Article View: comp.lang.misc
Article #5276Re: Displays (Was: Var scoping in Wirth-type languages)
From: Robert Firth
Date: Mon, 14 Mar 1988 14:50
Date: Mon, 14 Mar 1988 14:50
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In article <7629@sol.ARPA> crowl@cs.rochester.edu (Lawrence Crowl) writes: >Displays require one more load-to-register to implement than do static chains. >(Assuming you have enough registers to implement the display. Most new >processors do.) This statement is true ONLY for languages that do not have parametric procedures or procedure variables. Invoking a parametric procedure can require an arbitrary amount of a display to be reset, whereas the cost of maintaining the static chain is still very small. Moreover, the cost in other areas of reserving 5 or 6 registers for a display can be pretty high - you have that many fewer for locals, temporaries, parameters &c. By the way, what is the compiler supposed to do when a user nests procedures more deeply than you've allowed for in the display registers? Crash disgustingly?
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Path: arc1-ca.pugleaf.net!utzoo!mnetor!uunet!husc6!mit-eddie!bbn!rochester!PT.CS.CMU.EDU!sei!sei.cmu.edu!firth From: firth@sei.cmu.edu (Robert Firth) Newsgroups: comp.lang.misc Subject: Re: Displays (Was: Var scoping in Wirth-type languages) Message-ID: <4554@aw.sei.cmu.edu> Date: 14 Mar 88 14:50:22 GMT References: <3821@ihlpf.ATT.COM> <2791@enea.se> <3949@ihlpf.ATT.COM> <7562@sol.ARPA> <4426@june.cs.washington.edu> <7629@sol.ARPA> Sender: netnews@sei.cmu.edu Reply-To: firth@bd.sei.cmu.edu.UUCP (Robert Firth) Organization: Carnegie-Mellon University, SEI, Pgh, Pa Lines: 17