When will JVM use intrinsics

Question

Why certain code patterns when present within JVM internal classes are turned into an intrinsic function, whereas the same patterns when called from my own class are not.

Answer 1

The JVM has a list of methods, usually native ones, which is replaces with inlined machine code. This list appears in intrinsic header file in the OpenJDK though I can't find a link to it on the web.

See from line 581 in the link @Jack provided vmSymbols.hpp