JDK-8228369 broke C1's getAndSetObject() intrinsic with Shenandoah:

# Internal Error (/home/shade/trunks/jdk-jdk/src/hotspot/share/c1/c1_LIRGenerator.hpp:224), pid=20194, tid=20205
# assert(!opr->is_register() || opr->is_virtual()) failed: should never set result to a physical register

 V [libjvm.so+0x78417e] LIRGenerator::set_result(Instruction*, LIR_OprDesc*)+0x12e
V [libjvm.so+0x782a67] LIRGenerator::do_UnsafeGetAndSetObject(UnsafeGetAndSetObject*)+0xe7
V [libjvm.so+0x76b043] LIRGenerator::do_root(Instruction*)+0x93