From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Edelsohn <dje@watson.ibm.com>
To: law@cygnus.com
Cc: Zack Weinberg <zack@rabi.columbia.edu>, Jamie Lokier <egcs@tantalophile.demon.co.uk>, egcs@egcs.cygnus.com
Subject: Re: gcc-2.7 creates faster code than pgcc-1.1.1 
Date: Wed, 31 Mar 1999 23:46:00 -0000
Message-ID: <9903050403.AA36338@marc.watson.ibm.com>
References: <13506.920599740@hurl.cygnus.com>
X-SW-Source: 1999-03n/msg00203.html
Message-ID: <19990331234600.afWjID9JqOL00lJplKuy7q_YrIDNsVzRg-yp1reKTlw@z>

>>>>> Jeffrey A Law writes:

Jeff> True, but I don't believe the loop optimizer is prepared to do that since it
Jeff> doesn't keep track of what bits are active vs what bits are inactive in a 
Jeff> value.

	GCC is missing a general feature of value propagation which would
help with a lot of optimizations like this.  Hopefully this infrastructure
will be added or contributed someday.

David