An architectural framework for migration from CISC to higher performance platforms

TLDR

The paper proposes an architectural framework that enables CISC applications to migrate to higher‑performance platforms with minimal investment from users or developers. The framework implements a hardware mechanism that seamlessly switches between instruction sets, automatically translates object code using advanced global optimization and scheduling, and handles precise exceptions and self‑modifying code to preserve behavior while boosting performance. Relaxing strict compatibility on issues such as precise exceptions and self‑modifying code can yield additional performance gains, encouraging adoption of the newer architecture.

Abstract

We describe a novel architectural framework that allows software applications written for a given Complex Instruction Set Computer (CISC) to migrate to a different, higher performance architecture, without a significant investment on the part of the application user or developer. The framework provides a hardware mechanism for seamless switching between two instruction sets, resulting in a machine that enhances application performance while keeping the same program behavior (from a user perspective). High execution speed on migrated applications is achieved through automated translation of the object code of one machine to that of the other, using advanced global optimization and scheduling techniques. Issues affecting application behavior, such as precise exceptions, as well as self-modifying code, are addressed. Relaxation of full compatibility on these issues lead to further possible performance gains, encouraging applications to adopt the newer architecture.