Institute of Computer Languages
Compilers and Languages Group

Talks 2004 - Christian W. Probst

The Compilers and Languages Group invites you to a talk given by

Dr. Christian W. Probst

(University of California, Irvine) on

Proofing: Efficient SSA-based Java Bytecode Verification

Date:	Wednesday, June 16, 2004
Time:	16:15
Location:	TU Wien, building at the Freihaus, FH HS 4, Wiedner Hauptstraße 8, Turm B, yellow area, 2nd upper floor

Abstract:

Verification is essential for assuring the integrity of a Java Virtual Machine (JVM) when executing untrusted code. Existing verifier implementations perform an iterative data-flow analysis (DFA) to discover the precise type of values stored on the stack or in ad-hoc polymorphic registers.

We propose a novel verification algorithm based on Static Single Assignment form (SSA). For each value we match the type it is defined with against the type of each of the values uses. Interadjacent transitions of a value through stack and registers no longer have to be verified explicitly, as their correctness can be induced once the data flow from definition to all uses is known to be type-safe.

Our verification algorithm is more efficient than the traditional bytecode verifier, as it is also beneficial to later stages in the compilation pipeline. Whereas traditional JVMs treat the verifier as a black box and discard information gained during the DFA, our algorithm constructs an SSA-based representation of the program that can be re-used by optimizing just-in-time compilers often found in modern JVMs.

About Dr. Christian W. Probst:

Christian W. Probst is a postdoctoral researcher in the School of Information and Computer Science at the University of California, Irvine. His current research focuses on security and efficiency aspects of virtual machines and mobile code. Other research interests include scalable and demand-driven program analyses, dynamic and power aware compilation, compilation for resource-constrained devices, and XML and its applications.

Dr. Probst earned his Ph.D. in Computer Science from the Universität des Saarlandes, Saarbrücken, Germany.