From mboxrd@z Thu Jan 1 00:00:00 1970 From: Craig Burley To: moshier@mediaone.net Cc: tprince@cat.e-mail.com, bosch@gnat.com, egcs@cygnus.com, hjstein@bfr.co.il, jbuck@Synopsys.COM Subject: Re: /internet Date: Wed, 16 Dec 1998 09:37:00 -0000 Message-id: <199812161737.MAA14895@melange.gnu.org> References: X-SW-Source: 1998-12/msg00585.html >There has been general agreement that gcc is not supposed to make >optimizations that could change the value of an expression. >Associative law optimizations of floating-point expressions certainly >can change the value and they should continue to be disallowed. Users >should not have to fear that gcc is going to take arbitrary liberties >and rewrite their programs for them without very explicit permission. Even if this was true -- and IMO it isn't -- it doesn't apply to well- designed numerical-processing languages like Fortran, in which it is quite clear that A*B*C*D can be evaluated as (D*A)*(C*B), for example. Therefore, we should make the *back end* work properly in a language- independent sense. If people want the gcc to produce slower code than g77, that's okay -- they can have gcc explicitly group the operations for consumption by the back end, something Fortran doesn't generally need to do. tq vm, (burley)