Exploiting Hardware Resources: Register Assignment across Method Boundaries

Ian Rogers, Alasdair Rawsthorne

Abstract

Current microprocessor families present dramatically different numbers of programmer-visible register resources. For example, the Intel IA32 Instruction Set provides 8 general-purpose visible registers, most of which have special-purpose restrictions, while the IA64 architecture provides 128 registers. It is a challenge for existing code generators, particularly operating within the constraints of a just-in-time dynamic compiler, to use these varying resources across a number of architectures with uniform algorithms. This paper describes an implementation of Java using Dynamite, an existing Dynamic Binary Translation tool. Since one design goal of Dynamite is to keep semantic knowledge of its subject machine localized to a front-end module, the Dynamite code generator ignores method boundaries when allocating registers, allowing it to fully exploit all hardware register resources across the hot spots of a Java program, regardless of the control graphs represented.

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