From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55253C433B4 for ; Fri, 9 Apr 2021 21:41:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E93761182 for ; Fri, 9 Apr 2021 21:41:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234740AbhDIVlX (ORCPT ); Fri, 9 Apr 2021 17:41:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234079AbhDIVlX (ORCPT ); Fri, 9 Apr 2021 17:41:23 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E975C061762; Fri, 9 Apr 2021 14:41:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=P/s2Ue8tfUf8Zu4yN9wAj8vX3TNV9TrqTppYCfStYUo=; b=NwBfR88B939aVbdUd4cBDIJkvE lkUYFuPgXl3kUsRdPDUa8snafgqQ6RiPPmXv9tB/TGVwZ8bBKUncSGQJQ+7A3Y+rhj96J5aWMKo+n KC/NPmn8opCmHn5Op6jv3uaoxGc8t6e66pxky3AA2dnk5D485SxhylLEnSO4R2yGr8SgRxfS92yY1 5clT21rnYe2f0IeIBYTyJS0grml3zhPdmkR/twnrKmQGkj+05rAwW5LlJMf6AmrggSDaOO8wHtGCU aLxdEdXTXsklja4KBFJUNFi/TLMux0hpdZ7c3gJ0IDyJXqdD9h8Dvoem3lwyDpZfuF2S3F+x3cM4Y 6Yz/HyPQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lUyr3-000ysO-Hi; Fri, 09 Apr 2021 21:40:12 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id BF5D998647F; Fri, 9 Apr 2021 23:39:49 +0200 (CEST) Date: Fri, 9 Apr 2021 23:39:49 +0200 From: Peter Zijlstra To: David Malcolm Cc: Ard Biesheuvel , linux-toolchains@vger.kernel.org, Linux Kernel Mailing List , Josh Poimboeuf , Jason Baron , "Steven Rostedt (VMware)" Subject: Re: static_branch/jump_label vs branch merging Message-ID: <20210409213949.GA33256@worktop.programming.kicks-ass.net> References: <5f78b7e2f9ae937271ef52ee9e999a91c2719da9.camel@redhat.com> <3c062f70ffef2dcd48a661f7c8162fb8fbaf6869.camel@redhat.com> <0a9da587b0330bafdf612c3d51285e144b0b9e46.camel@redhat.com> <5a07bde1a9fa9a056a19637399b0635252ddb303.camel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5a07bde1a9fa9a056a19637399b0635252ddb303.camel@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-toolchains@vger.kernel.org On Fri, Apr 09, 2021 at 05:07:15PM -0400, David Malcolm wrote: > You've built a very specific thing out of asm-goto to fulfil the tough > requirements you outlined above - as well as the nops, there's a thing > in another section to contend with. > > How to merge these asm-goto constructs? By calling the function less, you emit less of them. Which then brings us back to the whole pure/const thing. > Doing so feels very special-case to the kernel and not something that > other GCC users would find useful. Doesn't it boil down to 'fixing' the pure/const vs asm-goto interaction? I could imagine that having that interaction fixed could allow other creative uses.