[DebugInfo] Fix bound generic types debug info generation

When generating full debug info for generic types, emit the
specification type as an opaque struct with the collection of
substituted generic parameters.

Author: augusto2112

lib/IRGen/IRGenDebugInfo.cpp

@@ -1184,11 +1184,10 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
       return OpaqueType;
     }
 
-    auto *opaqueType = createOpaqueStructWithSizedContainer(
-        Scope, Decl ? Decl->getNameStr() : "", File, Line, SizeInBits,
-        AlignInBits, Flags, MangledName, collectGenericParams(Type),
-        UnsubstitutedType);
-    return opaqueType;
+    auto *OpaqueType = createOpaqueStruct(
+        Scope, "", File, Line, SizeInBits, AlignInBits, Flags, MangledName,
+        collectGenericParams(Type), UnsubstitutedType);
+    return OpaqueType;
   }
 
   /// Create debug information for an enum with a raw type (enum E : Int {}).
@@ -1624,12 +1623,19 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
   llvm::DICompositeType *
   createOpaqueStruct(llvm::DIScope *Scope, StringRef Name, llvm::DIFile *File,
                      unsigned Line, unsigned SizeInBits, unsigned AlignInBits,
-                     llvm::DINode::DIFlags Flags, StringRef MangledName) {
-    return DBuilder.createStructType(
+                     llvm::DINode::DIFlags Flags, StringRef MangledName,
+                     llvm::DINodeArray BoundParams = {},
+                     llvm::DIType *SpecificationOf = nullptr) {
+
+    auto StructType = DBuilder.createStructType(
         Scope, Name, File, Line, SizeInBits, AlignInBits, Flags,
         /* DerivedFrom */ nullptr,
         DBuilder.getOrCreateArray(ArrayRef<llvm::Metadata *>()),
-        llvm::dwarf::DW_LANG_Swift, nullptr, MangledName);
+        llvm::dwarf::DW_LANG_Swift, nullptr, MangledName, SpecificationOf);
+
+    if (BoundParams)
+      DBuilder.replaceArrays(StructType, nullptr, BoundParams);
+    return StructType;
   }
 
   bool shouldCacheDIType(llvm::DIType *DITy, DebugTypeInfo &DbgTy) {
@@ -2012,11 +2018,9 @@ class IRGenDebugInfoImpl : public IRGenDebugInfo {
         // Force the creation of the unsubstituted type, don't create it
         // directly so it goes through all the caching/verification logic.
         auto unsubstitutedDbgTy = getOrCreateType(DbgTy);
-        DBuilder.retainType(unsubstitutedDbgTy);
-        return createOpaqueStructWithSizedContainer(
-            Scope, Decl->getName().str(), L.File, FwdDeclLine, SizeInBits,
-            AlignInBits, Flags, MangledName, collectGenericParams(EnumTy),
-            unsubstitutedDbgTy);
+        return createOpaqueStruct(
+            Scope, "", L.File, FwdDeclLine, SizeInBits, AlignInBits, Flags,
+            MangledName, collectGenericParams(EnumTy), unsubstitutedDbgTy);
       }
       return createOpaqueStructWithSizedContainer(
           Scope, Decl->getName().str(), L.File, FwdDeclLine, SizeInBits,

test/DebugInfo/BoundGenericStruct.swift

@@ -13,8 +13,11 @@ public let s = S<Int>(t: 0)
 // CHECK: ![[INT]] = !DICompositeType(tag: DW_TAG_structure_type, name: "$sSiD",
 
 
-// DWARF: !DICompositeType(tag: DW_TAG_structure_type, name: "$s18BoundGenericStruct1SVySiGD",
+// DWARF: !DICompositeType(tag: DW_TAG_structure_type,
 // DWARF-SAME:             templateParams: ![[PARAMS:[0-9]+]]
+// DWARF-SAME:             identifier: "$s18BoundGenericStruct1SVySiGD"
+// DWARF-SAME:             specification_of:
+
 // DWARF: ![[PARAMS]] = !{![[INTPARAM:[0-9]+]]}
 // DWARF: ![[INTPARAM]] = !DITemplateTypeParameter(type: ![[INT:[0-9]+]])
 // DWARF: ![[INT]] = !DICompositeType(tag: DW_TAG_structure_type, name: "Int", {{.*}}identifier: "$sSiD"