Emit line info for generator variants

Author: tmandry

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -392,6 +392,7 @@ fn vec_slice_metadata(
             align: pointer_align,
             flags: DIFlags::FlagZero,
             discriminant: None,
+            source_info: None,
         },
         MemberDescription {
             name: "length".to_owned(),
@@ -401,6 +402,7 @@ fn vec_slice_metadata(
             align: usize_align,
             flags: DIFlags::FlagZero,
             discriminant: None,
+            source_info: None,
         },
     ];
 
@@ -508,6 +510,7 @@ fn trait_pointer_metadata(
             align: data_ptr_field.align.abi,
             flags: DIFlags::FlagArtificial,
             discriminant: None,
+            source_info: None,
         },
         MemberDescription {
             name: "vtable".to_owned(),
@@ -517,6 +520,7 @@ fn trait_pointer_metadata(
             align: vtable_field.align.abi,
             flags: DIFlags::FlagArtificial,
             discriminant: None,
+            source_info: None,
         },
     ];
 
@@ -1026,6 +1030,12 @@ impl MetadataCreationResult<'ll> {
     }
 }
 
+#[derive(Debug)]
+struct SourceInfo<'ll> {
+    file: &'ll DIFile,
+    line: u32,
+}
+
 /// Description of a type member, which can either be a regular field (as in
 /// structs or tuples) or an enum variant.
 #[derive(Debug)]
@@ -1037,6 +1047,7 @@ struct MemberDescription<'ll> {
     align: Align,
     flags: DIFlags,
     discriminant: Option<u64>,
+    source_info: Option<SourceInfo<'ll>>,
 }
 
 impl<'ll> MemberDescription<'ll> {
@@ -1045,14 +1056,18 @@ impl<'ll> MemberDescription<'ll> {
         cx: &CodegenCx<'ll, '_>,
         composite_type_metadata: &'ll DIScope,
     ) -> &'ll DIType {
+        let (file, line) = self
+            .source_info
+            .map(|info| (info.file, info.line))
+            .unwrap_or_else(|| (unknown_file_metadata(cx), UNKNOWN_LINE_NUMBER));
         unsafe {
             llvm::LLVMRustDIBuilderCreateVariantMemberType(
                 DIB(cx),
                 composite_type_metadata,
                 self.name.as_ptr().cast(),
                 self.name.len(),
-                unknown_file_metadata(cx),
-                UNKNOWN_LINE_NUMBER,
+                file,
+                line,
                 self.size.bits(),
                 self.align.bits() as u32,
                 self.offset.bits(),
@@ -1124,6 +1139,7 @@ impl<'tcx> StructMemberDescriptionFactory<'tcx> {
                     align: field.align.abi,
                     flags: DIFlags::FlagZero,
                     discriminant: None,
+                    source_info: None,
                 }
             })
             .collect()
@@ -1185,6 +1201,7 @@ impl<'tcx> TupleMemberDescriptionFactory<'tcx> {
                     align,
                     flags: DIFlags::FlagZero,
                     discriminant: None,
+                    source_info: None,
                 }
             })
             .collect()
@@ -1244,6 +1261,7 @@ impl<'tcx> UnionMemberDescriptionFactory<'tcx> {
                     align: field.align.abi,
                     flags: DIFlags::FlagZero,
                     discriminant: None,
+                    source_info: None,
                 }
             })
             .collect()
@@ -1351,10 +1369,11 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
 
         let variant_info_for = |index: VariantIdx| match self.enum_type.kind {
             ty::Adt(adt, _) => VariantInfo::Adt(&adt.variants[index]),
-            ty::Generator(_, substs, _) => {
+            ty::Generator(def_id, substs, _) => {
                 let (generator_layout, generator_saved_local_names) =
                     generator_variant_info_data.as_ref().unwrap();
                 VariantInfo::Generator {
+                    def_id,
                     substs,
                     generator_layout: *generator_layout,
                     generator_saved_local_names,
@@ -1406,6 +1425,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                     align: self.layout.align.abi,
                     flags: DIFlags::FlagZero,
                     discriminant: None,
+                    source_info: variant_info.source_info(cx),
                 }]
             }
             Variants::Multiple {
@@ -1462,6 +1482,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                                 self.layout.ty.discriminant_for_variant(cx.tcx, i).unwrap().val
                                     as u64,
                             ),
+                            source_info: variant_info.source_info(cx),
                         }
                     })
                     .collect()
@@ -1527,7 +1548,8 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                         self.layout.fields.offset(tag_field),
                         self.layout.field(cx, tag_field).size,
                     );
-                    variant_info_for(*niche_variants.start()).map_struct_name(|variant_name| {
+                    let variant_info = variant_info_for(*niche_variants.start());
+                    variant_info.map_struct_name(|variant_name| {
                         name.push_str(variant_name);
                     });
 
@@ -1540,6 +1562,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                         align: variant.align.abi,
                         flags: DIFlags::FlagZero,
                         discriminant: None,
+                        source_info: variant_info.source_info(cx),
                     }]
                 } else {
                     variants
@@ -1589,6 +1612,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                                 align: self.layout.align.abi,
                                 flags: DIFlags::FlagZero,
                                 discriminant: niche_value,
+                                source_info: variant_info.source_info(cx),
                             }
                         })
                         .collect()
@@ -1631,6 +1655,7 @@ impl VariantMemberDescriptionFactory<'ll, 'tcx> {
                     align,
                     flags: DIFlags::FlagZero,
                     discriminant: None,
+                    source_info: None,
                 }
             })
             .collect()
@@ -1651,6 +1676,7 @@ enum EnumTagInfo<'ll> {
 enum VariantInfo<'a, 'tcx> {
     Adt(&'tcx ty::VariantDef),
     Generator {
+        def_id: DefId,
         substs: SubstsRef<'tcx>,
         generator_layout: &'tcx GeneratorLayout<'tcx>,
         generator_saved_local_names: &'a IndexVec<mir::GeneratorSavedLocal, Option<Symbol>>,
@@ -1699,6 +1725,24 @@ impl<'tcx> VariantInfo<'_, 'tcx> {
         };
         field_name.map(|name| name.to_string()).unwrap_or_else(|| format!("__{}", i))
     }
+
+    fn source_info(&self, cx: &CodegenCx<'ll, 'tcx>) -> Option<SourceInfo<'ll>> {
+        match self {
+            VariantInfo::Generator { def_id, variant_index, .. } => {
+                let span =
+                    cx.tcx.generator_layout(*def_id).variant_source_info[*variant_index].span;
+                if !span.is_dummy() {
+                    let loc = cx.lookup_debug_loc(span.lo());
+                    return Some(SourceInfo {
+                        file: file_metadata(cx, &loc.file, def_id.krate),
+                        line: loc.line.unwrap_or(UNKNOWN_LINE_NUMBER),
+                    });
+                }
+            }
+            _ => {}
+        }
+        None
+    }
 }
 
 /// Returns a tuple of (1) `type_metadata_stub` of the variant, (2) a
@@ -1778,7 +1822,8 @@ fn prepare_enum_metadata(
     span: Span,
     outer_field_tys: Vec<Ty<'tcx>>,
 ) -> RecursiveTypeDescription<'ll, 'tcx> {
-    let enum_name = compute_debuginfo_type_name(cx.tcx, enum_type, false);
+    let tcx = cx.tcx;
+    let enum_name = compute_debuginfo_type_name(tcx, enum_type, false);
 
     let containing_scope = get_namespace_for_item(cx, enum_def_id);
     // FIXME: This should emit actual file metadata for the enum, but we
@@ -1792,7 +1837,7 @@ fn prepare_enum_metadata(
     let discriminant_type_metadata = |discr: Primitive| {
         let enumerators_metadata: Vec<_> = match enum_type.kind {
             ty::Adt(def, _) => def
-                .discriminants(cx.tcx)
+                .discriminants(tcx)
                 .zip(&def.variants)
                 .map(|((_, discr), v)| {
                     let name = v.ident.as_str();
@@ -1815,15 +1860,16 @@ fn prepare_enum_metadata(
                 .collect(),
             ty::Generator(_, substs, _) => substs
                 .as_generator()
-                .variant_range(enum_def_id, cx.tcx)
+                .variant_range(enum_def_id, tcx)
                 .map(|variant_index| {
+                    debug_assert_eq!(tcx.types.u32, substs.as_generator().discr_ty(tcx));
                     let name = substs.as_generator().variant_name(variant_index);
                     unsafe {
                         Some(llvm::LLVMRustDIBuilderCreateEnumerator(
                             DIB(cx),
                             name.as_ptr().cast(),
                             name.len(),
-                            // Generators use u32 as discriminant type.
+                            // Generators use u32 as discriminant type, verified above.
                             variant_index.as_u32().into(),
                             true, // IsUnsigned
                         ))
@@ -1841,12 +1887,12 @@ fn prepare_enum_metadata(
             None => {
                 let (discriminant_size, discriminant_align) = (discr.size(cx), discr.align(cx));
                 let discriminant_base_type_metadata =
-                    type_metadata(cx, discr.to_ty(cx.tcx), rustc_span::DUMMY_SP);
+                    type_metadata(cx, discr.to_ty(tcx), rustc_span::DUMMY_SP);
 
                 let item_name;
                 let discriminant_name = match enum_type.kind {
                     ty::Adt(..) => {
-                        item_name = cx.tcx.item_name(enum_def_id).as_str();
+                        item_name = tcx.item_name(enum_def_id).as_str();
                         &*item_name
                     }
                     ty::Generator(..) => enum_name.as_str(),

src/librustc_middle/mir/query.rs

@@ -67,6 +67,10 @@ 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.

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/test/mir-opt/generator-drop-cleanup/rustc.main-{{closure}}.generator_drop.0.mir

@@ -1,5 +1,5 @@
 // MIR for `main::{{closure}}#0` 0 generator_drop
-// generator_layout = GeneratorLayout { field_tys: [std::string::String], variant_fields: [[], [], [], [_0]], storage_conflicts: BitMatrix { num_rows: 1, num_columns: 1, words: [1], marker: PhantomData } }
+// generator_layout = GeneratorLayout { field_tys: [std::string::String], variant_fields: [[], [], [], [_0]], variant_source_info: [SourceInfo { span: $DIR/generator-drop-cleanup.rs:10:15: 10:15 (#0), scope: scope[0] }, SourceInfo { span: $DIR/generator-drop-cleanup.rs:13:6: 13:6 (#0), scope: scope[0] }, SourceInfo { span: $DIR/generator-drop-cleanup.rs:13:6: 13:6 (#0), scope: scope[0] }, SourceInfo { span: $DIR/generator-drop-cleanup.rs:12:9: 12:14 (#0), scope: scope[1] }], storage_conflicts: BitMatrix { num_rows: 1, num_columns: 1, words: [1], marker: PhantomData } }
 
 fn main::{{closure}}#0(_1: *mut [generator@$DIR/generator-drop-cleanup.rs:10:15: 13:6 {std::string::String, ()}]) -> () {
     let mut _0: ();                      // return place in scope 0 at $DIR/generator-drop-cleanup.rs:10:15: 13:6

src/test/mir-opt/generator-tiny/rustc.main-{{closure}}.generator_resume.0.mir

@@ -1,5 +1,5 @@
 // MIR for `main::{{closure}}#0` 0 generator_resume
-// generator_layout = GeneratorLayout { field_tys: [HasDrop], variant_fields: [[], [], [], [_0]], storage_conflicts: BitMatrix { num_rows: 1, num_columns: 1, words: [1], marker: PhantomData } }
+// generator_layout = GeneratorLayout { field_tys: [HasDrop], variant_fields: [[], [], [], [_0]], variant_source_info: [SourceInfo { span: $DIR/generator-tiny.rs:19:16: 19:16 (#0), scope: scope[0] }, SourceInfo { span: $DIR/generator-tiny.rs:25:6: 25:6 (#0), scope: scope[0] }, SourceInfo { span: $DIR/generator-tiny.rs:25:6: 25:6 (#0), scope: scope[0] }, SourceInfo { span: $DIR/generator-tiny.rs:22:13: 22:18 (#0), scope: scope[1] }], storage_conflicts: BitMatrix { num_rows: 1, num_columns: 1, words: [1], marker: PhantomData } }
 
 fn main::{{closure}}#0(_1: std::pin::Pin<&mut [generator@$DIR/generator-tiny.rs:19:16: 25:6 {u8, HasDrop, ()}]>, _2: u8) -> std::ops::GeneratorState<(), ()> {
     debug _x => _10;                     // in scope 0 at $DIR/generator-tiny.rs:19:17: 19:19