Symbolic Cache: Fast Memory Access Based on Program Syntax Correlation of Loads and Stores

An increasing cache latency in next-generation processors incurs profound performance impacts in spite of advanced out-of-order execution techniques. One way to circumvent this cache latency problem is to predict load values at the onset of pipeline execution by exploiting either the load value locality or the address correlation of stores and loads. In this paper, we describe a new load value speculation mechanism based on the program syntax correlation of stores and loads. We establish a Symbolic Cache, which is accessed by the content of memory load and store instructions in early pipeline stages to achieve a zero-cycle load. Performance evaluation using SPEC95 and SPEC2000 integer programs with SimpleScalar tools shows that the symbolic cache provides higher accuracy than both the memory renaming and the value prediction scheme, especially when hardware resources are limited.