From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26988 invoked by alias); 29 Mar 2008 06:15:51 -0000 Received: (qmail 26979 invoked by uid 22791); 29 Mar 2008 06:15:51 -0000 X-Spam-Check-By: sourceware.org Received: from smtp-out.google.com (HELO smtp-out.google.com) (216.239.33.17) by sourceware.org (qpsmtpd/0.31) with ESMTP; Sat, 29 Mar 2008 06:15:22 +0000 Received: from zps78.corp.google.com (zps78.corp.google.com [172.25.146.78]) by smtp-out.google.com with ESMTP id m2T6FGv3006005; Sat, 29 Mar 2008 06:15:16 GMT Received: from smtp.corp.google.com (spacemonkey1.corp.google.com [192.168.120.115]) by zps78.corp.google.com with ESMTP id m2T6FD6C029227 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Fri, 28 Mar 2008 23:15:15 -0700 Received: from localhost.localdomain.google.com (adsl-76-249-168-94.dsl.pltn13.sbcglobal.net [76.249.168.94]) (authenticated bits=0) by smtp.corp.google.com (8.13.8/8.13.8) with ESMTP id m2T6FCwa013585 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Fri, 28 Mar 2008 22:15:13 -0800 To: QiangHuang Cc: gcc-help Subject: Re: V_MUST_DEF vs V_MAY_DEF ? References: <1807a3db0803282115u5a825d65k7c0c2bb252d8b178@mail.gmail.com> From: Ian Lance Taylor Date: Sat, 29 Mar 2008 06:15:00 -0000 In-Reply-To: <1807a3db0803282115u5a825d65k7c0c2bb252d8b178@mail.gmail.com> (QiangHuang's message of "Sat\, 29 Mar 2008 12\:15\:39 +0800") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-IsSubscribed: yes Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-help-owner@gcc.gnu.org X-SW-Source: 2008-03/txt/msg00296.txt.bz2 QiangHuang writes: > "V_MUST_DEF" and "V_MAY_DEF" , The two tags appear in the IL of > SSA in GCC.I know they have something to do with the virtual > operand,however,I wonder that what the exact distinction between them > is. See doc/tree-ssa.texi. But note that in gcc 4.3 the distinction was removed. Now there is only one kind of def. http://gcc.gnu.org/ml/gcc-patches/2006-12/msg00780.html > Corresponding to the 2 tags, is there "V_MUST_USE" or "V_MAY_USE"? No. Ian