From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12916 invoked by alias); 13 May 2003 18:50:39 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 12823 invoked from network); 13 May 2003 18:50:38 -0000 Received: from unknown (HELO desire.geoffk.org) (12.235.88.42) by sources.redhat.com with SMTP; 13 May 2003 18:50:38 -0000 Received: (from geoffk@localhost) by desire.geoffk.org (8.11.6/8.11.6) id h4DIoTs09965; Tue, 13 May 2003 11:50:29 -0700 X-Authentication-Warning: desire.geoffk.org: geoffk set sender to geoffk@geoffk.org using -f To: kenner@vlsi1.ultra.nyu.edu (Richard Kenner) Cc: gcc@gcc.gnu.org Subject: Re: [tree-ssa] Out of SSA status and issues References: <10305131528.AA14941@vlsi1.ultra.nyu.edu> From: Geoff Keating Date: Tue, 13 May 2003 18:50:00 -0000 In-Reply-To: <10305131528.AA14941@vlsi1.ultra.nyu.edu> Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/20.7 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-SW-Source: 2003-05/txt/msg01344.txt.bz2 kenner@vlsi1.ultra.nyu.edu (Richard Kenner) writes: > Consider instead that '*p' is just the name given a register's > contents. Neither 'i' nor '9' are processor internal. Both are > external to the cpu. The memory reference for 'i' is source code > implicit, the memory reference for '*p' is source code explicit. > > True, but given caching effects, it's hard to see how *p could be less > expensive than 'i'. Given the code i = *p; // operations that don't use 'i' or change '*p' foo(i); and this is the only use of 'i', surely this is always as fast or faster than foo(*p); due to reducing register pressure. -- - Geoffrey Keating