This has been introduced by JDK-8224624 in JDK 14 b12.

When running with -XX:+VerifyOops:

# Internal Error (/oracle/jdk_jdk/open/src/hotspot/share/asm/codeBuffer.cpp:1070), pid=28193, tid=28194
# assert(_offset >= 0) failed: offset for non comment?
#
# JRE version: (14.0) (fastdebug build )
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 14-internal+0-adhoc.tobias.open, mixed mode, tiered, compressed oops, g1 gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x95a959] CodeBuffer::block_comment(long, char const*)+0xe9
#

Stack: [0x00007fc056192000,0x00007fc056293000], sp=0x00007fc056290e60, free space=1019k
Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x95a959] CodeBuffer::block_comment(long, char const*)+0xe9
V [libjvm.so+0x127fd44] MacroAssembler::verify_oop(RegisterImpl*, char const*) [clone .part.69]+0x1e4
V [libjvm.so+0xde24b2] InterpreterMacroAssembler::profile_obj_type(RegisterImpl*, Address const&)+0xa2
V [libjvm.so+0xde359b] InterpreterMacroAssembler::profile_return_type(RegisterImpl*, RegisterImpl*, RegisterImpl*)+0x2ab
V [libjvm.so+0x17ee246] TemplateInterpreterGenerator::generate_return_entry_for(TosState, int, unsigned long)+0x496
V [libjvm.so+0x17eb87a] TemplateInterpreterGenerator::generate_all()+0x21a
V [libjvm.so+0x17e8c37] TemplateInterpreter::initialize()+0x187
V [libjvm.so+0xdf30ce] interpreter_init()+0xe
V [libjvm.so+0xdc291a] init_globals()+0x8a
V [libjvm.so+0x183e5e1] Threads::create_vm(JavaVMInitArgs*, bool*)+0x2e1
V [libjvm.so+0xf170a9] JNI_CreateJavaVM+0x69
C [libjli.so+0x41e6] JavaMain+0x86
C [libjli.so+0x8239] ThreadJavaMain+0x9