Is the hotspot JVM Bytecode Interpreter a tracing JIT?

Question

The question pretty much says it all, I've been looking around for an answer even through the VM spec but I it doesn't explicitly state it.

Answer 1

No.

There are some other JVMs with tracing JITs, though: HotPath and Maxine, for example.

Answer 2

Aside: for those who don't know what a tracing JIT is, the following description comes from this page:

Although tracing JITs are a complex technology, the core concept is about optimizing execution of the hot paths in a program. The emphasis is specifically on hot paths that return to the start of a path which sounds very much like a loop. However, the traditional definition of a programming loop is only a subset of these hot paths. The broader definition includes code that spans methods and possibly even modules. This broader definition of a loop is what’s called a trace.

Answer 3

Had to google what a "tracing JIT" was, but apparently it isn't.

> non-tracing JIT implementations (Sun’s Java VM

But it does optimise what you might call "hot spots".

How bytecode is optimised will not be part of the specification for the bytecode.