From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-patches-return-295467-listarch-gcc-patches=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 24471 invoked by alias); 28 Jun 2011 15:53:31 -0000
Received: (qmail 24463 invoked by uid 22791); 28 Jun 2011 15:53:31 -0000
X-SWARE-Spam-Status: No, hits=-3.2 required=5.0	tests=AWL,BAYES_00,T_RP_MATCHES_RCVD
X-Spam-Check-By: sourceware.org
Received: from cantor2.suse.de (HELO mx2.suse.de) (195.135.220.15)    by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 28 Jun 2011 15:53:16 +0000
Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.221.2])	by mx2.suse.de (Postfix) with ESMTP id 64B728AD27;	Tue, 28 Jun 2011 17:53:15 +0200 (CEST)
Date: Tue, 28 Jun 2011 16:37:00 -0000
From: Michael Matz <matz@suse.de>
To: Richard Guenther <richard.guenther@gmail.com>
Cc: Andrew Stubbs <andrew.stubbs@gmail.com>, gcc-patches@gcc.gnu.org,	patches@linaro.org
Subject: Re: [PATCH (3/7)] Widening multiply-and-accumulate pattern matching
In-Reply-To: <BANLkTim0wLcSTgAL9isO+dVXxgq-U8B4Sw@mail.gmail.com>
Message-ID: <Pine.LNX.4.64.1106281741170.17115@wotan.suse.de>
References: <4E034EF2.3070503@codesourcery.com> <4E03504B.9060305@codesourcery.com> <BANLkTi=a8B-DZZdG2bmOWQ8A+-pCSEsAbQ@mail.gmail.com> <4E044559.5000105@linaro.org> <BANLkTimfKyrARS+eRy+MWYVO2gLqp85JsQ@mail.gmail.com> <1A77B5B39081C241A68E6CF16983025F020906F6@EU1-MAIL.mgc.mentorg.com> <BANLkTi=1TRM7uHWxLD3Se=S-ibe0C13T-Q@mail.gmail.com> <4E09B142.4020402@codesourcery.com> <BANLkTim0wLcSTgAL9isO+dVXxgq-U8B4Sw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
X-IsSubscribed: yes
Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-patches.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-patches/>
List-Post: <mailto:gcc-patches@gcc.gnu.org>
List-Help: <mailto:gcc-patches-help@gcc.gnu.org>
Sender: gcc-patches-owner@gcc.gnu.org
X-SW-Source: 2011-06/txt/msg02152.txt.bz2

Hi,

On Tue, 28 Jun 2011, Richard Guenther wrote:

> I'd name the predicate value_preserving_conversion_p which I think is 
> what you mean.  harmless isn't really descriptive.
> 
> Note that you include non-value-preserving conversions, namely int -> 
> unsigned int.

It seems that Andrew really does want to accept them.  If so 
value_preserving_conversion_p would be the wrong name.  It seems to me he 
wants to accept those conversions that make it possible to retrieve the 
old value, i.e. when "T1 x; (T1)(T2)x == x", then T1->T2 has the 
to-be-named property.  bits_preserving?  Hmm.


Ciao,
Michael.