From f9b1730d415bb82d367b6729e048be729537c8c6 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Mon, 19 Jan 2015 14:02:14 +0000
Subject: [PATCH] Add comdat to thunks.

llvm-svn: 226465
---
 clang/lib/CodeGen/CGVTables.cpp                | 5 ++++-
 clang/test/CodeGenCXX/microsoft-abi-thunks.cpp | 6 +++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index 5416d441672c..772446776505 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -377,7 +377,10 @@ void CodeGenFunction::GenerateThunk(llvm::Function *Fn,
 
   // Set the right linkage.
   CGM.setFunctionLinkage(GD, Fn);
-  
+
+  if (CGM.supportsCOMDAT() && Fn->isWeakForLinker())
+    Fn->setComdat(CGM.getModule().getOrInsertComdat(Fn->getName()));
+
   // Set the right visibility.
   const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl());
   setThunkVisibility(CGM, MD, Thunk, Fn);
diff --git a/clang/test/CodeGenCXX/microsoft-abi-thunks.cpp b/clang/test/CodeGenCXX/microsoft-abi-thunks.cpp
index 39a67430891d..5ca04fe5046a 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-thunks.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-thunks.cpp
@@ -33,10 +33,10 @@ struct C : A, B {
   virtual ~C();
   // MANGLING-DAG: declare {{.*}} @"\01??1C@@UAE@XZ"({{.*}})
   // MANGLING-DAG: define {{.*}} @"\01??_GC@@UAEPAXI@Z"({{.*}})
-  // MANGLING-DAG: define {{.*}} @"\01??_EC@@W3AEPAXI@Z"({{.*}})
+  // MANGLING-DAG: define {{.*}} @"\01??_EC@@W3AEPAXI@Z"({{.*}}) {{.*}} comdat
   // MANGLING-X64-DAG: declare {{.*}} @"\01??1C@@UEAA@XZ"({{.*}})
   // MANGLING-X64-DAG: define {{.*}} @"\01??_GC@@UEAAPEAXI@Z"({{.*}})
-  // MANGLING-X64-DAG: define {{.*}} @"\01??_EC@@W7EAAPEAXI@Z"({{.*}})
+  // MANGLING-X64-DAG: define {{.*}} @"\01??_EC@@W7EAAPEAXI@Z"({{.*}}) {{.*}} comdat
 
   // Overrides public_f() of two subobjects with distinct vfptrs, thus needs a thunk.
   virtual void public_f();
@@ -61,7 +61,7 @@ struct C : A, B {
 
 C::C() {}  // Emits vftable and forces thunk generation.
 
-// CODEGEN-LABEL: define linkonce_odr x86_thiscallcc i8* @"\01??_EC@@W3AEPAXI@Z"(%struct.C* %this, i32 %should_call_delete)
+// CODEGEN-LABEL: define linkonce_odr x86_thiscallcc i8* @"\01??_EC@@W3AEPAXI@Z"(%struct.C* %this, i32 %should_call_delete) {{.*}} comdat
 // CODEGEN:   getelementptr i8* {{.*}}, i32 -4
 // FIXME: should actually call _EC, not _GC.
 // CODEGEN:   call x86_thiscallcc i8* @"\01??_GC@@UAEPAXI@Z"