--- a/hotspot/src/cpu/aarch64/vm/macroAssembler_aarch64.cpp	Tue Aug 29 12:17:02 2017 +0200
+++ b/hotspot/src/cpu/aarch64/vm/macroAssembler_aarch64.cpp	Thu Aug 24 16:12:40 2017 +0800
@@ -3630,6 +3630,12 @@
 }
 
 #if INCLUDE_ALL_GCS
+/*
+ * g1_write_barrier_pre -- G1GC pre-write barrier for store of new_val at
+ * store_addr.
+ *
+ * Allocates rscratch1
+ */
 void MacroAssembler::g1_write_barrier_pre(Register obj,
                                           Register pre_val,
                                           Register thread,
@@ -3645,10 +3651,8 @@
   Label done;
   Label runtime;
 
-  assert(pre_val != noreg, "check this code");
-
-  if (obj != noreg)
-    assert_different_registers(obj, pre_val, tmp);
+  assert_different_registers(obj, pre_val, tmp, rscratch1);
+  assert(pre_val != noreg &&  tmp != noreg, "expecting a register");
 
   Address in_progress(thread, in_bytes(JavaThread::satb_mark_queue_offset() +
                                        SATBMarkQueue::byte_offset_of_active()));
@@ -3722,12 +3726,22 @@
   bind(done);
 }
 
+/*
+ * g1_write_barrier_post -- G1GC post-write barrier for store of new_val at
+ * store_addr
+ *
+ * Allocates rscratch1
+ */
 void MacroAssembler::g1_write_barrier_post(Register store_addr,
                                            Register new_val,
                                            Register thread,
                                            Register tmp,
                                            Register tmp2) {
   assert(thread == rthread, "must be");
+  assert_different_registers(store_addr, new_val, thread, tmp, tmp2,
+                             rscratch1);
+  assert(store_addr != noreg && new_val != noreg && tmp != noreg
+         && tmp2 != noreg, "expecting a register");
 
   Address queue_index(thread, in_bytes(JavaThread::dirty_card_queue_offset() +
                                        DirtyCardQueue::byte_offset_of_index()));

--- a/hotspot/src/cpu/aarch64/vm/sharedRuntime_aarch64.cpp	Tue Aug 29 12:17:02 2017 +0200
+++ b/hotspot/src/cpu/aarch64/vm/sharedRuntime_aarch64.cpp	Thu Aug 24 16:12:40 2017 +0800
@@ -2067,7 +2067,7 @@
       __ g1_write_barrier_pre(noreg /* obj */,
                               r0 /* pre_val */,
                               rthread /* thread */,
-                              rscratch1 /* tmp */,
+                              rscratch2 /* tmp */,
                               true /* tosca_live */,
                               true /* expand_call */);
     }

--- a/hotspot/src/cpu/aarch64/vm/templateTable_aarch64.cpp	Tue Aug 29 12:17:02 2017 +0200
+++ b/hotspot/src/cpu/aarch64/vm/templateTable_aarch64.cpp	Thu Aug 24 16:12:40 2017 +0800
@@ -170,7 +170,7 @@
           // G1 barrier needs uncompressed oop for region cross check.
           Register new_val = val;
           if (UseCompressedOops) {
-            new_val = rscratch1;
+            new_val = rscratch2;
             __ mov(new_val, val);
           }
           __ store_heap_oop(Address(r3, 0), val);