Path: utzoo!utgpu!water!watmath!clyde!att!pacbell!ames!ll-xn!mit-eddie!bloom-beacon!gatech!purdue!i.cc.purdue.edu!k.cc.purdue.edu!l.cc.purdue.edu!cik
From: cik@l.cc.purdue.edu (Herman Rubin)
Newsgroups: comp.arch
Subject: Re: Self Modifying Code
Summary: What it you want a real trace?
Keywords: writing return address to routine front
Message-ID: <841@l.cc.purdue.edu>
Date: 21 Jul 88 11:36:55 GMT
References: <5254@june.cs.washington.edu> <76700032@p.cs.uiuc.edu> <361@scolex> <2317@pt.cs.cmu.edu>
Organization: Purdue University Statistics Department
Lines: 17


Occasionally I have needed to trace a program for debugging purposes.  I do not
mean the trace facilities usually included with HLLs; I mean that exactly what
happens on any given hardware instruction is printed out.  (Beware; know exactly
what you are doing and how much output you will get, as thousands of pages can
result.)  The only way to do this is to copy each instruction, possibly
modified to handle certain types of address modification and jump instructions,
to some place in memory and then execute it and print out what happens.
This should be done very carefully; in most cases there are much cheaper 
ways to achieve the same results.

I have located errors in programs which would have been difficult to find
otherwise.  
-- 
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907
Phone: (317)494-6054
hrubin@l.cc.purdue.edu (Internet, bitnet, UUCP)