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From: chip@dartvax.UUCP
Newsgroups: net.lang
Subject: Re: static links vs. displays
Message-ID: <302@dartvax.UUCP>
Date: Fri, 21-Oct-83 13:50:14 EDT
Article-I.D.: dartvax.302
Posted: Fri Oct 21 13:50:14 1983
Date-Received: Sat, 22-Oct-83 11:13:00 EDT
References: vax2.770
Lines: 22

To be brief, displays are better if you expect many references
to variables outside the current scope; other ways are better
if such references are rare.

The problem with displays is that they require some amount of
work for every procedure call and return.  Analysis has
shown that most programs use only local variables and global
variables--variables declared in some intermediate nesting
are seldom referenced.

Probably the most efficient scheme to date is Tanenbaum's,
which keeps only a local and global stack frame pointer;
other frames are accessible through a static link.

Modern optimizing compilers rarely use the display mechanism,
since procedure calls are heavily used in current programming
practice, and must be quite fast.
 
See:  "Implications of Structured Programming for Machine
      Architecture", A.S. Tanenbaum, CACM, March 1978.

      chip elliott        ....decvax!dartvax!chip