// call (Thread*)TlsGetValue(thread_index());
void MacroAssembler::get_thread(Register thread) {
   if (thread != rax) {
     push(rax);
   }
   push(rdi);
   push(rsi);
   push(rdx);
   push(rcx);
   push(r8);
   push(r9);
   push(r10);
   // XXX
   mov(r10, rsp);
   andq(rsp, -16);
   push(r10);
   push(r11);

   movl(c_rarg0, ThreadLocalStorage::thread_index());
   call(RuntimeAddress((address)TlsGetValue));

   pop(r11);
   pop(rsp);
   pop(r10);
   pop(r9);
   pop(r8);
   pop(rcx);
   pop(rdx);
   pop(rsi);
   pop(rdi);
   if (thread != rax) {
       mov(thread, rax);
       pop(rax);
   }
}
void MacroAssembler::get_thread(Register thread) {
  // call pthread_getspecific
  // void * pthread_getspecific(pthread_key_t key);
   if (thread != rax) {
     push(rax);
   }
   push(rdi);
   push(rsi);
   push(rdx);
   push(rcx);
   push(r8);
   push(r9);
   push(r10);
   // XXX
   mov(r10, rsp);
   andq(rsp, -16);
   push(r10);
   push(r11);

   movl(rdi, ThreadLocalStorage::thread_index());
   call(RuntimeAddress(CAST_FROM_FN_PTR(address, pthread_getspecific)));

   pop(r11);
   pop(rsp);
   pop(r10);
   pop(r9);
   pop(r8);
   pop(rcx);
   pop(rdx);
   pop(rsi);
   pop(rdi);
   if (thread != rax) {
       mov(thread, rax);
       pop(rax);
   }
}