From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11871 invoked by alias); 22 Apr 2004 13:34:00 -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 11800 invoked from network); 22 Apr 2004 13:33:48 -0000 Received: from unknown (HELO mtagate4.de.ibm.com) (195.212.29.153) by sources.redhat.com with SMTP; 22 Apr 2004 13:33:48 -0000 Received: from d12nrmr1507.megacenter.de.ibm.com (d12nrmr1507.megacenter.de.ibm.com [9.149.167.1]) by mtagate4.de.ibm.com (8.12.10/8.12.10) with ESMTP id i3MDXlPk130986; Thu, 22 Apr 2004 13:33:47 GMT Received: from d12ml102.megacenter.de.ibm.com (d12av02.megacenter.de.ibm.com [9.149.165.228]) by d12nrmr1507.megacenter.de.ibm.com (8.12.10/NCO/VER6.6) with ESMTP id i3MDXkFi047174; Thu, 22 Apr 2004 15:33:47 +0200 To: Joern Rennecke Cc: gcc@gcc.gnu.org, Mircea Namolaru MIME-Version: 1.0 Subject: Re: Exploiting dual mode operation From: Leehod Baruch Message-ID: Date: Thu, 22 Apr 2004 13:58:00 -0000 Content-Type: text/plain; charset="US-ASCII" X-SW-Source: 2004-04/txt/msg01064.txt.bz2 Hello, Thank you for your message. We see redundant sign extension removal as a partial redundancy problem. This will give us not only the redundant sign extensions, but also better placement for the remaining ones. As a result sign extension instructions may be moved and instructions that uses the highpart may be replaced with others that doesn't use it. This is not equivalent with live information for the highest part of the registers. Our approach will not require changes in the description file (which in our opinion is a major problem with your code) and will limit the changes to much fewer files. Leehod and Mircea Joern Rennecke 21/04/2004 09:26 PM To: Mircea Namolaru/Haifa/IBM@IBMIL cc: gcc@gcc.gnu.org, Leehod Baruch/Haifa/IBM@IBMIL Subject: Re: Exploiting dual mode operation > We are working on an optimization for eliminating redundant sign extension > instructions by making use of this duality. Currently this is done only in > very > simple cases. I have already submitted a patch for this: http://gcc.gnu.org/ml/gcc-patches/2004-01/msg03259.html It is still waiting for review.