Solaris 10 Sparc, Java 1.6.0_04-b12, Appserver 9.1.
The C2 compiler was looping in PhaseCFG::schedule_late. We were able to
gcore a corefile, which is attached along with all needed libraries:

current thread: t@20
=>[1] libjvm.so:PhaseCFG::insert_anti_dependences(0x2647ecb0, 0xa2a080, 0xa28578, 0xa27b30, 0x16b06ec, 0xffffffff), at 0xfec385d4
  [2] libjvm.so:PhaseCFG::schedule_late(0x2647ecb0, 0xa2bf80, 0x16ae764, 0xa28578, 0x7e, 0x1), at 0xfec3a1c4
  [3] libjvm.so:PhaseCFG::GlobalCodeMotion(0x2647ecb0, 0x2647ed28, 0x2647f5d0, 0x2647f0f0, 0x13b1f50, 0x14f0bb4), at 0xfe98846c
  [4] libjvm.so:Compile::Code_Gen(0x8, 0x2647f5d0, 0xff0ea000, 0x2647ecb0, 0x2647ed28, 0x0), at 0xfe989c1c
  [5] libjvm.so:Compile::Compile(0x2647f5d0, 0x5c649c, 0x1173da0, 0x5be4a8, 0x2647fc0c, 0x5c2478), at 0xfebd2e04
  [6] libjvm.so:andL_reg_regNode::emit(0x1173da0, 0x2647fc0c, 0x1323a40, 0xffffffff, 0xfefe3f68, 0xff0ea000), at 0xfe9a71bc
  [7] libjvm.so:CompileBroker::invoke_compiler_on_method(0x1a192c8, 0xe8800, 0xb4e, 0x0, 0xfe9a7140, 0x14c3000), at 0xfe9a7f50
  [8] libjvm.so:CompileBroker::compiler_thread_loop(0x0, 0xff120fe0, 0x14c3000, 0x13b1ec0, 0x2c800, 0x2c800), at 0xfea24e94
  [9] libjvm.so:JavaThread::allocate_threadObj(0x14c3000, 0x13b24b0, 0x14, 0xf, 0xff0ea000, 0x0), at 0xfef16e6c
  [10] libjvm.so:assign_distribution(0x14c3000, 0x12, 0x5a52, 0xff0ea000, 0xff05cfa5, 0xff121904), at 0xfee6c940