A New Abstraction for Summary-Based Pointer Analysis

We propose a new abstraction for pointer analysis based on the principle of matching pointer dereferences or ìmemory fetchesî with pointer assignments. Our abstraction, the Assign-Fetch Graph (AFG), has several advantages over traditional points-to graphs. It leads to concise procedure summaries for pointer analysis and sim- ilar computations; each procedure's summary information can be used effectively in arbitrary calling contexts. Different analysis variations can be formulated on the AFGó we present two possible variations. One is based on a standard o w-insensitive view of the program; the other takes some statement ordering into account and produces results that are both more precise and more quickly com- puted. Our abstraction also facilitates incremental summary-based pointer analysis, which is not generally possible with conventional points-to graphs. We show how the AFG simplies certain steps in updating pointer graphs and computing procedure summaries. For efcienc y and compactness, we build a single summary for each procedure under the optimistic assumption that distinct pointers from the environ- ment are not aliased. We restore soundness when the summary is used in a context with aliases. We present some results of the prac- tical impact of our technique.