Hotspot JIT optimizations

Question

In a lecture about JIT in Hotspot I want to give as many examples as possible of the specific optimizations that JIT performs.

I know just about "method inlining", but there should be much more. Give a vote for every example.

Answer 1

Well, you should scan Brian Goetz's articles for examples.

In brief, HotSpot can and will:

1. Inline methods
2. Join adjacent synchronized blocks on the same object
3. Eliminate locks if monitor is not reachable from other threads
4. Eliminate dead code (hence most of micro-benchmarks are senseless)
5. Drop memory write for non-volatile variables
6. Replace interface calls with direct method calls for methods only implemented once

et cetera