commit d914fd2163663b4fb7964a6b7001a8182b864705
author Peter Collingbourne <peter@pcc.me.uk> Mon Jun 18 20:58:54 2018 +0000
committer Peter Collingbourne <peter@pcc.me.uk> Mon Jun 18 20:58:54 2018 +0000
tree 3cb0856ac66a4e417c0247d169ad66b988ce9596
parent feb4537b442b9b34022edefb844157a05344fa31

IRgen: Mark aliases of ctors and dtors as unnamed_addr.

This is not only semantically correct but ensures that they will not
be marked as address-significant once D48155 lands.

Differential Revision: https://reviews.llvm.org/D48206

llvm-svn: 334982

clang/lib/CodeGen/CGCXX.cpp

diff --git a/clang/lib/CodeGen/CGCXX.cpp b/clang/lib/CodeGen/CGCXX.cpp
index cde4c9b..475f17b 100644
--- a/clang/lib/CodeGen/CGCXX.cpp
+++ b/clang/lib/CodeGen/CGCXX.cpp
@@ -109,17 +109,8 @@
       D->getType()->getAs<FunctionType>()->getCallConv())
     return true;
 
-  return TryEmitDefinitionAsAlias(GlobalDecl(D, Dtor_Base),
-                                  GlobalDecl(BaseD, Dtor_Base));
-}
-
-/// Try to emit a definition as a global alias for another definition.
-/// If \p InEveryTU is true, we know that an equivalent alias can be produced
-/// in every translation unit.
-bool CodeGenModule::TryEmitDefinitionAsAlias(GlobalDecl AliasDecl,
-                                             GlobalDecl TargetDecl) {
-  if (!getCodeGenOpts().CXXCtorDtorAliases)
-    return true;
+  GlobalDecl AliasDecl(D, Dtor_Base);
+  GlobalDecl TargetDecl(BaseD, Dtor_Base);
 
   // The alias will use the linkage of the referent.  If we can't
   // support aliases with that linkage, fail.
@@ -193,6 +184,9 @@
   auto *Alias = llvm::GlobalAlias::create(AliasValueType, 0, Linkage, "",
                                           Aliasee, &getModule());
 
+  // Destructors are always unnamed_addr.
+  Alias->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
+
   // Switch any previous uses to the alias.
   if (Entry) {
     assert(Entry->getType() == AliasType &&

clang/lib/CodeGen/CodeGenModule.h

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 8982398..bf22ad2 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -1193,7 +1193,6 @@
   /// are emitted lazily.
   void EmitGlobal(GlobalDecl D);
 
-  bool TryEmitDefinitionAsAlias(GlobalDecl Alias, GlobalDecl Target);
   bool TryEmitBaseDestructorAsAlias(const CXXDestructorDecl *D);
 
   llvm::GlobalValue *GetGlobalValue(StringRef Ref);

clang/lib/CodeGen/ItaniumCXXABI.cpp

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index b79e51f..d855afa 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -3693,6 +3693,9 @@
   // Create the alias with no name.
   auto *Alias = llvm::GlobalAlias::create(Linkage, "", Aliasee);
 
+  // Constructors and destructors are always unnamed_addr.
+  Alias->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
+
   // Switch any previous uses to the alias.
   if (Entry) {
     assert(Entry->getType() == Aliasee->getType() &&