Reflective case for Class::isInstance(Object) is backed by Runtime1::is_instance_of() which uses oopDesc::is_a() to do the job.

Consider improving the implementation based on backend functionality introduced by JDK-8331341.


hotspot/src/share/vm/c1/c1_LIRGenerator.cpp:
// Example: clazz.isInstance(object)
void LIRGenerator::do_isInstance(Intrinsic* x) {
...
  // TODO could try to substitute this node with an equivalent InstanceOf
  // if clazz is known to be a constant Class. This will pick up newly found
  // constants after HIR construction. I'll leave this to a future change.

  // as a first cut, make a simple leaf call to runtime to stay platform independent.
  // could follow the aastore example in a future change.