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Re: does virtualizing all methods slow C++ down ?

From Nobody <nobody@nowhere.com>
Subject Re: does virtualizing all methods slow C++ down ?
Date 2011-09-08 07:37 +0100
Message-Id <pan.2011.09.08.06.37.21.453000@nowhere.com>
Newsgroups comp.lang.c++
References (2 earlier) <j45rf0$d9e$1@dont-email.me> <j45tvf$f6c$1@speranza.aioe.org> <j462c0$vt9$1@dont-email.me> <Xns9F59C8DBAEFD2myfirstnameosapriee@216.196.109.131> <4b21a180-0317-45b2-850e-709f7a03c605@k9g2000vbd.googlegroups.com>
Organization Zen Internet

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On Wed, 07 Sep 2011 14:11:05 -0700, Joshua Maurice wrote:

>> some compilers provide extensions to convert a virtual function pointer
>> into a non-virtual one which can then be used inside the loop, providing
>> better optimization possibilities).
> 
> I don't know what that means.

I think that he is referring to automatic specialisation, i.e.:

	if (&obj->method == &Base::method)
		// generated code using inlined Base::method
	else if (&obj->method == &Derived::method)
		// generated code using inlined Derived::method
	...
	else
		// generated code calling obj->method() via vtable

This gets pretty hairy if there are multiple objects and many known
subclasses. And it only works if the method definitions are available.

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Thread

does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 11:31 -0500
  Re: does virtualizing all methods slow C++ down ? Christopher <cpisz@austin.rr.com> - 2011-09-06 10:00 -0700
    Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 14:09 -0500
      Re: does virtualizing all methods slow C++ down ? Christopher <cpisz@austin.rr.com> - 2011-09-06 12:35 -0700
        Re: does virtualizing all methods slow C++ down ? "Kevin P. Fleming" <news@kpfleming.us> - 2011-09-06 16:41 -0500
      Re: does virtualizing all methods slow C++ down ? "Balog Pal" <pasa@lib.hu> - 2011-09-11 12:02 +0200
    Re: does virtualizing all methods slow C++ down ? "Thomas J. Gritzan" <phygon_antispam@gmx.de> - 2011-09-07 02:42 +0200
      Re: does virtualizing all methods slow C++ down ? Noah Roberts <roberts.noah@gmail.com> - 2011-09-07 07:39 -0700
        Re: does virtualizing all methods slow C++ down ? Richard Damon <news.x.richarddamon@xoxy.net> - 2011-09-07 11:46 -0400
    Re: does virtualizing all methods slow C++ down ? Nobody <nobody@nowhere.com> - 2011-09-07 01:45 +0100
  Re: does virtualizing all methods slow C++ down ? Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-09-06 19:12 +0200
    Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 14:13 -0500
      Re: does virtualizing all methods slow C++ down ? jacob navia <jacob@spamsink.net> - 2011-09-06 21:57 +0200
        Re: does virtualizing all methods slow C++ down ? Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-09-06 22:40 +0200
          Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 16:13 -0500
            Re: does virtualizing all methods slow C++ down ? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-09-07 08:01 +0000
              Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-14 12:08 -0500
                Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-14 14:04 -0500
        Re: does virtualizing all methods slow C++ down ? Lynn McGuire <lmc@winsim.com> - 2011-09-06 16:11 -0500
          Re: does virtualizing all methods slow C++ down ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-07 11:44 -0500
            Re: does virtualizing all methods slow C++ down ? Joshua Maurice <joshuamaurice@gmail.com> - 2011-09-07 14:11 -0700
              Re: does virtualizing all methods slow C++ down ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-08 01:26 -0500
              Re: does virtualizing all methods slow C++ down ? Nobody <nobody@nowhere.com> - 2011-09-08 07:37 +0100
              Re: does virtualizing all methods slow C++ down ? zindorsky <nephi.allred@gmail.com> - 2011-09-09 10:20 -0700
                Re: does virtualizing all methods slow C++ down ? "Kevin P. Fleming" <news@kpfleming.us> - 2011-09-10 11:48 -0400
                Re: does virtualizing all methods slow C++ down ? Nobody <nobody@nowhere.com> - 2011-09-10 17:58 +0100
  Re: does virtualizing all methods slow C++ down ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-07 06:19 +0000
  Re: does virtualizing all methods slow C++ down ? Goran <goran.pusic@gmail.com> - 2011-09-06 23:52 -0700
    Re: does virtualizing all methods slow C++ down ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-07 07:57 +0000
      Re: does virtualizing all methods slow C++ down ? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-09-07 10:39 +0000
      Re: does virtualizing all methods slow C++ down ? Goran <goran.pusic@gmail.com> - 2011-09-07 04:30 -0700
        Re: does virtualizing all methods slow C++ down ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-07 13:04 +0000
          Re: does virtualizing all methods slow C++ down ? Goran <goran.pusic@gmail.com> - 2011-09-07 06:18 -0700
  Re: does virtualizing all methods slow C++ down ? ld <laurent.deniau@gmail.com> - 2011-09-08 05:34 -0700

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