From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23523 invoked by alias); 24 Jul 2017 14:52:20 -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 23376 invoked by uid 89); 24 Jul 2017 14:52:17 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.0 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD autolearn=no version=3.3.2 spammy= X-HELO: mail3-relais-sop.national.inria.fr Received: from mail3-relais-sop.national.inria.fr (HELO mail3-relais-sop.national.inria.fr) (192.134.164.104) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 24 Jul 2017 14:52:16 +0000 Received: from stedding-dock.saclay.inria.fr ([193.55.177.248]) by mail3-relais-sop.national.inria.fr with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Jul 2017 16:52:13 +0200 Date: Mon, 24 Jul 2017 14:52:00 -0000 From: Marc Glisse To: "Bin.Cheng" cc: gcc-patches List , Richard Biener Subject: Re: [PATCH GCC][1/2]Feed bound computation to folder in loop split In-Reply-To: Message-ID: References: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed X-SW-Source: 2017-07/txt/msg01435.txt.bz2 On Mon, 24 Jul 2017, Bin.Cheng wrote: > On Mon, Jul 24, 2017 at 3:31 PM, Marc Glisse wrote: >> On Mon, 24 Jul 2017, Bin.Cheng wrote: >> >>> On Mon, Jul 24, 2017 at 2:59 PM, Marc Glisse wrote: >>>> >>>> On Mon, 24 Jul 2017, Bin.Cheng wrote: >>>> >>>>> But since definition of _197 isn't in current stmt sequence, call "o31 >>>>> = do_valueize (valueize, o31)" will return NULL. As a result, it's >>>>> not matched. >>>> >>>> >>>> >>>> Wait, actually, how was your fold_build* version working? Why was the >>>> first >>>> addition "in the current generic tree" and why isn't it "in current stmt >>>> sequence"? >>> >>> Maybe I didn't express it clearly. In compute_new_first_bound, we >>> have stmt sequence "_124 = _197 + 1", and we try to simplify "_124 - >>> 1" by calling gimple_build. The definition of _197 is a PHI and isn't >>> in current stmt sequence. For fold_build* version, it builds >>> expression "_197 + 1 - 1" and simplifies it. >> >> >> It seems like it shouldn't be relevant whether the definition of _197 is in >> the stmt sequence or not, but indeed we seem to generate a lot of calls to >> do_valueize... I had misunderstood the issue, sorry. > Oh, no need at all, and thanks very much for all the explanation. >> >> Strangely, for a pattern like >> (simplify (plus @0 @1) @0) >> we generate no call to valueize, while for the following >> (simplify (plus @0 (minus @1 @2)) @0) >> we generate 3 calls to do_valueize. >> >> I think we need Richard to say what the intent is for the valueization >> function. It is used both to stop looking at defining stmt if the return is >> NULL, and to replace/optimize one SSA_NAME with another, but currently it >> seems hard to prevent looking at the defining statement without preventing >> from looking at the SSA_NAME at all. > Looks we don't really expand into def_stmt on leaf nodes, maybe > valueization can be saved in the case? Passes with a lattice (say PRE) use valueization to replace an SSA_NAME with an equivalent one, not just to let it look through the defining statement, so I am not sure if we can get rid of those completely, or if we need two different do_valueize wrappers for the 2 types of uses. -- Marc Glisse