Reliably reproduces in 11u after JDK-8272574 backport, but maybe it affects mainline too:

$ CONF=linux-x86_64-normal-server-fastdebug make run-test TEST=jdk/javadoc/doclet/ TEST_VM_OPTS="-XX:+UseParallelGC"

# Internal Error (/home/shade/trunks/shipilev-jdk11u-dev/src/hotspot/share/opto/loopPredicate.cpp:675), pid=116243, tid=119644
# assert(false) failed: cyclic dependency prevents range check elimination, idx: offset 6068, offset_ctrl 2894, predicate_proj 2892


Current CompileTask:
C2: 37659 6256 4 jdk.javadoc.internal.doclets.toolkit.util.DocLink::relativizeAgainst (90 bytes)

Stack: [0x00007f1b557e0000,0x00007f1b558e1000], sp=0x00007f1b558d9f40, free space=999k
Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x1b3a43a] VMError::report_and_die(int, char const*, char const*, __va_list_tag*, Thread*, unsigned char*, void*, void*, char const*, int, unsigned long)+0x1ca
V [libjvm.so+0x1b3b5a5] VMError::report_and_die(Thread*, void*, char const*, int, char const*, char const*, __va_list_tag*)+0x35
V [libjvm.so+0xbfb55a] report_vm_error(char const*, int, char const*, char const*, ...)+0x10a
V [libjvm.so+0x13a3ba9] IdealLoopTree::is_range_check_if(IfNode*, PhaseIdealLoop*, Invariance&, ProjNode*) const [clone .part.0]+0x3c9
V [libjvm.so+0x13a697e] PhaseIdealLoop::loop_predication_impl_helper(IdealLoopTree*, ProjNode*, ProjNode*, CountedLoopNode*, ConNode*, Invariance&, Deoptimization::DeoptReason)+0x37e
V [libjvm.so+0x13a845e] PhaseIdealLoop::loop_predication_impl(IdealLoopTree*) [clone .part.0]+0x50e
V [libjvm.so+0x13a92a9] IdealLoopTree::loop_predication(PhaseIdealLoop*)+0x109
V [libjvm.so+0x13a91e9] IdealLoopTree::loop_predication(PhaseIdealLoop*)+0x49
V [libjvm.so+0x13a91e9] IdealLoopTree::loop_predication(PhaseIdealLoop*)+0x49
V [libjvm.so+0x13a91e9] IdealLoopTree::loop_predication(PhaseIdealLoop*)+0x49
V [libjvm.so+0x13a91e9] IdealLoopTree::loop_predication(PhaseIdealLoop*)+0x49
V [libjvm.so+0x13ece96] PhaseIdealLoop::build_and_optimize(LoopOptsMode)+0x1266
V [libjvm.so+0xb0d7f7] Compile::optimize_loops(int&, PhaseIterGVN&, LoopOptsMode) [clone .part.0]+0x307
V [libjvm.so+0xb11dcf] Compile::Optimize()+0xd0f
V [libjvm.so+0xb13ddc] Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool, bool, DirectiveSet*)+0x1aec
V [libjvm.so+0x8ee144] C2Compiler::compile_method(ciEnv*, ciMethod*, int, DirectiveSet*)+0x334
V [libjvm.so+0xb246f0] CompileBroker::invoke_compiler_on_method(CompileTask*)+0x540
V [libjvm.so+0xb25d98] CompileBroker::compiler_thread_loop()+0x678
V [libjvm.so+0x1a6ebc2] JavaThread::thread_main_inner()+0x252
V [libjvm.so+0x1a67dfb] Thread::call_run()+0x7b
V [libjvm.so+0x164eb26] thread_native_entry(Thread*)+0x116



==============================
Test summary
==============================
   TEST TOTAL PASS FAIL ERROR
>> jtreg:test/langtools/jdk/javadoc/doclet 187 177 0 10 <<
==============================
TEST FAILURE