The following error can be seen when running hs :tier1 tests with ubsan configured (--enable-ubsan) .
Example tests showing it:
compiler/gcbarriers/UnsafeIntrinsicsTest_Shenandoah.jtr
gc/shenandoah/compiler/BarrierInInfiniteLoop.jtr

/jdk/src/hotspot/share/gc/shenandoah/shenandoahSimpleBitMap.inline.hpp:68:23: runtime error: signed integer overflow: -9223372036854775808 - 1 cannot be represented in type 'long int'
    #0 0x7f3392f27b50 in ShenandoahSimpleBitMap::find_last_set_bit(long, long) const /jdk/src/hotspot/share/gc/shenandoah/shenandoahSimpleBitMap.inline.hpp:68
    #1 0x7f3392f27b50 in ShenandoahRegionPartitions::find_index_of_previous_available_region(ShenandoahFreeSetPartitionId, long) const /jdk/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp:388
    #2 0x7f3392f27b50 in ShenandoahRegionPartitions::shrink_interval_if_range_modifies_either_boundary(ShenandoahFreeSetPartitionId, long, long) /jdk/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp:213
    #3 0x7f3392f27b50 in ShenandoahRegionPartitions::shrink_interval_if_boundary_modified(ShenandoahFreeSetPartitionId, long) /jdk/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp:229
    #4 0x7f3392f27b50 in ShenandoahRegionPartitions::move_from_partition_to_partition(long, ShenandoahFreeSetPartitionId, ShenandoahFreeSetPartitionId, unsigned long) /jdk/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp:323
    #5 0x7f3392f3b7a4 in ShenandoahFreeSet::reserve_regions(unsigned long) /jdk/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp:1118
    #6 0x7f3392f3f829 in ShenandoahFreeSet::finish_rebuild(unsigned long) /jdk/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp:1080
    #7 0x7f3392f3f829 in ShenandoahFreeSet::rebuild() /jdk/src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp:1088
    #8 0x7f3392f8d8b7 in ShenandoahHeap::initialize() /jdk/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp:379
    #9 0x7f33935bc78c in universe_init() /jdk/src/hotspot/share/memory/universe.cpp:859
    #10 0x7f3391893691 in init_globals() /jdk/src/hotspot/share/runtime/init.cpp:128
    #11 0x7f339352a740 in Threads::create_vm(JavaVMInitArgs*, bool*) /jdk/src/hotspot/share/runtime/threads.cpp:553
    #12 0x7f3391c2d497 in JNI_CreateJavaVM_inner /jdk/src/hotspot/share/prims/jni.cpp:3581
    #13 0x7f3391c2d497 in JNI_CreateJavaVM /jdk/src/hotspot/share/prims/jni.cpp:3672
    #14 0x7f3398f460e5 in InitializeJVM /jdk/src/java.base/share/native/libjli/java.c:1550
    #15 0x7f3398f460e5 in JavaMain /jdk/src/java.base/share/native/libjli/java.c:491
    #16 0x7f3398f4f748 in ThreadJavaMain /jdk/src/java.base/unix/native/libjli/java_md.c:642
    #17 0x7f3398efe6e9 in start_thread (/lib64/libpthread.so.0+0xa6e9) (BuildId: 2f8d3c2d0f4d7888c2598d2ff6356537f5708a73)
    #18 0x7f339851550e in clone (/lib64/libc.so.6+0x11850e) (BuildId: f732026552f6adff988b338e92d466bc81a01c37)