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From: bcase@cup.portal.com (Brian bcase Case)
Newsgroups: comp.arch
Subject: Re: Floating point register renaming
Message-ID: <27833@cup.portal.com>
Date: 12 Mar 90 22:12:18 GMT
References: <203042@<1990Mar7> <76700171@p.cs.uiuc.edu>
Organization: The Portal System (TM)
Lines: 13

>> 2) You can change the pipeline, and not recompile all of your code.
>
>Generally, a pipeline change means a new computer, usually bought for
>speed reasons.  Why not exploit all the new speed advantages?  And if
>you refuse to compile, is it so hard to write a Loader to insert NOops
>after instructions whose pipelines have lengthened?

Yes, it is so hard.  Indirect jumps are the problem.  A program
that computes a jump address, say, by using a procedure parameter
or looking in a switch table, will not function unless the
algorithm that computes the address is changed by the loader
too.  For certain cases, this is feasible, but in the most
general case, the problem cannot be solved.