OPTIMIZING THE JAVA VIRTUAL MACHINE INSTRUCTION SET BY ...

189
Figure 8.2: 201 compress Performance by Scoring Technique and Maximum Multicode
Length with 67 Despecializations
multicode substitution alone with the number of bytecode dispatch operations performed
for the strategy that offered the best performance when multicode substitution
was performed in the presence of despecialization.
This analysis revealed that fewer dispatches were removed when multicodes were
selected in the presence of despecialization for the 201 compress and 202 jess
benchmarks. Interestingly, while performing despecialization increased the total number
of transfers removed for 209 db and 222 mpegaudio, the reduction in the number
of transfers was not sufficiently larger to overcome the increase in the number of
transfers imposed by performing despecialization. As a result, performing despecialization
also increased the total number of bytecode dispatch operations performed
for these benchmarks. An overall decrease in the total number of transfers performed
was only observed for 213 javac and 228 jack.
8.4 Balancing Despecialization, Multicode Substitution
and Performance
An additional separate set of despecializations was also considered in conjunction with
multicode substitution. Its goal was to offer the best possible performance without