Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!decvax!wivax!linus!genrad!grkermit!masscomp!tjt From: tjt@masscomp.UUCP Newsgroups: net.lang.c Subject: Re: global & static registers? - (nf) Message-ID: <134@masscomp.UUCP> Date: Fri, 27-May-83 08:51:09 EDT Article-I.D.: masscomp.134 Posted: Fri May 27 08:51:09 1983 Date-Received: Sat, 28-May-83 14:47:35 EDT References: gatech.165 Lines: 16 Sorry, a "global optimizer" is unlikely to accomplish the same thing as a "global register" declaration. In compiler jargon, "local" optimization is performed within a block of simple in-line code (no branches and no labels), while "global" optimization performs flow analysis and optimization over loops, conditional expressions and the like. Although it may include flow analysis over procedure calls, that would be two orders of magnitude over what the current portable c compiler does so I doubt that it would be ready for usg6.0. Also, it would be very difficult to come up with good heuristics for automatically assigning variables to "global registers": I am assuming that assigning a global register will degrade the rest of the code enough that you only want global registers rarely. Tom Teixeira Massachusetts Computer Corporation (MASSCOMP) ...!decvax!genrad!masscom!tjt