Vmgen supports the construction of interpretive systems by generating the code for executing and dealing with virtual machine (VM) instructions from simple descriptions of the VM instructions.
Vmgen generates code for executing VM instructions (with optional tracing), for generating VM code, for disassembling VM code, and for profiling VM instruction sequences. A VM instruction description looks like this:
add ( i1 i2 -- i ) i = i1+i2;
Vmgen supports several techniques for writing efficient interpreters: virtual machine interpreters, threaded code, combining VM instructions into superinstructions, keeping the top-of-stack in a register, scheduling the dispatch of the next VM instruction, and a couple of minor optimizations. Interpreters created with vmgen usually are faster than competing interpreters and are typically only a factor of 2-10 slower than the code generateed by native-code compilers.
Vmgen has special support for stack-based VMs (but it can also be used to advantage when implementing a register-based VM).
Vmgen is currently distributed with Gforth (because it needs Gforth to run, and Gforth needs it to build), and is installed together with Gforth (read INSTALL for instructions).
Note that future versions of vmgen may require small changes in programs written for the present version (e.g., requiring a few additional macro definitions).
|NEWS.vmgen||09-Mar-2003 23:12||1.3K||Changes from earlier versions|
|vmgen-0.6.1.ps.gz||24-Mar-2003 18:08||106K||Manual (for letter and A4 paper)|