An Empirical Evaluation of Static, Dynamic, and Hybrid Slicing of WebAssembly Binaries

The WebAssembly standard aims to form a portable compilation target,
enabling the cross-platform distribution of programs written in a variety of
languages. This paper introduces and evaluates novel slicing approaches for
WebAssembly, including dynamic and hybrid approaches. Given a program
and a location in that program, a program slice is a reduced program that
preserves the behavior at the given location. A static slice does so for all
possible inputs, while a dynamic slice does so for a fixed set of inputs. Hybrid
slicing is a combination of static and dynamic slicing.
We build on Observational-Based Slicing (ORBS), where we explore the
design space for instantiating ORBS for WebAssembly. For example, ORBS
can be applied to the whole program or to only the function containing the
slicing criterion, and it can be applied before compilation to WebAssembly
or afterward. We evaluate the slices produced using various options quanti-
tatively and qualitatively. Our evaluation reveals that dynamic slicing at the
level of a function from a WebAssembly binary finds a sweet spot in terms of
slice time and slice size, and that a combination of static and dynamic slicers
achieves the best trade-off in terms of slicing time and slice size.