We run into peculiar problem in Leyden: due to current prototype limitation, we cannot yet store the generated code that has the expanded code buffer. The code buffer expansion routinely happens with late G1 barrier expansion, as G1BarrierSetC2 does not report any estimate for stub sizes.

So a method rich in these G1 stubs would blow the initial code size estimate, force the buffer resize, and thus disqualify itself from storing C2 code in Leyden. Whoops. Fortunately, we just need to implement G1BarrierSetC2::estimate_stub_size() in mainline to avoid a significant part of this problem.