From 4e93885bab8c3738fdad3286e99dc147157218e8 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Tue, 1 Feb 2011 05:33:52 +0000
Subject: [PATCH] Correctly merge available_externally and regular definitions
 when they have different visibilities.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124650 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Linker/LinkModules.cpp            | 6 ++++--
 test/Linker/available_externally_a.ll | 5 +++++
 test/Linker/available_externally_b.ll | 4 ++++
 3 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 test/Linker/available_externally_a.ll
 create mode 100644 test/Linker/available_externally_b.ll

diff --git a/lib/Linker/LinkModules.cpp b/lib/Linker/LinkModules.cpp
index ec39c932276..5aa06abdd98 100644
--- a/lib/Linker/LinkModules.cpp
+++ b/lib/Linker/LinkModules.cpp
@@ -434,8 +434,10 @@ static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src,
   }
 
   // Check visibility
-  if (Dest && Src->getVisibility() != Dest->getVisibility())
-    if (!Src->isDeclaration() && !Dest->isDeclaration())
+  if (Dest && Src->getVisibility() != Dest->getVisibility() &&
+      !Src->isDeclaration() && !Dest->isDeclaration() &&
+      !Src->hasAvailableExternallyLinkage() &&
+      !Dest->hasAvailableExternallyLinkage())
       return Error(Err, "Linking globals named '" + Src->getName() +
                    "': symbols have different visibilities!");
   return false;
diff --git a/test/Linker/available_externally_a.ll b/test/Linker/available_externally_a.ll
new file mode 100644
index 00000000000..3ae4ce29140
--- /dev/null
+++ b/test/Linker/available_externally_a.ll
@@ -0,0 +1,5 @@
+; RUN: llvm-link %s %p/available_externally_b.ll -S -o - | FileCheck %s
+
+@foo = available_externally unnamed_addr constant i32 0
+
+; CHECK: @foo = hidden unnamed_addr constant i32 0
diff --git a/test/Linker/available_externally_b.ll b/test/Linker/available_externally_b.ll
new file mode 100644
index 00000000000..526981715a6
--- /dev/null
+++ b/test/Linker/available_externally_b.ll
@@ -0,0 +1,4 @@
+; This file is for use with available_externally_a.ll
+; RUN: true
+
+@foo = hidden unnamed_addr constant i32 0