Re: [PATCH 2/4] New data structure for cgraph_summary introduced.

[Markus Trippelsdorf]

On 2014.11.14 at 01:19 -0500, Trevor Saunders wrote:
> On Thu, Nov 13, 2014 at 03:48:34PM +0100, Markus Trippelsdorf wrote:
> > On 2014.11.13 at 15:11 +0100, mliska wrote:
> > 
> > > +  /* Destructor.  */
> > > +  virtual ~cgraph_summary ()
> > > +  {
> > > +    destroy ();
> > > +  }
> > 
> > From https://gcc.gnu.org/wiki/CppConventions:
> > 
> > Constructors and destructors are often much larger than programmers
> > expect. Prefer non-inline versions unless you have evidence that the
> > inline version is needed.
> 
> I never really agreed with that, and we don't really follow it.  However
> it really doesn't matter in this case since its virtual.

It doesn't really matter if the destructor is virtual or not, because the same
bloat can happen.

Consider a trivial example that I've found on the web and compare the assembly
output with "virtual ~A ()" defined inline vs. out-of-line:

#include <string>

using namespace std;

class A
{
  string name;
  string address;
  string telephone;

public:
  A (){};
  virtual void
  function ()
  {
  }
  virtual ~A () {}
};

//A::~A (){};

class B : public A
{
public:
  B (){};
  void
  function ()
  {
  }
  ~B () {}
};

void
abc ()
{
  B b;
  b.function ();
}

int
main ()
{
  B b;
  b.function ();
  abc ();
}

-- 
Markus