Fast prolog with a VAM1p based prolog compiler

Abstract

The VAM (Vienna Abstract Machine) is a Prolog machine developed at the TU Wien. In contrast to the standard implementation technique (Warren Abstract Machine) an inference in the VAM is performed by unifying the goal and head arguments in a single undivided step. The interpreter based VAM2p implements unification by combining head and goal instructions during run time whereas the compiler based VAM1p combines the instructions during compile time. This enables compilers based on the VAM1p to make extensive optimizations like variable elimination, instruction elimination, extended clause indexing and fast last-call optimizations. This results in fast execution and small stack sizes. Our prototype compiler is implemented in Prolog and emits intermediate VAM1p code. This intermediate code is translated to native code instructions for the MIPS R3000 processor. The native code instructions are reordered using a Prolog based instruction scheduler and assembled using the MIPS assembler. The resulting programs achieve 3.1 MLips on a DecStation 5000/200.