place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
|
||||||
|
diag_expr_id: HirId,
|
||||||
|
) {
|
||||||
|
let parent = match self.hir.find_parent_node(place_with_id.hir_id) {
|
||||||
|
Some(parent) => parent,
|
||||||
|
None => place_with_id.hir_id,
|
||||||
|
};
|
||||||
|
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));
|
||||||
|
}
|
||||||
|
|
||||||
|
fn borrow(
|
||||||
|
&mut self,
|
||||||
|
place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
|
||||||
|
_diag_expr_id: HirId,
|
||||||
|
_bk: rustc_middle::ty::BorrowKind,
|
||||||
|
) {
|
||||||
|
place_hir_id(&place_with_id.place).map(|place| self.borrowed_places.insert(place));
|
||||||
|
}
|
||||||
|
|
||||||
|
fn mutate(
|
||||||
|
&mut self,
|
||||||
|
_assignee_place: &expr_use_visitor::PlaceWithHirId<'tcx>,
|
||||||
|
_diag_expr_id: HirId,
|
||||||
|
) {
|
||||||
|
}
|
||||||
|
|
||||||
|
fn fake_read(
|
||||||
|
&mut self,
|
||||||
|
_place: expr_use_visitor::Place<'tcx>,
|
||||||
|
_cause: rustc_middle::mir::FakeReadCause,
|
||||||
|
_diag_expr_id: HirId,
|
||||||
|
) {
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
/// Gives the hir_id associated with a place if one exists. This is the hir_id that we want to
|
||||||
|
/// track for a value in the drop range analysis.
|
||||||
|
fn place_hir_id(place: &Place<'_>) -> Option<HirId> {
|
||||||
|
match place.base {
|
||||||
|
PlaceBase::Rvalue | PlaceBase::StaticItem => None,
|
||||||
|
PlaceBase::Local(hir_id)
|
||||||
|
| PlaceBase::Upvar(ty::UpvarId { var_path: ty::UpvarPath { hir_id }, .. }) => Some(hir_id),
|
||||||
|
}
|
||||||
|
}
|
||||||
Loading…
Add table
Add a link
Reference in a new issue