jit

[Xu, Ningfeng]

Hi,

I am thinking about the general approach about JIT.
When one method is invoked at its first time, the JIT
will try to compile it into native code. Later on when
this method is called again, the control flow should
go to the native code. My question is that, after the
method is loaded up, before the compilation into the
native code, some bytecode instructions
have references to local variable array, runtime
constant pool. Such references are symbolic. But are
these symbolic references meaningful? I
mean, do they point to the runtime variables which
have the same value as ones when interpreter is
activated instead of Jit compiler?

If so, when a method is invoked in its first time, we
can access some runtime variables in Kaffe code, such
as parameters of this method, which are refered to by
elements in local variable array, and some instance
fields, which are refered by the runtime constant
pool. This can facilitate the compilation
optimization.

Is this true? Thanks.

Ningfeng Xu 


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