From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-return-61399-listarch-gcc=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 21499 invoked by alias); 11 Oct 2002 19:08:59 -0000
Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Archive: <http://gcc.gnu.org/ml/gcc/>
List-Post: <mailto:gcc@gcc.gnu.org>
List-Help: <http://gcc.gnu.org/ml/>
Sender: gcc-owner@gcc.gnu.org
Received: (qmail 21490 invoked from network); 11 Oct 2002 19:08:59 -0000
Received: from unknown (HELO nile.gnat.com) (205.232.38.5)
  by sources.redhat.com with SMTP; 11 Oct 2002 19:08:59 -0000
Received: by nile.gnat.com (Postfix, from userid 338)
	id BB0D0F2DF6; Fri, 11 Oct 2002 15:08:58 -0400 (EDT)
To: gcc@gcc.gnu.org, kevinlawton2001@yahoo.com
Subject: Re: Request of new __attribute__ for switch statements (elimination of the bounds check)
Message-Id: <20021011190858.BB0D0F2DF6@nile.gnat.com>
Date: Fri, 11 Oct 2002 13:22:00 -0000
From: dewar@gnat.com (Robert Dewar)
X-SW-Source: 2002-10/txt/msg00623.txt.bz2

<<But I don't know of any way to tell the compiler to _not_ generate
a bounds check on the switch variable 'byte'.  All of the target
space is covered.

To solve this, could we add an attribute to switch?

  switch (byte) __attribute (( no-bounds-check )) {
    ...
    }
>>

Surely this is NOT the solution in a case when it is obvious that no
check is needed. We have noticed this junk check being a problem in
GNAT, and what we do is to turn the last case into a default, but this
of course is definitely not optimial.