Don't emit an internal destructor that is identical to an external one.

It is not safe to emit alias to undefined (not supported by ELF or COFF), but
it is safe to rauw when the alias would have been internal or linkonce_odr.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194307 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/CGCXX.cpp b/lib/CodeGen/CGCXX.cpp
index f9b07d2386b6d5e720bf691ffa7c9ce2b708dc66..f79e079745cd3ee15a445c5ae55d64a8b72d3935 100644 (file)
--- a/lib/CodeGen/CGCXX.cpp
+++ b/lib/CodeGen/CGCXX.cpp
@@ -82,18 +82,12 @@ bool CodeGenModule::TryEmitBaseDestructorAsAlias(const CXXDestructorDecl *D) {
   if (!UniqueBase)
     return true;
 
-  /// If we don't have a definition for the destructor yet, don't
-  /// emit.  We can't emit aliases to declarations; that's just not
-  /// how aliases work.
-  const CXXDestructorDecl *BaseD = UniqueBase->getDestructor();
-  if (!BaseD->isImplicit() && !BaseD->hasBody())
-    return true;
-
   // If the base is at a non-zero offset, give up.
   const ASTRecordLayout &ClassLayout = Context.getASTRecordLayout(Class);
   if (!ClassLayout.getBaseClassOffset(UniqueBase).isZero())
     return true;
 
+  const CXXDestructorDecl *BaseD = UniqueBase->getDestructor();
   return TryEmitDefinitionAsAlias(GlobalDecl(D, Dtor_Base),
                                   GlobalDecl(BaseD, Dtor_Base),
                                   false);
@@ -146,14 +140,20 @@ bool CodeGenModule::TryEmitDefinitionAsAlias(GlobalDecl AliasDecl,
     return false;
   }
 
-  // Don't create an alias to a linker weak symbol unless we know we can do
-  // that in every TU. This avoids producing different COMDATs in different
-  // TUs.
-  if (llvm::GlobalValue::isWeakForLinker(TargetLinkage)) {
-    if (!InEveryTU)
+  if (!InEveryTU) {
+    /// If we don't have a definition for the destructor yet, don't
+    /// emit.  We can't emit aliases to declarations; that's just not
+    /// how aliases work.
+    if (Ref->isDeclaration())
       return true;
 
-    assert(Linkage == TargetLinkage);
+    // Don't create an alias to a linker weak symbol unless we know we can do
+    // that in every TU. This avoids producing different COMDATs in different
+    // TUs.
+    if (llvm::GlobalValue::isWeakForLinker(TargetLinkage)) {
+      assert(Linkage == TargetLinkage);
+      return true;
+    }
   }
 
   // Create the alias with no name.

diff --git a/test/CodeGenCXX/ctor-dtor-alias.cpp b/test/CodeGenCXX/ctor-dtor-alias.cpp
index 6e1c144e5de73b762d34cde8d3334c40124c9baa..745495ac68ff9f6b1ac1d039af317d48bbcba70b 100644 (file)
--- a/test/CodeGenCXX/ctor-dtor-alias.cpp
+++ b/test/CodeGenCXX/ctor-dtor-alias.cpp
@@ -73,3 +73,18 @@ namespace test5 {
   }
   B X;
 }
+
+namespace test6 {
+  // Test that we use ~A directly, even when ~A is not defined. The symbol for
+  // ~B would have been internal and still contain a reference to ~A.
+  struct A {
+    virtual ~A();
+  };
+  namespace {
+  struct B : public A {
+    ~B() {}
+  };
+  }
+  B X;
+  // CHECK-DAG: call i32 @__cxa_atexit({{.*}}@_ZN5test61AD2Ev
+}