From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17064 invoked by alias); 17 Nov 2009 15:50:49 -0000 Received: (qmail 16854 invoked by alias); 17 Nov 2009 15:50:31 -0000 Date: Tue, 17 Nov 2009 15:50:00 -0000 Message-ID: <20091117155031.16851.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug tree-optimization/30911] VRP fails to eliminate range checks in Ada code In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "charlet at adacore dot com" Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2009-11/txt/msg01402.txt.bz2 ------- Comment #72 from charlet at adacore dot com 2009-11-17 15:50 ------- Subject: Re: VRP fails to eliminate range checks in Ada code > > Is there anyway for the optimizers to get at this range information still? > > Or was range information removed because it is essentially impossible to use > > it correctly (if so this bug report should be closed as unfixable)? > > It was removed because it was impossible to use it correctly. The "fix" > is to derive range information from existing range checks, possibly > inter-procedurally. Right, as soon as you have one range check, the compiler can make more precise assumptions/conclusions about the actual range. Arno -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30911