SMT-based verification of low-level code requires modeling and reasoning about memory operations. Prior work has shown that optimizing memory representations is beneficial for scaling verification—pointer analysis, for example can be used to split memory into disjoint regions leading to faster SMT solving. However, these techniques are mostly designed for C and C++ programs with explicit operations for memory allocation which are not present in all languages. For instance, on the Ethereum virtual machine, memory is simply a monolithic array of bytes which can be freely accessed by Ethereum bytecode, and there is no allocation primitive. In this paper, we present a memory splitting transformation guided by a conservative memory analysis for Ethereum bytecode generated by the Solidity compiler. The analysis consists of two phases: recovering memory allocation and memory regions, followed by a pointer analysis. The goal of the analysis is to enable memory splitting which in turn speeds up verification. We have implemented both the analysis and the memory splitting transformation as part of a verification tool, CertoraProver, and show that the transformation speeds up SMT solving by up to 120× and additionally mitigates 16 timeouts when used on 229 real-world smart contract verification tasks.

DC-DC converters like boost, buck-boost and flyback converters have unstable internal dynamics and are classified as non-minimum phase systems. The linear approximation of these DC-DC converters around the equilibrium point shows a zero that maps to the open right-half plane (RHP) of the complex s-plane. This paper models the boost converter using State Space Averaging (SSA) and Enhanced State Space Averaging (ESSA) to show changes in bode response as function of sampling time. Further, we use Discrete Modeling Analysis (DMA) to model the changes in transfer function with change in sampling instant when sampled during off-time of the switch. The result shows that significant bandwidth improvement can be achieved when sampling instant is rightly chosen during the off-time. Such a choice is easily achieved with a digital implementation for a DC-DC converter.