From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10642 invoked by alias); 19 Jul 2012 07:12:36 -0000 Received: (qmail 10630 invoked by uid 22791); 19 Jul 2012 07:12:34 -0000 X-SWARE-Spam-Status: No, hits=-4.3 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00,KHOP_THREADED X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 19 Jul 2012 07:12:19 +0000 From: "jakub at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/54021] [c++0x] __builtin_constant_p should be constexpr Date: Thu, 19 Jul 2012 07:12:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: c++ X-Bugzilla-Keywords: X-Bugzilla-Severity: enhancement X-Bugzilla-Who: jakub at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2012-07/txt/msg01451.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54021 --- Comment #2 from Jakub Jelinek 2012-07-19 07:12:18 UTC --- Perhaps the C++ FE could when parsing a constexpr function during finish_call_expr of __builtin_constant_p just temporarily force optimize = 1 if it is zero to prevent folding it to 0 (or alternatively, if it folds to 0, build it non-folded), it would be an extension over how this builtin behaves right now, on the other side as constexpr is "optimized" even at -O0 it would match the intent of the builtin. The question is if/when it will be actually folded to 0 afterwards if not in constexpr context.