It's not always obvious what assembly will be generated after expanding all the macros of the HotSpot meta-assembly system. The following code shows how to print the actual code generated by HotSpot.

// #define DMS_DEBUG
#ifdef DMS_DEBUG
address barrier_start = masm->code()->insts_end();
 __ block_comment("nmethod_barrier begin");
 __ ldr_label(tmp0, guard);
 __ bind(skip);
 __ block_comment("nmethod_barrier end"); 

#ifdef DMS_DEBUG 
address barrier_end = masm->code()->insts_end(); 
tty->print_cr("DMS: barier %p %p bytes: %d", barrier_start, barrier_end, barrier_end - barrier_start); 

//  masm->code()->print();