System and method for swapping blocks of tagged stack entries between a

Abstract

A computer system has a CPU, a stack cache and a main memory. The main memory is a conventional untagged memory, where each memory location is a word having a bit size that is an integer power of 2 (e.g., 32, 64 or 128 bits per word). However, at least one stack cache associated with the CPU (and preferably integrated with the CPU on the same semiconductor circuit or in the same chip set) is a tagged memory where each data word of the stack cache has an associated tag. Whenever the stack cache overflows with data, at least a portion of the contents of the stack cache are stored in a previously established location in main memory so as to make room for storing additional data in the stack cache. In this stack cache swap out operation, the data values and tags in N evaluation stack entries of the evaluation stack cache are copied to the previously established main memory location. The N tags in the N copied evaluation stack entries are stored into a first predefined portion of the previously established main memory location, and the N data values in the N copied evaluation stack entries are stored into a second predefined portion of the previously established main memory location. During a cache fill operation, the N tags and data values of a stack block are copied from their respective main memory positions into the tag and data portions of a stack cache block.