From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from server.nextmovesoftware.com (server.nextmovesoftware.com [162.254.253.69]) by sourceware.org (Postfix) with ESMTPS id 4FC97385735D for ; Wed, 27 Jul 2022 07:52:04 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 4FC97385735D Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=nextmovesoftware.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=nextmovesoftware.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=nextmovesoftware.com; s=default; h=Content-Transfer-Encoding:Content-Type: MIME-Version:Message-ID:Date:Subject:In-Reply-To:References:Cc:To:From:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=DvxM4YwlcKwGTWbWDF9QmqukhAs0sSy3B6D0OXJIqTY=; b=eeiGpk/wQgStb4WLlYLzdhPXTH p/lOCyvYV5p5qqZEAX5JpZae73jE0A9fEO8aPPSQkAmFwGp8hQNpopihcsPQbayOLVX0RWzzc59se FTQobwnmVPTxEU3esOXwdpUPbh+WVfcDZbA1DugJCDivbHIiHl0V0nruNYVClwrAnTgsBWKaUK55n H6E1L7AGc6qGfSWqkG+XXMEbFRsr/28Nbzf9AUW2VEYA2E88qMBySBuinCCoh4FxOIR9aec+Im+KE jT8sHJQV50VEMa/iwYqeJ52rWUPZkfVUsOGHHbrQOVHbD4X2Psz+pyOo2BTxp9HyAwmYSpKs/nqk1 YQE//RAw==; Received: from host81-156-58-95.range81-156.btcentralplus.com ([81.156.58.95]:55743 helo=Dell) by server.nextmovesoftware.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1oGbpr-0004SY-ED; Wed, 27 Jul 2022 03:52:03 -0400 From: "Roger Sayle" To: "'Segher Boessenkool'" Cc: References: <003601d89245$a86f8830$f94e9890$@nextmovesoftware.com> <20220707223833.GA25951@gate.crashing.org> <00fa01d8a0e9$0efdfc60$2cf9f520$@nextmovesoftware.com> <20220726174451.GA25951@gate.crashing.org> <01f501d8a133$56fee8e0$04fcbaa0$@nextmovesoftware.com> <20220726221116.GC25951@gate.crashing.org> In-Reply-To: <20220726221116.GC25951@gate.crashing.org> Subject: RE: [PATCH] Add new target hook: simplify_modecc_const. Date: Wed, 27 Jul 2022 08:51:58 +0100 Message-ID: <003501d8a18d$c22ed760$468c8620$@nextmovesoftware.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQKM31p2pOYqjcFJ2r+wKuC+8ENZTgCpq+KpAm2gSXsBzF2qAwIW/B6aAjKLrHCr3+/KMA== Content-Language: en-gb X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - server.nextmovesoftware.com X-AntiAbuse: Original Domain - gcc.gnu.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - nextmovesoftware.com X-Get-Message-Sender-Via: server.nextmovesoftware.com: authenticated_id: roger@nextmovesoftware.com X-Authenticated-Sender: server.nextmovesoftware.com: roger@nextmovesoftware.com X-Source: X-Source-Args: X-Source-Dir: X-Spam-Status: No, score=-5.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, KAM_SHORT, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 27 Jul 2022 07:52:05 -0000 Hi Segher, > Thank you for telling the maintainer of combine the basics of what all of this > does! I hadn't noticed any of that before. You're welcome. I've also been maintaining combine for some time now: https://gcc.gnu.org/legacy-ml/gcc/2003-10/msg00455.html > They can be, as clearly documented (and obvious from the code), but you can > not ever have that in the RTL stream, which is needed for your patch to do > anything. That's the misunderstanding; neither this nor the previous SUBREG patch, affect/change what is in the RTL stream, no COMPARE nodes are every changed or modified, only eliminated by the propagation/fusion in combine (or CSE). We have --enable-checking=rtl to guarantee that the documented invariants always hold in the RTL stream. Cheers, Roger