220 40338 article Path: news.gmane.org!.POSTED!not-for-mail From: Rene Rivera Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Runtime code generation and self modifying code Date: Fri, 5 Oct 2018 10:48:17 -0500 Lines: 117 Approved: news@gmane.org Message-ID: References: <4489f889-977c-45f2-8a2f-186ee3b06bff@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="000000000000e641c105777d3323" X-Trace: blaine.gmane.org 1538754385 10506 195.159.176.226 (5 Oct 2018 15:46:25 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Fri, 5 Oct 2018 15:46:25 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCTJDOM7YALBBTMP33OQKGQEZHJFX5A@isocpp.org Fri Oct 05 17:46:21 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qt1-f198.google.com ([209.85.160.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1g8SJ1-0002ci-UX for gclcip-std-proposals@m.gmane.org; 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[209.85.220.41]) by mx.google.com with SMTPS id m20-v6sor4296797qtf.49.2018.10.05.08.48.29 for (Google Transport Security); Fri, 05 Oct 2018 08:48:29 -0700 (PDT) Received-SPF: pass (google.com: domain of grafikrobot@gmail.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; X-Received: by 2002:ac8:435b:: with SMTP id a27-v6mr9575944qtn.295.1538754508897; Fri, 05 Oct 2018 08:48:28 -0700 (PDT) In-Reply-To: <4489f889-977c-45f2-8a2f-186ee3b06bff@isocpp.org> X-Original-Sender: grafikrobot@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=tE4Q2nmK; spf=pass (google.com: domain of grafikrobot@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=grafikrobot@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:40338 Archived-At: --000000000000e641c105777d3323 Content-Type: text/plain; charset="UTF-8" While I understand, and concur, with others statements regarding code generation in the context of the the host program.. There are valid use cases for dynamic code generation. For example targeting emulators and GPUs. So perhaps you might want to rephrase your ideas in those terms. On Thu, Oct 4, 2018 at 7:35 PM Matthew Fioravante wrote: > One big area where dynamic languages are way ahead of C++ is runtime > dynamic code generation or self modifying code. > > > One tiny example is singleton initialization. The only safe way in C++ to > do non-constexpr singletons is by lazy init. > > The problem with lazy init is that you have to pay for a branch on every > access, and that usually involves an atomic check. > > What if you instead you atomically overwrote the check with NOPS. Then the > branch is gone and accessing the object is as efficient as if it weren't > lazy. > > Has anyone considered writing proposals for improving runtime code gen > with C++? > > -- > You received this message because you are subscribed to the Google Groups > "ISO C++ Standard - Future Proposals" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to std-proposals+unsubscribe@isocpp.org. > To post to this group, send email to std-proposals@isocpp.org. > To view this discussion on the web visit > https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/4489f889-977c-45f2-8a2f-186ee3b06bff%40isocpp.org > > . > -- -- Rene Rivera -- Grafik - Don't Assume Anything -- Robot Dreams - http://robot-dreams.net -- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAHEh_GiUrVM%3Da7QK%2BiNuXqFwxXCLyMA7WiRfWmHo_qmceV9JSw%40mail.gmail.com. --000000000000e641c105777d3323 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
While I understand, and concur, with others statements reg= arding code generation in the context of the the host program.. There are v= alid use cases for dynamic code generation. For example targeting emulators= and GPUs. So perhaps you might want to rephrase your ideas in those terms.=


On Thu, Oct 4, 201= 8 at 7:35 PM Matthew Fioravante <fmatthew5876@gmail.com> wrote:
One big area where dynamic languages are way ah= ead of C++ is runtime dynamic code generation or self modifying code.


One tiny example is singleton initia= lization. The only safe way in C++ to do non-constexpr singletons is by laz= y init.

The problem with lazy init is that yo= u have to pay for a branch on every access, and that usually involves an at= omic check.

What if you instead you atomically ove= rwrote the check with NOPS. Then the branch is gone and accessing the objec= t is as efficient as if it weren't lazy.

H= as anyone considered writing proposals for improving runtime code gen with = C++?

--
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
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To post to this group, send email to std-proposals@isocpp.org.
To view this discussion on the web visit = https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/4489f889-977c-= 45f2-8a2f-186ee3b06bff%40isocpp.org.


--
-- Rene Rivera
-- Grafik - Don't Assume An= ything
-- Robot Dreams -=C2=A0http://robot-dreams.net

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