Bay Area Roundtable (BART)

Just in Time Code Generation

Dynamic Code Generation and Sun's Java ^TM Hotspot^TM Virtual Machine
Robert Griesemer, Staff Engineer, Virtual Machine Technology, Sun Microsystems,
                      robert.griesemer@eng.sun.com

We present aspects of dynamic code generation relevant to Sun's new Java^TM Hotspot ^TM Virtual Machine. The Java language imposes a set of challenges on a fast implementation, some of which we try to solve with dynamic code generation. We give a brief history of older Java implementations and then discuss some of Java's peculiarities and how they affect the design of our VM. We conclude with a discussion and a wish list for future Java implementations and hardware.

Biography: Since 1997 Robert Griesemer has held the position of staff engineer with Sun Microsystems where he designed and implemented core parts of the runtime architecture of Sun's next-generation HotSpot Java Virtual Machine (including the Java interpreter). Prior to 1997, he was a member of the original Animorphic team (a.k.a. Longview Technologies, Inc.), responsible for the design and implementation of the Strongtalk bytecode set, bytecode compiler, interpreter and runtime system. He implemented major parts of the dynamic compilation system employed by the Strongtalk VM (including code generation for the x86 architecture) and designed and implemented the initial runtime system of Animorphics clean-house Java implementation, including a simple but fast JIT. Prior to this, Robert was a member of the Sather and pSather groups, working on the 2nd generation Sather compiler and class libraries. Robert received his Ph.D. from Federal Institute for Technology (ETH) in Zurich, Switzerland where he designed and implemented a dialect of the programming language Oberon for vector computers, including the implementation of a cross compiler for the Cray X-MP.

Dynamic Program Optimization - Portable Software on the Passing Lane?
Thomas Kistler, Information and Computer Science, University of California, Irvine,
                      kistler@ics.uci.edu

In the past few years, many efforts have been undertaken to find new sophisticated compiler optimizations that fully exploit the computing power of today's advanced microprocessors. Most of these algorithms do very well in statically linked software systems, but perform perceptibly worse for portable and mobile systems in which optimizations cannot be performed at compile-time any longer. In this talk we discuss and motivate a different approach in which optimizations are no longer performed at compile-time, but are delayed until runtime. We present a new system architecture that not only provides on-the-fly code generation from a portable intermediate representation but also contiguous re-optimization of the existing code-base. Critical program parts are re-optimized on a regular basis by a low-priority background process that is guided by up-to- the-minute profiling data which allows adapting optimizations to user session patterns. We conclude with an overview of new promising dynamic optimizations.

Biography: Thomas Kistler is a Ph.D. student in the Department of Information and Computer Science at the University of California, Irvine. He received his M.S. degree in computer science in 1995 from the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland. His research interests include programming languages, compilers, and dynamic program optimizations.

Coordinator: Michael Franz, Information and Computer Science, University of California, Irvine,
                            franz@ics.uci.edu

Directions to the meeting are available.

Next Meeting:
Friday, March 12, 1999
Topic: Security and Privacy, Meeting 1: Privacy in Electronic Commerce
Speakers: Paola Benassi, TRUSTe
                  Mark Ackerman, UC Irvine
Coordinator: Mark Ackerman, UC Irvine, ackerman@ics.uci.edu

Sustaining:

The Boeing Company * IBM * Microsoft Corporation * Northrop Grumman Corporation
Raytheon Company * Sun Microsystems Laboratories * TRW

Supporting:

Beckman Coulter * FileNet Corporation * Printronix, Inc.

Continuus Software Corporation * Hewlett Packard

For further information on BART or IRUS, contact
        Debra Brodbeck at (949) 824-2260; brodbeck@ics.uci.edu