Donate Your Java Class Files

mohnen@I2.Informatik.RWTH-Aachen.DE (Markus Mohnen)
5 Apr 2000 22:18:24 -0400

          From comp.compilers

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Donate Your Java Class Files mohnen@I2.Informatik.RWTH-Aachen.DE (2000-04-05)
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From: mohnen@I2.Informatik.RWTH-Aachen.DE (Markus Mohnen)
Newsgroups: comp.compilers
Date: 5 Apr 2000 22:18:24 -0400
Organization: RWTH Aachen / Informatik II
Keywords: Java

Donate Your Java Class Files


[This is the second call for donations, the first has been in August
1999. If you have responded to this, you might be interested in the
results we have obtained (see below).]

For our research we need Java class files as raw data. To get
realistic results, a wide variety of class files is necessary.
Therefore, we ask you to donate your class files.

We are perfectly happy at every class file you can share: Large or
small, applet or stand-alone, complete applications or single class
files, stable or erroneous. It does not matter which builder,
compiler, optimiser, obfuscator, or compressor you used to produce the

What Kind of Research?

In general, we are concerned with techniques for analysis and
optimisation of programs. At this time, we have two projects where we
need class files as test data:

Comparison of basic block graphs and single instruction graphs
            For more than two decades, basic block graphs have been the data
            structure used by optimising compilers. Recently, the
            conceptually simpler single instruction graphs have been
            proposed by Knoop, Koschützki, and Steffen. We want to
            investigate how these data structures influence the performance
            of several analyses like live variables and constant

Compression and optimisation of class files
            The Java class file format already contains a lot of opportunity
            for compression like the semantically redundant line number
            table and local variable table. Furthermore, peep hole
            optimisations and the results of further analyses can be used to
            reduce the size of the actual code.

However, we would like to use the donated class files in future
projects and maybe even share them with other researchers. If you do
not want us to do so, you can exclude it in the donation form.


Jopt is a Java class file optimiser written by Markus Jansen as his
master thesis. The aim of Jopt is to reduce the size of class
files. It is available for free at

Jopt was tested and evaluated with all donated classes. Based on the
dontated class files, an estimation for the reduction of a typical
class file is 21.24%.

Why Donating?

Well, you will not have a direct gain from donating. However, you will
help us to improve our knowledge on compiler optimisations. In the
long run, this will hopefully help to improve compiler
technology. Since it will only take you a minute, we kindly ask you to
help us by donating as many classes as you like.

Who We Are

We are a group of researchers at the Department of Computer Science of
the RWTH (aka University of Technology Aachen), Germany:

            Dr. Markus Mohnen
            Markus Jansen
            several students

Legal Stuff

If you donate class files, you will have no further obligations. We
will use the donated classes under the following restrictions:

1. We will not use the donated classes or any other information for
      commercial purposes.

2. We will not use the donated classes to construct programs.

3. We will not send emails to you.

4. We will not give the donated classes to other persons or
      organisations unless you allow us to do so.

5. We will not give the donated classes to other persons or
      organisations unless they agree to these restrictions.

Donate Here


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