Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!purdue!mentor.cc.purdue.edu!l.cc.purdue.edu!cik
From: cik@l.cc.purdue.edu (Herman Rubin)
Newsgroups: comp.arch
Subject: Re: undoing autoincrement
Summary: Undoing anything
Message-ID: <1184@l.cc.purdue.edu>
Date: 24 Mar 89 11:47:20 GMT
References: <21971@agate.BERKELEY.EDU>
Organization: Purdue University Statistics Department
Lines: 20

In article <21971@agate.BERKELEY.EDU>, matloff@tinman.Berkeley.EDU writes:
< <In article <21931@agate.BERKELEY.EDU> matloff@iris.ucdavis.edu (Norm Matloff) writes:
< <>In article xxx henry@utzoo.uucp (Henry Spencer) writes:
> 
> 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.
> 

Why is this problem restricted to autoincrement?  Any action taken after a
conditional branch instruction not wanted in the actual branch path taken
may have to be undone.


-- 
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907
Phone: (317)494-6054
hrubin@l.cc.purdue.edu (Internet, bitnet, UUCP)