From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27448 invoked by alias); 7 Apr 2017 09:19:48 -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 27423 invoked by uid 89); 7 Apr 2017 09:19:47 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy=our 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; Fri, 07 Apr 2017 09:19:46 +0000 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.13.8) with ESMTP id v379Jfru025331; Fri, 7 Apr 2017 04:19:41 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id v379JeFI025328; Fri, 7 Apr 2017 04:19:40 -0500 Date: Fri, 07 Apr 2017 09:19:00 -0000 From: Segher Boessenkool To: Eric Botcazou Cc: gcc-patches@gcc.gnu.org, Kelvin Nilsen Subject: Re: [PATCH] PR80101: Fix ICE in store_data_bypass_p Message-ID: <20170407091940.GV4402@gate.crashing.org> References: <3316696.3QEehbYcbO@polaris> <20170407074824.GU4402@gate.crashing.org> <2042575.QfhRid7aWy@polaris> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2042575.QfhRid7aWy@polaris> User-Agent: Mutt/1.4.2.3i X-IsSubscribed: yes X-SW-Source: 2017-04/txt/msg00356.txt.bz2 On Fri, Apr 07, 2017 at 10:39:03AM +0200, Eric Botcazou wrote: > > Or we could just change "blockage" and wait for the next bug report. > > That's my suggestion, yes. > > > Alternatively, we can arrange for the bypass functions to not ICE. We > > can do that specific to these rs6000 pipeline descriptions, by having > > our own version of store_data_bypass_p; or we can make that function > > work for all insns (its definition works fine for insn pairs where > > not both the producer and consumer are SETs). That's what Kelvin's > > patch does. What is the value in ICEing here? > > Telling the back-end writer that something may be wrong somewhere instead of > silently accepting nonsense? Why is it nonsense? The predicate gives the answer to the question "given these insns A and B, does A feed data that B stores in memory". That is a perfectly valid question to ask of any two insns. > How long have all the assertions been there? There are workarounds to this problem as well: mips_store_data_bypass_p, added in 2006. mep_store_data_bypass_p, added in 2009 (the port has been removed since then, of course). Segher