RFR: C1 xchg_oop needs temp register operand

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/c1-atomic-need-temp/webrev.02/

Current sh/jdk fails after C1 barrier modularization with:

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/home/shade/trunks/shenandoah-jdk/src/hotspot/share/c1/c1_LIR.hpp:413),
pid=71197, tid=71755
#  assert(is_single_cpu() && !is_virtual()) failed: type check
#

Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native
code)
V  [libjvm.so+0x1df5d82]  VMError::report_and_die(int, char const*, char const*, __va_list_tag*,
Thread*, unsigned char*, void*, void*, char const*, int, unsigned long)+0x532
V  [libjvm.so+0x1df69ef]  VMError::report_and_die(Thread*, void*, char const*, int, char const*,
char const*, __va_list_tag*)+0x2f
V  [libjvm.so+0xb26eaa]  report_vm_error(char const*, int, char const*, char const*, ...)+0x12a
V  [libjvm.so+0x7ab45c]  LIR_OprDesc::as_register() const+0x5c
V  [libjvm.so+0x7d5f21]  LIR_Assembler::atomic_op(LIR_Code, LIR_OprDesc*, LIR_OprDesc*,
LIR_OprDesc*, LIR_OprDesc*)+0xf1
V  [libjvm.so+0x7b9cb0]  LIR_Assembler::emit_lir_list(LIR_List*)+0xb0
V  [libjvm.so+0x7bac8b]  LIR_Assembler::emit_code(BlockList*)+0x14b
V  [libjvm.so+0x7562f6]  Compilation::emit_code_body()+0x1d6
V  [libjvm.so+0x758a86]  Compilation::compile_java_method()+0x5c6
V  [libjvm.so+0x759831]  Compilation::compile_method()+0x1f1
V  [libjvm.so+0x75a487]  Compilation::Compilation(AbstractCompiler*, ciEnv*, ciMethod*, int,
BufferBlob*, DirectiveSet*)+0x3e7
V  [libjvm.so+0x75c6da]  Compiler::compile_method(ciEnv*, ciMethod*, int, DirectiveSet*)+0x19a
V  [libjvm.so+0xa936ff]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x49f
V  [libjvm.so+0xa94541]  CompileBroker::compiler_thread_loop()+0x261
V  [libjvm.so+0x1d2f3bf]  JavaThread::thread_main_inner()+0x30f
V  [libjvm.so+0x1d2f6ad]  JavaThread::run()+0x22d
V  [libjvm.so+0x1522fc2]  thread_native_entry(Thread*)+0x112


Testing: tier1_gc_shenandoah, specjbb


Thanks,
-Aleksey