From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12941 invoked by alias); 27 Sep 2012 18:08:51 -0000 Received: (qmail 12929 invoked by uid 22791); 27 Sep 2012 18:08:50 -0000 X-SWARE-Spam-Status: No, hits=-5.4 required=5.0 tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,KHOP_THREADED,RCVD_IN_DNSWL_HI,RCVD_IN_HOSTKARMA_W,RP_MATCHES_RCVD,TW_ZJ X-Spam-Check-By: sourceware.org Received: from ausxipps301.us.dell.com (HELO ausxipps301.us.dell.com) (143.166.148.223) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 27 Sep 2012 18:08:44 +0000 X-Loopcount0: from 10.175.216.251 From: To: CC: , , Subject: Re: [PATCH v2, rtl-optimization]: Fix PR54457, [x32] Fail to combine 64bit index + constant Date: Thu, 27 Sep 2012 18:35:00 -0000 Message-ID: References: <877grgu0yt.fsf@talisman.home> <3730255.NiV98gQJ1a@polaris> In-Reply-To: Content-Type: text/plain; charset="us-ascii" Content-ID: <1E921F6568609547BE892AF18B8933FA@dell.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-IsSubscribed: yes 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 X-SW-Source: 2012-09/txt/msg01852.txt.bz2 On Sep 27, 2012, at 2:04 PM, Uros Bizjak wrote: >=20 >=20 >=20 >>>>> I agree (subreg:M (op:N A C) 0) to (op:M (subreg:N (A 0)) C) is >>>>> a good transformation, but why do we need to handle as special >>>>> the case where the subreg is itself the operand of a plus or minus? >>>>> I think it should happen regardless of where the subreg occurs. >>>>=20 >>>> Don't we need to restrict this to the low part though? >>>=20 >>> ... >=20 > After some off-line discussion with Richard, attached is v2 of the patch. >=20 > 2012-09-27 Uros Bizjak >=20 > PR rtl-optimization/54457 > * simplify-rtx.c (simplify_subreg): > Simplify (subreg:SI (op:DI ((x:DI) (y:DI)), 0) > to (op:SI (subreg:SI (x:DI) 0) (subreg:SI (x:DI) 0)). > ... Is it just specific to DI -> SI, or is it for any large mode -> smaller mod= e, like SI -> HI? paul