Vmgen | a Generator of Eecient Virtual Machine Interpreters

Machine Interpreters M. Anton Ertl1; ;y, David Gregg2, Andreas Krall1, and Bernd Paysan3 1Institut f ur Computersprachen, Technische Universit at Wien, Argentinierstra e 8, A-1040 Wien, Austria 2Department of Computer Science, Trinity College, Dublin 2, Ireland 3Stockmannstr. 14, D-81477 M unchen, Germany SUMMARY In a virtual machine interpreter, the code for each virtual machine instruction has similarities to code for other instructions. We present an interpreter generator that takes simple virtual machine instruction descriptions as input and generates C code for processing the instructions in several ways: execution, virtual machine code generation, disassembly, tracing, and pro ling. The generator is designed to support e cient interpreters: it supports threaded code, caching the top-of-stack item in a register, combining simple instructions into superinstructions, and other optimizations. We have used the generator to create interpreters for Forth and Java. The resulting interpreters are faster than other interpreters for the same languages and they are typically 2{10 times slower than code produced by native-code compilers. We also present results for the e ects of the individual optimizations supported by the generator.