From 1fb1a044e5cedc0ebda23ae0566565c336f9ceb5 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Fri, 7 Nov 2014 07:26:38 +0000
Subject: [PATCH] CodeGen, Itanium: Properly dllimport RTTI data

We would blindly assume that RTTI data should have the same linkage as
the vtable because we didn't think the RTTI data was external.  This
oversight stemmed because we didn't take dllimport into account.

This fixes PR21512.

llvm-svn: 221511
---
 clang/lib/CodeGen/ItaniumCXXABI.cpp      | 11 ++++++++++-
 clang/test/CodeGenCXX/dllimport-rtti.cpp | 18 +++++++++++-------
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 084fd3be5b3a..66ea0f684484 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -2190,6 +2190,11 @@ ItaniumRTTIBuilder::GetAddrOfExternalRTTIDescriptor(QualType Ty) {
                                   /*Constant=*/true,
                                   llvm::GlobalValue::ExternalLinkage, nullptr,
                                   Name);
+    if (const RecordType *RecordTy = dyn_cast<RecordType>(Ty)) {
+      const CXXRecordDecl *RD = cast<CXXRecordDecl>(RecordTy->getDecl());
+      if (RD->hasAttr<DLLImportAttr>())
+        GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
+    }
   }
 
   return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy);
@@ -2312,7 +2317,11 @@ static bool ShouldUseExternalRTTIDescriptor(CodeGenModule &CGM,
 
     // FIXME: this may need to be reconsidered if the key function
     // changes.
-    return CGM.getVTables().isVTableExternal(RD);
+    if (CGM.getVTables().isVTableExternal(RD))
+      return true;
+
+    if (RD->hasAttr<DLLImportAttr>())
+      return true;
   }
 
   return false;
diff --git a/clang/test/CodeGenCXX/dllimport-rtti.cpp b/clang/test/CodeGenCXX/dllimport-rtti.cpp
index 7ed7dadfe402..b5a5d543d6e2 100644
--- a/clang/test/CodeGenCXX/dllimport-rtti.cpp
+++ b/clang/test/CodeGenCXX/dllimport-rtti.cpp
@@ -1,13 +1,17 @@
-// RUN: %clang_cc1 -triple i686-windows-msvc -emit-llvm -std=c++1y -O1 -disable-llvm-optzns -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple i686-windows-msvc -emit-llvm -std=c++1y -O1 -disable-llvm-optzns -o - %s | FileCheck %s --check-prefix=MSVC
+// RUN: %clang_cc1 -triple i686-windows-gnu  -emit-llvm -std=c++1y -O1 -disable-llvm-optzns -o - %s | FileCheck %s --check-prefix=GNU
 
 struct __declspec(dllimport) S {
-  virtual void f();
+  virtual void f() {}
 } s;
-// CHECK-DAG: @"\01??_7S@@6B@" = available_externally dllimport
-// CHECK-DAG: @"\01??_R0?AUS@@@8" = linkonce_odr
-// CHECK-DAG: @"\01??_R1A@?0A@EA@S@@8" = linkonce_odr
-// CHECK-DAG: @"\01??_R2S@@8" = linkonce_odr
-// CHECK-DAG: @"\01??_R3S@@8" = linkonce_odr
+// MSVC-DAG: @"\01??_7S@@6B@" = available_externally dllimport
+// MSVC-DAG: @"\01??_R0?AUS@@@8" = linkonce_odr
+// MSVC-DAG: @"\01??_R1A@?0A@EA@S@@8" = linkonce_odr
+// MSVC-DAG: @"\01??_R2S@@8" = linkonce_odr
+// MSVC-DAG: @"\01??_R3S@@8" = linkonce_odr
+
+// GNU-DAG: @_ZTV1S = available_externally dllimport
+// GNU-DAG: @_ZTI1S = external dllimport
 
 struct U : S {
 } u;