Re: Optimizing in assembly language

bonzini@gnu.org (Paolo Bonzini)
22 Mar 2001 01:17:45 -0500

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[6 earlier articles]
Re: Optimizing in assembly language ceco@jupiter.com (Tzvetan Mikov) (2001-03-08)
Re: Optimizing in assembly language adrian@sartre.cs.rhbnc.ac.uk (A Johnstone) (2001-03-08)
Re: Optimizing in assembly language rhyde@transdimension.com (Randall Hyde) (2001-03-10)
Re: Optimizing in assembly language me@nospam.net (Scottie) (2001-03-10)
Re: Optimizing in assembly language thp@hill.cs.ucr.edu (Tom Payne) (2001-03-12)
Re: Optimizing in assembly language rhyde@transdimension.com (Randall Hyde) (2001-03-14)
Re: Optimizing in assembly language bonzini@gnu.org (2001-03-22)
Re: Optimizing in assembly language thp@hill.cs.ucr.edu (Tom Payne) (2001-03-22)
Re: Optimizing in assembly language Eric.Boon@ICT.nl (Eric Boon) (2001-03-22)
Re: Optimizing in assembly language uabbwat@uab.ericsson.se (Barry Watson) (2001-03-26)
Re: Optimizing in assembly language Martin.Ward@durham.ac.uk (2001-03-26)
Re: Optimizing in assembly language joachim_d@gmx.de (Joachim Durchholz) (2001-03-26)
Re: Optimizing in assembly language sunni@speakeasy.net (Shankar Unni) (2001-03-26)
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From: bonzini@gnu.org (Paolo Bonzini)
Newsgroups: comp.compilers
Date: 22 Mar 2001 01:17:45 -0500
Organization: Mailgate.ORG Server - http://www.Mailgate.ORG
References: 01-03-033
Keywords: assembler, optimize
Posted-Date: 22 Mar 2001 01:17:45 EST

> Transmeta must have solved the problem of 'morphing data tables by
> mistake':-) but I have not seen reports of how they cope with the most


> paranoid self modifying code often found in dongles ?


Both solutions are simple:
1) the code looks at x86 data, not at translated data, nobody knows
about translated data in fact. And the morpher never morphs
unreachable paths (being unreachable is a transitive relationship).


2) paranoid self modifying code will be slow; Transmeta says the
morpher will spend less time working on paranoid code, possibly
by interpreting it instead of compiling it. The problem is, that JITs
often create code that the morpher will think of as self modifying
(for example JITs that cache native code as there is need to run
it, instead of compiling everything at startup)


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