Andreas Wöß

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Building high-performance virtual machines is a complex and expensive undertaking; many popular languages still have low-performance implementations. We describe a new approach to virtual machine (VM) construction that amortizes much of the effort in initial construction by allowing new languages to be implemented with modest additional effort. The approach(More)
An abstract syntax tree (AST) interpreter is a simple and natural way to implement a programming language. However, it is also considered the slowest approach because of the high overhead of virtual method dispatch. Language implementers therefore define bytecodes to speed up interpretation, at the cost of introducing inflexible and hard to maintain(More)
Self-optimizing AST interpreters dynamically adapt to the provided input for faster execution. This adaptation includes initial tests of the input, changes to AST nodes, and insertion of guards that ensure assumptions still hold. Such specialization and speculation is essential for the performance of dynamic programming languages such as JavaScript. In(More)
Truffle is a Java-based framework for developing high-performance language runtimes. Language implementers aiming at developing new runtimes have to design all the runtime mechanisms for managing dynamically typed objects from scratch. This not only leads to potential code duplication, but also impacts the actual time needed to develop a fully-fledged(More)
Most high-performance dynamic language virtual machines duplicate language semantics in the interpreter, compiler, and runtime system. This violates the principle to not repeat yourself. In contrast, we define languages solely by writing an interpreter. The interpreter performs specializations, e.g., augments the interpreted program with type information(More)
We present a novel approach for allowing JavaScript applications to access C data structures without performance overhead or additional boiler plate code. Dynamic languages such as JavaScript do not have a fixed memory layout for run-time data nor do they allow low-level memory accesses, which makes interoperability with languages such as C hard. Our(More)
1. The acute action of an intravenous infusion (5 min) of guanfacine in doses of 0.01, 0.02 and 0.04 mg/kg on peripheral circulation was studied in five hypoertensive patients and compared with a placebo in a randomized study. The observations were combined for 2 h after drug administration. 2. Two phases of drug action were seen during and immediately(More)
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