From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Edelsohn To: law@cygnus.com Cc: Zack Weinberg , Jamie Lokier , egcs@egcs.cygnus.com Subject: Re: gcc-2.7 creates faster code than pgcc-1.1.1 Date: Thu, 04 Mar 1999 20:04:00 -0000 Message-id: <9903050403.AA36338@marc.watson.ibm.com> In-reply-to: Message from Jeffrey A Law of "Thu, 04 Mar 1999 19:09:00 MST." < 13506.920599740@hurl.cygnus.com > References: <13506.920599740@hurl.cygnus.com> X-SW-Source: 1999-03/msg00202.html >>>>> 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Edelsohn To: law@cygnus.com Cc: Zack Weinberg , Jamie Lokier , 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