Kevin Kofler wrote:
Andrew Overholt wrote:
* Kevin Kofler <kevin.kofler@xxxxxxxxx> [2009-01-29 15:10]:
Unfortunately, OpenJDK's JIT is actually faster than GCJ's native code
Why is this unfortunate?
Because it means GCJ sucks at generating native code. In principle, native
code should be more efficient because you don't have to go and recompile
that bytecode all the time. That a JIT manages to do better than GCJ's
native code is a sad state of affairs. I wish we had a decent AOT compiler
for Java so we can get rid of the slow bytecode once and for all. As it is
now, Java code is a lot slower than compiled code, and GCJ only makes it
worse instead of better.
I have heard some talk that there is some optimizations which only can
be done in runtime which can make JIT faster than precompiled code so
it's not necessary so easy to make GCJ faster than JIT and I don't think
there is big need for that either. The things where java is slow are
addressed better on using some native code libraries like the OpenGL
library. Telling is that oldskool demo people are using Java quite
extensively nowdays to do their projects. Have you even looked what the
bytecode really is? It's actually kind of assembly code which is adapted
to the current running platform trough interpreter or JIT.
-VPK
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