A formal model of a large memory that supports efficient execution

The validation and application of formal processor models benefits fundamentally from both efficient execution and automated reasoning about the models. We present a memory model written in the ACL2 logic, with both reasoning support and a runtime environment, that accomplishes these objectives. Our memory model provides a space-efficient implementation for an address space of 248 bytes, and is used in our development of an ISA model for x86 instructions. We define and prove invariants, and we use them to prove useful lemmas and to formally verify absence of run-time simulator errors. Our memory model also supports efficient execution through constant-time read and write access in an applicative setting.