Characterization of silent stores

The recent discovery that many store instructions are silent creates new opportunities for computer architects. A silent store does not change the state of the system because it writes a value that already exists at the write address, and can safely be eliminated from the dynamic instruction stream. We analyze silent stores in several benchmarks in the context of their high-level source code and explain why they occur. We also introduce the concept of critical silent stores and show that their removal is sufficient for eliminating avoidable writebacks. Finally, we show that frequently occurring stores are highly likely to be silent and that selectively squashing them can drastically reduce the total number of silent stores. This paper explores and illuminates several aspects of store value locality