From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29096 invoked by alias); 22 Sep 2014 09:00:29 -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 29043 invoked by uid 89); 22 Sep 2014 09:00:23 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-lb0-f171.google.com Received: from mail-lb0-f171.google.com (HELO mail-lb0-f171.google.com) (209.85.217.171) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Mon, 22 Sep 2014 09:00:21 +0000 Received: by mail-lb0-f171.google.com with SMTP id l4so6292085lbv.2 for ; Mon, 22 Sep 2014 02:00:17 -0700 (PDT) MIME-Version: 1.0 X-Received: by 10.152.170.167 with SMTP id an7mr1179664lac.94.1411376417725; Mon, 22 Sep 2014 02:00:17 -0700 (PDT) Received: by 10.25.145.80 with HTTP; Mon, 22 Sep 2014 02:00:17 -0700 (PDT) In-Reply-To: <87ppetnsxd.fsf@e105548-lin.cambridge.arm.com> References: <87ppetnsxd.fsf@e105548-lin.cambridge.arm.com> Date: Mon, 22 Sep 2014 09:00:00 -0000 Message-ID: Subject: Re: [PATCH 0/5] Fix handling of word subregs of wide registers From: Andrew Pinski To: GCC Patches , richard.sandiford@arm.com Content-Type: text/plain; charset=UTF-8 X-IsSubscribed: yes X-SW-Source: 2014-09/txt/msg01776.txt.bz2 On Thu, Sep 18, 2014 at 3:07 AM, Richard Sandiford wrote: > This series is a cleaned-up version of: > > https://gcc.gnu.org/ml/gcc/2014-03/msg00163.html > > The underlying problem is that the semantics of subregs depend on the > word size. You can't have a subreg for byte 2 of a 4-byte word, say, > but you can have a subreg for word 2 of a 4-word value (as well as lowpart > subregs of that word, etc.). This causes problems when an architecture has > wider-than-word registers, since the addressability of a word can then depend > on which register class is used. > > The register allocators need to fix up cases where a subreg turns out to > be invalid for a particular class. This is really an extension of what > we need to do for CANNOT_CHANGE_MODE_CLASS. > > Tested on x86_64-linux-gnu, powerpc64-linux-gnu and aarch64_be-elf. This sounds like something which should be tested on spu as it is the main target that I can think of which has wider-than-word registers and that has had issues with subreg. I can't remember if the simulator for SPU is free (as in beer) and would run on anything besides PowerPC. It has been more than 4 years since I looked into the spu back-end also. Thanks, Andrew Pinski > > Thanks, > Richard >