From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 57559 invoked by alias); 20 Aug 2019 06:56:55 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 57551 invoked by uid 89); 20 Aug 2019 06:56:55 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,KAM_SHORT,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.1 spammy=our X-HELO: mail-lf1-f53.google.com Received: from mail-lf1-f53.google.com (HELO mail-lf1-f53.google.com) (209.85.167.53) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 20 Aug 2019 06:56:53 +0000 Received: by mail-lf1-f53.google.com with SMTP id c9so3274766lfh.4 for ; Mon, 19 Aug 2019 23:56:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=6SMppThjV9nUyAnQ9GFH+Pf/QGHY0oJZ0aIf49bgeL4=; b=tXlxgfOBkd+kUO1Rjl2r2IXSs2hmTWc/sTS0MlIu4SsTkvbbP1iWx8lAT6IyLRD2nP GNR6K3ae9aeaTblSryjORbWQOpyzYavN3tdbiZku+6Z+ml9SnqGXOlqNqEPSyL/PBLVT XP+iSzIKorMN7XWCDtJhtKFUIuGT5SQOL5e5WuKycCyGt9jGoqtBzsZo6HHHE7USulLC GUMTJeKwurfBxl+i/P1ytc1tQpuNL5HfN6mn6GPS2y8LwA8aeXtvaupiiGL/Ro3RR3CW b6YbLgrP/TdVYILjnSIFpttxkGAcZ/80/0TnZKHD1xwnV71XAqyQICQUl7661HhWlpJr GLig== MIME-Version: 1.0 References: <70b9bcc9-e12a-78b4-b8cc-a67b7ca3d38d@redhat.com> <20190810060553.m6e42sovw7s4xqoa@jocasta.intra> <20190815173559.kbp3uja7jklx74iy@jocasta.intra> <3c6c87ce-a38f-728d-e083-aa066d531790@redhat.com> <20190816112357.ep7fns6skm5emoey@jocasta.intra> <5693be1f-4351-94ab-9096-f6e4f9f875c1@redhat.com> <20190819073553.pi644qzyokxmynr2@jocasta.intra> <16f173b7-d835-48f9-aaed-d5d38d4748ca@redhat.com> <20190819150711.GL31406@gate.crashing.org> <20190819180644.wn7s2dxdgjlwvdw7@jocasta.intra> In-Reply-To: <20190819180644.wn7s2dxdgjlwvdw7@jocasta.intra> From: Richard Biener Date: Tue, 20 Aug 2019 06:56:00 -0000 Message-ID: Subject: Re: Special Memory Constraint [was Re: Indirect memory addresses vs. lra] To: John Darrington Cc: Segher Boessenkool , Vladimir Makarov , GCC Development Content-Type: text/plain; charset="UTF-8" X-IsSubscribed: yes X-SW-Source: 2019-08/txt/msg00150.txt.bz2 On Mon, Aug 19, 2019 at 8:06 PM John Darrington wrote: > > On Mon, Aug 19, 2019 at 10:07:11AM -0500, Segher Boessenkool wrote: > > > ? As I remember there were a few other ideas from Richard Biener and > > Segher Boessenkool.? I also proposed to add a new address register which > > will be always a fixed stack memory slot at the end. Unfortunately I am > > not familiar with the target and the port to say in details how to do > > it.? But I think it is worth to try. > > The m68hc11 port used the fake Z register approach, and I believe it had > some special machine pass to get rid of it right before assembler output. > > (r171302 is when it was removed -- last version was > https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/config/m68hc11/m68hc11.c;h=1e414102c3f1fed985e4fb8db7954342e965190b;hb=bae8bb65d842d7ffefe990c1f0ac004491f3c105#l4061 > for the machine reorg stuff). > > No idea how well it works... But it's only needed if you are forced to > have a frame pointer IIUC? > > > Segher > > > Most of these suggestions involve adding some sort of virtual registers > So I hacked the machine description to add two new registers Z1 and Z2 > with the same mode as X and Y. > > Obviously the assembler balks at this. However the compiler still > ICEs at the same place as before. > > So this suggests that our original diagnosis, viz: there are not enough > address registers was not accurate, and in fact there is some other > problem? That sounds likely. Given you have indirect addressing you could simulate N virtual regs by placing them in a virtual reg table in memory and accessed via a fixed address register (assuming all instructions that would need an address reg also can take that indirect from memory). Richard. > J' > > -- > Avoid eavesdropping. Send strong encrypted email. > PGP Public key ID: 1024D/2DE827B3 > fingerprint = 8797 A26D 0854 2EAB 0285 A290 8A67 719C 2DE8 27B3 > See http://sks-keyservers.net or any PGP keyserver for public key. >