Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!oliveb!apple!baum
From: baum@Apple.COM (Allen J. Baum)
Newsgroups: comp.arch
Subject: Re: undoing autoincrement
Message-ID: <27799@apple.Apple.COM>
Date: 24 Mar 89 17:40:43 GMT
References: <21971@agate.BERKELEY.EDU>
Reply-To: baum@apple.UUCP (Allen Baum)
Organization: Apple Computer, Inc.
Lines: 19

[]
> matloff@iris.ucdavis.edu (Norm Matloff) writes:
>baum@apple.com had asked:
>
>%Why would an autoincrement be undone on a branch?
>
>Suppose there is an instruction containing autoincrement immediately following
>a conditional branch instruction.  If the pipe is such that the autoinc is
>done during or before the branch decision, the autoinc will have to be undone.
>
>Again, all this depends on whether the pipe is designed that way.
>

Well, suppose that I have an ADD instruction following a conditional branch,
and the ADD is evaluated before the branch decision. Do I have to undo the
ADD? Whats the difference? Am I missing something here?

		  baum@apple.com		(408)974-3385
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