Debug Info: Using declarations/DW_TAG_imported_declaration of variables, types, and functions.

Basic support is implemented here - it still doesn't account for
declared-but-not-defined variables or functions. It cannot handle out of
order (declared, 'using', then defined) cases for variables, but can
handle that for functions (& can handle declared, 'using'd, and not
defined at all cases for types).

llvm-svn: 181393

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -2097,6 +2097,17 @@ llvm::DIType CGDebugInfo::CreateMemberType(llvm::DIFile Unit, QualType FType,
   return Ty;
 }
 
+llvm::DIDescriptor CGDebugInfo::getDeclarationOrDefinition(const Decl *D) {
+  if (const TypeDecl *RD = dyn_cast<TypeDecl>(D))
+    return CreatePointeeType(QualType(RD->getTypeForDecl(), 0), llvm::DIFile());
+  llvm::DenseMap<const Decl *, llvm::WeakVH>::iterator I =
+      DeclCache.find(D->getCanonicalDecl());
+  if (I == DeclCache.end())
+    return llvm::DIDescriptor();
+  llvm::Value *V = I->second;
+  return llvm::DIDescriptor(dyn_cast_or_null<llvm::MDNode>(V));
+}
+
 /// getFunctionDeclaration - Return debug info descriptor to describe method
 /// declaration for the given method definition.
 llvm::DISubprogram CGDebugInfo::getFunctionDeclaration(const Decl *D) {
@@ -2265,6 +2276,8 @@ void CGDebugInfo::EmitFunctionStart(GlobalDecl GD, QualType FnType,
                                getLineNumber(CurLoc), Flags,
                                CGM.getLangOpts().Optimize,
                                Fn, TParamsArray, SPDecl);
+  if (HasDecl)
+    DeclCache.insert(std::make_pair(D->getCanonicalDecl(), llvm::WeakVH(SP)));
 
   // Push function on region stack.
   llvm::MDNode *SPN = SP;
@@ -2875,10 +2888,11 @@ void CGDebugInfo::EmitGlobalVariable(llvm::GlobalVariable *Var,
     LinkageName = StringRef();
   llvm::DIDescriptor DContext = 
     getContextDescriptor(dyn_cast<Decl>(D->getDeclContext()));
-  DBuilder.createStaticVariable(DContext, DeclName, LinkageName,
+  llvm::DIGlobalVariable GV = DBuilder.createStaticVariable(DContext, DeclName, LinkageName,
                                 Unit, LineNo, getOrCreateType(T, Unit),
                                 Var->hasInternalLinkage(), Var,
                                 getStaticDataMemberDeclaration(D));
+  DeclCache.insert(std::make_pair(D->getCanonicalDecl(), llvm::WeakVH(GV)));
 }
 
 /// EmitGlobalVariable - Emit information about an objective-c interface.
@@ -2923,22 +2937,38 @@ void CGDebugInfo::EmitGlobalVariable(const ValueDecl *VD,
   // Do not use DIGlobalVariable for enums.
   if (Ty.getTag() == llvm::dwarf::DW_TAG_enumeration_type)
     return;
-  DBuilder.createStaticVariable(Unit, Name, Name, Unit,
+  llvm::DIGlobalVariable GV = DBuilder.createStaticVariable(Unit, Name, Name, Unit,
                                 getLineNumber(VD->getLocation()),
                                 Ty, true, Init,
                                 getStaticDataMemberDeclaration(VD));
+  DeclCache.insert(std::make_pair(VD->getCanonicalDecl(), llvm::WeakVH(GV)));
+}
+
+llvm::DIScope CGDebugInfo::getCurrentContextDescriptor(const Decl *D) {
+  if (!LexicalBlockStack.empty())
+    return llvm::DIScope(LexicalBlockStack.back());
+  return getContextDescriptor(D);
 }
 
 void CGDebugInfo::EmitUsingDirective(const UsingDirectiveDecl &UD) {
-  llvm::DIScope Scope =
-      LexicalBlockStack.empty()
-          ? getContextDescriptor(cast<Decl>(UD.getDeclContext()))
-          : llvm::DIScope(LexicalBlockStack.back());
   DBuilder.createImportedModule(
-      Scope, getOrCreateNameSpace(UD.getNominatedNamespace()),
+      getCurrentContextDescriptor(cast<Decl>(UD.getDeclContext())),
+      getOrCreateNameSpace(UD.getNominatedNamespace()),
       getLineNumber(UD.getLocation()));
 }
 
+void CGDebugInfo::EmitUsingDecl(const UsingDecl &UD) {
+  assert(UD.shadow_size() &&
+         "We shouldn't be codegening an invalid UsingDecl containing no decls");
+  // Emitting one decl is sufficient - debuggers can detect that this is an
+  // overloaded name & provide lookup for all the overloads.
+  const UsingShadowDecl &USD = **UD.shadow_begin();
+  if (llvm::DIDescriptor Target = getDeclarationOrDefinition(USD.getUnderlyingDecl()))
+    DBuilder.createImportedDeclaration(
+        getCurrentContextDescriptor(cast<Decl>(USD.getDeclContext())), Target,
+        getLineNumber(USD.getLocation()));
+}
+
 /// getOrCreateNamesSpace - Return namespace descriptor for the given
 /// namespace decl.
 llvm::DINameSpace 

clang/lib/CodeGen/CGDebugInfo.h

@@ -35,6 +35,7 @@ namespace clang {
   class ObjCIvarDecl;
   class ClassTemplateSpecializationDecl;
   class GlobalDecl;
+  class UsingDecl;
 
 namespace CodeGen {
   class CodeGenModule;
@@ -94,6 +95,7 @@ class CGDebugInfo {
 
   llvm::DenseMap<const char *, llvm::WeakVH> DIFileCache;
   llvm::DenseMap<const FunctionDecl *, llvm::WeakVH> SPCache;
+  llvm::DenseMap<const Decl *, llvm::WeakVH> DeclCache;
   llvm::DenseMap<const NamespaceDecl *, llvm::WeakVH> NameSpaceCache;
   llvm::DenseMap<const Decl *, llvm::WeakVH> StaticDataMemberCache;
 
@@ -265,6 +267,9 @@ public:
   /// \brief - Emit C++ using directive.
   void EmitUsingDirective(const UsingDirectiveDecl &UD);
 
+  /// \brief - Emit C++ using declaration.
+  void EmitUsingDecl(const UsingDecl &UD);
+
   /// getOrCreateRecordType - Emit record type's standalone debug info. 
   llvm::DIType getOrCreateRecordType(QualType Ty, SourceLocation L);
 
@@ -286,6 +291,8 @@ private:
   /// getContextDescriptor - Get context info for the decl.
   llvm::DIScope getContextDescriptor(const Decl *Decl);
 
+  llvm::DIScope getCurrentContextDescriptor(const Decl *Decl);
+
   /// createRecordFwdDecl - Create a forward decl for a RecordType in a given
   /// context.
   llvm::DIType createRecordFwdDecl(const RecordDecl *, llvm::DIDescriptor);
@@ -329,6 +336,10 @@ private:
   llvm::DIType CreateMemberType(llvm::DIFile Unit, QualType FType,
                                 StringRef Name, uint64_t *Offset);
 
+  /// \brief Retrieve the DIDescriptor, if any, for the canonical form of this
+  /// declaration.
+  llvm::DIDescriptor getDeclarationOrDefinition(const Decl *D);
+
   /// getFunctionDeclaration - Return debug info descriptor to describe method
   /// declaration for the given method definition.
   llvm::DISubprogram getFunctionDeclaration(const Decl *D);

clang/lib/CodeGen/CGDecl.cpp

@@ -72,14 +72,13 @@ void CodeGenFunction::EmitDecl(const Decl &D) {
   case Decl::Block:
   case Decl::Captured:
   case Decl::ClassScopeFunctionSpecialization:
+  case Decl::UsingShadow:
     llvm_unreachable("Declaration should not be in declstmts!");
   case Decl::Function:  // void X();
   case Decl::Record:    // struct/union/class X;
   case Decl::Enum:      // enum X;
   case Decl::EnumConstant: // enum ? { X = ? }
   case Decl::CXXRecord: // struct/union/class X; [C++]
-  case Decl::Using:          // using X; [C++]
-  case Decl::UsingShadow:
   case Decl::NamespaceAlias:
   case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
   case Decl::Label:        // __label__ x;
@@ -89,6 +88,10 @@ void CodeGenFunction::EmitDecl(const Decl &D) {
     // None of these decls require codegen support.
     return;
 
+  case Decl::Using:          // using X; [C++]
+    if (CGDebugInfo *DI = getDebugInfo())
+      DI->EmitUsingDecl(cast<UsingDecl>(D));
+    return;
   case Decl::UsingDirective: // using namespace X; [C++]
     if (CGDebugInfo *DI = getDebugInfo())
       DI->EmitUsingDirective(cast<UsingDirectiveDecl>(D));

clang/test/CodeGenCXX/debug-info-namespace.cpp

@@ -4,6 +4,10 @@ namespace A {
 #line 1 "foo.cpp"
 namespace B {
 int i;
+void f1() { }
+void f1(int) { }
+struct foo;
+struct bar { };
 }
 using namespace B;
 }
@@ -16,22 +20,37 @@ int func(bool b) {
     return i;
   }
   using namespace A;
-  return B::i;
+  using B::foo;
+  using B::bar;
+  using B::f1;
+  using B::i;
+  bar x;
+  return i;
 }
 
+// This should work even if 'i' and 'func' were declarations & not definitions,
+// but it doesn't yet.
+
 // CHECK: [[CU:![0-9]*]] = {{.*}}[[MODULES:![0-9]*]], metadata !""} ; [ DW_TAG_compile_unit ]
 // CHECK: [[FILE:![0-9]*]] {{.*}}debug-info-namespace.cpp"
-// CHECK: [[FUNC:![0-9]*]] {{.*}} ; [ DW_TAG_subprogram ] [line 9] [def] [func]
+// CHECK: [[NS:![0-9]*]] = {{.*}}, metadata [[FILE2:![0-9]*]], metadata [[CTXT:![0-9]*]], {{.*}} ; [ DW_TAG_namespace ] [B] [line 1]
-// CHECK: [[FILE2:![0-9]*]]} ; [ DW_TAG_file_type ] [{{.*}}foo.cpp]
-// CHECK: [[VAR:![0-9]*]] = {{.*}}, metadata [[NS:![0-9]*]], metadata !"i", {{.*}} ; [ DW_TAG_variable ] [i]
-// CHECK: [[NS]] = {{.*}}, metadata [[FILE2]], metadata [[CTXT:![0-9]*]], {{.*}} ; [ DW_TAG_namespace ] [B] [line 1]
 // CHECK: [[CTXT]] = {{.*}}, metadata [[FILE]], null, {{.*}} ; [ DW_TAG_namespace ] [A] [line 3]
-// CHECK: [[MODULES]] = metadata !{metadata [[M1:![0-9]*]], metadata [[M2:![0-9]*]], metadata [[M3:![0-9]*]], metadata [[M4:![0-9]*]]}
+// CHECK: [[F1:![0-9]*]] {{.*}} ; [ DW_TAG_subprogram ] [line 4] [def] [f1]
-// CHECK: [[M1]] = metadata !{i32 {{[0-9]*}}, metadata [[CTXT]], metadata [[NS]], i32 4} ; [ DW_TAG_imported_module ]
+// CHECK: [[FUNC:![0-9]*]] {{.*}} ; [ DW_TAG_subprogram ] [line 13] [def] [func]
-// CHECK: [[M2]] = metadata !{i32 {{[0-9]*}}, metadata [[CU]], metadata [[CTXT]], i32 7} ; [ DW_TAG_imported_module ]
+// CHECK: [[FILE2]]} ; [ DW_TAG_file_type ] [{{.*}}foo.cpp]
-// CHECK: [[M3]] = metadata !{i32 {{[0-9]*}}, metadata [[LEX:![0-9]*]], metadata [[NS]], i32 11} ; [ DW_TAG_imported_module ]
+// CHECK: [[I:![0-9]*]] = {{.*}}, metadata [[NS]], metadata !"i", {{.*}} ; [ DW_TAG_variable ] [i]
-// CHECK: [[LEX]] = metadata !{i32 {{[0-9]*}}, metadata [[FILE2]], metadata [[FUNC]], i32 10, i32 0, i32 0} ; [ DW_TAG_lexical_block ]
+// CHECK: [[MODULES]] = metadata !{metadata [[M1:![0-9]*]], metadata [[M2:![0-9]*]], metadata [[M3:![0-9]*]], metadata [[M4:![0-9]*]], metadata [[M5:![0-9]*]], metadata [[M6:![0-9]*]], metadata [[M7:![0-9]*]], metadata [[M8:![0-9]*]]}
-// CHECK: [[M4]] = metadata !{i32 {{[0-9]*}}, metadata [[FUNC]], metadata [[CTXT]], i32 14} ; [ DW_TAG_imported_module ]
+// CHECK: [[M1]] = metadata !{i32 {{[0-9]*}}, metadata [[CTXT]], metadata [[NS]], i32 8} ; [ DW_TAG_imported_module ]
+// CHECK: [[M2]] = metadata !{i32 {{[0-9]*}}, metadata [[CU]], metadata [[CTXT]], i32 11} ; [ DW_TAG_imported_module ]
+// CHECK: [[M3]] = metadata !{i32 {{[0-9]*}}, metadata [[LEX:![0-9]*]], metadata [[NS]], i32 15} ; [ DW_TAG_imported_module ]
+// CHECK: [[LEX]] = metadata !{i32 {{[0-9]*}}, metadata [[FILE2]], metadata [[FUNC]], i32 14, i32 0, i32 0} ; [ DW_TAG_lexical_block ]
+// CHECK: [[M4]] = metadata !{i32 {{[0-9]*}}, metadata [[FUNC]], metadata [[CTXT]], i32 18} ; [ DW_TAG_imported_module ]
+// CHECK: [[M5]] = metadata !{i32 {{[0-9]*}}, metadata [[FUNC]], metadata [[FOO:![0-9]*]], i32 19} ; [ DW_TAG_imported_declaration ]
+// CHECK: [[FOO]] {{.*}} ; [ DW_TAG_structure_type ] [foo] [line 5, size 0, align 0, offset 0] [fwd] [from ]
+// CHECK: [[M6]] = metadata !{i32 {{[0-9]*}}, metadata [[FUNC]], metadata [[BAR:![0-9]*]], i32 20} ; [ DW_TAG_imported_declaration ]
+// CHECK: [[BAR]] {{.*}} ; [ DW_TAG_structure_type ] [bar] [line 6, {{.*}}] [from ]
+// CHECK: [[M7]] = metadata !{i32 {{[0-9]*}}, metadata [[FUNC]], metadata [[F1]], i32 21} ; [ DW_TAG_imported_declaration ]
+// CHECK: [[M8]] = metadata !{i32 {{[0-9]*}}, metadata [[FUNC]], metadata [[I]], i32 22} ; [ DW_TAG_imported_declaration ]
 
 // FIXME: It is confused on win32 to generate file entry when dosish filename is given.
 // REQUIRES: shell