While trying to reproduce JDK-8058823 I encountered crashes in the C1 register allocator at several different places.

# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007f0904a25e26, pid=24942, tid=139676230784768
#
# JRE version: Java(TM) SE Runtime Environment (8.0_40-b06) (build 1.8.0_40-ea-fastdebug-b06)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.40-b10-fastdebug compiled mode linux-amd64 compressed oops)
# Problematic frame:
# V [libjvm.so+0x4c9e26] LIR_OpVisitState::visit(LIR_Op*)+0xc76

Stack: [0x00007f08e80e9000,0x00007f08e81ea000], sp=0x00007f08e81e7b30, free space=1018k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x4c9e26] LIR_OpVisitState::visit(LIR_Op*)+0xc76
V [libjvm.so+0x5212c6] LinearScan::verify_no_oops_in_fixed_intervals()+0x1d6
V [libjvm.so+0x52c9bf] LinearScan::verify()+0x5f
V [libjvm.so+0x533a19] LinearScan::do_linear_scan()+0x1c9
V [libjvm.so+0x48bd3d] Compilation::emit_lir()+0x27d
V [libjvm.so+0x48d35c] Compilation::compile_java_method()+0x1bc
V [libjvm.so+0x48d4ce] Compilation::compile_method()+0x5e
V [libjvm.so+0x48da30] Compilation::Compilation(AbstractCompiler*, ciEnv*, ciMethod*, int, BufferBlob*)+0x3a0
V [libjvm.so+0x48f002] Compiler::compile_method(ciEnv*, ciMethod*, int)+0x132
V [libjvm.so+0x6a6596] CompileBroker::invoke_compiler_on_method(CompileTask*)+0x556
V [libjvm.so+0x6a7bf4] CompileBroker::compiler_thread_loop()+0x5a4
V [libjvm.so+0xf622a1] JavaThread::thread_main_inner()+0x221
V [libjvm.so+0xf6259d] JavaThread::run()+0x2ad
V [libjvm.so+0xd6bf58] java_start(Thread*)+0x108
C [libpthread.so.0+0x80a4] start_thread+0xc4


Other instances include:

# SIGSEGV (0xb) at pc=0x00007f807ec42f54, pid=16584, tid=140189100709632
Stack: [0x00007f80517c9000,0x00007f80518ca000], sp=0x00007f80518c72c0, free space=1016k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x512f54] LinearScan::is_sorted(IntervalArray*)+0x34
V [libjvm.so+0x513171] LinearScan::create_unhandled_lists(Interval**, Interval**, bool (*)(Interval const*), bool (*)(Interval const*))+0x31
V [libjvm.so+0x52f944] LinearScan::allocate_registers()+0x94
V [libjvm.so+0x531ea9] LinearScan::do_linear_scan()+0x159
V [libjvm.so+0x48a35d] Compilation::emit_lir()+0x27d

# Internal Error (/HUDSON/workspace/8-2-build-linux-amd64/jdk8u40/1504/hotspot/src/share/vm/c1/c1_LinearScan.cpp:4162), pid=16152, tid=139673415390976
# assert(is_split_parent()) failed: can only be called for split parents
Stack: [0x00007f08403f1000,0x00007f08404f2000], sp=0x00007f08404ef680, free space=1017k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0xfdf312] VMError::report_and_die()+0x2d2
V [libjvm.so+0x720c04] report_vm_error(char const*, int, char const*, char const*)+0x84
V [libjvm.so+0x52a2ff] Interval::split_child_at_op_id(int, LIR_OpVisitState::OprMode)+0x3f
V [libjvm.so+0x52bbb0] RegisterVerifier::process_operations(LIR_List*, IntervalList*)+0xa10
V [libjvm.so+0x52bf06] RegisterVerifier::process_block(BlockBegin*)+0x146
V [libjvm.so+0x52c237] RegisterVerifier::verify(BlockBegin*)+0x1d7
V [libjvm.so+0x52c45a] LinearScan::verify_registers()+0x19a
V [libjvm.so+0x52ca0d] LinearScan::verify()+0xad
V [libjvm.so+0x533a19] LinearScan::do_linear_scan()+0x1c9
V [libjvm.so+0x48bd3d] Compilation::emit_lir()+0x27d
V [libjvm.so+0x48d35c] Compilation::compile_java_method()+0x1bc

# SIGSEGV (0xb) at pc=0x00007f083eb7a538, pid=32696, tid=139673014662912
Stack: [0x00007f08285c7000,0x00007f08286c8000], sp=0x00007f08286c5ba0, free space=1018k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x4b6538] VerifyBlockBeginField::block_do(BlockBegin*)+0x18
V [libjvm.so+0x4bbe46] BlockBegin::iterate_postorder(BlockClosure*)+0xd6
V [libjvm.so+0x4b14c9] IR::verify()+0x39
V [libjvm.so+0x532004] LinearScan::do_linear_scan()+0x2b4
V [libjvm.so+0x48a35d] Compilation::emit_lir()+0x27d
V [libjvm.so+0x48b97c] Compilation::compile_java_method()+0x1bc