Address-free 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 (SC), which is accessed in early pipeline stages to achieve a zero-cycle load. Instead of using memory addresses, the SC is accessed by the encoding bits of base register ID plus the displacement directly from the instruction code. Performance evaluations using SPEC95 and SPEC2000 integer programs on SimpleScalar simulation tools show that the SC achieves higher prediction accuracy in comparison with other load value speculation methods, especially when hardware resources are limited.