From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 72946 invoked by alias); 2 Sep 2016 16:33:06 -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 72932 invoked by uid 89); 2 Sep 2016 16:33:05 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.6 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=inefficient, enkovich.gnu@gmail.com, Hx-languages-length:2718, enkovichgnugmailcom X-HELO: mail-vk0-f48.google.com Received: from mail-vk0-f48.google.com (HELO mail-vk0-f48.google.com) (209.85.213.48) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 02 Sep 2016 16:33:03 +0000 Received: by mail-vk0-f48.google.com with SMTP id f76so27872244vke.0 for ; Fri, 02 Sep 2016 09:33:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=aUPtdtSqlMn9HzEXLddQinBjnOEzGMV6Q8Ur+7cFqfs=; b=JzalijF9GVV7Bm5G21mAPeuDJbcaarmJvjJvPeqmU1pdeDktQZcCe4l91NWc1Iadr0 ZdT0VF7CVtbp/h+13B+fzthrGK4hUDNgFAbxfAVSkK04wSW4WZ0/pTgK+Vvgy4ofpw36 y0NNn6i1+mQByknnB1ufbQ46/yOlGch4zdYtqnamA97e/b1olA1haiCa6n7+fwK0Hz8x Q7IeEBPn9zrKp1GTzFc6AqbXpfOPlmrMjLWEqXWi8VdO6pegu0Kc8okKkba/8TXz0VzZ 8ZtXI3t8NC87mEyMv41G8EmNfkNAW5MFQkF/WIggpaz8t8FztoTAHrvr1yC8sbVs0X2t PZwQ== X-Gm-Message-State: AE9vXwNtZH4kpif1MmhgImG6jlJUYXaEHmZccbwYvMfHSh83fYK0n38ekPPIVlYpR55c2il8Tqb5V3vFWb+WRQ== X-Received: by 10.31.80.135 with SMTP id e129mr13859807vkb.151.1472833981432; Fri, 02 Sep 2016 09:33:01 -0700 (PDT) MIME-Version: 1.0 Received: by 10.103.118.143 with HTTP; Fri, 2 Sep 2016 09:33:00 -0700 (PDT) In-Reply-To: References: <20160519194450.GH40563@msticlxl57.ims.intel.com> <18ccae1a-30c3-c23c-e28f-287f9d41eaa0@redhat.com> <20160628122439.GB4143@msticlxl57.ims.intel.com> <20160720143705.GA2605@msticlxl57.ims.intel.com> <4bb744cb-92df-ca29-54e2-82162216e88c@redhat.com> <5cacdc29-e916-f460-3c44-5fa6450a24a9@redhat.com> <37fbe5e6-6e44-ffff-5467-21e162919586@redhat.com> <44d301f6-3fce-e32e-ad4b-a2440596b99e@redhat.com> From: "Bin.Cheng" Date: Fri, 02 Sep 2016 16:33:00 -0000 Message-ID: Subject: Re: [PATCH, vec-tails 07/10] Support loop epilogue combining To: Yuri Rumyantsev Cc: Jeff Law , Ilya Enkovich , Richard Biener , gcc-patches , Igor Zamyatin Content-Type: text/plain; charset=UTF-8 X-IsSubscribed: yes X-SW-Source: 2016-09/txt/msg00103.txt.bz2 On Fri, Sep 2, 2016 at 3:46 PM, Yuri Rumyantsev wrote: > Hi Jeff, > > I am trying to reduce cost of repeated call of if-conversion for > epilogue vectorization. I'd like to clarify your recommendation - > should I design additional support for versioning in > vect_do_peeling_for_loop_bound or lightweight version of if-conversion Hi Yuri, I didn't read the patch, so please correct me if I mis-understand anything. It might be better not to introduce versioning logic in peeling stuff if possible. The peeling part is complicated and generates somehow inefficient CFG. I am preparing patches rewriting the peeling stuff. Thanks, bin > is sufficient? Any help in clarification will be appreciated. > > Thanks ahead. > Yuri. > > 2016-08-01 19:10 GMT+03:00 Jeff Law : >> On 08/01/2016 03:09 AM, Ilya Enkovich wrote: >>> >>> 2016-07-26 18:38 GMT+03:00 Ilya Enkovich : >>>> >>>> 2016-07-26 18:26 GMT+03:00 Jeff Law : >>>>> >>>>> On 07/26/2016 03:57 AM, Ilya Enkovich wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> Ilya, what's the fundamental reason why we need to run >>>>>>> if-conversion again? Yes, I know you want to if-convert the >>>>>>> epilogue, but why? >>>>>>> >>>>>>> What are the consequences of not doing if-conversion on the >>>>>>> epilogue? Presumably we miss a vectorization opportunity on the >>>>>>> tail. But that may be a reasonable limitation to allow the >>>>>>> existing work to move forward while you go back and revamp things a >>>>>>> little. >>>>>> >>>>>> >>>>>> >>>>>> If we have some control-flow in a loop then we have to if-convert it >>>>>> for vectorizer. We need to preserve both versions: if-converted one >>>>>> for vectorizer and the original one to be used if vectorization >>>>>> fails. For epilogues we have similar situation and need two >>>>>> versions. I do it by running if-conversion on a copy of original >>>>>> loop. Note that it doesn't run full if-conversion pass. If-conversion >>>>>> is called for epilogue loop only. >>>>> >>>>> >>>>> Right. So what I think Richi wants you to try is to use the >>>>> if-converted >>>>> loop to construct the if-converted epilogue. It seems conceptually >>>>> simple >>>>> and low cost -- the question is on the implementation side. I have no >>>>> clue >>>>> how painful that would be. >>>> >>>> >>>> Probably another part of if-conversion may be re-used to build required >>>> epilogue. I'll have a look. >>> >>> >>> Hi, >>> >>> Yuri will continue my work from this point. >> >> Understood. I'm actually got some comments on #5 and Yuri is already on the >> CC list for that draft message. >> >> Jeff