Adaptive multi-level compilation in a trace-based Java JIT compiler

http://dl.acm.org/citation.cfm?id=2384630&CFID=173817186&CFTOKEN=20831145
an extended work of IBM's Trace-based JVM published in CGO 2011.

The ``meat'' of this paper is : Trace Recompilation via Trace-Transition Graph.

That is, they select traces to be recompiled via Trace-Transition Graph.

First, the recompiled code fragments are still TRACE! not region.
Their scenario is there may be short fragmented traces due to the limit of maximum length in the initial trace building phase. They set max-trace-length to two.
They would like to merge those fragmented traces into one trace.

The other interesting part is the construction of the Trace-Transition Graph.
The information needed are : 1. transition between traces, and 2. how frequency between transition.
They did not use hardware performance monitoring information.
Instead, they periodically check which transition between traces and record the frequency.
They use Branch-and-link instruction for transitions between traces, rather than using jump.
In this approach, the linker register record who the source trace is.