From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9394 invoked by alias); 8 Apr 2008 21:27:57 -0000 Received: (qmail 9386 invoked by uid 22791); 8 Apr 2008 21:27:57 -0000 X-Spam-Check-By: sourceware.org Received: from mu-out-0910.google.com (HELO mu-out-0910.google.com) (209.85.134.189) by sourceware.org (qpsmtpd/0.31) with ESMTP; Tue, 08 Apr 2008 21:27:41 +0000 Received: by mu-out-0910.google.com with SMTP id w9so3121124mue.6 for ; Tue, 08 Apr 2008 14:27:37 -0700 (PDT) Received: by 10.86.68.20 with SMTP id q20mr5474236fga.59.1207690057176; Tue, 08 Apr 2008 14:27:37 -0700 (PDT) Received: by 10.86.73.11 with HTTP; Tue, 8 Apr 2008 14:27:37 -0700 (PDT) Message-ID: <178adb870804081427p65a1e9abx14cd791596730c80@mail.gmail.com> Date: Tue, 08 Apr 2008 22:15:00 -0000 From: Omar To: "Jim Wilson" Subject: Re: Understanding Predicate and Constrains Cc: gcc-help@gcc.gnu.org In-Reply-To: <178adb870804081133t4b2a71c4j9f1f802bb02f075c@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <178adb870804071349p62932c37h3c67d236a12795b3@mail.gmail.com> <47FB974E.1070505@tuliptree.org> <178adb870804081024n6c055d2boab4bed7750f5b16d@mail.gmail.com> <178adb870804081133t4b2a71c4j9f1f802bb02f075c@mail.gmail.com> 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: 2008-04/txt/msg00111.txt.bz2 Jim, After further reading, the Internals document answered my question. I realized that CONST_OK_FOR_LETTER_P is under the "Obsolete Macros for Defining Constraints" section, which states: "Machine-specific constraints can be defined with these macros instead of the machine description constructs described in Section 14.8.6 [Define Constraints], page 274. This mechanism is obsolete. New ports should not use it..." So, to answer myself: Yes, define_constraint definitions are used instead of the CONST_OK_FOR_LETTER_P macro. Thanks for your patience! -Omar On Tue, Apr 8, 2008 at 1:33 PM, Omar wrote: > > Jim, > First, thanks a lot for your comments. > > > It current sources, you want to define a > > $target/constraints.md file that has a (define_contraint "I" ...) pattern. > I have been looking at other targets, and they seem to use the > CONST_OK_FOR_LETTER_P macro for this purpose. > Is the define_constraint equivalent to what the macro CONST_OK_FOR > _LETTER_P used to stand for? > I am trying to understand is define_constraint replaces this macro's > functionality. > > Your comment confirms my suspicion: > > Most gcc internals stuff like this is not well documented. > > You just try it, and if it works fine, if > > it doesn't, then change it. > > -Omar >