This is the README file for Petit.  For instructions on how to build
Petit, see the file "CompilationInstructions".

Petit is a research tool for dependence analysis and program
transformations developed from Michael Wolfe's Tiny Tool.  Petit was
developed at the University of Maryland by the Omega Project.
Petit operates on programs in a simple Fortran-like language.

Petit relies on the the Omega Library for performing its analyses.
The library is a system for building, manipulating, and querying sets
of integer tuples and relations between integer tuples.  The current
release is a minor release that contains a directory reorganization
and some changes to support the current release of Petit.

Features of Petit include:
 * Memory- and Value-based dependence analysis, based on the Omega test
 * Nonlinear dependence analysis using uninterpreted function symbols
 * Capabilities that improve the accuracy of data dependence
   analysis (induction variable recognition, forward
   substitution).
 * An interface for building new analyses that simplifies building
   sets of constraints describing programs
 * An interface to allow easier integration of our dependence analysis
   techniques into other compilers
 * A program transformation system for finding computation decompositions
   (not available in this release)
 * An X Window System / Motif interface for examining programs and dependence
   relations

Petit is available for FTP at ftp://ftp.cs.umd.edu/pub/omega/petit.
Petit uses the Omega Library to perform its analyses; the library is
available at ftp://ftp.cs.umd.edu/pub/omega/omega_library.

More information on the Omega Project as well as papers written by the
group are available on the WWW at http://www.cs.umd.edu/projects/omega,
or by sending mail to omega@cs.umd.edu.

This implementation is a research prototype and has not been subjected
to rigorous testing. In other words:

    THERE ARE BUGS IN THIS SOFTWARE

We don't know of any at the moment (other that the ones listed
under KNOWN BUGS/LIMITATIONS below), but we are sure that other,
undiscovered bugs remain in the software.

If you register with us as someone who has a copy of the Petit,
we will send you update notices.  Send email to omega@cs.umd.edu to 
be added to the list of registered users. 

We welcome any research groups to incorporate our software into their
compilers. Please stay in contact with us if you plan to make serious
us of Petit or the Omega Library so that we can provide you with
updates and get feedback from your use.

We are grateful to Michael Wolfe for placing tiny in the public
domain, which allowed us to build on top of his software.

The implementation of the Omega test and extensions to petit have
been done by a number of people at the University of Maryland:
  Udayan Borkar
  Wayne Kelly
  Evan Rosser
  Vadim Maslov
  William Pugh
  Tatiana Shpeisman
  Jerry Sobieski
  Dave Wonnacott

Our work on this software has been supported by NSF grants CCR-8908900 and 
CCR-9157384 and by a Packard Fellowship, as well as being based on
Michael Wolfe's original implementation of tiny.

        FILES
        -----

The following tar files can be ftp-ed from ftp.cs.umd.edu (128.8.128.8) 
from the directory pub/omega:


 * README             This file
 * WOLFE_README       The readme file that originally accompanied Michael 
                      Wolfe's distribution of tiny
 * src.tar.Z        Source for the omega test, our enhanced version of petit,
                      and f2p, a FORTRAN to petit converter
 * sparc_demo.tar.Z   Sun Sparc executable versions of the programs that can be
          made from the src files, demo files, and documentation of
          on how to use petit.
 * decstation_demo.tar.Z 
                      Decstation executable versions of the programs 
                      that can be made from the src files.  demo files,
                      and documentation of how to use petit.
 * demo.tar.Z        Test files for demos
 * test.tar.Z        Regression test files 
 * doc.tar.Z        Some documentation

Together, these tar files constitute the entire petit system, with the
following directories:

 * include header files (from src.tar.Z)
 * src     source code (from src.tar.Z)
 * obj     makefile (from src.tar.Z), generated files (from sparc_demo.tar)
 * doc     documentation for petit
 * demo     sample files documented to show features of the Omega test and
     petit
 * f2p     A FORTRAN to petit converter based on f2c (from src.tar.Z)
 * rt     regression test sample files and expected results (from test.tar.Z)
 * misc     shell scripts used for regression testing (rt.tar and src.tar)

The executable programs are:

 * "petit"   the petit environment, upgraded to use the omega test and
       test for refinement, killing, and covering of dependences

 * "f2p"     A FORTRAN to petit converter based on f2c