From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,8c8bbb1419c8e81a X-Google-Attributes: gid103376,public From: kilgallen@eisner.decus.org (Larry Kilgallen) Subject: Re: Waiver question Date: 1997/05/01 Message-ID: <1997May1.071854.1@eisner>#1/1 X-Deja-AN: 238632789 X-Nntp-Posting-Host: eisner.decus.org References: <1997Apr28.151327.1@eisner> <5k52k2$7v0$1@news.nyu.edu> X-Nntp-Posting-User: KILGALLEN X-Trace: 862485541/27708 Organization: LJK Software Newsgroups: comp.lang.ada Date: 1997-05-01T00:00:00+00:00 List-Id: In article , dewar@merv.cs.nyu.edu (Robert Dewar) writes: > Richard Kenner said > > < is that problem that will be remedied on Alpha processors starting > with EV56.>> > > Of course in Ada they do not *need* to be atomic -- if you waste a bit > of space to make sure stand alone objects are not too close together, > and the same in records. > > You don't need to worry about atomic access in any packed structure of > course, and the standard string type is packed (i.e. it is erroneous > for one task to store the 3rd charater of a string while another task > loads the fourth character). Although a compiler can take care to place separate components of an unpacked structure into separate quadwords, a programmer can use representation clauses to bring them back together. If a programmer uses representation clauses that is an implicit declaration that they know what they are doing, so compiler warnings seem inappropriate. But programmers often do not know what they are doing. Alpha programs often have code which does not properly handle atomicity, and until recently even VMS had at least one such piece of code (not written in Ada) of which I am aware. Larry KIlgallen