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=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 7EC8FC43381 for ; Tue, 19 Mar 2019 10:11:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D43620989 for ; Tue, 19 Mar 2019 10:11:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Ya6l0hgu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727442AbfCSKL5 (ORCPT ); Tue, 19 Mar 2019 06:11:57 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:38638 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726703AbfCSKLz (ORCPT ); Tue, 19 Mar 2019 06:11:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Zp5T4D2YXKefBpPzhTowsVZAxi5fFXjhAzZ4KtfEyDk=; b=Ya6l0hgun1s6Zpn9dww71boij RbjqlWDVEKTj3gVcyyT68IrkTjAP1yv2tadkhx3hOk5WhHwTSI2lYEZr+qawVPKdagIIYJpL0CRh0 fIPiQoWjyVs6IuQ8NiS+8/buEILTZJODWF8QMyRujEy5+ix/nTxqqChukYuB28MVTOb2zL1fpmo+Q W1lT3tepxs8yc2vXIMwtyyYwKlDi1ShTqaj2lbgYJU4TQO6efA7/bRDwn49n3uHE1pRjRCyZG1Tvo Z77Judsbuw+u4wg8t4ctVSjhLW1CZSjjB5czIMmTXCtH+yAf2OQ4VjCgTW713afclv2MH1KfvJPiE aAJRsDDMQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1h6BiQ-0007tn-Oe; Tue, 19 Mar 2019 10:11:26 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E388C2020F503; Tue, 19 Mar 2019 11:11:23 +0100 (CET) Date: Tue, 19 Mar 2019 11:11:23 +0100 From: Peter Zijlstra To: Josh Poimboeuf Cc: torvalds@linux-foundation.org, tglx@linutronix.de, hpa@zytor.com, julien.thierry@arm.com, will.deacon@arm.com, luto@amacapital.net, mingo@kernel.org, catalin.marinas@arm.com, james.morse@arm.com, valentin.schneider@arm.com, brgerst@gmail.com, luto@kernel.org, bp@alien8.de, dvlasenk@redhat.com, linux-kernel@vger.kernel.org, dvyukov@google.com, rostedt@goodmis.org Subject: Re: [PATCH 02/25] tracing: Improve "if" macro code generation Message-ID: <20190319101123.GX6058@hirez.programming.kicks-ass.net> References: <20190318153840.906404905@infradead.org> <20190318155140.058627431@infradead.org> <20190318233720.76j6ywkdulmnhu2o@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190318233720.76j6ywkdulmnhu2o@treble> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 18, 2019 at 06:37:20PM -0500, Josh Poimboeuf wrote: > On Mon, Mar 18, 2019 at 04:38:42PM +0100, Peter Zijlstra wrote: > > With CONFIG_PROFILE_ALL_BRANCHES, the "if" macro converts the > > conditional to an array index. This can cause GCC to create horrible > > code. When there are nested ifs, the generated code uses register > > values to encode branching decisions. > > > > Make it easier for GCC to optimize by keeping the conditional as a > > conditional rather than converting it to an integer. This shrinks the > > generated code quite a bit, and also makes the code sane enough for > > objtool to understand. > > > > Cc: rostedt@goodmis.org > > Cc: valentin.schneider@arm.com > > Cc: luto@amacapital.net > > Cc: brgerst@gmail.com > > Cc: catalin.marinas@arm.com > > Cc: mingo@kernel.org > > Cc: dvlasenk@redhat.com > > Cc: will.deacon@arm.com > > Cc: julien.thierry@arm.com > > Cc: torvalds@linux-foundation.org > > Cc: dvyukov@google.com > > Cc: bp@alien8.de > > Cc: tglx@linutronix.de > > Cc: james.morse@arm.com > > Cc: luto@kernel.org > > Cc: hpa@zytor.com > > Reported-by: Peter Zijlstra > > Signed-off-by: Josh Poimboeuf > > Signed-off-by: Peter Zijlstra (Intel) > > Link: https://lkml.kernel.org/r/20190307174802.46fmpysxyo35hh43@treble > > Missing "From" me. Right, sorry, quilt eats that and I sometimes forget to fix up :/