### News

20-JAN-2020

##### PGX and Graal/Truffle/Active Libraries

A guest lecture in the CS4200 Compiler Construction course at Delft University of Technology (https://tudelft-cs4200-2019.github.io/) about PGX and Graal/Truffle/Active Libraries.

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06-JAN-2020

##### Computationally Easy, Spectrally Good Multipliers for Congruential Pseudorandom Number Generators

Congruential pseudorandom number generators rely on good multipliers, that is, integers that have good performance with respect to the spectral test. We provide lists of multipliers with a good lattice structure up to dimension eight for generators with typical power-of-two moduli, analyzing in detail multipliers close to the square root of the modulus, whose product can be computed quickly.

21-NOV-2019

##### A DSL-based framework for performance assessment

Performance assessment is an essential verification practice in both research and industry for software quality assurance. Experiment setups for performance assessment tend to be complex. A typical experiment needs to be run for a variety of involved hardware, software versions, system settings and input parameters. Typical approaches for performance assessment are based on scripts. They do not document all variants explicitly, which makes it hard to analyze and reproduce experiment results correctly. In general they tend to be monolithic which makes it hard to extend experiment setups systematically and to reuse features such as result storage and analysis consistently across experi- ments. In this paper, we present a generic approach and a DSL-based framework for performance assessment. The DSL helps the user to set and organize the variants in an experiment setup explicitly. The Runtime module in our framework executes experiments after which results are stored together with the corresponding setups in a database. Database queries provide easy access to the results of previous experiments and the correct analysis of experiment results in context of the experiment setup. Furthermore, we describe operations for common problems in performance assessment such as outlier detection. At Oracle, we successfully instantiate the framework and use it to nightly assess the performance of PGX [12, 6], a toolkit for parallel graph analytics.

18-OCT-2019

##### Design Space Exploration of Power Delivery For Advanced Packaging Technologies

***Note: this is work the VLSI Research group did with Prof. Bakir back in 2017. The student is now graduating, and wants to finalize/publish this work.*** In this paper, a design space exploration of power delivery networks is performed for multi-chip 2.5-D and 3-D IC technologies. The focus of the paper is the effective placement of the voltage regulator modules (VRMs) for power supply noise (PSN) suppression. Multiple on-package VRM configurations have been analyzed and compared. Additionally, 3D IC chipon-VRM and backside-of-the-package VRM configurations are studied. From the PSN perspective, the 3D IC chip-on-VRM case suppresses the PSN the most even with high current density hotspots. The paper also studies the impact of different parameters such as VRM-chip distance on the package, on-chip decoupling capacitor density, etc. on the PSN.

08-OCT-2019

##### GraalVM Slides for JAX London

These are intro-level slides to be presented at https://jaxlondon.com

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12-SEP-2019

##### Computers and Hacking: A 50-Year View

[Slides for a 20-minute keynote talk for the MIT HackMIT hackathon weekend, Saturday, September 14, 2019.] Fifty years ago, computers were expensive, institutional rather than personal, and hard to get access to. Today computers are relatively inexpensive, personal well as institutional, and ubiquitous. Some of the best hacking—and engineering—today involves creative use of relatively limited (and therefore cost-effective) computer resources.

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01-SEP-2019

01-SEP-2019

01-JUL-2019

30-JUN-2019

##### Vandal: A scalable security analysis framework for smart contracts

The rise of modern blockchains has facilitated the emergence of smart contracts: autonomous programs that live and run on the blockchain. Smart contracts have seen a rapid climb to prominence, with applications predicted in law, business, commerce, and governance. Smart contracts are commonly written in a high-level language such as Ethereum's Solidity, and translated to compact low-level bytecode for deployment on the blockchain. Once deployed, the bytecode is autonomously executed, usually by a% Turing-complete virtual machine. As with all programs, smart contracts can be highly vulnerable to malicious attacks due to deficient programming methodologies, languages, and toolchains, including buggy compilers. At the same time, smart contracts are also high-value targets, often commanding large amounts of cryptocurrency. Hence, developers and auditors need security frameworks capable of analysing low-level bytecode to detect potential security vulnerabilities.

23-MAY-2019

##### What is a Secure Programming Language? (lecture + tutorial)

Lecture and tutorial using GraalVM and Simple Language.

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16-MAY-2019

##### What is a Secure Programming Language?

Our most sensitive and important software systems are written in programming languages that are inherently insecure, making the security of the systems themselves extremely challenging. It is often said that these systems were written with the best tools available at the time, so over time with newer languages will come more security. But we contend that all of today's mainstream programming languages are insecure, including even the most recent ones that come with claims that they are designed to be secure''. Our real criticism is the lack of a common understanding of what secure'' might mean in the context of programming language design. We propose a simple data-driven definition for a secure programming language: that it provides first-class language support to address the causes for the most common, significant vulnerabilities found in real-world software. To discover what these vulnerabilities actually are, we have analysed the National Vulnerability Database and devised a novel categorisation of the software defects reported in the database. This leads us to propose three broad categories, which account for over 50\% of all reported software vulnerabilities, that \emph{as a minimum} any secure language should address. While most mainstream languages address at least one of these categories, interestingly, we find that none address all three. Looking at today's real-world software systems, we observe a paradigm shift in design and implementation towards service-oriented architectures, such as microservices. Such systems consist of many fine-grained processes, typically implemented in multiple languages, that communicate over the network using simple web-based protocols, often relying on multiple software environments such as databases. In traditional software systems, these features are the most common locations for security vulnerabilities, and so are often kept internal to the system. In microservice systems, these features are no longer internal but external, and now represent the attack surface of the software system as a whole. The need for secure programming languages is probably greater now than it has ever been.

19-APR-2019

##### Non-Volatile Memory and Java: Part 3

A series of short articles about the impact of non-volatile memory (NVM) on the Java platform. In the first two articles I described the main hardware and software characteristics of Intel’s new Optane persistent memory. In this article I will discuss the implications of these characteristics on how we build software.

19-APR-2019

##### Non-volatile memory and Java, part 2: the view from software

In the first article I described the main hardware characteristics of Intel’s new Optane persistent memory. In this article I will discuss several software issues.