The RuntimeStub's name is lost when dumping C2's runtime stub with -XX:+PrintFrameConverterAssembly.
However, it do exist when dumping with -XX:+PrintStubCode.
It would be more friendly if the stub's name was dumped as well for JVM debuggers with -XX:+PrintFrameConverterAssembly.

It can be fixed by
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diff -r 56089cf6152c src/hotspot/share/opto/output.cpp
--- a/src/hotspot/share/opto/output.cpp Tue Feb 26 05:46:02 2019 -0800
+++ b/src/hotspot/share/opto/output.cpp Thu Feb 28 19:52:40 2019 +0800
@@ -1556,6 +1556,8 @@
       }
       if (method() != NULL) {
         method()->print_metadata();
+ } else if (stub_name() != NULL) {
+ tty->print_cr("Generating RuntimeStub - %s", stub_name());
       }
       dump_asm(node_offsets, node_offset_limit);
       if (xtty != NULL) {
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