Hello,
we know that there are some techniques that make virtual calls not so
expensive in JVM like Inline Cache or Polymorphic Inline Cache.
Let's consider the following situation:
Base is an interface.
public void f(Base[] b) {
for(int i = 0; i < b.length; i++) {
b[i].m();
}
}
I see from my profiler that calling virtual (interface) method m is
relatively expensive.
f is on the hot path and it was compiled to machine code (C2) but I see
that call to m is a real virtual call. It means that it was not optimised
by JVM.
The question is, how to deal with a such situation? Obviously, I cannot
make the method m not virtual here because it requires a serious redesign.
Can I do anything or I have to accept it? I was thinking how to "force" or
"convince" a JVM to
1. use polymorphic inline cache here - the number of different types in b
is quite low - between 4-5 types.
2. to unroll this loop - length of b is also relatively small. After an
unroll it is possible that Inline Cache will be helpful here.
Thanks in advance for any advices.
Regards,
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