Don't create hidden dllimport global values

[• espindola]

Summary

hidden visibility is almost the opposite of dllimport. We were producing them before (dllimport wins in the existing llvm implementation), but now the llvm verifier produces an error.

[colden]

Confirmed, this fixes my issue! Thanks!

[rnk]

lgtm

[• espindola]

323361

lib/CodeGen/CodeGenModule.cpp

 
 llvm::ConstantInt *CodeGenModule::getSize(CharUnits size) {
   return llvm::ConstantInt::get(SizeTy, size.getQuantity());
 }
 
 void CodeGenModule::setGlobalVisibility(llvm::GlobalValue *GV,
                                         const NamedDecl *D,
                                         ForDefinition_t IsForDefinition) const {
+  if (GV->hasDLLImportStorageClass())
+    return;
   // Internal definitions always have default visibility.
   if (GV->hasLocalLinkage()) {
     GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
     return;
   }
 
   // Set visibility for definitions.
   LinkageInfo LV = D->getLinkageAndVisibility();

test/CodeGenCXX/hidden-dllimport.cpp

+// RUN: %clang_cc1 -triple x86_64-pc-windows-msvc -emit-llvm -fvisibility-inlines-hidden -o - %s | FileCheck %s
+
+// We used to declare this hidden dllimport, which is contradictory.
+
+// CHECK: declare dllimport void @"\01?bar@foo@@QEAAXXZ"(%struct.foo*)
+
+struct __attribute__((dllimport)) foo {
+  void bar() {}
+};
+void zed(foo *p) { p->bar(); }