Stack caching for interpreters

Abstract

An interpreter can spend a significant part of its execution time on accessing arguments of virtual machine instructions. This paper explores two methods to reduce this overhead for virtual stack machines by caching topof-stack values in (real machine) registers. The dynamic method is based on having, for every possible state of the cache, one specialized version of the whole interpreter; the execution of an instruction usually changes the state of the cache and the next instruction is executed in the version corresponding to the new state. In the static method a state machine that keeps track of the cache state is added to the compiler. Common instructions exist in specialized versions for several states, but it is not necessary to have a version of every instruction for every cache state. Stack manipulation instructions are optimized away.