Set the visibility to 'hidden' when previous

declaration of global var is __private_extern__.
// rdar://9609649


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133157 91177308-0d34-0410-b5e6-96231b3b80d8

Author: Fariborz Jahanian

lib/CodeGen/CodeGenModule.cpp

@@ -206,8 +206,17 @@ void CodeGenModule::setGlobalVisibility(llvm::GlobalValue *GV,
 
   // Set visibility for definitions.
   NamedDecl::LinkageInfo LV = D->getLinkageAndVisibility();
-  if (LV.visibilityExplicit() || !GV->hasAvailableExternallyLinkage())
-    GV->setVisibility(GetLLVMVisibility(LV.visibility()));
+  if (LV.visibilityExplicit() || !GV->hasAvailableExternallyLinkage()) {
+    Visibility Vis = LV.visibility();
+    if (Vis == DefaultVisibility)
+      if (const VarDecl *VD = dyn_cast<VarDecl>(D))
+        if (const VarDecl *Old = VD->getPreviousDeclaration()) {
+          Visibility OldVis = Old->getLinkageAndVisibility().visibility();
+          if (OldVis == HiddenVisibility)
+            Vis = HiddenVisibility;
+        }
+    GV->setVisibility(GetLLVMVisibility(Vis));
+  }
 }
 
 /// Set the symbol visibility of type information (vtable and RTTI)

test/CodeGen/private-extern-redef.c

@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -triple x86_64-darwin-apple -emit-llvm -o - %s | FileCheck %s
+// rdar://9609649
+
+__private_extern__ const int I;
+__private_extern__ const int J = 927;
+
+__private_extern__ const int K;
+const int K = 37;
+
+const int L = 10;
+__private_extern__ const int L;
+
+__private_extern__ int M;
+int M = 20;
+
+__private_extern__ int N;
+int N;
+
+__private_extern__ int O;
+int O=1;
+
+__private_extern__ int P;
+extern int P;
+
+void bar(int);
+
+void foo() {
+  bar(I);
+}
+
+// CHECK: @J = hidden constant
+// CHECK: @K = hidden constant
+// CHECK: @L = constant
+// CHECK: @M = hidden global
+// CHECK: @O = hidden global
+// CHECK: @I = external hidden
+// CHECK: @N = common hidden global
+// CHECK-NOT: @P
+