JDK-8251462 changed semantics of CompilationPolicy::highest_compile_level() and CompilationPolicy::can_be_compiled() to take into the account compiler availability due to command line flags restrictions. For example, if C2 is not available because of the TieredStopAtLevel setting, the answer to these queries will be that the highest level is 3, and that methods can't be compiled at level 4.

MakeMethodNotCompilableTest.java assumes (even in the presence of the mentioned restrictions) that with tiered compilation it is always the case that both compilers can be used.