From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 14990 invoked by alias); 4 Nov 2014 20:13:14 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 14980 invoked by uid 89); 4 Nov 2014 20:13:13 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.2 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Tue, 04 Nov 2014 20:13:10 +0000 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id sA4KD81X032649 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 4 Nov 2014 15:13:08 -0500 Received: from [10.10.50.165] (vpn-50-165.rdu2.redhat.com [10.10.50.165]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id sA4KD7LH027903; Tue, 4 Nov 2014 15:13:07 -0500 Message-ID: <54593352.2000700@redhat.com> Date: Tue, 04 Nov 2014 20:13:00 -0000 From: Andrew MacLeod User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Richard Biener , Richard Henderson , gcc-patches CC: Jeff Law , Andrew Haley Subject: Re: [patch] Provide a can_compare_and_swap_p target hook. References: <5458FE9C.2090409@redhat.com> <54590C19.40208@redhat.com> <54591348.1010904@redhat.com> <545913A4.5010400@redhat.com> <54591B3A.8030908@redhat.com> <70044BE8-9F38-4BDB-B73F-6E2FC9AC2629@gmail.com> In-Reply-To: <70044BE8-9F38-4BDB-B73F-6E2FC9AC2629@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2014-11/txt/msg00228.txt.bz2 On 11/04/2014 02:53 PM, Richard Biener wrote: > On November 4, 2014 7:30:18 PM CET, Andrew MacLeod wrote: >> On 11/04/2014 12:57 PM, Richard Henderson wrote: >>> On 11/04/2014 06:56 PM, Andrew MacLeod wrote: >>>> On 11/04/2014 12:25 PM, Richard Henderson wrote: >>>>> On 11/04/2014 05:28 PM, Andrew MacLeod wrote: >>>>>> + bool >>>>>> + default_can_compare_and_swap_p (machine_mode mode, bool >> allow_libcall) >>>>>> + { >>>>>> + return can_compare_and_swap_p (mode, allow_libcall); >>>>>> + } >>>>> This is silly. I think the problem you point out can be better >> fixed by moving >>>>> the can_compare_and_swap_p prototype elsewhere. >>>>> >>>> yeah, except it uses some of the optab table stuff that is static to >>>> optabs.c... so the basic functionality remains there. >>> I said move the prototype. Of course the implementation remains >> where it is. >> prototype is in optabs.h where it belongs since its defined in >> optabs.c. :-) >> >> I'm not sure why this is much different than something like the >> targhook >> for builtin_support_vector_misalignment(), other than we are calling >> the >> routine in optabs.c rather than putting the actual code in targhooks.c. >> > >from targhooks.c: >> bool >> default_builtin_support_vector_misalignment (machine_mode mode, >> const_tree type, <...>) >> { >> if (optab_handler (movmisalign_optab, mode) != CODE_FOR_nothing) >> return true; >> return false; >> } >> >> the idea is to move all the functionality that front ends need into >> well >> defined and controlled places so we can increase the separation. "can >> perform a compare_and_swap operation" is clearly a target specific >> question isn't it? > I would rather question what is so special about java that it needs to ask that and other frontends not. Don't we have generic atomics support now? > > Richard. > True... I don't know if this is a thing that simply predates our current level of support or if it is something else that is java specific for its builtins. Don't know enough about java to comment. aph? Looks like you wrote the originals in 2006... Can the java CAS builtins simply use our current atomic calls rather than doing their own thing and querying whether the target has a sync compare and swap operation? Andrew