Emit line info for generator variants

src/librustc_codegen_llvm/type_of.rs

@@ -70,10 +70,10 @@ fn uncached_llvm_type<'a, 'tcx>(
                     write!(&mut name, "::{}", def.variants[index].ident).unwrap();
                 }
             }
-            if let (&ty::Generator(_, substs, _), &Variants::Single { index })
+            if let (&ty::Generator(_, _, _), &Variants::Single { index })
                  = (&layout.ty.kind, &layout.variants)
             {
-                write!(&mut name, "::{}", substs.as_generator().variant_name(index)).unwrap();
+                write!(&mut name, "::{}", ty::GeneratorSubsts::variant_name(index)).unwrap();
             }
             Some(name)
         }

src/librustc_index/bit_set.rs

@@ -700,7 +700,7 @@ impl<T: Idx> GrowableBitSet<T> {
 ///
 /// All operations that involve a row and/or column index will panic if the
 /// index exceeds the relevant bound.
-#[derive(Clone, Debug, Eq, PartialEq, RustcDecodable, RustcEncodable)]
+#[derive(Clone, Eq, PartialEq, RustcDecodable, RustcEncodable)]
 pub struct BitMatrix<R: Idx, C: Idx> {
     num_rows: usize,
     num_columns: usize,
@@ -876,6 +876,22 @@ impl<R: Idx, C: Idx> BitMatrix<R, C> {
     }
 }
 
+impl<R: Idx, C: Idx> fmt::Debug for BitMatrix<R, C> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        /// Forces its contents to print in regular mode instead of alternate mode.
+        struct OneLinePrinter<T>(T);
+        impl<T: fmt::Debug> fmt::Debug for OneLinePrinter<T> {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                write!(fmt, "{:?}", self.0)
+            }
+        }
+
+        write!(fmt, "BitMatrix({}x{}) ", self.num_rows, self.num_columns)?;
+        let items = self.rows().flat_map(|r| self.iter(r).map(move |c| (r, c)));
+        fmt.debug_set().entries(items.map(OneLinePrinter)).finish()
+    }
+}
+
 /// A fixed-column-size, variable-row-size 2D bit matrix with a moderately
 /// sparse representation.
 ///

src/librustc_middle/mir/query.rs

@@ -10,6 +10,8 @@ use rustc_index::vec::IndexVec;
 use rustc_span::{Span, Symbol};
 use rustc_target::abi::VariantIdx;
 use smallvec::SmallVec;
+use std::cell::Cell;
+use std::fmt::{self, Debug};
 
 use super::{Field, SourceInfo};
 
@@ -58,7 +60,7 @@ rustc_index::newtype_index! {
 }
 
 /// The layout of generator state.
-#[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
+#[derive(Clone, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
 pub struct GeneratorLayout<'tcx> {
     /// The type of every local stored inside the generator.
     pub field_tys: IndexVec<GeneratorSavedLocal, Ty<'tcx>>,
@@ -67,12 +69,72 @@ pub struct GeneratorLayout<'tcx> {
     /// be stored in multiple variants.
     pub variant_fields: IndexVec<VariantIdx, IndexVec<Field, GeneratorSavedLocal>>,
 
+    /// The source that led to each variant being created (usually, a yield or
+    /// await).
+    pub variant_source_info: IndexVec<VariantIdx, SourceInfo>,
+
     /// Which saved locals are storage-live at the same time. Locals that do not
     /// have conflicts with each other are allowed to overlap in the computed
     /// layout.
     pub storage_conflicts: BitMatrix<GeneratorSavedLocal, GeneratorSavedLocal>,
 }
 
+impl Debug for GeneratorLayout<'_> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        /// Prints an iterator of (key, value) tuples as a map.
+        struct MapPrinter<'a, K, V>(Cell<Option<Box<dyn Iterator<Item = (K, V)> + 'a>>>);
+        impl<'a, K, V> MapPrinter<'a, K, V> {
+            fn new(iter: impl Iterator<Item = (K, V)> + 'a) -> Self {
+                Self(Cell::new(Some(Box::new(iter))))
+            }
+        }
+        impl<'a, K: Debug, V: Debug> Debug for MapPrinter<'a, K, V> {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                fmt.debug_map().entries(self.0.take().unwrap()).finish()
+            }
+        }
+
+        /// Prints the generator variant name.
+        struct GenVariantPrinter(VariantIdx);
+        impl From<VariantIdx> for GenVariantPrinter {
+            fn from(idx: VariantIdx) -> Self {
+                GenVariantPrinter(idx)
+            }
+        }
+        impl Debug for GenVariantPrinter {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                let variant_name = ty::GeneratorSubsts::variant_name(self.0);
+                if fmt.alternate() {
+                    write!(fmt, "{:9}({:?})", variant_name, self.0)
+                } else {
+                    write!(fmt, "{}", variant_name)
+                }
+            }
+        }
+
+        /// Forces its contents to print in regular mode instead of alternate mode.
+        struct OneLinePrinter<T>(T);
+        impl<T: Debug> Debug for OneLinePrinter<T> {
+            fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+                write!(fmt, "{:?}", self.0)
+            }
+        }
+
+        fmt.debug_struct("GeneratorLayout")
+            .field("field_tys", &MapPrinter::new(self.field_tys.iter_enumerated()))
+            .field(
+                "variant_fields",
+                &MapPrinter::new(
+                    self.variant_fields
+                        .iter_enumerated()
+                        .map(|(k, v)| (GenVariantPrinter(k), OneLinePrinter(v))),
+                ),
+            )
+            .field("storage_conflicts", &self.storage_conflicts)
+            .finish()
+    }
+}
+
 #[derive(Debug, RustcEncodable, RustcDecodable, HashStable)]
 pub struct BorrowCheckResult<'tcx> {
     /// All the opaque types that are restricted to concrete types

src/librustc_middle/ty/sty.rs

@@ -522,8 +522,7 @@ impl<'tcx> GeneratorSubsts<'tcx> {
 
     /// Calls `f` with a reference to the name of the enumerator for the given
     /// variant `v`.
-    #[inline]
-    pub fn variant_name(self, v: VariantIdx) -> Cow<'static, str> {
+    pub fn variant_name(v: VariantIdx) -> Cow<'static, str> {
         match v.as_usize() {
             Self::UNRESUMED => Cow::from(Self::UNRESUMED_NAME),
             Self::RETURNED => Cow::from(Self::RETURNED_NAME),

src/librustc_mir/transform/generator.rs

@@ -422,6 +422,9 @@ struct LivenessInfo {
     /// The set of saved locals live at each suspension point.
     live_locals_at_suspension_points: Vec<BitSet<GeneratorSavedLocal>>,
 
+    /// Parallel vec to the above with SourceInfo for each yield terminator.
+    source_info_at_suspension_points: Vec<SourceInfo>,
+
     /// For every saved local, the set of other saved locals that are
     /// storage-live at the same time as this local. We cannot overlap locals in
     /// the layout which have conflicting storage.
@@ -473,6 +476,7 @@ fn locals_live_across_suspend_points(
 
     let mut storage_liveness_map = IndexVec::from_elem(None, body.basic_blocks());
     let mut live_locals_at_suspension_points = Vec::new();
+    let mut source_info_at_suspension_points = Vec::new();
     let mut live_locals_at_any_suspension_point = BitSet::new_empty(body.local_decls.len());
 
     for (block, data) in body.basic_blocks().iter_enumerated() {
@@ -518,6 +522,7 @@ fn locals_live_across_suspend_points(
             live_locals_at_any_suspension_point.union(&live_locals);
 
             live_locals_at_suspension_points.push(live_locals);
+            source_info_at_suspension_points.push(data.terminator().source_info);
         }
     }
 
@@ -541,6 +546,7 @@ fn locals_live_across_suspend_points(
     LivenessInfo {
         saved_locals,
         live_locals_at_suspension_points,
+        source_info_at_suspension_points,
         storage_conflicts,
         storage_liveness: storage_liveness_map,
     }
@@ -754,6 +760,7 @@ fn compute_layout<'tcx>(
     let LivenessInfo {
         saved_locals,
         live_locals_at_suspension_points,
+        source_info_at_suspension_points,
         storage_conflicts,
         storage_liveness,
     } = liveness;
@@ -768,7 +775,18 @@ fn compute_layout<'tcx>(
     }
 
     // Leave empty variants for the UNRESUMED, RETURNED, and POISONED states.
+    // In debuginfo, these will correspond to the beginning (UNRESUMED) or end
+    // (RETURNED, POISONED) of the function.
     const RESERVED_VARIANTS: usize = 3;
+    let body_span = body.source_scopes[OUTERMOST_SOURCE_SCOPE].span;
+    let mut variant_source_info: IndexVec<VariantIdx, SourceInfo> = [
+        SourceInfo::outermost(body_span.shrink_to_lo()),
+        SourceInfo::outermost(body_span.shrink_to_hi()),
+        SourceInfo::outermost(body_span.shrink_to_hi()),
+    ]
+    .iter()
+    .copied()
+    .collect();
 
     // Build the generator variant field list.
     // Create a map from local indices to generator struct indices.
@@ -787,11 +805,13 @@ fn compute_layout<'tcx>(
             remap.entry(locals[saved_local]).or_insert((tys[saved_local], variant_index, idx));
         }
         variant_fields.push(fields);
+        variant_source_info.push(source_info_at_suspension_points[suspension_point_idx]);
     }
     debug!("generator variant_fields = {:?}", variant_fields);
     debug!("generator storage_conflicts = {:#?}", storage_conflicts);
 
-    let layout = GeneratorLayout { field_tys: tys, variant_fields, storage_conflicts };
+    let layout =
+        GeneratorLayout { field_tys: tys, variant_fields, variant_source_info, storage_conflicts };
 
     (remap, layout, storage_liveness)
 }

src/librustc_mir/util/pretty.rs

@@ -131,7 +131,7 @@ fn dump_matched_mir_node<'tcx, F>(
         }
         writeln!(file, " {} {}", disambiguator, pass_name)?;
         if let Some(ref layout) = body.generator_layout {
-            writeln!(file, "// generator_layout = {:?}", layout)?;
+            writeln!(file, "/* generator_layout = {:#?} */", layout)?;
         }
         writeln!(file)?;
         extra_data(PassWhere::BeforeCFG, &mut file)?;

src/test/codegen/async-fn-debug-msvc.rs

@@ -0,0 +1,48 @@
+// Verify debuginfo for generators:
+//  - Each variant points to the file and line of its yield point
+//  - The generator types and variants are marked artificial
+//  - Captured vars from the source are not marked artificial
+//
+// ignore-tidy-linelength
+// compile-flags: -C debuginfo=2 --edition=2018
+// only-msvc
+
+async fn foo() {}
+async fn async_fn_test() {
+    foo().await;
+    let s = String::from("foo");
+    foo().await;
+}
+
+// FIXME: No way to reliably check the filename.
+
+// CHECK-DAG:  [[ASYNC_FN:!.*]] = !DINamespace(name: "async_fn_test"
+// CHECK-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_union_type, name: "generator-0", scope: [[ASYNC_FN]], {{.*}}flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// For brevity, we only check the struct name and members of the last variant.
+// CHECK-SAME: file: [[FILE:![0-9]*]], line: 11,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 15,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 15,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 12,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 14,
+// CHECK-SAME: baseType: [[VARIANT:![0-9]*]]
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      [[S1:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Suspend1", scope: [[ASYNC_FN]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "RUST$ENUM$DISR", scope: [[S1]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "s", scope: [[S1]]
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
+
+fn main() {
+    let _dummy = async_fn_test();
+}

src/test/codegen/async-fn-debug.rs

@@ -0,0 +1,51 @@
+// Verify debuginfo for async fn:
+//  - Each variant points to the file and line of its yield point
+//  - The generator types and variants are marked artificial
+//  - Captured vars from the source are not marked artificial
+//
+// ignore-tidy-linelength
+// compile-flags: -C debuginfo=2 --edition=2018
+// ignore-msvc
+
+async fn foo() {}
+async fn async_fn_test() {
+    foo().await;
+    let s = String::from("foo");
+    foo().await;
+}
+
+// FIXME: No way to reliably check the filename.
+
+// CHECK-DAG:  [[ASYNC_FN:!.*]] = !DINamespace(name: "async_fn_test"
+// CHECK-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "generator-0", scope: [[ASYNC_FN]], {{.*}}flags: DIFlagArtificial
+// CHECK:      [[VARIANT:!.*]] = !DICompositeType(tag: DW_TAG_variant_part, scope: [[ASYNC_FN]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-SAME: discriminator: [[DISC:![0-9]*]]
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "0", scope: [[VARIANT]],
+// CHECK-SAME: file: [[FILE:![0-9]*]], line: 11,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "Unresumed", scope: [[GEN]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "1", scope: [[VARIANT]],
+// CHECK-SAME: file: [[FILE]], line: 15,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "2", scope: [[VARIANT]],
+// CHECK-SAME: file: [[FILE]], line: 15,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "3", scope: [[VARIANT]],
+// CHECK-SAME: file: [[FILE]], line: 12,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "4", scope: [[VARIANT]],
+// CHECK-SAME: file: [[FILE]], line: 14,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      [[S1:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Suspend1", scope: [[GEN]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "s", scope: [[S1]]
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
+// CHECK:      [[DISC]] = !DIDerivedType(tag: DW_TAG_member, name: "__state", scope: [[ASYNC_FN]],
+// CHECK-SAME: flags: DIFlagArtificial
+
+fn main() {
+    let _dummy = async_fn_test();
+}

src/test/codegen/generator-debug-msvc.rs

@@ -0,0 +1,52 @@
+// Verify debuginfo for generators:
+//  - Each variant points to the file and line of its yield point
+//  - The generator types and variants are marked artificial
+//  - Captured vars from the source are not marked artificial
+//
+// ignore-tidy-linelength
+// compile-flags: -C debuginfo=2
+// only-msvc
+
+#![feature(generators, generator_trait)]
+use std::ops::Generator;
+
+fn generator_test() -> impl Generator<Yield = i32, Return = ()> {
+    || {
+        yield 0;
+        let s = String::from("foo");
+        yield 1;
+    }
+}
+
+// FIXME: No way to reliably check the filename.
+
+// CHECK-DAG:  [[GEN_FN:!.*]] = !DINamespace(name: "generator_test"
+// CHECK-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_union_type, name: "generator-0", scope: [[GEN_FN]], {{.*}}flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// For brevity, we only check the struct name and members of the last variant.
+// CHECK-SAME: file: [[FILE:![0-9]*]], line: 14,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 18,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 18,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 15,
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
+// CHECK-SAME: file: [[FILE]], line: 17,
+// CHECK-SAME: baseType: [[VARIANT:![0-9]*]]
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      [[S1:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Suspend1", scope: [[GEN_FN]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "RUST$ENUM$DISR", scope: [[S1]],
+// CHECK-SAME: flags: DIFlagArtificial
+// CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "s", scope: [[S1]]
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
+
+fn main() {
+    let _dummy = generator_test();
+}