PR14606: Debug Info for namespace aliases/DW_TAG_imported_module

This resolves the last of the PR14606 failures in the GDB 7.5 test
suite. (but there are still unresolved issues in the imported_decl case
- we need to implement optional/lazy decls for functions & variables
like we already do for types)

llvm-svn: 182329

4 files changed, 36 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index a8ab1c1c6b4..eff9d2284f0 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3084,6 +3084,30 @@ void CGDebugInfo::EmitUsingDecl(const UsingDecl &UD) {
         getLineNumber(USD.getLocation()));
 }
 
+llvm::DIImportedEntity
+CGDebugInfo::EmitNamespaceAlias(const NamespaceAliasDecl &NA) {
+  if (CGM.getCodeGenOpts().getDebugInfo() < CodeGenOptions::LimitedDebugInfo)
+    return llvm::DIImportedEntity(0);
+  llvm::WeakVH &VH = NamespaceAliasCache[&NA];
+  if (VH)
+    return llvm::DIImportedEntity(cast<llvm::MDNode>(VH));
+  llvm::DIImportedEntity R(0);
+  if (const NamespaceAliasDecl *Underlying =
+          dyn_cast<NamespaceAliasDecl>(NA.getAliasedNamespace()))
+    // This could cache & dedup here rather than relying on metadata deduping.
+    R = DBuilder.createImportedModule(
+        getCurrentContextDescriptor(cast<Decl>(NA.getDeclContext())),
+        EmitNamespaceAlias(*Underlying), getLineNumber(NA.getLocation()),
+        NA.getName());
+  else
+    R = DBuilder.createImportedModule(
+        getCurrentContextDescriptor(cast<Decl>(NA.getDeclContext())),
+        getOrCreateNameSpace(cast<NamespaceDecl>(NA.getAliasedNamespace())),
+        getLineNumber(NA.getLocation()), NA.getName());
+  VH = R;
+  return R;
+}
+
 /// getOrCreateNamesSpace - Return namespace descriptor for the given
 /// namespace decl.
 llvm::DINameSpace
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index f19f750e60f..cca6e1ba31c 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -101,6 +101,7 @@ class CGDebugInfo {
   /// using declarations) that aren't covered by other more specific caches.
   llvm::DenseMap<const Decl *, llvm::WeakVH> DeclCache;
   llvm::DenseMap<const NamespaceDecl *, llvm::WeakVH> NameSpaceCache;
+  llvm::DenseMap<const NamespaceAliasDecl *, llvm::WeakVH> NamespaceAliasCache;
   llvm::DenseMap<const Decl *, llvm::WeakVH> StaticDataMemberCache;
 
   /// Helper functions for getOrCreateType.
@@ -277,6 +278,9 @@ public:
   /// \brief - Emit C++ using declaration.
   void EmitUsingDecl(const UsingDecl &UD);
 
+  /// \brief - Emit C++ namespace alias.
+  llvm::DIImportedEntity EmitNamespaceAlias(const NamespaceAliasDecl &NA);
+
   /// getOrCreateRecordType - Emit record type's standalone debug info.
   llvm::DIType getOrCreateRecordType(QualType Ty, SourceLocation L);
 
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index ce7a13d4567..9741f5878e0 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -79,7 +79,6 @@ void CodeGenFunction::EmitDecl(const Decl &D) {
   case Decl::Enum:      // enum X;
   case Decl::EnumConstant: // enum ? { X = ? }
   case Decl::CXXRecord: // struct/union/class X; [C++]
-  case Decl::NamespaceAlias:
   case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
   case Decl::Label:        // __label__ x;
   case Decl::Import:
@@ -88,6 +87,10 @@ void CodeGenFunction::EmitDecl(const Decl &D) {
     // None of these decls require codegen support.
     return;
 
+  case Decl::NamespaceAlias:
+    if (CGDebugInfo *DI = getDebugInfo())
+        DI->EmitNamespaceAlias(cast<NamespaceAliasDecl>(D));
+    return;
   case Decl::Using:          // using X; [C++]
     if (CGDebugInfo *DI = getDebugInfo())
         DI->EmitUsingDecl(cast<UsingDecl>(D));
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 3a967c6fdc3..e65128813e1 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -2879,10 +2879,13 @@ void CodeGenModule::EmitTopLevelDecl(Decl *D) {
   case Decl::ClassTemplate:
   case Decl::FunctionTemplate:
   case Decl::TypeAliasTemplate:
-  case Decl::NamespaceAlias:
   case Decl::Block:
   case Decl::Empty:
     break;
+  case Decl::NamespaceAlias:
+    if (CGDebugInfo *DI = getModuleDebugInfo())
+        DI->EmitNamespaceAlias(cast<NamespaceAliasDecl>(*D));
+    return;
   case Decl::UsingDirective: // using namespace X; [C++]
     if (CGDebugInfo *DI = getModuleDebugInfo())
       DI->EmitUsingDirective(cast<UsingDirectiveDecl>(*D));