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From: fnf@mcdsun.UUCP (Fred Fish)
Newsgroups: comp.lang.c
Subject: Re: Types
Message-ID: <371@mcdsun.UUCP>
Date: Fri, 4-Sep-87 12:33:38 EDT
Article-I.D.: mcdsun.371
Posted: Fri Sep  4 12:33:38 1987
Date-Received: Sat, 5-Sep-87 19:50:17 EDT
References: <7264@brl-adm.ARPA> <734@sdchema.sdchem.UUCP> <293@osupyr.UUCP> <366@mcdsun.UUCP> <333@swlabs.UUCP>
Reply-To: fnf@mcdsun.UUCP (Fred Fish)
Organization: Motorola Microcomputer Division
Lines: 39

In article <333@swlabs.UUCP> jack@swlabs.UUCP (Jack Bonn) writes:
>1) Are there many of these optimizing linkers out there?

Not to my knowledge.  But I would be VERY interested in any references
anyone might be able to provide on either existing implementations or
proposed implementations.

>2) Is it true that to debug in assembler, the listing must be
>   generated after the link is done?  I think that this would be

Yes, I suppose this is true.  Since the linker has total freedom to
change the code in anyway it sees fit, up to and including moving
instructions around and inserting or deleting instructions of its own
devising.  This also has obvious ramifications for people that write 
self-modifying code and for symbolic debuggers.  Of course there is a
"do-what-I-wrote" mode that just does a "dumb" link, but that doesn't
help you much when your bug is fatal to the optimized version but innocuous
in the "dumb" version.

>4) Won't it be true that two identical links may not even be the same
>   length since the orderings in the libraries may change.  Won't this
>   make real-time analysis difficult, since the number of bytes of
>   instructions may change from link to link.

True again, which brings you to item 5 as you noted below.  BTW I'm not
sure what you mean by "make real-time analysis difficult".  Are you
refering to analysis of real-time systems or analysis in real-time or 
something else?

>5) Has there been any attempt to adjust the ordering of the modules to
>   improve the overall optimization?  It seems that this is an analogous

Yes.  :-)

-Fred
-- 
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= Fred Fish  Motorola Computer Division, 3013 S 52nd St, Tempe, Az 85282  USA
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