Article View: comp.arch
Article #20497Re: undoing autoincrement
From: Allen J. Baum
Date: Fri, 24 Mar 1989 17:40
Date: Fri, 24 Mar 1989 17:40
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> 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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Path: arc1-ca.pugleaf.net!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