diff options
4 files changed, 61 insertions, 12 deletions
diff --git a/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs index 16806fdba4f..b3dd3031db2 100644 --- a/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs +++ b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_build.rs @@ -304,8 +304,8 @@ impl<'a, 'tcx> Visitor<'tcx> for DropRangeVisitor<'a, 'tcx> { let mut reinit = None; match expr.kind { ExprKind::Assign(lhs, rhs, _) => { - self.visit_expr(lhs); self.visit_expr(rhs); + self.visit_expr(lhs); reinit = Some(lhs); } @@ -433,7 +433,7 @@ impl<'a, 'tcx> Visitor<'tcx> for DropRangeVisitor<'a, 'tcx> { self.drop_ranges.add_control_edge(self.expr_index, *target) }), - ExprKind::Break(destination, ..) => { + ExprKind::Break(destination, value) => { // destination either points to an expression or to a block. We use // find_target_expression_from_destination to use the last expression of the block // if destination points to a block. @@ -443,7 +443,11 @@ impl<'a, 'tcx> Visitor<'tcx> for DropRangeVisitor<'a, 'tcx> { // will refer to the end of the block due to the post order traversal. self.find_target_expression_from_destination(destination).map_or((), |target| { self.drop_ranges.add_control_edge_hir_id(self.expr_index, target) - }) + }); + + if let Some(value) = value { + self.visit_expr(value); + } } ExprKind::Call(f, args) => { @@ -465,6 +469,12 @@ impl<'a, 'tcx> Visitor<'tcx> for DropRangeVisitor<'a, 'tcx> { ExprKind::AddrOf(..) | ExprKind::Array(..) + // FIXME(eholk): We probably need special handling for AssignOps. The ScopeTree builder + // in region.rs runs both lhs then rhs and rhs then lhs and then sets all yields to be + // the latest they show up in either traversal. With the older scope-based + // approximation, this was fine, but it's probably not right now. What we probably want + // to do instead is still run both orders, but consider anything that showed up as a + // yield in either order. | ExprKind::AssignOp(..) | ExprKind::Binary(..) | ExprKind::Block(..) @@ -502,6 +512,9 @@ impl<'a, 'tcx> Visitor<'tcx> for DropRangeVisitor<'a, 'tcx> { // Increment expr_count here to match what InteriorVisitor expects. self.expr_index = self.expr_index + 1; + + // Save a node mapping to get better CFG visualization + self.drop_ranges.add_node_mapping(pat.hir_id, self.expr_index); } } @@ -521,7 +534,7 @@ impl DropRangesBuilder { } }); } - debug!("hir_id_map: {:?}", tracked_value_map); + debug!("hir_id_map: {:#?}", tracked_value_map); let num_values = tracked_value_map.len(); Self { tracked_value_map, diff --git a/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_visualize.rs b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_visualize.rs index c0a0bfe8e1c..e8d31be79d9 100644 --- a/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_visualize.rs +++ b/compiler/rustc_hir_typeck/src/generator_interior/drop_ranges/cfg_visualize.rs @@ -2,6 +2,7 @@ //! flow graph when needed for debugging. use rustc_graphviz as dot; +use rustc_hir::{Expr, ExprKind, Node}; use rustc_middle::ty::TyCtxt; use super::{DropRangesBuilder, PostOrderId}; @@ -80,10 +81,14 @@ impl<'a> dot::Labeller<'a> for DropRangesGraph<'_, '_> { .post_order_map .iter() .find(|(_hir_id, &post_order_id)| post_order_id == *n) - .map_or("<unknown>".into(), |(hir_id, _)| self - .tcx - .hir() - .node_to_string(*hir_id)) + .map_or("<unknown>".into(), |(hir_id, _)| format!( + "{}{}", + self.tcx.hir().node_to_string(*hir_id), + match self.tcx.hir().find(*hir_id) { + Some(Node::Expr(Expr { kind: ExprKind::Yield(..), .. })) => " (yield)", + _ => "", + } + )) ) .into(), ) diff --git a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs index 7990d95310b..7af52605385 100644 --- a/compiler/rustc_hir_typeck/src/generator_interior/mod.rs +++ b/compiler/rustc_hir_typeck/src/generator_interior/mod.rs @@ -71,10 +71,8 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> { yield_data.expr_and_pat_count, self.expr_count, source_span ); - if self.fcx.sess().opts.unstable_opts.drop_tracking - && self - .drop_ranges - .is_dropped_at(hir_id, yield_data.expr_and_pat_count) + if self + .is_dropped_at_yield_location(hir_id, yield_data.expr_and_pat_count) { debug!("value is dropped at yield point; not recording"); return false; @@ -173,6 +171,18 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> { } } } + + /// If drop tracking is enabled, consult drop_ranges to see if a value is + /// known to be dropped at a yield point and therefore can be omitted from + /// the generator witness. + fn is_dropped_at_yield_location(&self, value_hir_id: HirId, yield_location: usize) -> bool { + // short-circuit if drop tracking is not enabled. + if !self.fcx.sess().opts.unstable_opts.drop_tracking { + return false; + } + + self.drop_ranges.is_dropped_at(value_hir_id, yield_location) + } } pub fn resolve_interior<'a, 'tcx>( diff --git a/tests/ui/async-await/await-sequence.rs b/tests/ui/async-await/await-sequence.rs new file mode 100644 index 00000000000..726c4284ec1 --- /dev/null +++ b/tests/ui/async-await/await-sequence.rs @@ -0,0 +1,21 @@ +// edition:2021 +// compile-flags: -Z drop-tracking +// build-pass + +use std::collections::HashMap; + +fn main() { + let _ = real_main(); +} + +async fn nop() {} + +async fn real_main() { + nop().await; + nop().await; + nop().await; + nop().await; + + let mut map: HashMap<(), ()> = HashMap::new(); + map.insert((), nop().await); +} |