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10.1.3 Evaluating the Impact of Despecialization in Resource
Constrained Environments
The study presented in Chapter 5 examined the impact despecialization had on 20
benchmarks running on 8 computing platforms. However, these platforms are all
desktop computing environments. They fail to include either top end server class
equipment or more resource constrained portable computing environments such as
hand-held computers, PDAs and cellular phones. While it is anticipated that server
equipment will show despecialization characteristics similar to desktop computing
environments, it is unclear whether the same results will be achieved on resource constrained
platforms where code density is of greater concern and just-in-time compilers
may not be available.
In addition to expanding the number of platforms tested, the benchmarks tested
should also be expanded. Whenever possible, the new benchmarks introduced should
reflect the reality of the applications typically executed on the platform. In particular,
the benchmarks selected for a resource constrained environment should be of a size
and level of computational complexity similar to the applications typically executed
on those platforms. Many of the current applications are too scientific in nature to
reflect the typical application for resource constrained environments.
10.2 Multicodes
Chapter 7 presented an initial study on multicodes. This study showed that the
runtime for some benchmarks was reduced by as much as 30 percent. The following
subsections examine areas of future research, some of which may allow further
performance gains to be achieved.
10.2.1 Loosening the Definition of a Multicode Block
Section 7.1 included the definition for a multicode block. It included a condition
that, other than as the result of an exception, the first bytecode within a multicode
block will execute if and only if all of the bytecodes within the block will execute.
In practice, it should be possible to loosen the definition of a multicode block to
remove this restriction. Instead, a multicode block could be defined as a sequence of
bytecodes that meets the following constraints: