CodeGen: tweak CFString emission for COFF targets

The `isa' member was previously not given the correct DLL Storage.  Ensure that
we give the `isa' constant `__CFConstantStringClassReference' the correct DLL
storage.  Default to dllimport unless an explicit specification gives it a
dllexport storage.

llvm-svn: 271361

1 files changed, 21 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index eb3adcb6e7d..badc5938062 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3099,6 +3099,27 @@ CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) {
     Ty = llvm::ArrayType::get(Ty, 0);
     llvm::Constant *GV =
         CreateRuntimeVariable(Ty, "__CFConstantStringClassReference");
+
+    if (getTarget().getTriple().isOSBinFormatCOFF()) {
+      IdentifierInfo &II = getContext().Idents.get(GV->getName());
+      TranslationUnitDecl *TUDecl = getContext().getTranslationUnitDecl();
+      DeclContext *DC = TranslationUnitDecl::castToDeclContext(TUDecl);
+      llvm::GlobalValue *CGV = cast<llvm::GlobalValue>(GV);
+
+      const VarDecl *VD = nullptr;
+      for (const auto &Result : DC->lookup(&II))
+        if ((VD = dyn_cast<VarDecl>(Result)))
+          break;
+
+      if (!VD || !VD->hasAttr<DLLExportAttr>()) {
+        CGV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
+        CGV->setLinkage(llvm::GlobalValue::ExternalLinkage);
+      } else {
+        CGV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass);
+        CGV->setLinkage(llvm::GlobalValue::ExternalLinkage);
+      }
+    }
+
     // Decay array -> ptr
     V = llvm::ConstantExpr::getGetElementPtr(Ty, GV, Zeros);
     CFConstantStringClassRef = V;