Number basic blocks deterministically when computing an approximated global schedule. Currently, ServerCompilerScheduler::schedule() assigns different numbers to the basic blocks of the same graph whenever the approximated global schedule is recomputed. This complicates tracing control flow information across IGV sessions and makes debugging IGV itself more difficult.

For an example, see the two attached clustered graphs which correspond to the same graph ("Before matching" in the attached graph file) loaded in two different IGV sessions.