From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=55WY=7Q=cs.washington.edu=kmatsui@sourceware.org>
Received: from mail-ot1-x32a.google.com (mail-ot1-x32a.google.com [IPv6:2607:f8b0:4864:20::32a])
	by sourceware.org (Postfix) with ESMTPS id 46B393858D28
	for <gcc@gcc.gnu.org>; Fri, 24 Mar 2023 07:09:20 +0000 (GMT)
DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 46B393858D28
Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=cs.washington.edu
Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=cs.washington.edu
Received: by mail-ot1-x32a.google.com with SMTP id k14-20020a9d700e000000b0069faa923e7eso450460otj.10
        for <gcc@gcc.gnu.org>; Fri, 24 Mar 2023 00:09:20 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=cs.washington.edu; s=goo201206; t=1679641758;
        h=to:subject:message-id:date:from:mime-version:from:to:cc:subject
         :date:message-id:reply-to;
        bh=gCQbzR5TxF8QTdADUQ1TT2GhXf7f2eDj3d8SC7V6KJo=;
        b=EYfGO0j6UwOAtk5kBsAj3AKkXUp0kyMXn+p4JVcC+OW783eG7t5An3+wqOuGSXyJ6k
         V3XWmvMRKrnnRlFVxsH7SiWVCXAByw9IWC6r++8gtKeP/oyFAkNepP+JJivT1RbsiEsx
         kf403jvNWVumcKZ6nHfw/Fpu9S2+wjSGnoYkA=
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
        d=1e100.net; s=20210112; t=1679641758;
        h=to:subject:message-id:date:from:mime-version:x-gm-message-state
         :from:to:cc:subject:date:message-id:reply-to;
        bh=gCQbzR5TxF8QTdADUQ1TT2GhXf7f2eDj3d8SC7V6KJo=;
        b=jTHOJ7OqSw/LgZs9Gub6kuIzy/HwjmLYtm6F5kgsa8k9JRPW/K8MdEhUYFB3HxRRvM
         U/cOwK3BhQgw9NGEFXVipPDCxFAVbUNToUS+TVhfJS8YWBVXHyYqVeOvwkRF5vZ4MBmE
         ndG34jHdLGD/D3gBVPD4sxV6nnPnYmp7RgpYzRyYE6oYJPNZKcn0rP4ApaIoBkPu4AAz
         6vG/2bMjEXGlu9actM5KZ4U2lNwtjxuFsWJUlObjm0FolRU+UxMoLuSXz3GS59G2vKkw
         IqHP74Xm3mfNyEpKiXvhwoqFmRC+T3kOqVIfcTG6bc+gTg+KOpS13XV8nYkORD34wx7w
         8nIg==
X-Gm-Message-State: AO0yUKUVtEpLjhWNCsdFu1e8SbaBGXVj2juTvotEg1eF3n9iyNqdFQUW
	vkn8u62wGMcDcTsGJJGXTnxvikbQLRk4QbFRmlonum6763q9/qap8M4=
X-Google-Smtp-Source: AKy350ZDsuJ38jk+3MARBomSMdyLuOPDsI88OhpwSkhYsztXXG8OFvNlP1qlBX6nMzutmU4oLtsdperHX1nIJhFGATU=
X-Received: by 2002:a05:6130:3a9:b0:68d:6360:77b with SMTP id
 az41-20020a05613003a900b0068d6360077bmr1010173uab.1.1679641057349; Thu, 23
 Mar 2023 23:57:37 -0700 (PDT)
MIME-Version: 1.0
From: Ken Matsui <kmatsui@cs.washington.edu>
Date: Thu, 23 Mar 2023 23:57:26 -0700
Message-ID: <CAML+3pVn50Urx8TgnhW=GX1dX27tkxmU3O-1ZUmp-Eyagh8eKQ@mail.gmail.com>
Subject: [GSoC] Question about Relatively Simple Library Traits
To: gcc@gcc.gnu.org
Content-Type: text/plain; charset="UTF-8"
X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org
List-Id: <gcc.gcc.gnu.org>

Hi,

I am working on the GSoC project, "C++: Implement compiler built-in
traits for the standard library traits". I found the following library
traits that I am not sure if implementing built-in traits brings
reasonable speed up.

* std::is_fundamental
* std::is_arithmetic
* std::is_scalar
* std::is_object
* std::is_compound
* std::is_scoped_enum

For example, std::is_object has no template specializations, but its
inheriting class looks complicated.

__not_<__or_<is_function<_Tp>, is_reference<_Tp>, is_void<_Tp>>>::type

If we define the built-in trait for this trait, we have: (as
equivalence of the above code)

__bool_constant<__is_object(_Tp)>

And __is_object built-in trait should be like:

!(type1 == FUNCTION_TYPE || type1 == ...)

In this case, could someone tell me which one would be faster? Or, is
there no other way to know which but to benchmark?

Sincerely,
Ken Matsui