Using registers to optimize cross-domain call performance

Abstract

This paper describes a new technique to improve the performance of cross-domain calls and returns in a capability-based computer system. Using register optimization information obtained from the compiler, a trusted linker can minimize the number of registers that must be saved, restored, or cleared when changing from one protection domain to another. The size of the performance gain depends on the level of trust between the calling and called protection domains. The paper presents alternate implementations for an extended VAX architecture and for a RISC architecture and reports performance measurements done on a re-microprogrammed VAX-11/730 processor.