Path: utzoo!utgpu!water!watmath!clyde!rutgers!mit-eddie!ll-xn!ames!ucbcad!ucbvax!hplabs!pyramid!voder!apple!baum
From: baum@apple.UUCP (Allen J. Baum)
Newsgroups: comp.arch
Subject: Re: taken -vs- untaken branches, Fortran FREQUENCY declaration
Message-ID: <7150@apple.UUCP>
Date: 8 Jan 88 19:08:53 GMT
References: <496@cresswell.quintus.UUCP> <638@l.cc.purdue.edu> <836@ima.ISC.COM> <645@l.cc.purdue.edu>
Reply-To: baum@apple.UUCP (Allen Baum)
Organization: Apple Computer, Inc.
Lines: 13

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Someone asked:
>As I recall, the original FORTRAN (for the IBM 704) had a FREQUENCY
>statement which allowed the programmer to give hints about the
>probability of branches being taken.  It was used by the compiler for
>index register optimization.  Why did it disappear in later versions?

I was once told that the reason it was discontinued was that the programmers
intuition about which was the frequent case was frequently (arg) wrong, and
that the statements hurt as much as they helped.

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