Re: Machine code parsers (entropy of machine code)

derek@knosof.co.uk (Derek M Jones)
26 Nov 1996 20:25:00 -0500

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Related articles
Machine code parsers (entropy of machine code) andrey@ix.netcom.com (Andrey I. Savov) (1996-11-24)
Re: Machine code parsers (entropy of machine code) derek@knosof.co.uk (1996-11-26)
Re: Machine code parsers (entropy of machine code) andrey@ix.netcom.com (Andrey I. Savov) (1996-12-01)
Re: Machine code parsers (entropy of machine code) derek@knosof.co.uk (1996-12-03)
Re: Machine code parsers (entropy of machine code) jacob@jacob.remcomp.fr (1996-12-07)
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From: derek@knosof.co.uk (Derek M Jones)
Newsgroups: comp.compilers,comp.compilers.tools.pccts
Date: 26 Nov 1996 20:25:00 -0500
Organization: Knowledge Software Ltd
References: 96-11-147
Keywords: assembler, performance

Andrey,


> Does anyone know what is the usual entropy of the following:
>
> 1. Assembly code generated by widely used compilers for Pentium and PowerPC
> platforms. Different compiler optimization options that may affect this
> parameter are consideration. For Pentium only 32-bit code is interesting.
> 2. Code parts in the operating system which are likely to be written in
> Assembly (not generated by compiler).
>


I think that perhaps we can talk about the entropy of instruction
sets. But the code egnerated by different compilers?


I once did a little experiment. I measured how well gzip compressed
executable programs for a vareity of machines. There did seem to
be some correlation between compression ratios for the same programs,
compiled for different cpu's.


Do you think optmised code will have a higher or lower entropy?


derek


--
Derek M Jones tel: +44 (0) 1252 520 667
Knowledge Software Ltd email: derek@knosof.co.uk
Applications Standards Conformance Testing http://www.knosof.co.uk
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