See this comment for an example:

https://github.com/openjdk/panama-foreign/pull/610#issuecomment-963026304

The hottest method list includes StubRoutines::updateBytesAdler32 but it has been misattributed: these instructions are actually in optimized_upcall_stub which isn't listed with the -XX:+PrintStubCode output (nor is it prefixed with StubRoutines::). There are actually quite a few stubs like this: if any of them appear in the perfasm output they will be labelled with with the last stub successfully parsed.