DebugInfo: hoist definition into global context when needed

[compnerd]

Summary

When generating debug info for a static inline member which is initialized for
the DLLExport storage class, hoist the definition into a non-composite type
context. Otherwise, we would trigger an assertion when generating the DIE for
the associated global value as the debug context has a type association. This
addresses PR22669.

Thanks to David Blakie for help in coming up with a solution to this!

[majnemer]

lib/CodeGen/CGDebugInfo.cpp

2381–2382

Shouldn't this be morally equivalent to DC->getEnclosingNamespaceContext()?

[friss]

lib/CodeGen/CGDebugInfo.cpp

2379–2382

The message makes it look like this change addresses a very particular case related to dllexport, yet the logic makes no mention of it. Care to elaborate why this doesn't change anything is other cases?

[abdulras]

lib/CodeGen/CGDebugInfo.cpp

2379–2382

The dllexport simply makes it easier to expose the issue as the member will be forcefully instantiated, and thus force the materialization of the debug info.

[compnerd]

Address comments from David Blakie.

[dblaikie]

Looks great, please commit.

Thanks!

• David

[compnerd]

(accepting to close)

[compnerd]

Committed in SVN r230816.

lib/CodeGen/CGDebugInfo.cpp

   // FIXME: Generalize this for even non-member global variables where the
   // declaration and definition may have different lexical decl contexts, once
   // we have support for emitting declarations of (non-member) global variables.
-  VDContext = getContextDescriptor(
-      dyn_cast<Decl>(VD->isStaticDataMember() ? VD->getLexicalDeclContext()
-                                              : VD->getDeclContext()));
+  const DeclContext *DC = VD->isStaticDataMember() ? VD->getLexicalDeclContext()
+                                                   : VD->getDeclContext();
+  // When a record type contains an in-line initialization of a static data
+  // member, and the record type is marked as __declspec(dllexport), an implicit
+  // definition of the member will be created in the record context.  DWARF
+  // doesn't seem to have a nice way to describe this in a form that consumers
+  // are likely to understand, so fake the "normal" situation of a definition
+  // outside the class by putting it in the global scope.
+  if (DC->isRecord())
+    DC = CGM.getContext().getTranslationUnitDecl();
+  VDContext = getContextDescriptor(dyn_cast<Decl>(DC));
 }
 
 llvm::DISubprogram

 CGDebugInfo::getOrCreateStaticDataMemberDeclarationOrNull(const VarDecl *D) {
   if (!D->isStaticDataMember())
     return llvm::DIDerivedType();
+
   auto MI = StaticDataMemberCache.find(D->getCanonicalDecl());
   if (MI != StaticDataMemberCache.end()) {
     assert(MI->second && "Static data member declaration should still exist");

test/CodeGenCXX/inline-dllexport-member.cpp

+// RUN: %clang_cc1 -triple i686-windows-gnu -fms-compatibility -g -emit-llvm %s -o - \
+// RUN:    | FileCheck %s
+
+struct __declspec(dllexport) s {
+  static const unsigned int ui = 0;
+};
+
+// CHECK: , [[SCOPE:![^,]*]], {{.*}}, i32* @_ZN1s2uiE, {{.*}}} ; [ DW_TAG_variable ] [ui] [line 5] [def]
+// CHECK: [[SCOPE]] = {{.*}} ; [ DW_TAG_file_type ]
+