Rollup merge of #84752 - lrh2000:generator-debuginfo, r=tmandry

Fix debuginfo for generators

First, all fields except the discriminant (including `outer_fields`) should be put into structures inside the variant part, which gives an equivalent layout but offers us much better integration with debuggers.

Second, artificial flags in generator variants should be removed.
 - Literally, variants are not artificial. We have `yield` statements, upvars and inner variables in the source code.
 - Functionally, we don't want debuggers to suppress the variants. It contains the state of the generator, which is useful when debugging. So they shouldn't be marked artificial.
 - Debuggers may use artificial flags to find the active variant. In this case, marking variants artificial will make debuggers not work properly.

Fixes #62572.
Fixes #79009.

And refer https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Debuginfo.20for.20generators.

Author: Dylan-DPC

compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs

@@ -309,6 +309,7 @@ impl RecursiveTypeDescription<'ll, 'tcx> {
                     unfinished_type,
                     member_holding_stub,
                     member_descriptions,
+                    None,
                 );
                 MetadataCreationResult::new(metadata_stub, true)
             }
@@ -1459,6 +1460,7 @@ struct EnumMemberDescriptionFactory<'ll, 'tcx> {
     layout: TyAndLayout<'tcx>,
     tag_type_metadata: Option<&'ll DIType>,
     containing_scope: &'ll DIScope,
+    common_members: Vec<Option<&'ll DIType>>,
     span: Span,
 }
 
@@ -1493,10 +1495,6 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
         } else {
             type_metadata(cx, self.enum_type, self.span)
         };
-        let flags = match self.enum_type.kind() {
-            ty::Generator(..) => DIFlags::FlagArtificial,
-            _ => DIFlags::FlagZero,
-        };
 
         match self.layout.variants {
             Variants::Single { index } => {
@@ -1523,14 +1521,15 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                     self.enum_type,
                     variant_type_metadata,
                     member_descriptions,
+                    Some(&self.common_members),
                 );
                 vec![MemberDescription {
                     name: if fallback { String::new() } else { variant_info.variant_name() },
                     type_metadata: variant_type_metadata,
                     offset: Size::ZERO,
                     size: self.layout.size,
                     align: self.layout.align.abi,
-                    flags,
+                    flags: DIFlags::FlagZero,
                     discriminant: None,
                     source_info: variant_info.source_info(cx),
                 }]
@@ -1572,6 +1571,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                             self.enum_type,
                             variant_type_metadata,
                             member_descriptions,
+                            Some(&self.common_members),
                         );
 
                         MemberDescription {
@@ -1584,7 +1584,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                             offset: Size::ZERO,
                             size: self.layout.size,
                             align: self.layout.align.abi,
-                            flags,
+                            flags: DIFlags::FlagZero,
                             discriminant: Some(
                                 self.layout.ty.discriminant_for_variant(cx.tcx, i).unwrap().val
                                     as u64,
@@ -1621,6 +1621,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                         self.enum_type,
                         variant_type_metadata,
                         variant_member_descriptions,
+                        Some(&self.common_members),
                     );
 
                     // Encode the information about the null variant in the union
@@ -1667,7 +1668,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                         offset: Size::ZERO,
                         size: variant.size,
                         align: variant.align.abi,
-                        flags,
+                        flags: DIFlags::FlagZero,
                         discriminant: None,
                         source_info: variant_info.source_info(cx),
                     }]
@@ -1695,6 +1696,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                                 self.enum_type,
                                 variant_type_metadata,
                                 member_descriptions,
+                                Some(&self.common_members),
                             );
 
                             let niche_value = if i == dataful_variant {
@@ -1717,7 +1719,7 @@ impl EnumMemberDescriptionFactory<'ll, 'tcx> {
                                 offset: Size::ZERO,
                                 size: self.layout.size,
                                 align: self.layout.align.abi,
-                                flags,
+                                flags: DIFlags::FlagZero,
                                 discriminant: niche_value,
                                 source_info: variant_info.source_info(cx),
                             }
@@ -1849,13 +1851,6 @@ impl<'tcx> VariantInfo<'_, 'tcx> {
         }
         None
     }
-
-    fn is_artificial(&self) -> bool {
-        match self {
-            VariantInfo::Generator { .. } => true,
-            VariantInfo::Adt(..) => false,
-        }
-    }
 }
 
 /// Returns a tuple of (1) `type_metadata_stub` of the variant, (2) a
@@ -1881,8 +1876,7 @@ fn describe_enum_variant(
             &variant_name,
             unique_type_id,
             Some(containing_scope),
-            // FIXME(tmandry): This doesn't seem to have any effect.
-            if variant.is_artificial() { DIFlags::FlagArtificial } else { DIFlags::FlagZero },
+            DIFlags::FlagZero,
         )
     });
 
@@ -1945,11 +1939,6 @@ fn prepare_enum_metadata(
 ) -> RecursiveTypeDescription<'ll, 'tcx> {
     let tcx = cx.tcx;
     let enum_name = compute_debuginfo_type_name(tcx, enum_type, false);
-    // FIXME(tmandry): This doesn't seem to have any effect.
-    let enum_flags = match enum_type.kind() {
-        ty::Generator(..) => DIFlags::FlagArtificial,
-        _ => DIFlags::FlagZero,
-    };
 
     let containing_scope = get_namespace_for_item(cx, enum_def_id);
     // FIXME: This should emit actual file metadata for the enum, but we
@@ -2082,7 +2071,7 @@ fn prepare_enum_metadata(
                     UNKNOWN_LINE_NUMBER,
                     layout.size.bits(),
                     layout.align.abi.bits() as u32,
-                    enum_flags,
+                    DIFlags::FlagZero,
                     None,
                     0, // RuntimeLang
                     unique_type_id_str.as_ptr().cast(),
@@ -2102,6 +2091,7 @@ fn prepare_enum_metadata(
                 layout,
                 tag_type_metadata: discriminant_type_metadata,
                 containing_scope,
+                common_members: vec![],
                 span,
             }),
         );
@@ -2171,7 +2161,7 @@ fn prepare_enum_metadata(
         }
     };
 
-    let mut outer_fields = match layout.variants {
+    let outer_fields = match layout.variants {
         Variants::Single { .. } => vec![],
         Variants::Multiple { .. } => {
             let tuple_mdf = TupleMemberDescriptionFactory {
@@ -2203,18 +2193,21 @@ fn prepare_enum_metadata(
             UNKNOWN_LINE_NUMBER,
             layout.size.bits(),
             layout.align.abi.bits() as u32,
-            enum_flags,
+            DIFlags::FlagZero,
             discriminator_metadata,
             empty_array,
             variant_part_unique_type_id_str.as_ptr().cast(),
             variant_part_unique_type_id_str.len(),
         )
     };
-    outer_fields.push(Some(variant_part));
 
     let struct_wrapper = {
         // The variant part must be wrapped in a struct according to DWARF.
-        let type_array = create_DIArray(DIB(cx), &outer_fields);
+        // All fields except the discriminant (including `outer_fields`)
+        // should be put into structures inside the variant part, which gives
+        // an equivalent layout but offers us much better integration with
+        // debuggers.
+        let type_array = create_DIArray(DIB(cx), &[Some(variant_part)]);
 
         let type_map = debug_context(cx).type_map.borrow();
         let unique_type_id_str = type_map.get_unique_type_id_as_string(unique_type_id);
@@ -2229,7 +2222,7 @@ fn prepare_enum_metadata(
                 UNKNOWN_LINE_NUMBER,
                 layout.size.bits(),
                 layout.align.abi.bits() as u32,
-                enum_flags,
+                DIFlags::FlagZero,
                 None,
                 type_array,
                 0,
@@ -2251,6 +2244,7 @@ fn prepare_enum_metadata(
             layout,
             tag_type_metadata: None,
             containing_scope,
+            common_members: outer_fields,
             span,
         }),
     )
@@ -2283,7 +2277,13 @@ fn composite_type_metadata(
         DIFlags::FlagZero,
     );
     // ... and immediately create and add the member descriptions.
-    set_members_of_composite_type(cx, composite_type, composite_type_metadata, member_descriptions);
+    set_members_of_composite_type(
+        cx,
+        composite_type,
+        composite_type_metadata,
+        member_descriptions,
+        None,
+    );
 
     composite_type_metadata
 }
@@ -2293,6 +2293,7 @@ fn set_members_of_composite_type(
     composite_type: Ty<'tcx>,
     composite_type_metadata: &'ll DICompositeType,
     member_descriptions: Vec<MemberDescription<'ll>>,
+    common_members: Option<&Vec<Option<&'ll DIType>>>,
 ) {
     // In some rare cases LLVM metadata uniquing would lead to an existing type
     // description being used instead of a new one created in
@@ -2311,10 +2312,13 @@ fn set_members_of_composite_type(
         }
     }
 
-    let member_metadata: Vec<_> = member_descriptions
+    let mut member_metadata: Vec<_> = member_descriptions
         .into_iter()
         .map(|desc| Some(desc.into_metadata(cx, composite_type_metadata)))
         .collect();
+    if let Some(other_members) = common_members {
+        member_metadata.extend(other_members.iter());
+    }
 
     let type_params = compute_type_parameters(cx, composite_type);
     unsafe {

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

@@ -1,7 +1,7 @@
 // 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
+//  - The discriminants are marked artificial
+//  - Other fields are not marked artificial
 //
 //
 // compile-flags: -C debuginfo=2 --edition=2018
@@ -17,26 +17,32 @@ async fn async_fn_test() {
 // 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-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_union_type, name: "generator-0", scope: [[ASYNC_FN]]
 // 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-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
 // CHECK-SAME: file: [[FILE]], line: 15,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
 // CHECK-SAME: file: [[FILE]], line: 15,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
 // CHECK-SAME: file: [[FILE]], line: 12,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // 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-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      [[S1:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Suspend1", scope: [[ASYNC_FN]],
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // 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]]

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

@@ -1,7 +1,7 @@
 // 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
+//  - The discriminants are marked artificial
+//  - Other fields are not marked artificial
 //
 //
 // compile-flags: -C debuginfo=2 --edition=2018
@@ -17,29 +17,36 @@ async fn async_fn_test() {
 // 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-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "generator-0", scope: [[ASYNC_FN]]
 // CHECK:      [[VARIANT:!.*]] = !DICompositeType(tag: DW_TAG_variant_part, scope: [[ASYNC_FN]],
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  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-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DICompositeType(tag: DW_TAG_structure_type, name: "Unresumed", scope: [[GEN]],
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "1", scope: [[VARIANT]],
 // CHECK-SAME: file: [[FILE]], line: 15,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "2", scope: [[VARIANT]],
 // CHECK-SAME: file: [[FILE]], line: 15,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "3", scope: [[VARIANT]],
 // CHECK-SAME: file: [[FILE]], line: 12,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "4", scope: [[VARIANT]],
 // CHECK-SAME: file: [[FILE]], line: 14,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      [[S1:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Suspend1", scope: [[GEN]],
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, name: "s", scope: [[S1]]
 // CHECK-NOT:  flags: DIFlagArtificial
 // CHECK-SAME: )

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

@@ -1,7 +1,7 @@
 // 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
+//  - The discriminants are marked artificial
+//  - Other fields are not marked artificial
 //
 //
 // compile-flags: -C debuginfo=2
@@ -21,26 +21,32 @@ fn generator_test() -> impl Generator<Yield = i32, Return = ()> {
 // 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-DAG:  [[GEN:!.*]] = !DICompositeType(tag: DW_TAG_union_type, name: "generator-0", scope: [[GEN_FN]]
 // 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-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
 // CHECK-SAME: file: [[FILE]], line: 18,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
 // CHECK-SAME: file: [[FILE]], line: 18,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      {{!.*}} = !DIDerivedType(tag: DW_TAG_member, scope: [[GEN]],
 // CHECK-SAME: file: [[FILE]], line: 15,
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // 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-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // CHECK:      [[S1:!.*]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Suspend1", scope: [[GEN_FN]],
-// CHECK-SAME: flags: DIFlagArtificial
+// CHECK-NOT:  flags: DIFlagArtificial
+// CHECK-SAME: )
 // 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]]