From a0706a9ff4469b137ed6eea3f484a0152bab4c88 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Mon, 25 Jun 2012 14:30:31 +0000
Subject: [PATCH] If a constant or a function has linkonce_odr linkage and
 unnamed_addr, mark it hidden. Being linkonce_odr guarantees that it is
 available in every dso that needs it. Being a constant/function with
 unnamed_addr guarantees that the copies don't have to be merged.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159136 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/GlobalValue.h          |  6 ++++++
 lib/Transforms/IPO/GlobalOpt.cpp    | 11 +++++++++++
 test/Transforms/GlobalOpt/hidden.ll | 14 ++++++++++++++
 3 files changed, 31 insertions(+)
 create mode 100644 test/Transforms/GlobalOpt/hidden.ll

diff --git a/include/llvm/GlobalValue.h b/include/llvm/GlobalValue.h
index 8b969f3354c..3b83b5a05c2 100644
--- a/include/llvm/GlobalValue.h
+++ b/include/llvm/GlobalValue.h
@@ -122,6 +122,9 @@ public:
   static bool isAvailableExternallyLinkage(LinkageTypes Linkage) {
     return Linkage == AvailableExternallyLinkage;
   }
+  static bool isLinkOnceODRLinkage(LinkageTypes Linkage) {
+    return Linkage == LinkOnceODRLinkage;
+  }
   static bool isLinkOnceLinkage(LinkageTypes Linkage) {
     return Linkage == LinkOnceAnyLinkage || Linkage == LinkOnceODRLinkage;
   }
@@ -202,6 +205,9 @@ public:
   bool hasAvailableExternallyLinkage() const {
     return isAvailableExternallyLinkage(Linkage);
   }
+  bool hasLinkOnceODRLinkage() const {
+    return isLinkOnceODRLinkage(Linkage);
+  }
   bool hasLinkOnceLinkage() const {
     return isLinkOnceLinkage(Linkage);
   }
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index 35f98b22653..2f1af187f92 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1731,6 +1731,12 @@ bool GlobalOpt::ProcessGlobal(GlobalVariable *GV,
     return true;
   }
 
+  if (GV->hasLinkOnceODRLinkage() && GV->hasUnnamedAddr() && GV->isConstant() &&
+      GV->getVisibility() != GlobalValue::HiddenVisibility) {
+    GV->setVisibility(GlobalValue::HiddenVisibility);
+    return true;
+  }
+
   if (!GV->hasLocalLinkage())
     return false;
 
@@ -1743,6 +1749,7 @@ bool GlobalOpt::ProcessGlobal(GlobalVariable *GV,
   if (!GS.isCompared && !GV->hasUnnamedAddr()) {
     GV->setUnnamedAddr(true);
     NumUnnamed++;
+    return true;
   }
 
   if (GV->isConstant() || !GV->hasInitializer())
@@ -1917,6 +1924,10 @@ bool GlobalOpt::OptimizeFunctions(Module &M) {
       F->eraseFromParent();
       Changed = true;
       ++NumFnDeleted;
+    } else if (F->hasLinkOnceODRLinkage() && F->hasUnnamedAddr() &&
+               F->getVisibility() != GlobalValue::HiddenVisibility) {
+      F->setVisibility(GlobalValue::HiddenVisibility);
+      Changed = true;
     } else if (F->hasLocalLinkage()) {
       if (F->getCallingConv() == CallingConv::C && !F->isVarArg() &&
           !F->hasAddressTaken()) {
diff --git a/test/Transforms/GlobalOpt/hidden.ll b/test/Transforms/GlobalOpt/hidden.ll
new file mode 100644
index 00000000000..301e158d534
--- /dev/null
+++ b/test/Transforms/GlobalOpt/hidden.ll
@@ -0,0 +1,14 @@
+; RUN: opt %s -globalopt -S | FileCheck %s
+
+@foo = linkonce_odr unnamed_addr constant i32 42
+; CHECK: @foo = linkonce_odr hidden unnamed_addr constant i32 42
+
+define linkonce_odr void @bar() unnamed_addr {
+; CHECK: define linkonce_odr hidden void @bar() unnamed_addr {
+  ret void
+}
+
+define i32* @zed() {
+  call void @bar()
+  ret i32* @foo
+}
-- 
2.34.1