[ObjC-GNUstep] Fix ivars for dll{im,ex}ported classes.

[theraven]

Summary

If a class is dllexported or imported then the ivar offset variables
must be as well.

clang/lib/CodeGen/CGObjCGNU.cpp

 //===------- CGObjCGNU.cpp - Emit LLVM Code from ASTs for a Module --------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
if (EarlyInitList.size() > 0) {
           &CGM.getModule());
       llvm::IRBuilder<> b(llvm::BasicBlock::Create(CGM.getLLVMContext(), "entry",
             Init));
       for (const auto &lateInit : EarlyInitList) {
         auto *global = TheModule.getGlobalVariable(lateInit.first);
         if (global) {
           llvm::GlobalVariable *GV = lateInit.second.first;
           b.CreateAlignedStore(
-              global,
+              llvm::ConstantExpr::getBitCast(global, PtrTy),
               b.CreateStructGEP(GV->getValueType(), GV, lateInit.second.second),
               CGM.getPointerAlign().getAsAlign());
         }
       }
       b.CreateRetVoid();
       // We can't use the normal LLVM global initialisation array, because we
       // need to specify that this runs early in library initialisation.
       auto *InitVar = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
std::string GetIVarOffsetVariableName(const ObjCInterfaceDecl *ID,
     CGM.getContext().getObjCEncodingForType(Ivar->getType(), TypeEncoding);
     // Prevent the @ from being interpreted as a symbol version.
     std::replace(TypeEncoding.begin(), TypeEncoding.end(),
       '@', '\1');
     const std::string Name = "__objc_ivar_offset_" + ID->getNameAsString()
       + '.' + Ivar->getNameAsString() + '.' + TypeEncoding;
     return Name;
   }
-  llvm::Value *EmitIvarOffset(CodeGenFunction &CGF,
+
+  llvm::GlobalVariable *EmitIvarOffsetVariable(
                               const ObjCInterfaceDecl *Interface,
-                              const ObjCIvarDecl *Ivar) override {
+                              const ObjCIvarDecl *Ivar) {
     const std::string Name = GetIVarOffsetVariableName(Ivar->getContainingInterface(), Ivar);
     llvm::GlobalVariable *IvarOffsetPointer = TheModule.getNamedGlobal(Name);
-    if (!IvarOffsetPointer)
+    if (!IvarOffsetPointer) {
       IvarOffsetPointer = new llvm::GlobalVariable(TheModule, IntTy, false,
               llvm::GlobalValue::ExternalLinkage, nullptr, Name);
+      if (CGM.getTriple().isOSBinFormatCOFF()) {
+        if (Interface->hasAttr<DLLExportAttr>() &&
+            (Ivar->getCanonicalAccessControl() != ObjCIvarDecl::Private) &&
+            (Ivar->getCanonicalAccessControl() != ObjCIvarDecl::Package))
+          IvarOffsetPointer->setDLLStorageClass(
+            llvm::GlobalValue::DLLExportStorageClass);
+        else if (Interface->hasAttr<DLLImportAttr>())
+          IvarOffsetPointer->setDLLStorageClass(
+            llvm::GlobalValue::DLLImportStorageClass);
+      }
+    }
+    return IvarOffsetPointer;
+  }
+
+  llvm::Value *EmitIvarOffset(CodeGenFunction &CGF,
+                              const ObjCInterfaceDecl *Interface,
+                              const ObjCIvarDecl *Ivar) override {
+    llvm::GlobalVariable *IvarOffsetPointer = EmitIvarOffsetVariable(Interface, Ivar);
     CharUnits Align = CGM.getIntAlign();
     llvm::Value *Offset =
         CGF.Builder.CreateAlignedLoad(IntTy, IvarOffsetPointer, Align);
     if (Offset->getType() != PtrDiffTy)
       Offset = CGF.Builder.CreateZExtOrBitCast(Offset, PtrDiffTy);
     return Offset;
   }
   void GenerateClass(const ObjCImplementationDecl *OID) override {
else {
         std::string TypeStr;
         //Context.getObjCEncodingForType(ivarTy, TypeStr, IVD, true);
         Context.getObjCEncodingForMethodParameter(Decl::OBJC_TQ_None, ivarTy, TypeStr, true);
         ivarBuilder.add(MakeConstantString(TypeStr));
         // int *offset;
         uint64_t BaseOffset = ComputeIvarBaseOffset(CGM, OID, IVD);
         uint64_t Offset = BaseOffset - superInstanceSize;
         llvm::Constant *OffsetValue = llvm::ConstantInt::get(IntTy, Offset);
-        std::string OffsetName = GetIVarOffsetVariableName(classDecl, IVD);
-        llvm::GlobalVariable *OffsetVar = TheModule.getGlobalVariable(OffsetName);
-        if (OffsetVar)
-          OffsetVar->setInitializer(OffsetValue);
-        else
-          OffsetVar = new llvm::GlobalVariable(TheModule, IntTy,
-            false, llvm::GlobalValue::ExternalLinkage,
-            OffsetValue, OffsetName);
+        llvm::GlobalVariable *OffsetVar = EmitIvarOffsetVariable(classDecl, IVD);
         auto ivarVisibility =
             (IVD->getAccessControl() == ObjCIvarDecl::Private ||
              IVD->getAccessControl() == ObjCIvarDecl::Package ||
              classDecl->getVisibility() == HiddenVisibility) ?
                     llvm::GlobalValue::HiddenVisibility :
                     llvm::GlobalValue::DefaultVisibility;
         OffsetVar->setVisibility(ivarVisibility);
         ivarBuilder.add(OffsetVar);

clang/test/CodeGenObjC/gnustep2-dllexport-ivar.m

+// RUN: %clang_cc1 -triple x86_64-unknown-windows-msvc -S -emit-llvm -fobjc-runtime=gnustep-2.0 -o - %s | FileCheck %s
+
+__attribute__((dllexport))
+@interface Cls
+{
+  int implicit_prot;
+  @public
+  int pub;
+  @protected
+  int prot;
+  @private
+  int priv;
+  @package
+  int pkg;
+}
+@end
+@implementation Cls @end
+
+// CHECK: @__objc_ivar_offset_Cls.implicit_prot.i = dllexport global i32 0
+// CHECK: @__objc_ivar_offset_Cls.pub.i = dllexport global i32 4
+// CHECK: @__objc_ivar_offset_Cls.prot.i = dllexport global i32 8
+// CHECK: @__objc_ivar_offset_Cls.priv.i = hidden global i32 12
+// CHECK: @__objc_ivar_offset_Cls.pkg.i = hidden global i32 16
+
+__attribute__((dllimport))
+@interface ClsImport
+{
+  int implicit_prot;
+  @public
+  int pub;
+  @protected
+  int prot;
+}
+@end
+
+@interface Sub : ClsImport @end
+
+@implementation Sub
+- (id)init
+{
+  implicit_prot = 0;
+  pub = 1;
+  prot = 2;
+  return self;
+}
+@end