1 files changed, 56 insertions, 9 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index a270976934f..a8ab1c1c6b4 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -611,7 +611,7 @@ llvm::DIDescriptor CGDebugInfo::createContextChain(const Decl *Context) {
 /// then emit record's fwd if debug info size reduction is enabled.
 llvm::DIType CGDebugInfo::CreatePointeeType(QualType PointeeTy,
                                             llvm::DIFile Unit) {
-  if (DebugKind != CodeGenOptions::LimitedDebugInfo)
+  if (DebugKind > CodeGenOptions::LimitedDebugInfo)
     return getOrCreateType(PointeeTy, Unit);
 
   // Limit debug info for the pointee type.
@@ -735,7 +735,7 @@ llvm::DIType CGDebugInfo::CreateType(const BlockPointerType *Ty,
 llvm::DIType CGDebugInfo::CreateType(const TypedefType *Ty, llvm::DIFile Unit) {
   // Typedefs are derived from some other type.  If we have a typedef of a
   // typedef, make sure to emit the whole chain.
-  llvm::DIType Src = getOrCreateType(Ty->getDecl()->getUnderlyingType(), Unit);
+  llvm::DIType Src = CreatePointeeType(Ty->getDecl()->getUnderlyingType(), Unit);
   if (!Src.Verify())
     return llvm::DIType();
   // We don't set size information, but do specify where the typedef was
@@ -2188,6 +2188,30 @@ llvm::DIType CGDebugInfo::CreateMemberType(llvm::DIFile Unit, QualType FType,
   return Ty;
 }
 
+llvm::DIDescriptor CGDebugInfo::getDeclarationOrDefinition(const Decl *D) {
+  // We only need a declaration (not a definition) of the type - so use whatever
+  // we would otherwise do to get a type for a pointee. (forward declarations in
+  // limited debug info, full definitions (if the type definition is available)
+  // in unlimited debug info)
+  if (const TypeDecl *TD = dyn_cast<TypeDecl>(D)) {
+    llvm::DIFile DefUnit = getOrCreateFile(TD->getLocation());
+    return CreatePointeeType(CGM.getContext().getTypeDeclType(TD), DefUnit);
+  }
+  // Otherwise fall back to a fairly rudimentary cache of existing declarations.
+  // This doesn't handle providing declarations (for functions or variables) for
+  // entities without definitions in this TU, nor when the definition proceeds
+  // the call to this function.
+  // FIXME: This should be split out into more specific maps with support for
+  // emitting forward declarations and merging definitions with declarations,
+  // the same way as we do for types.
+  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) {
@@ -2359,6 +2383,8 @@ 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;
@@ -2973,10 +2999,11 @@ 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.
@@ -3021,22 +3048,42 @@ 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());
+  if (CGM.getCodeGenOpts().getDebugInfo() < CodeGenOptions::LimitedDebugInfo)
+    return;
   DBuilder.createImportedModule(
-      Scope, getOrCreateNameSpace(UD.getNominatedNamespace()),
+      getCurrentContextDescriptor(cast<Decl>(UD.getDeclContext())),
+      getOrCreateNameSpace(UD.getNominatedNamespace()),
       getLineNumber(UD.getLocation()));
 }
 
+void CGDebugInfo::EmitUsingDecl(const UsingDecl &UD) {
+  if (CGM.getCodeGenOpts().getDebugInfo() < CodeGenOptions::LimitedDebugInfo)
+    return;
+  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