src/cpu/x86/vm/c1_LIRAssembler_x86.cpp

rev 10271 : 8147844: new method j.l.Runtime.onSpinWait() and the corresponding x86 hotspot instrinsic
Summary: adds c1 & c2 x86 intrinsics for j.l.Runtime.onSpinWait() that utilize the PAUSE instruction
Reviewed-by: iveresov, kvn, vlivanov
Contributed-by: Ivan Krylov <ivan@azul.com>, Yuri Gaevsky <ygaevsky@azul.com>

*** 3884,3893 ****
--- 3884,3897 ----
  
  void LIR_Assembler::membar_storeload() {
    __ membar(Assembler::Membar_mask_bits(Assembler::StoreLoad));
  }
  
+ void LIR_Assembler::on_spin_wait() {
+   __ pause ();
+ }
+ 
  void LIR_Assembler::get_thread(LIR_Opr result_reg) {
    assert(result_reg->is_register(), "check");
  #ifdef _LP64
    // __ get_thread(result_reg->as_register_lo());
    __ mov(result_reg->as_register(), r15_thread);