From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 74109 invoked by alias); 16 May 2018 14:56:51 -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 74087 invoked by uid 89); 16 May 2018 14:56:50 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.1 required=5.0 tests=AWL,BAYES_00,KAM_SHORT,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.2 spammy= X-HELO: gate.crashing.org Received: from gate.crashing.org (HELO gate.crashing.org) (63.228.1.57) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 16 May 2018 14:56:48 +0000 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id w4GEue8i017488; Wed, 16 May 2018 09:56:41 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id w4GEueeV017487; Wed, 16 May 2018 09:56:40 -0500 Date: Wed, 16 May 2018 15:13:00 -0000 From: Segher Boessenkool To: Kyrill Tkachov Cc: Richard Biener , GCC Patches , Richard Earnshaw , james.greenhalgh@arm.com, Marcus Shawcroft Subject: Re: [patch AArch64] Do not perform a vector splat for vector initialisation if it is not useful Message-ID: <20180516145639.GO17342@gate.crashing.org> References: <5AFA983C.5070609@foss.arm.com> <5AFBEDD5.5020004@foss.arm.com> <5AFC03AF.8040200@foss.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5AFC03AF.8040200@foss.arm.com> User-Agent: Mutt/1.4.2.3i X-IsSubscribed: yes X-SW-Source: 2018-05/txt/msg00743.txt.bz2 On Wed, May 16, 2018 at 11:10:55AM +0100, Kyrill Tkachov wrote: > On 16/05/18 10:42, Richard Biener wrote: > >Segher, do you know where canonicalization rules are documented? > >IIRC we do not actively try to canonicalize in most cases. > > The documentation we have for RTL canonicalisation is at: > https://gcc.gnu.org/onlinedocs/gccint/Insn-Canonicalizations.html#Insn-Canonicalizations > > It doesn't mention anything about vec_merge AFAICS so I couldn't convince > myself that there > is a canonicalisation that we enforce (though maybe someone can prove me > wrong). Many canonicalisations aren't documented, it's never clear which of the canonicalisations are how canonical :-/ Segher