Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!oliveb!pyramid!prls!mips!larry
From: larry@mips.COM (Larry Weber)
Newsgroups: comp.arch
Subject: Re: Binaries and Max Speed
Message-ID: <10596@gumby.mips.COM>
Date: 4 Jan 89 00:55:57 GMT
References: <22745@apple> <2700003@prisma> <5847@polya.Stanford.EDU> <19240@shemp.CS.UCLA.EDU> <13114@cup.portal.com>
Reply-To: larry@mips.COM (Larry Weber)
Organization: MIPS Computer Systems, Sunnyvale, CA
Lines: 29

In article <13114@cup.portal.com> bcase@cup.portal.com (Brian bcase Case) writes:
>>>I don't know of any applications where one can't recompile to get the
>>>last 3% if it is really important. -- stuff deleted --
>>
>>In this case, I don't even see a reason for recompilation of source
>>programs. One can always write a "relatively" simple program to get
>>rid of the NOPs. 
>
>I claim this isn't true.  Getting rid of NOPs changes code addresses.
>You'll have to find all places where code addresses are referenced,
>including tables for case statements and other places where code
>addresses are computed at run time (procedure parameters?), and change
>them too.  This is a hard problem.

Hard problem? Not really, just you must be careful to modify all the
addresses correctly.  Also, if your coding style (or the compilers) is
to intermix code and data in a hap-hazzard way or if you like to 
write into the code area (:-{) these add significant difficulty.

The Mips program pixie is used to add insturmentation to a program
for performance analysis.  It must change the addresses to account
for the added code.  Deleting code is much the same.

Larry
-- 
-Larry Weber  DISCLAIMER: I speak only for myself, and I sometimes deny that.
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