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More comments and small cleanups

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This commit is contained in:
Eric Holk 2021-11-18 17:26:30 -08:00
parent b39fb9bb7b
commit 904c270149
3 changed files with 108 additions and 112 deletions
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1
compiler/rustc_passes/src/region.rs
View File

@ -255,6 +255,7 @@ fn resolve_expr<'tcx>(visitor: &mut RegionResolutionVisitor<'tcx>, expr: &'tcx h
hir::ExprKind::AssignOp(..)
| hir::ExprKind::Index(..)
| hir::ExprKind::Unary(..)
| hir::ExprKind::Call(..)
| hir::ExprKind::MethodCall(..) => {
// FIXME(https://github.com/rust-lang/rfcs/issues/811) Nested method calls
//

214
compiler/rustc_typeck/src/check/generator_interior.rs
View File

@ -182,39 +182,6 @@ fn record(
}
}
}
fn visit_call(
&mut self,
call_expr: &'tcx Expr<'tcx>,
callee: &'tcx Expr<'tcx>,
args: &'tcx [Expr<'tcx>],
) {
match &callee.kind {
ExprKind::Path(qpath) => {
let res = self.fcx.typeck_results.borrow().qpath_res(qpath, callee.hir_id);
match res {
// Direct calls never need to keep the callee `ty::FnDef`
// ZST in a temporary, so skip its type, just in case it
// can significantly complicate the generator type.
Res::Def(
DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn),
_,
) => {
// NOTE(eddyb) this assumes a path expression has
// no nested expressions to keep track of.
self.expr_count += 1;
// Record the rest of the call expression normally.
for arg in args {
self.visit_expr(arg);
}
}
_ => intravisit::walk_expr(self, call_expr),
}
}
_ => intravisit::walk_expr(self, call_expr),
}
}
}
pub fn resolve_interior<'a, 'tcx>(
@ -252,7 +219,6 @@ pub fn resolve_interior<'a, 'tcx>(
intravisit::walk_body(&mut drop_range_visitor, body);
drop_range_visitor.drop_ranges.propagate_to_fixpoint();
// drop_range_visitor.drop_ranges.save_graph("drop_ranges.dot");
InteriorVisitor {
fcx,
@ -395,7 +361,31 @@ fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
let mut guard_borrowing_from_pattern = false;
match &expr.kind {
ExprKind::Call(callee, args) => self.visit_call(expr, callee, args),
ExprKind::Call(callee, args) => match &callee.kind {
ExprKind::Path(qpath) => {
let res = self.fcx.typeck_results.borrow().qpath_res(qpath, callee.hir_id);
match res {
// Direct calls never need to keep the callee `ty::FnDef`
// ZST in a temporary, so skip its type, just in case it
// can significantly complicate the generator type.
Res::Def(
DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn),
_,
) => {
// NOTE(eddyb) this assumes a path expression has
// no nested expressions to keep track of.
self.expr_count += 1;
// Record the rest of the call expression normally.
for arg in args.iter() {
self.visit_expr(arg);
}
}
_ => intravisit::walk_expr(self, expr),
}
}
_ => intravisit::walk_expr(self, expr),
},
ExprKind::Path(qpath) => {
intravisit::walk_expr(self, expr);
let res = self.fcx.typeck_results.borrow().qpath_res(qpath, expr.hir_id);
@ -675,6 +665,26 @@ fn check_must_not_suspend_def(
false
}
// The following structs and impls are used for drop range analysis.
//
// Drop range analysis finds the portions of the tree where a value is guaranteed to be dropped
// (i.e. moved, uninitialized, etc.). This is used to exclude the types of those values from the
// generator type. See `InteriorVisitor::record` for where the results of this analysis are used.
//
// There are three phases to this analysis:
// 1. Use `ExprUseVisitor` to identify the interesting values that are consumed and borrowed.
// 2. Use `DropRangeVisitor` to find where the interesting values are dropped or reinitialized,
// and also build a control flow graph.
// 3. Use `DropRanges::propagate_to_fixpoint` to flow the dropped/reinitialized information through
// the CFG and find the exact points where we know a value is definitely dropped.
//
// The end result is a data structure that maps the post-order index of each node in the HIR tree
// to a set of values that are known to be dropped at that location.
/// 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.
struct ExprUseDelegate<'tcx> {
hir: Map<'tcx>,
/// Maps a HirId to a set of HirIds that are dropped by that node.
@ -691,7 +701,65 @@ fn mark_consumed(&mut self, consumer: HirId, target: HirId) {
}
}
/// This struct facilitates computing the ranges for which a place is uninitialized.
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: hir::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: hir::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: hir::HirId,
) {
}
fn fake_read(
&mut self,
_place: expr_use_visitor::Place<'tcx>,
_cause: rustc_middle::mir::FakeReadCause,
_diag_expr_id: hir::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),
}
}
/// 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`.
struct DropRangeVisitor<'tcx> {
hir: Map<'tcx>,
/// Maps a HirId to a set of HirIds that are dropped by that node.
@ -756,6 +824,9 @@ fn reinit_expr(&mut self, expr: &hir::Expr<'_>) {
}
}
/// Applies `f` to consumable portion of a HIR node.
///
/// The `node` parameter should be the result of calling `Map::find(place)`.
fn for_each_consumable(place: HirId, node: Option<Node<'_>>, mut f: impl FnMut(HirId)) {
f(place);
if let Some(Node::Expr(expr)) = node {
@ -771,57 +842,6 @@ fn for_each_consumable(place: HirId, node: Option<Node<'_>>, mut f: impl FnMut(H
}
}
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),
}
}
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: hir::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: hir::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: hir::HirId,
) {
}
fn fake_read(
&mut self,
_place: expr_use_visitor::Place<'tcx>,
_cause: rustc_middle::mir::FakeReadCause,
_diag_expr_id: hir::HirId,
) {
}
}
impl<'tcx> Visitor<'tcx> for DropRangeVisitor<'tcx> {
type Map = intravisit::ErasedMap<'tcx>;
@ -832,26 +852,6 @@ fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
let mut reinit = None;
match expr.kind {
// ExprKind::AssignOp(_op, lhs, rhs) => {
// // These operations are weird because their order of evaluation depends on whether
// // the operator is overloaded. In a perfect world, we'd just ask the type checker
// // whether this is a method call, but we also need to match the expression IDs
// // from RegionResolutionVisitor. RegionResolutionVisitor doesn't know the order,
// // so it runs both orders and picks the most conservative. We'll mirror that here.
// let mut old_count = self.expr_count;
// self.visit_expr(lhs);
// self.visit_expr(rhs);
// 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);
// // We should have visited the same number of expressions in either order.
// assert_eq!(old_count, self.expr_count);
// self.intersect_drop_ranges(old_drops);
// }
ExprKind::If(test, if_true, if_false) => {
self.visit_expr(test);

5
compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs
View File

@ -203,11 +203,6 @@ fn compute_predecessors(&self) -> IndexVec<PostOrderId, Vec<PostOrderId>> {
}
preds
}
// pub fn save_graph(&self, filename: &str) {
// use std::fs::File;
// dot::render(self, &mut File::create(filename).unwrap()).unwrap();
// }
}
impl<'a> dot::GraphWalk<'a> for DropRanges {