From 9610d77508bdca13e0475783ff404428611c9683 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Mon, 17 Jun 2013 20:04:51 +0000
Subject: [PATCH] Cleanup linkage computation for static locals.

With this patch we assign VisibleNoLinkage to static locals in inline functions.
This lets us simplify CodeGen a bit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@184114 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/Decl.cpp            |  6 +++++-
 lib/CodeGen/CGDecl.cpp      |  8 +++-----
 test/CodeGenCXX/linkage.cpp | 11 +++++++++++
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index a36fcf2507..c799161e9b 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -1043,9 +1043,13 @@ static LinkageInfo getLVForLocalDecl(const NamedDecl *D,
 
       return LV;
     }
+
+    if (!Var->isStaticLocal())
+      return LinkageInfo::none();
   }
 
-  if (!isa<TagDecl>(D))
+  ASTContext &Context = D->getASTContext();
+  if (!Context.getLangOpts().CPlusPlus)
     return LinkageInfo::none();
 
   const FunctionDecl *FD = getOutermostFunctionContext(D);
diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index cb15748646..614eaab3f3 100644
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -126,10 +126,8 @@ void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
 
     // If the function definition has some sort of weak linkage, its
     // static variables should also be weak so that they get properly
-    // uniqued.  We can't do this in C, though, because there's no
-    // standard way to agree on which variables are the same (i.e.
-    // there's no mangling).
-    if (getLangOpts().CPlusPlus) {
+    // uniqued.
+    if (D.isExternallyVisible()) {
       const Decl *D = CurCodeDecl;
       while (true) {
         if (isa<BlockDecl>(D)) {
@@ -143,7 +141,7 @@ void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
         }
       }
       // FIXME: Do we really only care about FunctionDecls here?
-      if (D && isa<FunctionDecl>(D)) {
+      if (isa<FunctionDecl>(D)) {
         llvm::GlobalValue::LinkageTypes ParentLinkage =
             CGM.getFunctionLinkage(cast<FunctionDecl>(D));
         if (llvm::GlobalValue::isWeakForLinker(ParentLinkage))
diff --git a/test/CodeGenCXX/linkage.cpp b/test/CodeGenCXX/linkage.cpp
index 7c67029399..c7feaefeb8 100644
--- a/test/CodeGenCXX/linkage.cpp
+++ b/test/CodeGenCXX/linkage.cpp
@@ -209,3 +209,14 @@ namespace test16 {
   }
   void *test() { return foo<int>::bar(); }
 }
+
+namespace test17 {
+  // CHECK-DAG: @_ZZN6test173fooILi42EEEPivE3bar = weak_odr
+  // CHECK-DAG: define weak_odr i32* @_ZN6test173fooILi42EEEPiv(
+  template<int I>
+  int *foo() {
+    static int bar;
+    return &bar;
+  }
+  template int *foo<42>();
+}
-- 
2.40.0