--- a/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp	Mon Mar 25 09:07:55 2019 -0700
+++ b/src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp	Mon Mar 25 19:49:32 2019 +0300
@@ -73,16 +73,13 @@
 }
 
 void ShenandoahBarrierSetAssembler::arraycopy_epilogue(MacroAssembler* masm, DecoratorSet decorators, bool is_oop,
-                                                       Register start, Register end, Register scratch, RegSet saved_regs) {
+                                                       Register start, Register count, Register scratch, RegSet saved_regs) {
   if (is_oop) {
     __ push(saved_regs, sp);
-    // must compute element count unless barrier set interface is changed (other platforms supply count)
-    assert_different_registers(start, end, scratch);
-    __ lea(scratch, Address(end, BytesPerHeapOop));
-    __ sub(scratch, scratch, start);               // subtract start to get #bytes
-    __ lsr(scratch, scratch, LogBytesPerHeapOop);  // convert to element count
+    assert_different_registers(start, count, scratch);
+    assert_different_registers(c_rarg0, count);
     __ mov(c_rarg0, start);
-    __ mov(c_rarg1, scratch);
+    __ mov(c_rarg1, count);
     __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_array_post_entry), 2);
     __ pop(saved_regs, sp);
   }