[DebugInfo] Handle types with @_originallyDefinedIn in DebugInfo

When processing a nominal type that has the @_originallyDefinedIn attribute,
IRGenDebugInfo emits a forward declaration of the type as a child
of the original module, and the type with a specification pointing to
the forward declaration. We do this so LLDB has enough information to
both find the type in reflection metadata (the parent module name) and
find it in the swiftmodule (the module name in the type mangled name).

rdar://137146961

Author: augusto2112

lib/IRGen/IRGenDebugInfo.cpp

@@ -1792,6 +1792,28 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
       return InternalType;
     }
 
+    llvm::DIType *SpecificationOf = nullptr;
+    if (auto *TypeDecl = DbgTy.getType()->getNominalOrBoundGenericNominal()) {
+      // If this is a nominal type that has the @_originallyDefinedIn attribute,
+      // IRGenDebugInfo emits a forward declaration of the type as a child
+      // of the original module, and the type with a specification pointing to
+      // the forward declaraation. We do this so LLDB has enough information to
+      // both find the type in reflection metadata (the parent module name) and
+      // find it in the swiftmodule (the module name in the type mangled name).
+      if (auto Attribute =
+              TypeDecl->getAttrs().getAttribute<OriginallyDefinedInAttr>()) {
+        auto Identifier = IGM.getSILModule().getASTContext().getIdentifier(
+            Attribute->OriginalModuleName);
+
+        void *Key = (void *)Identifier.get();
+        auto InnerScope =
+            getOrCreateModule(Key, TheCU, Attribute->OriginalModuleName, {});
+        SpecificationOf = DBuilder.createForwardDecl(
+            llvm::dwarf::DW_TAG_structure_type, TypeDecl->getNameStr(),
+            InnerScope, File, 0, llvm::dwarf::DW_LANG_Swift, 0, 0);
+      }
+    }
+
     // Here goes!
     switch (BaseTy->getKind()) {
     case TypeKind::BuiltinUnboundGeneric:
@@ -1894,7 +1916,8 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
             llvm::dwarf::DW_TAG_structure_type, MangledName, Scope, L.File,
             FwdDeclLine, llvm::dwarf::DW_LANG_Swift, 0, AlignInBits);
       return createOpaqueStruct(Scope, Name, L.File, FwdDeclLine, SizeInBits,
-                                AlignInBits, Flags, MangledName);
+                                AlignInBits, Flags, MangledName, {},
+                                SpecificationOf);
     }
 
     case TypeKind::Class: {
@@ -1931,7 +1954,8 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
         return DIType;
       }
       return createPointerSizedStruct(Scope, Decl->getNameStr(), L.File,
-                                      FwdDeclLine, Flags, MangledName);
+                                      FwdDeclLine, Flags, MangledName,
+                                      SpecificationOf);
     }
 
     case TypeKind::Protocol: {
@@ -1977,11 +2001,11 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
         return createSpecializedStructOrClassType(
             StructTy, Decl, Scope, L.File, L.Line, SizeInBits, AlignInBits,
             Flags, MangledName);
-      
+
       return createOpaqueStructWithSizedContainer(
           Scope, Decl ? Decl->getNameStr() : "", L.File, FwdDeclLine,
           SizeInBits, AlignInBits, Flags, MangledName,
-          collectGenericParams(StructTy));
+          collectGenericParams(StructTy), SpecificationOf);
     }
 
     case TypeKind::BoundGenericClass: {
@@ -1999,9 +2023,9 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
       // attribute accordingly.
       assert(SizeInBits ==
              CI.getTargetInfo().getPointerWidth(clang::LangAS::Default));
-      return createPointerSizedStruct(Scope,
-                                      Decl ? Decl->getNameStr() : MangledName,
-                                      L.File, FwdDeclLine, Flags, MangledName);
+      return createPointerSizedStruct(
+          Scope, Decl ? Decl->getNameStr() : MangledName, L.File, FwdDeclLine,
+          Flags, MangledName, SpecificationOf);
     }
 
     case TypeKind::Pack:
@@ -2122,7 +2146,7 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
       }
       return createOpaqueStruct(Scope, Decl->getName().str(), L.File,
                                 FwdDeclLine, SizeInBits, AlignInBits, Flags,
-                                MangledName);
+                                MangledName, {}, SpecificationOf);
     }
 
     case TypeKind::BoundGenericEnum: {
@@ -2142,7 +2166,8 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
       }
       return createOpaqueStructWithSizedContainer(
           Scope, Decl->getName().str(), L.File, FwdDeclLine, SizeInBits,
-          AlignInBits, Flags, MangledName, collectGenericParams(EnumTy));
+          AlignInBits, Flags, MangledName, collectGenericParams(EnumTy),
+          SpecificationOf);
     }
 
     case TypeKind::BuiltinVector: {
@@ -2322,7 +2347,8 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
     }
   }
 
-  llvm::DIType *getOrCreateType(DebugTypeInfo DbgTy) {
+  llvm::DIType *getOrCreateType(DebugTypeInfo DbgTy,
+                                llvm::DIScope *Scope = nullptr) {
     // Is this an empty type?
     if (DbgTy.isNull())
       // We can't use the empty type as an index into DenseMap.
@@ -2354,7 +2380,6 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
     //
     // FIXME: Builtin and qualified types in LLVM have no parent
     // scope. TODO: This can be fixed by extending DIBuilder.
-    llvm::DIScope *Scope = nullptr;
     // Make sure to retrieve the context of the type alias, not the pointee.
     DeclContext *Context = nullptr;
     const Decl *TypeDecl = nullptr;

test/DebugInfo/originally_defined_in.swift

@@ -0,0 +1,14 @@
+// RUN: %target-swift-frontend -primary-file %s -emit-ir -g -o - | %FileCheck %s
+
+ @_originallyDefinedIn(
+      module: "Other", iOS 2.0, macOS 2.0, tvOS 2.0, watchOS 2.0)
+ @available(iOS 1.0, macOS 1.0, tvOS 1.0, watchOS 1.0, *)
+ public struct A {
+     let i = 10
+ }
+
+ // CHECK: !DICompositeType(tag: DW_TAG_structure_type, name: "A",{{.*}}identifier: "$s21originally_defined_in1AVD",{{.*}}specification_of: ![[S1:[0-9]+]]
+ // CHECK: [[S1]] = !DICompositeType(tag: DW_TAG_structure_type, name: "A", scope: ![[S2:[0-9]+]]
+ // CHECK: [[S2]] = !DIModule({{.*}}name: "Other"
+
+let a = A()