From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5670 invoked by alias); 25 Oct 2002 17:10:18 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 5519 invoked from network); 25 Oct 2002 17:10:15 -0000 Received: from unknown (HELO hiauly1.hia.nrc.ca) (132.246.100.193) by sources.redhat.com with SMTP; 25 Oct 2002 17:10:15 -0000 Received: from hiauly1.hia.nrc.ca (localhost [127.0.0.1]) by hiauly1.hia.nrc.ca (8.12.0.Beta16/8.12.0.Beta16) with ESMTP id g9PHAE00029842 for ; Fri, 25 Oct 2002 13:10:15 -0400 (EDT) Received: (from dave@localhost) by hiauly1.hia.nrc.ca (8.12.0.Beta16/8.12.0.Beta16) id g9PHADIW029840; Fri, 25 Oct 2002 13:10:13 -0400 (EDT) Message-Id: <200210251710.g9PHADIW029840@hiauly1.hia.nrc.ca> Subject: Re: Reload patch for PA call rewrite. To: law@redhat.com Date: Fri, 25 Oct 2002 10:10:00 -0000 From: "John David Anglin" Cc: rth@redhat.com, gcc-patches@gcc.gnu.org In-Reply-To: <200210251604.g9PG40xc017772@porcupine.cygnus.com> from "Jeff Law" at Oct 25, 2002 10:04:00 am MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SW-Source: 2002-10/txt/msg01528.txt.bz2 > It's possible the improvements are on the return path side -- by returning > to the caller's parent rather than the caller itself, we avoid one hard > to predict branch (the "bv" in the caller) and maybe one easy to predict > branch (branch to the epilogue). Yes, I can see that returns are hard to predict since they are indirect and we save one with the sibcall. We definitely should implement the BTS for returns. I tried the same test on hppa-linux and there wasn't any difference in the timing with and without sibcalls. I'm going to try 32-bit hpux. Possibly, there is a linux/hpux difference. Possibly, there is a difference wrt the P bit in the ITLB between these systems. Dave -- J. David Anglin dave.anglin@nrc.ca National Research Council of Canada (613) 990-0752 (FAX: 952-6605)