Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site cornell.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!mtuxo!mtunh!mtung!mtunf!ariel!vax135!cornell!jqj From: jqj@cornell.UUCP (J Q Johnson) Newsgroups: net.arch Subject: Re: Orthogonal addressing doesn't help multis. Message-ID: <2693@cornell.UUCP> Date: Tue, 25-Jun-85 07:05:49 EDT Article-I.D.: cornell.2693 Posted: Tue Jun 25 07:05:49 1985 Date-Received: Wed, 26-Jun-85 06:38:56 EDT References: <419@oakhill.UUCP> <6415@boring.UUCP> Reply-To: jqj@gvax.UUCP (J Q Johnson) Organization: Cornell Univ. CS Dept. Lines: 13 Summary: In article <482@cmcl2.UUCP> edler@cmcl2.UUCP (Jan Edler) writes: >Even if you have a uniprocessor with instructions like add-to-memory, >and those instructions are atomic with respect to interrupts, >it is probably not possible to take advantage of this property when >writing in a language other than assembly. The programmer would not generally >know when the "atomic" instructions would be used, and when the compiler >might optomize them away, so he/she wouldn't be able to depend on them. I don't understand. Presumably such instructions would be generated by corresponding high-level constructs in your favorite concurrent programming language (e.g. all operations on variables declared as semaphores use the atomic instructions). If the parser can figure out when you intend to take advantage of such a feature, it can certainly tell the optimizer!