Commit 7eae8c6e authored by Richard Smith's avatar Richard Smith
Browse files

Don't update the vptr at the start of the destructor of a final class. 

In this case, we know statically that we're destroying the most-derived
class, so the vptr must already point to the current class and never
needs to be updated.
parent 85e56589

clang/lib/CodeGen/CGClass.cpp

+5 −0
Original line number Diff line number Diff line
@@ -1424,6 +1424,11 @@ static bool CanSkipVTablePointerInitialization(CodeGenFunction &CGF, 
  if (!ClassDecl->isDynamicClass())

    return true;



  // For a final class, the vtable pointer is known to already point to the

  // class's vtable.

  if (ClassDecl->isEffectivelyFinal())

    return true;



  if (!Dtor->hasTrivialBody())

    return false;

clang/test/CodeGenCXX/destructors.cpp

+34 −0
Original line number Diff line number Diff line
@@ -529,4 +529,38 @@ namespace test11 { 
  }



}



namespace final_dtor {

  struct A {

    virtual void f();

    // CHECK6-LABEL: define {{.*}} @_ZN10final_dtor1AD2Ev(

    // CHECK6: store {{.*}} @_ZTV

    // CHECK6-LABEL: {{^}}}

    virtual ~A() { f(); }

  };

  struct B : A {

    // CHECK6-LABEL: define {{.*}} @_ZN10final_dtor1BD2Ev(

    // CHECK6: store {{.*}} @_ZTV

    // CHECK6-LABEL: {{^}}}

    virtual ~B() { f(); }

  };

  struct C final : A {

    // CHECK6-LABEL: define {{.*}} @_ZN10final_dtor1CD2Ev(

    // CHECK6-NOT: store {{.*}} @_ZTV

    // CHECK6-LABEL: {{^}}}

    virtual ~C() { f(); }

  };

  struct D : A {

    // CHECK6-LABEL: define {{.*}} @_ZN10final_dtor1DD2Ev(

    // CHECK6-NOT: store {{.*}} @_ZTV

    // CHECK6-LABEL: {{^}}}

    virtual ~D() final { f(); }

  };

  void use() {

    {A a;}

    {B b;}

    {C c;}

    {D d;}

  }

}

#endif