JDK-8308869 added a _method field to SubTypeCheckNode which is printed in SubTypeCheckNode::dump_spec. A double whitespace is printed because method->print_short_name already adds a whitespace before the name (JIRA removes it in below line, I replaced the whitespace by _):

3 SubTypeCheck === _ 44 35 [[ 87 ]] profiled at:__compiler.c2.irTests.ProfileAtTypeCheck::test15:5 !jvms: ProfileAtTypeCheck::test15 @ bci:5 (line 399)